The 2.5 billion-year-old Mt. McRae Shale from Western Australia was analyzed for thallium and molybdenum isotope compositions, revealing a pattern that indicates manganese oxide minerals were being buried over large regions of the ancient sea floor. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago. Credit: Chad Ostrander, ASU
Oxygen in the form of the oxygen molecule (O2), produced by plants and vital for animals, is thankfully abundant in Earth’s atmosphere and oceans. Researchers studying the history of O2 on Earth, however, know that it was relatively scarce for much of our planet’s 4.6 billion-year existence.
So when and where did O2 begin to build up on Earth?
By studying ancient rocks, researchers have determined that sometime between 2.5 and 2.3 billion years ago, Earth underwent what scientists call the “Great Oxidation Event” or “GOE” for short. O2 first accumulated in Earth’s atmosphere at this time and has been present ever since.
Through numerous studies in this field of research, however, evidence has emerged that there were minor amounts of O2 in small areas of Earth’s ancient shallow oceans before the GOE. And in a study published recently in the journal Nature Geoscience, a research team led by scientists at Arizona State University (ASU) has provided compelling evidence for significant ocean oxygenation before the GOE, on a larger scale and to greater depths than previously recognized.
For this study, the team targeted a set of 2.5 billion-year-old marine sedimentary rocks from Western Australia known as the Mt. McRae Shale. “These rocks were perfect for our study because they were shown previously to have been deposited during an anomalous oxygenation episode before the Great Oxidation Event,” says lead author Chadlin Ostrander of ASU’s School of Earth and Space Exploration.
Shales are sedimentary rocks that were, at some time in Earth’s past, deposited on the sea floor of ancient oceans. In some cases, these shales contain the chemical fingerprints of the ancient oceans they were deposited in.
For this research, Ostrander dissolved shale samples and separated elements of interest in a clean lab, then measured isotopic compositions on a mass spectrometer. This process was completed with the help of co-authors Sune Nielsen at Woods Hole Oceanographic Institution (Massachusetts); Jeremy Owens at Florida State University; Brian Kendall at the University of Waterloo (Ontario, Canada); scientists Gwyneth Gordon and Stephen Romaniello of ASU’s School of Earth and Space Exploration; and Ariel Anbar of ASU’s School of Earth and Space Exploration and School of Molecular Sciences. Data collection took over a year and utilized facilities at Woods Hole Oceanographic Institution, Florida State University, and ASU.
Using mass spectrometers, the team measured the thallium and molybdenum isotope compositions of the Mt. McRae Shale. This was the first time both isotope systems had been measured in the same set of shale samples. As hypothesized, a predictable thallium and molybdenum isotope pattern emerged, indicating that manganese oxide minerals were being buried in the sea floor over large regions of the ancient ocean. For this burial to occur, O2 needed to have been present all the way down to the sea floor 2.5 billion-years-ago.
These findings improve scientists’ understanding of Earth’s ocean oxygenation history. Accumulation of O2 was probably not restricted to small portions of the surface ocean prior to the GOE. More likely, O2 accumulation extended over large regions of the ocean and extended far into the ocean’s depths. In some of these areas, O2 accumulation seems to have even extended all the way down to the sea floor.
“Our discovery forces us to re-think the initial oxygenation of Earth,” states Ostrander. “Many lines of evidence suggest that O2 started to accumulate in Earth’s atmosphere after about 2.5 billion years ago during the GOE. However, it is now apparent that Earth’s initial oxygenation is a story rooted in the ocean. O2 probably accumulated in Earth’s oceans — to significant levels, according to our data — well before doing so in the atmosphere.”
“Now that we know when and where O2 began to build up, the next question is why” says ASU President’s Professor and co-author Anbar. “We think that bacteria that produce O2 were thriving in the oceans long before O2 began to build up in the atmosphere. What changed to cause that build-up? That’s what we’re working on next.”
Reference:
Chadlin M. Ostrander, Sune G. Nielsen, Jeremy D. Owens, Brian Kendall, Gwyneth W. Gordon, Stephen J. Romaniello, Ariel D. Anbar. Fully oxygenated water columns over continental shelves before the Great Oxidation Event. Nature Geoscience, 2019; DOI: 10.1038/s41561-019-0309-7
More than 10 miles into the backcountry of Yellowstone National Park, on the edge of the caldera, lives a high-elevation community so diverse that Montana State University scientists call it “incredible, unique and truly weird.”
The community of microorganisms lives in a sapphire blue hot spring 8,600 feet above sea level on the Continental Divide. It’s a pool where volcanic gases rise to mix with snowmelt and rainwater, a phenomenon that allows for exceptionally high levels of diversity, said Dan Colman, assistant research professor in the Department of Microbiology and Immunology in the College of Agriculture and the College of Letters and Science.
Colman found more microbial biodiversity in a thumbnail-sized sample than is present if one were to combine all of the animal and plant biodiversity in Yellowstone. Some were Bacteria and others were Archaea, two of the three domains of life, and fewer than half of them had been detected before in hydrothermal systems. Some may even be modern relatives of ancient microbes, potentially offering lessons about life on early Earth and the potential for life on other planets.
“We think that this work has some pretty broad implications that stretch across several disciplines,” said Colman, lead author of a scientific paper that explained MSU’s findings in the hot spring known as Smoke Jumper 3 or SJ3.
The paper was published Feb. 8 in the online journal Nature Communications. Coauthors were associate professor Eric Boyd and doctoral student Melody Lindsay, both in the Department of Microbiology and Immunology.
Boyd said the paper is unique in that it doesn’t just describe the diversity found in a hot spring; it also explains the conditions that allowed for that diversity to develop and be maintained.
“A lot of people are interested in discovering diversity. That’s the end goal. That’s admirable,” Boyd said. “What Dan wanted to know is why. Why do we have so much diversity, and why are some springs more diverse than others?”
Colman attributes that diversity to the unique geochemistry of the Smoke Jumper Geyser Basin, especially SJ3. He said SJ3 is about the perfect place to begin to understand how geological processes lead to elevated volcanic gases in hydrothermal systems and how that, in turn, supports microbial life that is dependent on chemical sources of energy instead of light energy.
“We show that it is due to its geographic location and, not to mention, that it sits atop one of the world’s largest active volcanoes,” he said. “SJ3 is located at high elevation on the Continental Divide, features that prevent deep hydrothermal water aquifers from reaching this area.”
Colman said SJ3 and other similar springs are fed by high volumes of volcanic gases that are generated by boiling of hydrothermal waters as they rise toward the surface. These gases can mix with near-surface waters, such as recent rainfall or melted snow.
He noted that the volcanic gas that ends up in SJ3 is very different from the gases that are present in our atmosphere in that it lacks oxygen. Rather, the volcanic gas is enriched in hydrogen, methane and carbon monoxide, while the water it infiltrates is very oxidized, or rich in oxygen. The mixing of such different types of fluids probably enhances the conditions that can support microbial life, leading to higher diversity and providing new opportunities to take advantage of their “gassy” environment.
Comparing SJ3 to a buffet, Colman said, “Just like a greater variety of food attracts more and different types of people, so does a hot spring that offers a variety of chemical conditions.”
So why did the MSU researchers focus on this particular hot spring when Yellowstone has 14,000 hot springs they could have investigated?
Long interested in the role of hydrogen in supporting microbes that get their energy from chemicals instead of light, Boyd said Smoke Jumper hot springs and the park’s other hot springs were surveyed in the 1920s and early 1930s by scientists from the Carnegie Institute of Washington. They published their findings in 1935, and later work by the U.S. Geological Survey pointed to especially high volumes of volcanic gas in the Smoke Jumper Geyser Basin. Knowing this, Boyd and four others spent a day in Yellowstone in July 2014, collecting samples from SJ3 and three nearby hot springs.
“Just looking at a hot spring doesn’t necessarily tell you how biodiverse it is,” Boyd said. “But as soon as we measured the pH of the spring and made other measurements, we knew we were sampling a unique spring.”
Colman said it took roughly another three years to run the genetic sequencing tests and analyze the results that revealed the diversity of the microbial community. Most hot springs contain a couple of types of microbial organisms. This one held representatives from almost half of all the known groups of microorganisms living on Earth, including dozens and dozens of uncultivated archaeal and bacterial lineages.
“Moreover, many of the lineages that we detected in SJ3 have recently garnered significant attention because of their potential to inform on the evolution of methanogenesis (the biological creation of methane), in addition to previously unknown types of methanogens, and deep branching microbial lineages associated with subsurface environments and many other enigmatic lineages,” Colman said. “It is likely that additional studies of such systems and the intriguing organisms within them will yield additional important insights into microbial ecology and will shed new light on their role in the evolution of biogeochemical processes.”
Reference:
Daniel R. Colman, Melody R. Lindsay, Eric S. Boyd. Mixing of meteoric and geothermal fluids supports hyperdiverse chemosynthetic hydrothermal communities. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-08499-1
Eocene shark teeth from northwestern Madagascar. Credit: Samonds et al, 2019
Eocene-aged sediments of Madagascar contain a previously unknown fauna of sharks and rays, according to a study released February 27, 2019 in the open-access journal PLOS ONE by Karen Samonds of Northern Illinois University and colleagues. This newly-described fauna is the first report of sharks and rays of this age in Madagascar.
The Mahajanga basin of northwestern Madagascar yields abundant fossil remains of terrestrial and marine ecosystems, but little is known about fossil sharks and rays during the Eocene Epoch, 55-34 million years ago, in this region. This is in contrast to the numerous shark and ray faunas known from other Eocene sites around the globe, and to shark and ray ecosystems known from older and younger sediments in the Mahajanga basin.
In this study, Samonds and colleagues collected isolated teeth, dental plates, and stingray spines from ancient coastal sediments of the Ampazony and Katsepy regions of the basin, dated to the middle to late Eocene. They identified at least 10 species of sharks and rays, including one new species, Carcharhinus underwoodi. This is the oldest named species of Carcharhinus, a genus that has been globally distributed for the past 35 million years but is known only rarely from the Eocene.
Aside from the new species, the fauna of Eocene Madagascar shares many species with Eocene ecosystems across North Africa, suggesting these animals were widespread in southern seas at that time. On the other hand, the Madagascar fauna is uniquely lacking in sandsharks and dominated by eagle rays, indicating a somewhat unusual ecosystem, unsurprising given Madagascar’s long history of isolation. The authors caution that this study provides an incomplete picture given that they collected only fossils larger than 2 millimeters. They recommend that future studies target smaller material for a more complete view of the ancient ecosystem.
Reference:
Karen E. Samonds, Tsiory H. Andrianavalona, Lane A. Wallett, Iyad S. Zalmout, David J. Ward. A middle – late Eocene neoselachian assemblage from nearshore marine deposits, Mahajanga Basin, northwestern Madagascar. PLOS ONE, 2019; 14 (2): e0211789 DOI: 10.1371/journal.pone.0211789
Note: The above post is reprinted from materials provided by PLOS.
Virginia Tech Assistant Professor Michelle Stocker holds a rock with an enbedded Chinle frog hipbone fossil. The size of an eyelash — look for the small brownish line with a dot at the bottom — the fossil was found in Arizona. Credit: Image courtesy of Virginia Tech
A team of paleontologists led by Virginia Tech’s Michelle Stocker and Sterling Nesbitt of the Department of Geosciences have identified fossil fragments of what are thought to be the oldest known frogs in North America.
The fossils are comprised of several small pieces of hip bone, called an ilium, from Chinle frogs, a distant long-extinct branch of, but not a direct ancestor of, modern frogs. The fragments are packed into rock and are smaller than a pinky nail. They represent the first known and earliest equatorial remains of a salientian — the group containing living frogs, and their most-closely related fossil relatives — from the Late Triassic, roughly 216 million years ago.
The name of the fossil derives from where they were found, the Chinle Formation of Arizona.
Stocker, an assistant professor of geosciences in the Virginia Tech College of Science, says the fossils, discovered in May 2018, underscore the importance of microfossil collection and analysis for understanding extinct species whose total length is under three feet in length.
“This new find highlights just how much there is still to learn about the Late Triassic ecosystem, and how much we find when we just look a little closer,” Stocker said. “We’re familiar with the charismatic archosaurs from the Chinle Formation, but we know that based on other ecosystems, they should make up a small percentage of the animals that lived together. With this new focus we’re able to fill in a lot of those missing smaller components with new discoveries.”
Coming from multiple individuals, the hip bones are are long and hollow, with a hip socket offset rather than centered. The bones of the frogs show how tiny they were: Just a bit over half-an-inch long. “The Chinle frog could fit on the end of your finger,” Stocker added.
Stocker and her team include researchers from Virginia Tech, Arizona’s Petrified Forest National Park, and the University of Florida’s Museum of Natural History, with the findings published today in the online journal Biology Letters. Even though the fossils are part of the Chinle frog family, they are not yet naming the specific fossils.
“We refrain from naming this Chinle frog because we are continuing to process microvertebrate matrix that will likely yield additional skull and postcranial material that has the potential to be even more informative,” Stocker added.
The Chinle frog shares more features with living frogs and Prosalirus, an Early Jurassic frog found in sediments from the present-day Navajo Nation, than to Triadobatrachus, an Early Triassic frog found in modern day Madagascar in Africa. “These are the oldest frogs from near the equator,” Stocker added. “The oldest frogs overall are roughly 250 million years old from Madagascar and Poland, but those specimens are from higher latitudes and not equatorial.”
Added Nesbitt, also an assistant professor of geosciences, “Now we know that tiny frogs were present approximately 215 million years ago from North America, we may be able to find other members of the modern vertebrate communities in the Triassic Period.”
(During the Triassic, the separate continents we recognize today formed the single landmass named Pangaea. Present-day Arizona was located roughly 10 degrees north of the equator.)
The team added this discovery also marks the first time that frog fossils have been found directly with phytosaurs, and other early dinosaurs.
The Virginia Tech team included both undergraduate and graduate students from across the university, using fossils found in the field and dousing additional rock samples repeatedly in water buckets. Further study of the fossils was completed by CT scans. The undergraduates who accompanied Stocker and Nesbitt on the spring 2018 expedition to Arizona included Elizabeth Evans, a major in the School of Performing Arts; Rebecca Hawkins, majoring in the Department of Fish and Wildlife Conservation; and Hector Lopez, majoring in biological sciences.
“Through my internship with Drs. Stocker and Nesbitt in Arizona, I learned firsthand the hard work that paleontologists put into finding fossils,” said Hawkins, a sophomore in the College of Natural Resources and Environment. “Every day you have to brave long treks, heavy loads, scorching heat, and more. But, with just the right combination of patience and luck, you can find something truly amazing that makes the toil worth it, like a tiny frog hip that tells a big story.”
“Our development of methods that recover delicate bones from small-bodied vertebrates enabled this exciting discovery,” said Ben Kligman, a Ph.D. student in Geosciences from Philadelphia, Pennsylvania. “Our aim is to use similar techniques in the Chinle Formation to uncover the early history of other small-bodied animals including lizards, salamanders, turtles, and mammals.”
Funding for the study came from the National Science Foundation, the National Geographic Society, the David B. Jones Foundation, the Petrified Forest Museum Association, and the Friends of Petrified Forest National Park
Taking a soil core from underwater soil is a bit trickier than soil that’s on the surface. Scientists have to utilize boats and plunge the sampling equipment through water and down into the soil. Credit: Mark Stolt
Soils all over the Earth’s surface are rigorously tested and managed. But what about soils that are down in the murky depths? Although not traditional soils, underwater soils have value and function. Some scientists are working to get them the recognition and research they deserve.
One of these scientists is Mark Stolt from the University of Rhode Island. He and his team are working to sample and map underwater soils.
“Considering that nearly half of the United States population lives within coastal counties, these soils impact many of their lives relative to commercial, recreational, and transportation activities,” he explains. “Soil maps provide a mechanism to manage these areas and make fundamental use and management decisions that affect people every day. Unlike land, you can’t put a price on underwater soils.”
Underwater soils are affected by human activities such as dredging, aquaculture, and restoration, all of which affects water quality. In dredging, layers of the underwater soil are removed to make room — for example, to allow the bottom of a ship to pass. That soil has to go somewhere. If put on land the effects can be unknown.
Aquaculture, raising aquatic plants (for example, nori) or animals (such as oysters), makes use of underwater habitats. In traditional agriculture, farmers are typically concerned about the state of their soil. However, underwater soil is poorly understood. What makes a good or bad soil for aquaculture is uncertain.
The underwater soils also face some threats from land activity, adds Stolt. For example, if too much fertilizer is put on a field it can run off into nearby bodies of water. This encourages algae growth. When that algae dies and decomposes, the water — and underwater soils — lose the oxygen fish and plants need.
“These soils are the foundation and structure of a myriad of habitats and ecosystems,” Stolt says. “For example, submerged aquatic vegetation are rooted plants that derive much of their nutrients from underwater soils. They trap sediment and minimize coastal erosion. They are a huge sink for carbon dioxide that is eventually stored in the soils, and like other plants, they add oxygen. Not to mention provide habitats for the animals that live in them. Their importance goes on and on.”
By taking measures of the soils, researchers are able to add data to the National Cooperative Soil Survey maps. These provide uniform and rigorous assessments for soil and are used throughout the country. Stolt says soil scientists need to develop faster and better ways to create these maps.
Stolt and his team have been able to add new classifications of underwater soils. These classifications lay out the properties of the soil and provide information on how it was formed, and how it can be used and managed.
“There is still lots and lots to learn about underwater soils, but some of our experiences suggest these soils are quite resilient,” Stolt says. “For example, we tested whether long-term high-production oyster aquaculture (up to 20 years) would have a negative effect on the underwater soil. Although there were some negative effects, the soils essentially remained the same in this particular area.”
Stolt and his team continue to map underwater soils to help define and understand their value.
“I am interested in the application of soils information toward solving environmental issues and problems,” he says. “I live in the Ocean State. We are surrounded by estuaries. I want to see them correctly managed and protected for everyone.”
Stolt presented his research at the International Meeting of the Soil Science Society of America, Jan. 6-9, in San Diego. Studies from this work were funded by NOAA, Rhode Island Sea Grant, NIFA, and USDA-NRCS.
Two opposed diamond anvils in a diamond anvil cell edge. Credit: Dr James Drewitt
Understanding the global carbon cycle provides scientists with vital clues about the planet’s habitability.
It’s the reason why the Earth has a clement stable climate and a low carbon dioxide atmosphere compared to that of Venus, for instance, which is in a runaway greenhouse state with high surface temperatures and a thick carbon dioxide atmosphere.
One major difference between Earth and Venus is the existence of active plate tectonics on Earth, which make our environment unique within our solar system.
But the atmosphere, oceans, and Earth’s crust are only part of the story. The mantle, which represents 75% of Earth’s volume, potentially holds more carbon than all other reservoirs combined.
Carbon — one of the essential building blocks of organic life — is taken into Earth’s interior by subduction, where it drastically lowers the melting point of the solid mantle, forming carbonated melts (carbon-rich molten rocks) in the shallow mantle, fuelling surface volcanoes. Carbonate minerals may also be transported much deeper into the Earth, reaching the lower mantle, but what happens next is uncertain.
Answering that question is beset with challenges — conditions deep within the Earth are extreme and samples from the mantle are rare. The solution is to recreate those conditions in the lab using sophisticated technology.
Now a team of experimental geoscientists from the University of Bristol have done just that. Their results, published open access in Earth and Planetary Science Letters, uncover new clues about what happens to carbonate minerals when they are transported into the mantle via subduction of the oceanic crust (where one of Earth’s tectonic plates slides below another).
Their findings have uncovered a barrier to subduction of carbonate beyond depths of around 1,000km, where it reacts with silica in the oceanic crust to form diamonds that are stored in the deep Earth over geological timescales.
Dr James Drewitt from the School of Earth Sciences explains: “Do carbonate minerals remain stable through the Earth’s lower mantle, and if not, what pressure/temperature changes does it take to spark reactions between the minerals and what do they look like? These are the questions we wanted to find the answers to — and the only way to get those answers was to reproduce the conditions of the Earth’s interior.”
Dr Drewitt and his team subjected synthetic carbonate rocks to very high pressures and temperatures comparable to deep Earth conditions of up to 90 GPa (about 900,000 atmospheres) and 2000 degrees C using a laser-heated diamond anvil cell. They found that carbonate remains stable up to depths of 1,000-1,300km, almost halfway to the core.
Under these conditions carbonate then reacts with surrounding silica to form a mineral known as bridgmanite, which forms most of the Earth’s mantle. The carbon released by this reaction is in the form of solid carbon dioxide. As the hot surrounding mantle eventually heats up the subducted slab, this solid carbon dioxide breaks down to form superdeep diamonds.
Dr Drewitt adds: “Eventually the superdeep diamonds could be returned to the surface in upwelling mantle plumes, and this process could represent one of the sources of superdeep diamonds that we find at the surface and which provide the only direct evidence we have of the composition of the deep earth.
“This is exciting because the deepest humans have ever been able to drill is about 12 km, less than half the depth of Earth’s crust. This pales in comparison to the massive scale of Earth’s mantle, which extends to nearly 3,000 km depth.”
The team used a diamond anvil cell to generate pressures equivalent to those found at these depths, loading samples under a microscope into a pressure chamber drilled out of a metal gasket which is then compressed between the gem quality, brilliant cut diamond anvils. The crystal structure of those samples was then analysed using x-ray diffraction at the UK synchrotron facility in Oxfordshire.
Dr Drewitt now plans to apply these high pressure and high-temperature experiments along with advanced computer simulation techniques to other minerals and materials, adding: “As well as carbon, there is potentially several ocean’s worth of water transported deep into the mantle, and when released this will induce melting of Earth’s upper and lower mantle.
“However, we cannot adequately test or understand current models of the dynamic behaviour of this water rich molten rock because we do not know their composition or their physical properties. The experiments at extreme conditions and advanced computer simulations that we are currently working on will help to resolve these problems.”
Reference:
James W.E. Drewitt, Michael J. Walter, Hongluo Zhang, Sorcha C. McMahon, David Edwards, Benedict J. Heinen, Oliver T. Lord, Simone Anzellini, Annette K. Kleppe. The fate of carbonate in oceanic crust subducted into earth’s lower mantle. Earth and Planetary Science Letters, 2019; 511: 213 DOI: 10.1016/j.epsl.2019.01.041
The fossil, Amiskwia sagittiformis from the Burgess Shale (508 million years old), preserving bilateral jaw elements inside its head. These jaw elements resemble those seen in rotifers and gnathostomulids, while the body resemble arrow worms Credit: Luke Alexander Parry/University of Bristol—Yale University
Amiskwia was originally described by the famous palaeontologist Charles Doolittle Walcott (1850-1927) in 1911 who compared it to the modern arrow worms (chaetognaths) — a group of ocean-dwelling worms that are fierce predators, equipped with an array of spines on their head for grasping small prey.
Such organisms are found world-wide at sites like the famous Burgess Shale in the Canadian Rockies, where their soft bodies are preserved intact.
The strange anatomies exhibited by these animals led the American palaeontologist Stephen Jay Gould (1941-2002) to speculate that these organisms represented extinct body plans that are no longer seen today and that if we were to wind back the clocks to the Cambrian, more than 500-million-years-ago, and re-run the tape of life, then perhaps the animals alive today would look very different.
More than 50 years after Doolittle Walcott came up with his theory about Amiskwia, scientists investigated its affinities and rejected his interpretation as they could not find evidence of the canonical grasping spines.
Instead, they suggested it could be a ribbon worm, or its own distinct lineage only distantly related to anything that resembles it today.
When Dr Jakob Vinther from the University of Bristol’s Schools of Earth Sciences and Biological Sciences and Luke Parry, now at Yale University, studied specimens of Amiskwia, kept at the Smithsonian Institution they found something that had been missed before.
Dr Vinther said: “I coated the specimen with ammonium chloride smoke to make the relief of the fossil stand out and then I could see that in the head was a pair of robust elements.”
Interpreting these structures as a set of jaws, their resemblance led him to think of a group of animals, called gnathiferans, which include rotifers, gnathostomulids and micrognathozoans. These animals are microscopic worms, with a distinctive internal jaw apparatus.
The scientists realised that Amiskwia suddenly had a jaw of a gnathiferan, but a body of an arrow worm.
Dr Vinther said: “The bizarre combination of anatomy seemed altogether alien back in 2012.
“Some people have proposed that there could be a relationship between arrow worms and gnathiferans based on their shared possession of a jaw apparatus, both made of a substance called chitin.
“However, there was little other evidence to suggest a relationship, such as evidence from phylogenetic analyses of DNA.”
Luke Parry added: “It altogether seemed like heresy to propose that gnathiferans and arrow worms may be related back then so we held off publishing our intriguing results out of fear of criticism from our peers.
“However, new DNA studies have since emerged that found arrow worms to be more and more closely affiliated to the Gnathifera in the Tree of Life.
“In particular, some researchers found that arrow worms share a duplication of the important Hox genes with a gnathiferan, the rotifers. We suddenly felt no more in a deadlock situation.”
Now the authors have published their findings in the journal Current Biology. The study follows a new phylogenetic study, which finds robust support for arrow worms forming an evolutionary group with gnathiferans.
Luke Parry said: “We were excited to see that these researchers found a relationship between arrow worms and rotifers.
“Our phylogenetic analysis, based on anatomical features, strongly suggest a relationship between these two groups of animals as well.”
The researchers find that Amiskwia is a stem lineage to arrow worms that possess the jaw apparatus seen in gnathiferan worms.
This jaw evolved into the fearsome grasping spines in living arrow worms, which now is an important link in the marine food chain. Small crustacean larvae have evolved long protective spines to protect themselves from being swallowed by arrow worms.
Reference:
Jakob Vinther, Luke A. Parry. Bilateral Jaw Elements in Amiskwia sagittiformis Bridge the Morphological Gap between Gnathiferans and Chaetognaths. Current Biology, 2019; DOI: 10.1016/j.cub.2019.01.052
New research on an extinct weasel relative reveals what it might have eaten when it lived in North America and Asia about 20 million years ago. The oddly shaped skull of Leptarctus primus has long led to conflicting theories about its diet. But the new work, based on biomechanical modeling and published this week in the Journal of Vertebrate Paleontology, shows that Leptarctus was likely a carnivorous predator, with capability for omnivory and a broader diet when prey was scarce, and had a skull that functioned similarly to that of the living American badger.
Leptarctus primus, which lived in the Miocene and was just a little larger than a housecat, has intrigued researchers because of its unusual and extremely robust skull.
“For a mammal, its skull is really strange,” said co-author Z. Jack Tseng, a research associate at the American Museum of Natural History and an assistant professor of pathology and anatomical sciences at the Jacobs School of Medicine and Biomedical Science at the University at Buffalo. “It’s heavily built — like a tank — with very thick zygomatic cheek bones. The top of its head looks like it’s wearing a helmet.”
Strikingly, Leptarctus primus has two parallel ridges that line the top of the head (other carnivorans typically have a single central ridge or have smooth skulls). For many years, paleontologists have debated the ecological niche of Leptarctus based on conflicting interpretations of the strong parallel skull ridges, distinctive skull shape, and the shape of its teeth and chewing wear. Previous interpretations of their feeding lifestyle ranged widely, across virtually every type of known feeding behavior in carnivorans (dogs, cats, hyaenas, bears, seals, and weasels and their relatives), including herbivore, carnivore, insectivore, and omnivore. But because of the lack of quantitative research into how Leptarctus skulls functioned, the question of their diets remained unanswered.
In this study, led by Alixandra Prybyla, who was a student in the Museum’s National Science Foundation Summer Research Experience for Undergraduates program while at Columbia University, the researchers took an engineering approach. The team compared an almost complete fossil skull of Leptarctus primus with 18 species of modern carnivorans with known diets as well as to other fossil species, using bite simulations based on CT scans of the skulls and virtual modeling of feeding mechanics.
According to John Flynn, study co-author, research team leader, and Frick curator of fossil mammals in the Museum’s Division of Paleontology, “Traditional methods of studying skull, tooth, and skeleton anatomy are still essential for understanding how fossil species lived. But high-resolution x-ray CT images and sophisticated computerized engineering modeling tools have completely transformed our ability to accurately reconstruct feeding habits in extinct animals.”
They found that among the other species analyzed, the skull of Leptarctus is mechanically most similar to the skull of the American badger. Despite some differences in their skull appearances, the computer simulations indicate that the badger is the best living biomechanical analog for understanding the dietary lifestyle of Leptarctus. Based upon those comparisons, the team determined that it was primarily a carnivore and an active predator, but that it could also have been an omnivore feeding on a wider range of plant and insect foods when necessary.
“It was probably hunting down prey and taking in whatever it had access to most of the time,” Tseng said.
Prybyla added: “This complete skull of Leptarctus represents an untapped wellspring of information on the history of ancient relatives of weasels, otters, badgers, and skunks. It’s wonderful what one specimen can illuminate for researchers. To spearhead a project of this magnitude as an undergraduate student was extremely empowering.”
The researchers will conduct future studies using similar engineering modeling tools to look at variations in skull feeding mechanics among other species in the leptarctine group, to determine how many different types of feeding adaptations may have existed among these unusual extinct predators.
Reference:
Alixandra N. Prybyla, Zhijie Jack Tseng, John J. Flynn. Biomechanical simulations of Leptarctus primus (Leptarctinae, Carnivora), and new evidence for a badger-like feeding capability. Journal of Vertebrate Paleontology, 2019; e1531290 DOI: 10.1080/02724634.2018.1531290
Layered lava flows within the Wai Subgroup from near Ambenali Ghat, Western Ghats. Credit: Courtney Sprain
Based on new data published today in the journal Science, it seems increasingly likely that an asteroid or comet impact 66 million years ago reignited massive volcanic eruptions in India, half a world away from the impact site in the Caribbean Sea.
But it leaves unclear to what degree the two catastrophes contributed to the near-simultaneous mass extinction that killed off the dinosaurs and many other forms of life.
The research sheds light on huge lava flows that have erupted periodically over Earth’s history, and how they have affected the atmosphere and altered the course of life on the planet.
In the study, University of California, Berkeley, scientists report the most precise and accurate dates yet for the intense volcanic eruptions in India that coincided with the worldwide extinction at the end of the Cretaceous Period, the so-called K-Pg boundary. The million-year sequence of eruptions spewed lava flows for distances of at least 500 kilometers across the Indian continent, creating the so-called Deccan Traps flood basalts that in some places are nearly 2 kilometers thick.
“Now that we have dated Deccan Traps lava flows in more and different locations, we see that the transition seems to be the same everywhere. I would say, with pretty high confidence, that the eruptions occurred within 50,000 years, and maybe 30,000 years, of the impact, which means they were synchronous within the margin of error,” said Paul Renne, a professor-in-residence of earth and planetary science at UC Berkeley, director of the Berkeley Geochronology Center and senior author of the study, which will appear online Feb. 21. “That is an important validation of the hypothesis that the impact renewed lava flows.”
The new dates also confirm earlier estimates that the lava flows continued for about a million years, but contain a surprise: three-quarters of the lava erupted after the impact. Previous studies suggested that about 80 percent of the lava erupted before the impact.
If most of the Deccan Traps lava had erupted before the impact, then gases emitted during the eruptions could have been the cause of global warming within the last 400,000 years of the Cretaceous Period, during which temperatures increased, on average, about 8 degrees Celsius (14.4 degrees Fahrenheit). During this period of warming, species would have evolved suited to hothouse conditions, only to be confronted by global cooling from the dust or by climate cooling gases caused by either the impact or the volcanos.
The cold would have been a shock from which most creatures would never have recovered, disappearing entirely from the fossil record: literally, a mass extinction.
But if most of the Deccan Traps lava emerged after the impact, this scenario needs rethinking.
“This changes our perspective on the role of the Deccan Traps in the K-Pg extinction,” said first author Courtney Sprain, a former UC Berkeley doctoral student who is now a postdoc at the University of Liverpool in the United Kingdom. “Either the Deccan eruptions did not play a role — which we think unlikely — or a lot of climate-modifying gases were erupted during the lowest volume pulse of the eruptions.”
The hypothesis that climate-altering volcanic gases leak out of underground magma chambers frequently, and not just during eruptions, is supported by evidence from present-day volcanos, such as those of the gas-spewing Mt. Etna in Italy and Popocatepetl in Mexico, the researchers said. Magma stewing below the surface is known to transmit gases to the atmosphere, even without eruptions.
“We are suggesting that it is very likely that a lot of the gases that come from magma systems precede eruptions; they don’t necessarily correlate with eruptions,” Renne said. In the case of the K-Pg extinction, the symptoms of significant climate change occurred before the peak in volcanic eruptions.
Flood basalts
Renne, Sprain and their colleagues are using a precise dating method, argon-argon dating, to determine when the impact occurred and when the Deccan Traps erupted to clarify the sequence of catastrophes at the end of the Cretaceous Period and beginning of the Tertiary Period — the K-Pg boundary, formerly referred to as the K-T boundary.
In 2013, using rocks from Montana, they obtained the most precise date yet for the impact, and in 2018, they updated that to 66,052,000 years ago, give or take 8,000 years. Then, in 2015, they determined from a handful of samples in India that, in at least one spot, the peak of the Deccan Traps eruptions occurred within about 50,000 years of that date, which means, in geologic time, that the incidents were basically simultaneous.
Now, with three times more rock samples from areas covering more of the Deccan Traps, the researchers have established that the time of peak eruptions was the same across much of the Indian continent. This supports the group’s hypothesis that the asteroid impact triggered super-earthquakes that caused a strong burst of volcanism in India, which is almost directly opposite the impact site, the Chicxulub crater in the Caribbean Sea.
Sprain and Renne argue that the coincident catastrophes likely delivered a one-two punch to life on Earth, but the details are unclear. Volcanic eruptions produce lots of gases, but some, like carbon dioxide and methane, warm the planet, while others, like sulfur aerosols, are cooling. The impact itself would have sent dust into the atmosphere that blocked sunlight and cooled the Earth, though no one knows for how long.
“Both the impact and Deccan volcanism can produce similar environmental effects, but these are occurring on vastly differing timescales,” Sprain said. “Therefore, to understand how each agent contributed to the extinction event, assessing timing is key.”
Which gases in the Deccan Traps are emitted when is a question that’s hard to answer, because there are no flood basalt eruptions going on today, despite numerous ones in Earth’s history. The most recent, near the Columbia River in the Pacific Northwest, dwindled 15 million years ago after 400,000 years of eruptions.
The paucity of information about flood basalts is one reason Renne and Sprain are interested in the Deccan Traps, which are still young enough to contain information about the sequence, effects and scale of the eruptions, and perhaps the cause.
“It makes we wonder whether we may see some external forcing mechanism, like the impact for the Deccan Traps, for other flood basalts that lead up to major peaks in eruptions, like the Columbia River basalts or the Siberian Traps,” Renne said. “Could a major earthquake in nearby subduction zones or the accumulation of pressure due to rising magma unleash these major episodes in flood basalts?”
Sprain noted that, in the same issue of Science, a research group at Princeton University also will publish new dates related to the Deccan Traps, some of which differ from those of the Berkeley group. Whereas the Berkeley group dated the mineral plagioclase from the actual lava flows, the Princeton group dated zircons in the sediment deposited between flows. Because it’s unclear where the zircons came from, however, those dates provide only a maximum age for the lava, she said.
Reference:
Courtney J. Sprain, Paul R. Renne, Loÿc Vanderkluysen, Kanchan Pande, Stephen Self, Tushar Mittal. The eruptive tempo of Deccan volcanism in relation to the Cretaceous-Paleogene boundary. Science, 2019 DOI: 10.1126/science.aav1446
Basaltic dykes with a newly determined Age of 619 Million years in Novillo Gneiss, Tamaulipas (Mexico). Dark grey dykes cut whitish gneiss in centre of image. Credit: Bodo Weber (CICESE)
A major volcanic event could have triggered one of the largest glaciations in Earth’s history — the Gaskiers glaciation, which turned the Earth into a giant snowball approximately 580 million years ago. Researchers from Heidelberg University and colleagues from Mexico have discovered remnants of such a large igneous province that resulted from vast lava flows. At the time, it extended over three continents, which today comprises the Earth’s crust in parts of Mexico, North America, and northern Europe. The basaltic eruptions must have covered an area of at least a thousand kilometres in diameter. The results of the research were published in the journal “Geophysical Research Letters.”
Volcanism is a natural process that releases the greenhouse gas carbon dioxide (CO2) into the atmosphere. Weathering of silicate rocks on Earth’s surface traps atmospheric CO2 and sequesters it in carbonate rocks. “That guarantees long-term stability of Earth’s temperate surface conditions in comparison to the hostile environment of its cosmic neighbours, hot Venus and cold Mars,” explains Prof. Dr Axel K. Schmitt of the Institute of Earth Sciences at Heidelberg University. Disturbances of this equilibrium, however, are known to have occurred throughout Earth’s history. “At the end of the Proterozoic Eon, there were three worldwide glaciations. From space, the Earth would have resembled a snowball,” adds the geoscientist.
Extreme volcanic outpourings resulting in so-called large igneous provinces could be responsible for these Snowball Earth global glaciations. When continental land masses break up, it causes a volcanic binge that also releases massive amounts of CO2 into the atmosphere, which can cause short-term global warming. Then, however, the lava rock begins to weather. “The weathering process is especially intense at tropical latitudes. Over timescales of millions to tens of millions of years, the weathered rocks can sequester sufficient carbon dioxide to plunge Earth’s climate into an extreme ice age,” explains Prof. Schmitt.
The German-Mexican team which included researchers from the Centro de Investigación Científica y de Educación Superior de Ensenda (CICESE) studied basaltic dike rocks from the Novillo Gneiss in the Mexican state of Tamaulipas. These dikes are the roots of lava flows that have been long eroded. The research team demonstrated that dike rocks from Mexico are indistinguishable in their trace element and isotopic compositions to dated rocks from Canada and Norway. Moreover, the Heidelberg team was successful in retrieving microscopic mineral grains of baddeleyite from the Mexican samples.
Baddeleyite exclusively crystallises in magma and thus is a reliable indicator for the timing of volcanism. In this case, with the help of a high spatial resolution ion microprobe at the Institute of Earth Sciences, the rare mineral was determined to be 619 million years old. According to Prof. Schmitt, this date perfectly matches the time when the rocks found in Canada and Norway were formed. The researchers speculate that the long-term climate effects of this large igneous province led to the Gaskiers glaciation approximately 40 million years later.
Reference:
Bodo Weber, Axel K. Schmitt, Alejandro Cisneros de León, Reneé González-Guzmán. Coeval Early Ediacaran Breakup of Amazonia, Baltica, and Laurentia: Evidence From Micro-Baddeleyite Dating of Dykes From the Novillo Canyon, Mexico. Geophysical Research Letters, 2019; DOI: 10.1029/2018GL079976
A newly discovered, diminutive — by T. rex standards — relative of the tyrant king of dinosaurs reveals crucial new information about when and how T. rex came to rule the North American roost.
Meet Moros intrepidus, a small tyrannosaur who lived about 96 million years ago in the lush, deltaic environment of what is now Utah during the Cretaceous period. The tyrannosaur, whose name means “harbinger of doom,” is the oldest Cretaceous tyrannosaur species yet discovered in North America, narrowing a 70-million-year gap in the fossil record of tyrant dinosaurs on the continent.
“With a lethal combination of bone-crunching bite forces, stereoscopic vision, rapid growth rates, and colossal size, tyrant dinosaurs reigned uncontested for 15 million years leading up to the end-Cretaceous extinction — but it wasn’t always that way,” says Lindsay Zanno, paleontologist at North Carolina State University, head of paleontology at the North Carolina Museum of Sciences and lead author of a paper describing the research. “Early in their evolution, tyrannosaurs hunted in the shadows of archaic lineages such as allosaurs that were already established at the top of the food chain.”
Medium-sized, primitive tyrannosaurs have been found in North America dating from the Jurassic (around 150 million years ago). By the Cretaceous — around 81 million years ago — North American tyrannosaurs had become the enormous, iconic apex predators we know and love. The fossil record between these time periods has been a blank slate, preventing scientists from piecing together the story behind the ascent of tyrannosaurs in North America. “When and how quickly tyrannosaurs went from wallflower to prom king has been vexing paleontologists for a long time,” says Zanno. “The only way to attack this problem was to get out there and find more data on these rare animals.”
That’s exactly what Zanno and her team did. A decade spent hunting for dinosaur remains within rocks deposited at the dawn of the Late Cretaceous finally yielded teeth and a hind limb from the new tyrannosaur. In fact, the lower leg bones of Moros were discovered in the same area where Zanno had previously found Siats meekerorum, a giant meat-eating carcharodontosaur that lived during the same period. Moros is tiny by comparison — standing only three or four feet tall at the hip, about the size of a modern mule deer. Zanno estimates that the Moros was over seven years old when it died, and that it was nearly full-grown.
But don’t let the size fool you. “Moros was lightweight and exceptionally fast,” Zanno says. “These adaptations, together with advanced sensory capabilities, are the mark of a formidable predator. It could easily have run down prey, while avoiding confrontation with the top predators of the day.
“Although the earliest Cretaceous tyrannosaurs were small, their predatory specializations meant that they were primed to take advantage of new opportunities when warming temperatures, rising sea-level and shrinking ranges restructured ecosystems at the beginning of the Late Cretaceous,” Zanno says. “We now know it took them less than 15 million years to rise to power.”
The bones of Moros also revealed the origin of T. rex’s lineage on the North American continent. When the scientists placed Moros within the family tree of tyrannosaurs they discovered that its closest relatives were from Asia. “T. rex and its famous contemporaries such as Triceratops may be among our most beloved cultural icons, but we owe their existence to their intrepid ancestors who migrated here from Asia at least 30 million years prior,” Zanno says. “Moros signals the establishment of the iconic Late Cretaceous ecosystems of North America.”
The research appears in Communications Biology, and was supported in part by Canyonlands Natural History Association. Lecturer Terry Gates, postdoctoral research scholar Aurore Canoville and graduate student Haviv Avrahami from NC State, as well as the Field Museum’s Peter Makovicky and Ryan Tucker from Stellenbosch University, contributed to the work.
Reference:
Lindsay E. Zanno, Ryan T. Tucker, Aurore Canoville, Haviv M. Avrahami, Terry A. Gates, Peter J. Makovicky. Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record. Communications Biology, 2019; 2 (1) DOI: 10.1038/s42003-019-0308-7
Adzebill skeleton on display in the Canterbury Museum, New Zealand. Among the giant bird’s closest living relatives are the tiny flufftails from Madagascar and Africa. Credit: Canterbury Museum
Scientists have revealed the African origins of New Zealand’s most mysterious giant flightless bird — the now extinct adzebill — showing that some of its closest living relatives are the pint-sized flufftails from Madagascar and Africa.
Led by the University of Adelaide, the research in the journal Diversity showed that among the closest living relatives of the New Zealand adzebills — which weighed up to 19 kilograms — are the tiny flufftails, which can weigh as little as 25 grams. The closeness of the relationship strongly suggests that the ancestors of the adzebills flew to New Zealand after it became physically isolated from other land.
This finding mirrors the close relationship between New Zealand’s kiwi and the extinct Madagascan elephant birds, published by University of Adelaide researchers in 2014, hinting at an unappreciated biological connection between Madagascar and New Zealand.
Like the better-known moa, the two species of adzebill — the North Island adzebill and South Island adzebill -disappeared following the arrival of early Maori in New Zealand, who hunted them and cleared their forest habitats. Unlike the moa, adzebills were predators and not herbivores.
“The adzebill were almost completely wingless and had an enormous reinforced skull and beak, almost like an axe, which is where they got their English name,” says Alexander Boast, lead author and former Masters student at the University of Adelaide.
“If they hadn’t gone extinct, they would be among the largest living birds.”
A team of researchers from Australia, New Zealand, and the US analysed genetic data from the two adzebill species.
“A lot of past genetic research and publicity has focused on the moa, which we know were distant relatives of the ostrich, emu, and cassowary,” says co-author Dr Kieren Mitchell, postdoctoral researcher at the University of Adelaide.
“But noone had analysed the genetics of the adzebill, despite a lot of debate about exactly what they were and where they came from.”
“We know that adzebills have been in New Zealand for a relatively long time, since we previously discovered a 19 million-year-old adzebill fossil on the South Island,” says co-author Associate Professor Trevor Worthy, a palaeontologist at Flinders University.
“A key question is whether they’ve been present since New Zealand broke away from the other fragments of the supercontinent Gondwana or whether their ancestors flew to New Zealand from elsewhere later on.”
Researchers at both the University of Adelaide’s Australian Centre for Ancient DNA and Curtin University’s Ancient DNA Lab sequenced adzebill DNA from fragments of bone and eggshell. They compared this to DNA from living birds to discover the identity and origin of the adzebill.
“It’s possible that ancient migration of birds between Madagascar and New Zealand may have occurred via Antarctica,” says Dr Mitchell.
“Some coastal regions of the continent remained forested and ice free until as recently as 30 million years ago.”
Dr Paul Scofield, Senior Curator Natural History at Canterbury Museum says: “The North Island adzebill likely evolved from its South Island counterpart relatively recently. We know the North and South Islands were joined by a narrow piece of land around two million years ago. Adzebills probably developed in the South Island, then walked over this land bridge to the North Island.”
Reference:
alexander P. Boast, Brendan Chapman , Michael B. Herrera, Trevor H. Worthy, R. Paul Scofield, Alan J. D. Tennyson, Peter Houde, Michael Bunce, Alan Cooper and Kieren J. Mitchell. Mitochondrial Genomes from New Zealand’s Extinct Adzebills (Aves: Aptornithidae: Aptornis) Support a Sister-Taxon Relationship with the Afro-Madagascan Sarothruridae. Diversity, 2019 DOI: 10.3390/d11020024
Total human carbon dioxide emissions could match those of Earth’s last major greenhouse warming event in fewer than five generations, new research finds.
A new study finds humans are pumping carbon dioxide into the atmosphere at a rate nine to 10 times higher than the greenhouse gas was emitted during the Paleocene–Eocene Thermal Maximum (PETM), a global warming event that occurred roughly 56 million years ago.
The results suggest if carbon emissions continue to rise, the total amount of carbon dioxide injected into the atmosphere since humans started burning fossil fuels could equal the amount released during the PETM as soon as 2159.
“You and I won’t be here in 2159, but that’s only about four generations away,” said Philip Gingerich, a paleoclimate researcher at the University of Michigan and author of the new study in the AGU journal Paleoceanography and Paleoclimatology. “When you start to think about your children and your grandchildren, and your great-grandchildren, you’re about there.”
Scientists often use the PETM as a benchmark against which to compare modern climate change. But the new study shows we’re on track to meet this benchmark much sooner than previously thought, as the pace of today’s warming far outstrips any climate event that has happened since the extinction of the dinosaurs.
“Given a business-as-usual assumption for the future, the rates of carbon release that are happening today are really unprecedented, even in the context of an event like the PETM,” said Gabriel Bowen, a geophysicist at the University of Utah who was not connected to the new study. “We don’t have much in the way of geologic examples to draw from in understanding how the world responds to that kind of perturbation.”
The exact environmental consequences of PETM-like carbon levels are unclear, but the increased temperatures will likely drive many species to extinction with the lucky ones being able to adapt or migrate, according to Larisa DeSantis, a paleontologist at Vanderbilt University who was not connected to the new study. In addition, it will take thousands of years for the climate system cool down, she said.
“It’s not just about 100 years from now; it’s going to take significant periods of time for that carbon dioxide to make its way back into the Earth’s crust,” DeSantis said. “It’s not a short-term event. We’re really committing ourselves to many thousands of years of a warmer world if we don’t take action quickly.”
Studying past climate change
The PETM was a global warming event that occurred roughly 56 million years ago. Scientists are unsure what caused it, but during the event massive quantities of carbon dioxide were released into Earth’s atmosphere, rapidly spiking global temperatures by 5 to 8 degrees Celsius (9 to 14 degrees Fahrenheit). Average global temperatures during the PETM peaked at about 23 degrees Celsius (73 degrees Fahrenheit), about 7 degrees Celsius (13 degrees Fahrenheit) higher than today’s average.
Scientists think that during this time and the warm period that followed, the poles were ice-free and the Arctic was home to palm trees and crocodiles. It’s not the hottest Earth has ever been, but the PETM was the warmest period since the extinction of the dinosaurs 66 million years ago.
Scientists can’t pin down exactly how much carbon was injected into the atmosphere during the PETM or exactly how long the event lasted. But their best estimates say between 3,000 and 7,000 gigatons of carbon accumulated over a period of 3,000 to 20,000 years, based on ocean sediment cores that show changes to carbonate minerals laid down during this time.
The massive carbon release and temperature spike drastically altered Earth’s climate, causing a major extinction of organisms in the deep ocean that are a key link in the marine food web. Land animals got smaller and migrated north to cooler climates. Some groups of modern mammals, including primates, appeared for the first time soon after the PETM, but scientists are unsure whether this happened as a direct result of the rapid environmental change.
Comparing past with present
Climate scientists use the PETM as a case study for understanding what environmental changes might happen under current human-caused climate change and when those changes might take effect. But they can only average carbon emissions during the PETM over the whole duration of the event — thousands of years. They don’t know what those emissions rates were like on a yearly basis, so it’s difficult to compare them to the pace of carbon emissions today.
In the new study, Gingerich found a way to mathematically compare modern carbon emissions to PETM emissions on the same time scale. The results showed current carbon emission rates are nine to 10 times higher than those during the PETM.
“To me, it really brought home how rapidly and how great the consequences are of the carbon we’re producing as a people,” Gingerich said.
Projecting current emissions into the future, Gingerich found that if emissions continue to rise, we could be facing another PETM-like event in fewer than five generations. The total carbon accumulated in the atmosphere could hit the lowest estimate of carbon accumulated during the PETM — 3,000 gigatons — in the year 2159. It would hit the maximum estimated emissions — 7,126 gigatons — in 2278, based on Gingerich’s calculations. Humans have emitted roughly 1,500 gigatons of carbon as of 2016.
“The fact that we could reach warming equivalent to the PETM very quickly, within the next few hundred years, is terrifying,” DeSantis said.
The findings suggest scientists may not be able to predict the environmental or biological changes that will happen in the coming years based on what happened during the PETM because today’s warming is occurring so much faster, according to DeSantis. What makes predictions harder is that today’s climate starts from a cooler baseline than the PETM and the species that inhabit Earth are different than those of 56 million years ago.
“It’s hard to compare biotic effects because the world during the PETM was quite different,” DeSantis said. “We live in a very different world today, with different groups of animals, with humans being the dominant species… but we know there are many negative consequences of dramatic warming on vast numbers of species, including our own.”
Reference:
Philip D. Gingerich. Temporal Scaling of Carbon Emission and Accumulation Rates: Modern Anthropogenic Emissions Compared to Estimates of PETM-Onset Accumulation. Paleoceanography and Paleoclimatology, 2019; DOI: 10.1029/2018PA003379
Scientists excavate a dinosaur bone bed along the Colville River. Credit: Patrick Druckenmiller photo
A research team has discovered a previously unknown species of marsupial that lived in Alaska’s Arctic during the era of dinosaurs, adding a vivid new detail to a complex ancient landscape.
The thumb-sized animal, named Unnuakomys hutchisoni, lived in the Arctic about 69 million years ago during the late Cretaceous Period. Its discovery, led by scientists from the University of Colorado and University of Alaska Fairbanks, is outlined in an article published in the Journal of Systematic Palaeontology.
The discovery adds to the picture of an environment that scientists say was surprisingly diverse. The tiny animal, which is the northernmost marsupial ever discovered, lived among a unique variety of dinosaurs, plants and other animals.
Alaska’s North Slope, which was at about 80 degrees north latitude when U. hutchisoni lived there, was once thought to be a barren environment during the late Cretaceous. That perception has gradually changed since dinosaurs were discovered along the Colville River in the 1980s, with new evidence showing the region was home to a diverse collection of unique species that didn’t exist anywhere else.
Finding a new marsupial species in the far north adds a new layer to that evolving view, said Patrick Druckenmiller, the director of the University of Alaska Museum of the North.
“Northern Alaska was not only inhabited by a wide variety of dinosaurs, but in fact we’re finding there were also new species of mammals that helped to fill out the ecology,” said Druckenmiller, who has studied dinosaurs in the region for more than a decade. “With every new species, we paint a new picture of this ancient polar landscape.”
Marsupials are a type of mammal that carries underdeveloped offspring in a pouch. Kangaroos and koalas are the best-known modern marsupials. Ancient relatives were much smaller during the late Cretaceous, Druckenmiller said. Unnuakomys hutchisoni was probably more like a tiny opossum, feeding on insects and plants while surviving in darkness for as many as four months each winter.
The research team, whose project was funded with a National Science Foundation grant, identified the new marsupial using a painstaking process. With the help of numerous graduate and undergraduate students, they collected, washed and screened ancient river sediment collected on the North Slope and then carefully inspected it under a microscope. Over many years, they were able to locate numerous fossilized teeth roughly the size of a grain of sand.
“I liken it to searching for proverbial needles in haystacks — more rocks than fossils,” said Florida State University paleobiologist Gregory Erickson, who contributed to the paper.
Jaelyn Eberle, curator of fossil vertebrates at the University of Colorado Museum of Natural History, led the effort to examine those teeth and a few tiny jawbones. Their analysis revealed a new species and genus of marsupial.
Mammal teeth have unique cusps that differ from species to species, making them a bit like fingerprints for long-dead organisms, said Eberle, the lead author of the study.
“If I were to go down to the Denver Zoo and crank open the mouth of a lion and look in — which I don’t recommend — I could tell you its genus and probably its species based only on its cheek teeth,” Eberle said.
The name Unnuakomys hutchisoni combines the Iñupiaq word for “night” and the Greek word “mys” for mouse, a reference to the dark winters the animal endured, and a tribute to J. Howard Hutchison, a paleontologist who discovered the fossil-rich site where its teeth were eventually found.
Other co-authors of the Journal of Systematic Palaeontology paper include William Clemens, of the University of California, Berkeley; Paul McCarthy, of UAF; and Anthony Fiorillo, of the Perot Museum of Nature and Science.
Reference:
Jaelyn J. Eberle, William A. Clemens, Paul J. McCarthy, Anthony R. Fiorillo, Gregory M. Erickson, Patrick S. Druckenmiller. Northernmost record of the Metatheria: a new Late Cretaceous pediomyid from the North Slope of Alaska. Journal of Systematic Palaeontology, 2019; 1 DOI: 10.1080/14772019.2018.1560369
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Site Name: Brimham Rocks County: North Yorkshire
Brimham Rocks, near Pateley Bridge, consists of a series of Millstone Grit tors together with amosaic of upland plant communities including dry and wet heath, birch woodland and acid bog.The tors and the various associated rock weathering forms in Millstone Grit (Upper Carboniferous) make this a classic geomorphological site, significant for studies of past and present weathering processes and their contribution to landscape evolution. The heath and bog habitats represent important examples of plant communities, formerly more widespread, which have been reduced by agricultural improvement, drainage and afforestation.
The areas of open heathland adjacent to the rocks consist primarily of heather Calluna vulgaris, bilberry Vaccinium myrtillus, and wavy hair-grass Deschampsia flexuosa with scattered birch Betula sp., rowan Sorbus aucuparia and oak Quercus robur. Bracken Pteridium aquilinum occurs around the stacks, and cowberry Vaccinium vitis-idaea is found on the eastern side of the site. The presence of a population of the uncommon chickweed wintergreen Trientalis europaea is of note. On the north-eastern edge birch is regenerating freely in the absence of fires and grazing pressures.
Pockets of wet heath comprise common cotton-grass Eriophorum angustifolium, deer grass Trichophorum cespitosum, purple moor-grass Molinia caerulea, bog mosses Sphagnum spp. and cross-leaved heath Erica tetralix, and occasionally, cranberry Vaccinium oxycoccus. Bog asphodel Narthecium ossifragum and marsh violet Viola palustris together with water blinks Montia fontana, marsh thistle Cirsium palustre and wood horsetail Equisetum sylvaticum occur in a water-logged area associated with a small beck in the south of the site
Also of note is the occurrence of the local Holly Blue Celastrina argiolus and Green Hairstreak Callophrys rubi butterflies.
Brimham Rocks, England
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Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Brimham Rocks are balancing rock formations on Brimham Moor in North Yorkshire, England.
Debris flows are fast moving, liquefied landslides of mixed and unconsolidated water and debris that look like flowing concrete. They are defined by their non-newtonian flow dynamics, and behave as Bingham plastics. This characteristic can lead to the formation of levees at the margins of unconstrained debris flows as the margins of the flow freeze.
They are differentiated from mudflows by their coarser and more poorly sorted sediment load. Flows can carry material ranging in size from clay to boulders, and may contain a large amount of woody debris such as logs and tree stumps. Flows can be triggered by intense rainfall, glacial melt, or a combination of the two. Speed of debris flows can vary from 5 km/h to up to 80 km/h in extreme cases.
Volumes of material delivered by single events vary from less than 100 to more than 100,000 cubic metres. Variables considered important in debris flow initiation include slope angle, available loose sediment, and degree of land disturbance by activities such as forest harvesting.
Debris flows are often more frequent following forest and brush fires, as experience in southern California clearly demonstrates. Debris flows are extremely destructive to life and property, and claim thousands of lives world-wide in any given year.
They are a particular problem in steep mountainous areas subjected to intense rainstorms, and have received particular attention from researchers in Japan, Western USA, Western Canada, New Zealand, the European Alps, and Kazakhstan.
Graphic showing the Transition Zone inside the Earth Princeton seismologist Jessica Irving worked with then-graduate student Wenbo Wu and another collaborator to determine the roughness at the top and bottom of the transition zone, a layer within the mantle, using scattered earthquake waves. They found that the top of the transition zone, a layer located 410 kilometers down, is mostly smooth, but the base of the transition zone, 660 km down, in some places is much rougher than the global surface average. “In other words, stronger topography than the Rocky Mountains or the Appalachians is present at the 660-km boundary,” said Wu. NOTE: This graphic is not to scale. Credit: Kyle McKernan, Office of Communications
Most schoolchildren learn that the Earth has three (or four) layers: a crust, mantle and core, which is sometimes subdivided into an inner and outer core. That’s not wrong, but it does leave out several other layers that scientists have identified within the Earth.
In a study published this week in Science, Princeton geophysicists Jessica Irving and Wenbo Wu, in collaboration with Sidao Ni from the Institute of Geodesy and Geophysics in China, used data from an enormous earthquake in Bolivia to find mountains and other topography on a layer located 660 kilometers (410 miles) straight down, which separates the upper and lower mantle. (Lacking a formal name for this layer, the researchers simply call it “the 660-km boundary.”)
To peer deep into the Earth, scientists use the most powerful waves on the planet, which are generated by massive earthquakes. “You want a big, deep earthquake to get the whole planet to shake,” said Irving, an assistant professor of geosciences.
Big earthquakes are vastly more powerful than small ones — energy increases 30-fold with every step up the Richter scale — and deep earthquakes, “instead of frittering away their energy in the crust, can get the whole mantle going,” Irving said. She gets her best data from earthquakes that are magnitude 7.0 or higher, she said, as the shockwaves they send out in all directions can travel through the core to the other side of the planet — and back again. For this study, the key data came from waves picked up after a magnitude 8.2 earthquake — the second-largest deep earthquake ever recorded — that shook Bolivia in 1994.
“Earthquakes this big don’t come along very often,” she said. “We’re lucky now that we have so many more seismometers than we did even 20 years ago. Seismology is a different field than it was 20 years ago, between instruments and computational resources.”
Seismologists and data scientists use powerful computers, including Princeton’s Tiger supercomputer cluster, to simulate the complicated behavior of scattering waves in the deep Earth.
The technology depends on a fundamental property of waves: their ability to bend and bounce. Just as light waves can bounce (reflect) off a mirror or bend (refract) when passing through a prism, earthquake waves travel straight through homogenous rocks but reflect or refract when they encounter any boundary or roughness.
“We know that almost all objects have surface roughness and therefore scatter light,” said Wu, the lead author on the new paper, who just completed his geosciences Ph.D. and is now a postdoctoral researcher at the California Institute of Technology. “That’s why we can see these objects — the scattering waves carry the information about the surface’s roughness. In this study, we investigated scattered seismic waves traveling inside the Earth to constrain the roughness of the Earth’s 660-km boundary.”
The researchers were surprised by just how rough that boundary is — rougher than the surface layer that we all live on. “In other words, stronger topography than the Rocky Mountains or the Appalachians is present at the 660-km boundary,” said Wu. Their statistical model didn’t allow for precise height determinations, but there’s a chance that these mountains are bigger than anything on the surface of the Earth. The roughness wasn’t equally distributed, either; just as the crust’s surface has smooth ocean floors and massive mountains, the 660-km boundary has rough areas and smooth patches. The researchers also examined a layer 410 kilometers (255 miles) down, at the top of the mid-mantle “transition zone,” and they did not find similar roughness.
“They find that Earth’s deep layers are just as complicated as what we observe at the surface,” said seismologist Christine Houser, an assistant professor at the Tokyo Institute of Technology who was not involved in this research. “To find 2-mile (1-3 km) elevation changes on a boundary that is over 400 miles (660 km) deep using waves that travel through the entire Earth and back is an inspiring feat. … Their findings suggest that as earthquakes occur and seismic instruments become more sophisticated and expand into new areas, we will continue to detect new small-scale signals which reveal new properties of Earth’s layers.”
What it means
The presence of roughness on the 660-km boundary has significant implications for understanding how our planet formed and continues to function. That layer divides the mantle, which makes up about 84 percent of the Earth’s volume, into its upper and lower sections. For years, geoscientists have debated just how important that boundary is. In particular, they have investigated how heat travels through the mantle — whether hot rocks are carried smoothly from the core-mantle boundary (almost 2,000 miles down) all the way up to the top of the mantle, or whether that transfer is interrupted at this layer. Some geochemical and mineralogical evidence suggests that the upper and lower mantle are chemically different, which supports the idea that the two sections don’t mix thermally or physically. Other observations suggest no chemical difference between the upper and lower mantle, leading some to argue for what’s called a “well-mixed mantle,” with both the upper and lower mantle participating in the same heat-transfer cycle.
“Our findings provide insight into this question,” said Wu. Their data suggests that both groups might be partially right. The smoother areas of the 660-km boundary could result from more thorough vertical mixing, while the rougher, mountainous areas may have formed where the upper and lower mantle don’t mix as well.
In addition, the roughness the researchers found, which existed at large, moderate and small scales, could theoretically be caused by heat anomalies or chemical heterogeneities. But because of how heat in transported within the mantle, Wu explained, any small-scale thermal anomaly would be smoothed out within a million years. That leaves only chemical differences to explain the small-scale roughness they found.
What could cause significant chemical differences? The introduction of rocks that used to belong to the crust, now resting quietly in the mantle. Scientists have long debated the fate of the slabs of sea floor that get pushed into the mantle at subduction zones, the collisions happening found all around the Pacific Ocean and elsewhere around the world. Wu and Irving suggest that remnants of these slabs may now be just above or just below the 660-km boundary.
“It’s easy to assume, given we can only detect seismic waves traveling through the Earth in its current state, that seismologists can’t help understand how Earth’s interior has changed over the past 4.5 billion years,” said Irving. “What’s exciting about these results is that they give us new information to understand the fate of ancient tectonic plates which have descended into the mantle, and where ancient mantle material might still reside.”
She added: “Seismology is most exciting when it lets us better understand our planet’s interior in both space and time.”
Reference:
Wenbo Wu, Sidao Ni and Jessica Irving. Inferring Earth’s discontinuous chemical layering from the 660-kilometer boundary topography. Science, 2019 DOI: 10.1126/science.aav0822
Note: The above post is reprinted from materials provided by Princeton University. Original written by Liz Fuller-Wright.
View of Mount Agung on November 10, 2017 from the Rendang Volcano Observatory, operated by CVGHM. Photo by Jake Lowenstern, US Geological Survey
A team of scientists, led by the University of Bristol, has used satellite technology provided by the European Space Agency (ESA) to uncover why the Agung volcano in Bali erupted in November 2017 after 50 years of dormancy.
Their findings, published today in the journal Nature Communications, could have important implications for forecasting future eruptions in the area.
Two months prior to the eruption, there was a sudden increase in the number of small earthquakes occurring around the volcano, triggering the evacuation of 100,000 people.
The previous eruption of Agung in 1963 killed nearly 2,000 people and was followed by a small eruption at its neighboring volcano, Batur.
Because this past event was among the deadliest volcanic eruptions of the 20th Century, a great effort was deployed by the scientific community to monitor and understand the re-awakening of Agung.
During this time, a team of scientists from the University of Bristol’s School of Earth Sciences, led by Dr Juliet Biggs used Sentinel-1 satellite imagery provided by the ESA to monitor the ground deformation at Agung.
Dr Biggs said: “From remote sensing, we are able to map out any ground motion, which may be an indicator that fresh magma is moving beneath the volcano.”
In the new study, carried out in collaboration with the Center for Volcanology and Geological Hazard Mitigation in Indonesia (CVGHM), the team detected uplift of about 8-10 cm on the northern flank of the volcano during the period of intense earthquake activity.
Dr Fabien Albino, also from Bristol’s School of Earth Sciences, added: “Surprisingly, we noticed that both the earthquake activity and the ground deformation signal were located five kilometres away from the summit, which means that magma must be moving sideways as well as vertically upwards.
“Our study provides the first geophysical evidence that Agung and Batur volcanoes may have a connected plumbing system.
“This has important implications for eruption forecasting and could explain the occurrence of simultaneous eruptions such as in 1963.”
Reference:
Fabien Albino, Juliet Biggs, Devy Kamil Syahbana. Dyke intrusion between neighbouring arc volcanoes responsible for 2017 pre-eruptive seismic swarm at Agung. Nature Communications, 2019; 10 (1) DOI: 10.1038/s41467-019-08564-9
Bubbles of liquid carbon dioxide float out of the seafloor at a vent on Northwest Eifuku volcano off the coast of Japan. Credit: Bob Embley, NOAA Office of Ocean Exploration
The world’s oceans could harbor an unpleasant surprise for global warming, based on new research that shows how naturally occurring carbon gases trapped in reservoirs atop the seafloor escaped to superheat the planet in prehistory.
Scientists say events that began on the ocean bottom thousands of years ago so disrupted the Earth’s atmosphere that it melted away the ice age. Those new findings challenge a long-standing paradigm that ocean water alone regulated carbon dioxide in the atmosphere during glacial cycles. Instead, the study shows geologic processes can dramatically upset the carbon cycle and cause global change.
For today’s world, the findings could portend an ominous development. The undersea carbon reservoirs released greenhouse gas to the atmosphere as oceans warmed, the study shows, and today the ocean is heating up again due to humanmade global warming.
If undersea carbon reservoirs are upset again, they would emit a huge new source of greenhouse gases, exacerbating climate change. Temperature increases in the ocean are on pace to reach that tipping point by the end of the century. For example, a big carbon reservoir beneath the western Pacific near Taiwan is already within a few degrees Celsius of destabilizing.
Moreover, the phenomenon is a threat unaccounted for in climate model projections. Undersea carbon dioxide reservoirs are relatively recent discoveries and their characteristics and history are only beginning to be understood.
Those findings come from a new research paper produced by an international team of Earth scientists led by USC and published in January in the journal Environmental Research Letters.
“We’re using the past as a way to anticipate the future,” said Lowell Stott, professor of Earth sciences at the USC Dornsife College of Letters, Arts and Sciences and lead author of the study. “We know there are vast reservoirs of carbon gas at the bottom of the oceans. We know when they were disrupted during the Pleistocene it warmed the planet.
“We have to know if these carbon reservoirs could be destabilized again. It’s a wild card for which we need to account,” Stott said.
At issue are expanses of carbon dioxide and methane accumulating underwater and scattered across the seafloor. They form as volcanic activity releases heat and gases that can congeal into liquid and solid hydrates, which are compounds stuck together in an icy slurry that encapsulates the reservoirs.
These undersea carbon reservoirs largely stay put unless perturbed, but the new study shows the natural reservoirs are vulnerable in a warming ocean and provides proof the Earth’s climate has been affected by rapid release of geologic carbon.
The scientists say it occurred in the distant past when the Earth was much warmer, and it’s happened more recently — about 17,000 years ago at the end of the Pleistocene epoch when glaciers advanced and receded, which is the focus on the new study. Warming was evident due to changes in atmospheric greenhouse gas concentrations, based on ice cores, marine and continental records.
But how did that happen? What forced such dramatic change in the first place? Scientists have been searching for that answer for 40 years, with focus on oceans because they’re a giant carbon sink and play a central role in carbon dioxide variations.
They soon realized that processes that regulate carbon to the ocean operated too slowly to account for the surge in atmospheric greenhouse gases that led to warming that ended the ice age. So, scientists around the world began examining the role of Earth’s hydrothermal systems and their impact on deep-ocean carbon to see how it affected the atmosphere.
The new study by scientists at USC, the Australian National University and Lund University in Sweden, focused on the Eastern Equatorial Pacific (EEP) hundreds of miles off the coast of Ecuador. The EEP is a primary conduit through which the ocean releases carbon to the atmosphere.
The scientists report evidence of deep-sea hydrothermal systems releasing greenhouse gases to the ocean and atmosphere at the end of the last ice age, just as the oceans were beginning to warm. They measured increased deposition of hydrothermal metals in ancient marine sediments. They correlated glaciation intervals with variations in atmospheric carbon dioxide with differences in marine microorganism ages. They found a four-fold increase in zinc in protozoa (foraminifera) shells, a telltale sign of widespread hydrothermal activity.
Taken together, the new data show that there were major releases of naturally occurring carbon from the EEP, which contributed to dramatic change in Earth’s temperature as the ice age was ending, the study says.
Elsewhere around the world, more and more deep-ocean carbon reservoirs are being discovered. They mostly occur near hydrothermal vents, of which scores have been identified so far, especially in the Pacific, Atlantic and Indian oceans. They occur where the Earth’s crust spreads or collides, creating ideal conditions for the formation of deep-sea carbon dioxide reservoirs. Only about one-third of the ocean’s volcanic regions have been surveyed.
One such reservoir of undersea carbon dioxide, seen in the accompanying video, was discovered about 4,000 feet deep off the coast of Taiwan. Similar discoveries of carbon gas reservoirs have been made off the coast of Okinawa, in the Aegean Sea, in the Gulf of California and off the west coast of Canada.
“The grand challenge is we don’t have estimates of the size of these or which ones are particularly vulnerable to destabilization,” Stott said. “It’s something that needs to be determined.”
In many cases, the carbon reservoirs are bottled up by their hydrate caps. But those covers are sensitive to temperature changes. As oceans warm, the caps can melt, a development the paper warns would lead to a double wallop for climate change — a new source of geologic carbon in addition to the humanmade greenhouse gases.
Oceans absorb nearly all the excess energy from the Earth’s atmosphere, and as a result they have been warming rapidly in recent decades. Over the past quarter-century, Earth’s oceans have retained 60 percent more heat each year than scientists previously had thought, other studies have shown. Throughout the marine water column, ocean heat has increased for the last 50 years. The federal government’s Climate Science Special Report projected a global increase in average sea surface temperatures of up to 5 degrees Fahrenheit by the end of the century, given current emissions rates. Temperature gains of that magnitude throughout the ocean could eventually destabilize the geologic hydrate reservoirs, Stott said.
“The last time it happened, climate change was so great it caused the end of the ice age. Once that geologic process begins, we can’t turn it off,” Stott said.
Moreover, other similar events have happened in the distant past, helping shape the Earth’s environment over and over again. In earlier research, Stott discovered a large, carbon anomaly that occurred 55 million years ago. It disrupted the ocean’s chemistry, causing extensive dissolution of marine carbonates and the extinction of many marine organisms. The ocean changes were accompanied by a rapid rise in global temperatures, an event called the Paleocene-Eocene Thermal Maxima (PETM), a period lasting less than 20,000 years during which so much carbon was released to the atmosphere that Earth’s temperatures surged to about 8 degrees Celsius hotter than today.
“Until quite recently, we had no idea these events occurred. The PETM event is a good analog for what can happen when undersea carbon escapes through the water column to the atmosphere. And now we know the PETM event was not a unique event, that this has happened more recently,” Stott said.
The study comes with some caveats. Much of the ocean floor is unexplored, so scientists don’t know the full extent of the carbon dioxide reservoirs. There is no inventory of greenhouse gases from these geologic sources. And ocean warming is not uniform, making it difficult to predict when and where the undersea carbon reservoirs will be affected. It would take much more study to answer those questions.
Nonetheless, the study makes clear the undersea carbon reservoirs are vulnerable to ocean warming.
“Geologic carbon reservoirs such as these are not explicitly included in current marine carbon budgets” used to model the impacts of climate change, the study says. Yet, “even if only a small percentage of the unsampled hydrothermal systems contain separate gas or liquid carbon dioxide phases, it could change the global marine carbon budget substantially.”
Said Stott: “Discoveries of accumulations of liquid, hydrate and gaseous carbon dioxide in the ocean has not been accounted for because we didn’t know these reservoirs existed until recently, and we didn’t know they affected global change in a significant ways.
“This study shows that we’ve been missing a critical component of the marine carbon budget. It shows these geologic reservoirs can release large amounts of carbon from the oceans. Our paper makes the case that this process has happened before and it could happen again.”
The study authors are Lowell Stott of USC, Kathleen M. Harazin of the Australian National University and Nadine B. Quintana Krupinski of Lund University, Sweden. U.S. funding for the study comes from a National Science Foundation Marine Geology and Geophysics Grant (1558990).
Reference:
Lowell Douglas Stott, Kathleen M. Harazin, Nadine B. Quintana Krupinski. Hydrothermal carbon release to the ocean and atmosphere from the Eastern Equatorial Pacific during the Last Glacial Termination. Environmental Research Letters, 2019; DOI: 10.1088/1748-9326/aafe28
This is an illustration depicting Mnyamawamtuka in its environmental setting. Credit: Mark Witton
A new dinosaur that wears its “heart” on its tail provides new clues to how ecosystems evolved on the African continent during the Cretaceous period according to researchers at Ohio University.
The OHIO team identified and named the new species of dinosaur in an article published this week in PLOS ONE. The new dinosaur, the third now described from southwestern Tanzania by the NSF-funded team, is yet another member of the large, long-necked titanosaur sauropods. The partial skeleton was recovered from Cretaceous-age (~100 million years ago) rocks exposed in a cliff surface in the western branch of the great East African Rift System.
The new dinosaur is named Mnyamawamtuka moyowamkia (Mm-nya-ma-wah-mm-too-ka mm-oh-yo-wa-mm-key-ah), a name derived from Swahili for “animal of the Mtuka (with) a heart-shaped tail” in reference to the name of the riverbed (Mtuka) in which it was discovered and due to the unique shape of its tail bones.
The initial discovery of Mnyamawamtuka took place in 2004, when part of the skeleton was discovered high in a cliff wall overlooking the seasonally dry Mtuka riverbed, with annual excavations continuing through 2008. “Although titanosaurs became one of the most successful dinosaur groups before the infamous mass extinction capping the Age of Dinosaurs, their early evolutionary history remains obscure, and Mnyamawamtuka helps tell those beginnings, especially for their African-side of the story,” said lead author Dr. Eric Gorscak, a recent Ph.D. graduate of Ohio University, current research associate at the Field Museum of Natural History (Chicago) and new assistant professor at the Midwestern University in Downers Grove, just outside of Chicago. “The wealth of information from the skeleton indicates it was distantly related to other known African titanosaurs, except for some interesting similarities with another dinosaur, Malawisaurus, from just across the Tanzania-Malawi border,” noted Dr. Gorscak.
Titanosaurs are best known from Cretaceous-age rocks in South America, but other efforts by the team include new species discovered in Tanzania, Egypt, and other parts of the African continent that reveal a more complex picture of dinosaurian evolution on the planet. “The discovery of dinosaurs like Mnyamawamtuka and others we have recently discovered is like doing a four-dimensional connect the dots,” said Dr. Patrick O’Connor, professor of anatomy at Ohio University and Gorscak’s advisor during his Ph.D. research. “Each new discovery adds a bit more detail to the picture of what ecosystems on continental Africa were like during the Cretaceous, allowing us to assemble a more holistic view of biotic change in the past.”
The excavation process spanned multiple years, and included field teams suspended by ropes and large-scale mechanical excavators to recover one of the more complete specimens from this part of the sauropod dinosaur family tree. “Without the dedication of several field teams, including some whose members donned climbing gear for the early excavations, the skeleton would have eroded away into the river during quite intense wet seasons in this part of the East African Rift System,” added O’Connor.
“This latest discovery is yet another fine example of how Ohio University researchers work the world over in their pursuit of scientific research,” Ohio University President M. Duane Nellis said. “This team has turned out a number of notable discoveries which collectively contribute significantly to our understanding of the natural world.”
Mnyamawamtuka and the other Tanzanian titanosaurs are not the only animals discovered by the research team. Remains of bizarre relatives of early crocodiles, the oldest evidence for “insect farming,” and tantalizing clues about the early evolution of monkeys and apes have been discovered in recent years. Such findings from the East African Rift provide a crucial glimpse into ancient ecosystems of Africa and provide the impetus for future work elsewhere on the continent.
“This new dinosaur gives us important information about African fauna during a time of evolutionary change,” said Judy Skog, a program director in the National Science Foundation’s Division of Earth Sciences, which funded the research. “The discovery offers insights into paleogeography during the Cretaceous. It’s also timely information about an animal with heart-shaped tail bones during this week of Valentine’s Day.”
Recent findings by the research team in the Rukwa Rift Basin include:
· Early evidence for monkey-ape split, Rukwa Rift Basin Project
· Early evidence of insect farming — Fossil Termite Nests, Rukwa Rift Basin
“The Tanzanian story is far from over but we know enough to start asking what paleontological and geological similarities and dissimilarities there are with nearby rock units. Revisiting Malawi is my top priority to address these broader, regional questions,” said Gorscak, who also participates in ongoing projects in Egypt and Kenya. “With Mnyamawamtuka and other discoveries, I’m not sure to view it as writing or reading the next chapters in the paleontological book of Africa. I’m just excited to see where this story is going to take us.”
Reference:
Eric Gorscak, Patrick M. O’Connor. A new African Titanosaurian Sauropod Dinosaur from the middle Cretaceous Galula Formation (Mtuka Member), Rukwa Rift Basin, Southwestern Tanzania. PLOS ONE, 2019; 14 (2): e0211412 DOI: 10.1371/journal.pone.0211412
