Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1,200 °C (1,292 to 2,192 °F). The structures resulting from subsequent solidification and cooling are also sometimes described as lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms.
A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption. When it has stopped moving, lava solidifies to form igneous rock. The term lava flow is commonly shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties.
Lava sampling: Why do we do it?
Hot lava samples provide important information about what’s going on in a volcano’s magma chambers.
We know from laboratory experiments that the more magnesium there is in magma, the hotter it is. Chemical analysis, therefore, provides the means not only to determine the crystallization history of lava but also to establish the temperature at which it was erupted.
For example, Kilauea’s 1997 lavas are chemically different from lavas erupted from 1985 to 1997. Chemical analyses show that magma was supplied by two distinct magma bodies.
Bismuth is a chemical element with symbol Bi and atomic number 83. It is a pentavalent post-transition metal and one of the pnictogens with chemical properties resembling its lighter homologs arsenic and antimony. Elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it a pink tinge. Bismuth is marginally radioactive, and the most naturally diamagnetic element, and has one of the lowest values of thermal conductivity among metals.
Bismuth was long considered the element with the highest atomic mass that is stable, but in 2003 it was discovered to be extremely weakly radioactive: its only primordial isotope, bismuth-209, decays via alpha decay with a half-life more than a billion times the estimated age of the universe. Because of its tremendously long half-life, bismuth may still be considered stable for almost all purposes.
Bismuth metal has been known since ancient times, although it was often confused with lead and tin, which share some physical properties. The etymology is uncertain, but possibly comes from Arabic bi ismid, meaning having the properties of antimony or the German words weiße Masse or Wismuth (“white mass”), translated in the mid-sixteenth century to New Latin bisemutum.
Bismuth compounds account for about half the production of bismuth. They are used in cosmetics, pigments, and a few pharmaceuticals, notably bismuth subsalicylate, used to treat diarrhea. Bismuth’s unusual propensity to expand upon freezing is responsible for some of its uses, such as in casting of printing type. Bismuth has unusually low toxicity for a heavy metal. As the toxicity of lead has become more apparent in recent years, there is an increasing use of bismuth alloys (presently about a third of bismuth production) as a replacement for lead.
Findings about the effect of a volcano’s age on its likelihood to erupt will be applied to the Merapi volcano in Indonesia, among others. Credit: Jimmy McIntyre, licensed under CC BY-SA 2.0
The eruption of a volcano can have devastating consequences – killing people and destroying livelihoods, as well as releasing vast amounts of ash into the sky that disrupts air travel and alters the climate. Knowing what goes on underground, however, would facilitate better warnings for when an eruption will occur – and help save lives while keeping damage to a minimum.
“Understanding volcanoes is an international effort. The impact of eruptions does not stop at borders,” said volcanologist Dr. Catherine Annen of the University Savoie Mont Blanc in France.
Though relatively small, the eruption of the Eyjafjallajökull volcano in southern Iceland in 2010 sticks in many people’s memories. Its drifting plume of ash led to the widespread cancellation of flights across Europe.
Today, other, bigger volcanoes seem to be on the brink of eruption. Seismic observations suggest that Italy’s Campi Flegrei, a supervolcano close to millions of people living in and around Naples, is amassing magma in a dangerous ‘hot zone’.
But such observations only give rough forecasts – usually days, weeks or months in advance – of when a volcano will erupt. “The uncertainty arises from the fact that we cannot see what is happening underground,” said Dr. Annen.
Scientists such as Dr. Annen already have a fair idea of what goes on. Being less dense than surrounding rock, magma from deep within the Earth can rise up, potentially finding an outlet at thinner points – volcanoes – in the planet’s crust.
Foaming and freezing
Magma cools as it rises, and if we are lucky it will freeze, or solidify, before ever erupting. On the other hand, the pressure close to the surface drops too, and this liberates dissolved gases, which increase the chances of a foaming explosion – a bit like opening a shaken fizzy drink bottle.
Dr. Stephan Kolzenburg, a volcanologist at McGill University in Montreal, Canada, said: “These two processes – foaming and freezing – compete, and depending on which one wins, the volcano will or will not erupt.”
The foaming and solidification processes also lie at the heart of mathematical volcano models. Through a research project called DYNAVOLC, Dr. Kolzenburg hopes that by better understanding the competition between the two processes, and by linking them to geophysical signals recorded on the Earth’s surface, he will be able to improve the hazard maps depicting the areas most likely to be affected by volcanic eruptions.
Although his research project only began in April, it has already yielded results. In one study, Dr. Kolzenburg found that the faster magma and lava flows, the faster it solidifies – knowledge that could improve the volcano models.
Not all volcanoes behave in the same way, however. Having had longer to store magma, old volcanoes tend to be hotter than young volcanoes, and this determines, for instance, the level of ground swelling close to eruption.
Volcano’s age
Dr. Annen is interested in how a volcano’s age affects this and other potential warning signals. Through a project called MAGMATS, she is simulating on computers the interaction of magma and gases to understand how key volcano parameters change over thousands to hundreds of thousands of years.
Such parameters include temperature, gas content and magma content – none of which vary in a simple, linear fashion with one another. “Simulating the processes is challenging,” she said.
Nevertheless, the work should help the prediction of an eruption to be better tailored to a volcano’s age – and thus more accurate. Dr. Annen hopes to apply her findings to four active volcanoes: Campi Flegrei in Italy, Uturunku in Bolivia, Merapi in Indonesia and Krafla in Iceland.
“I would like to know if there are large volumes of magma ready to erupt close to the surface – or if, on the contrary, any eruption must first involve new magma transfer from deeper levels,” she said. Ultimately, she hopes that ‘any decision about evacuation will be better informed.”
Representative Image: A light photograph of a pyritized, egg-bearing specimen of Triarthrus eatoni. Credit: Image courtesy of Western Illinois University
The first appearance of trilobites in the fossil record dates to 521 million years ago in the oceans of the Cambrian Period, when the continents were still inhospitable to most life forms. Few groups of animals adapted as successfully as trilobites, which were arthropods that lived on the seabed for 270 million years until the mass extinction at the end of the Permian approximately 252 million years ago.
The longer ago organisms lived, the more rare are their fossils and the harder it is to understand their way of life; paleontologists face a daunting task in endeavoring to establish evolutionary relationships in time and space.
Surmounting the difficulties inherent in the investigation of a group of animals that lived such a long time ago, Brazilian scientists affiliated with the Biology Department of São Paulo State University’s Bauru School of Sciences (FC-UNESP) and the Paleontology Laboratory of the University of São Paulo’s Ribeirão Preto School of Philosophy, Science and Letters (FFCLRP-USP) have succeeded for the first time in inferring paleobiogeographic patterns among trilobites.
Paleobiogeography is a branch of paleontology that focuses on the distribution of extinct plants and animals and their relations with ancient geographic features. The study was conducted by Fábio Augusto Carbonaro, a postdoctoral researcher at UNESP’s Bauru Macroinvertebrate Paleontology Laboratory (LAPALMA) headed by Professor Renato Pirani Ghilardi. Other participants included Max Cardoso Langer, a professor at FFCLRP-USP, and Silvio Shigueo Nihei, a professor at the same university’s Bioscience Institute (IB-USP).
The researchers analyzed the morphological differences and similarities of the 11 species of trilobites described so far in the genus Metacryphaeus; these trilobites lived during the Devonian between 416 million and 359 million years ago (mya) in the cold waters of the sea that covered what is now Bolivia, Peru, Brazil, the Malvinas (Falklands) and South Africa.
The Devonian Period is subdivided into seven stages. Metacryphaeus lived during the Lochkovian (419.2-410.8 mya) and Pragian (410.8- 407.6 mya) stages, which are the earliest Devonian stages.
The results of the research were published in Scientific Reports and are part of the project “Paleobiogeography and migratory routes of paleoinvertebrates of the Devonian in Brazil,” which is supported by São Paulo Research Foundation -FAPESP and Brazil’s National Council for Scientific and Technological Development (CNPq). Ghilardi is the project’s principal investigator.
“When they became extinct in the Permian, 252 million years ago, the trilobites left no descendants. Their closest living relatives are shrimps, and, more remotely, spiders, scorpions, sea spiders and mites,” Ghilardi said.
Trilobite fossils are found abundantly all over the world, he explained — so abundantly that they are sometimes referred to as the cockroaches of the sea. The comparison is not unwarranted because anatomically, the trilobites resemble cockroaches. The difference is that they were not insects and had three longitudinal body segments or lobes (hence the name).
In the northern hemisphere, the trilobite fossil record is very rich. Paleontologists have so far described ten orders comprising over 17,000 species. The smallest were 1.5 millimeters long, while the largest were approximately 70 cm long and 40 cm wide. Perfectly preserved trilobites can be found in some regions, such as Morocco. These can be beautiful when used to create cameos or intaglio jewelry. Trilobite fossils from Brazil, Peru and Bolivia, in contrast, are often poorly preserved, consisting merely of the impressions left in benthic mud by their exoskeletons.
“Although their state of preservation is far from ideal, there are thousands of trilobite fossils in the sediments that form the Paraná basin in the South region of Brazil, and the Parnaíba basin along the North-Northeast divide,” said Ghilardi, who also chairs the Brazilian Paleontology Society.
According to Ghilardi, their poor state of preservation could be due to the geological conditions and climate prevailing in these regions during the Paleozoic Era, when the portions of dry land that would one day form South America were at the South Pole and entirely covered by ice for prolonged periods.
During the Devonian, South America and Africa were connected as part of the supercontinent Gondwana. South Africa was joined with Uruguay and Argentina in the River Plate region, and Brazil’s southern states were continuous with Namibia and Angola.
Parsimonious analysis
The research began with an analysis of 48 characteristics (size, shape and structure of organs and anatomical parts) found in some 50 fossil specimens of the 11 species of Metacryphaeus.
“In principle, these characteristics serve to establish their phylogeny — the evolutionary history of all species in the universe, analyzed in terms of lines of descent and relationships among broader groups,” Ghilardi said.
Known as a parsimonious analysis, this method is widely used to establish relationships among organisms in a given ecosystem, and in recent years, it has also begun to be used in the study of fossils.
According to Ghilardi, parsimony, in general, is the principle that the simplest explanation of the data is the preferred explanation. In the analysis of phylogeny, it means that the hypothesis regarding relationships that requires the smallest number of characteristic changes between the species analyzed (in this case, trilobites of the genus Metacryphaeus) is the one that is most likely to be correct.
The biogeographic contribution to the study was made by Professor Nihei, who works at IB-USP as a taxonomist and insect systematist. The field of systematics is concerned with evolutionary changes between ancestries, while taxonomy focuses on classifying and naming organisms.
“Biogeographic analysis typically involves living groups the ages of which are estimated by molecular phylogeny, or the so-called molecular clock, which estimates when two species probably diverged on the basis of the number of molecular differences in their DNA. In this study of trilobites, we used age in a similar manner, but it was obtained from the fossil record,” Nihei said.
“The main point of the study was to use fossils in a method that normally involves molecular biogeography. Very few studies of this type have previously involved fossils. I believe our study paves the way for a new approach based on biogeographic methods requiring a chronogram [a molecularly dated cladogram] because this chronogram can also be obtained from fossil taxa such as those studied by paleontologists, rather than molecular cladograms for living animals.”
As a vertebrate paleontologist who specializes in dinosaurs, Langer acknowledged that he knows little about trilobites but a great deal about the modern computational techniques used in parsimonious analysis, on which his participation in the study was based. “I believe the key aspect of this study, and the reason it was accepted for publication in as important a journal as Scientific Reports, is that it’s the first ever use of parsimony to understand the phylogeny of a trilobite genus in the southern hemisphere,” he said.
Gondwanan dispersal
The results of the paleobiogeographical analyses reinforce the pre-existing theory that Bolivia and Peru formed the ancestral home of Metacryphaeus.
“The models estimate a 100% probability that Bolivia and Peru formed the ancestral area of the Metacryphaeus clade and most of its internal clades,” Ghilardi said. Confirmation of the theory shows that parsimonious models have the power to suggest the presence of clades at a specific moment in the past even when there are no known physical records of that presence.
In the case of Metacryphaeus, the oldest records in Bolivia and Peru date from the early Pragian stage (410.8-407.6 mya), but the genus is believed to have evolved in the region during the Lochkovian stage (419.2-410.8 mya).
Parsimony, therefore, suggests Metacryphaeus originated in Bolivia and Peru some time before 410.8 mya but not earlier than 419.2 mya. In any event, it is believed to be far older than any known fossils.
According to Ghilardi, the results can be interpreted as showing that the adaptive radiation of Metacryphaeus to other areas of western Gondwana occurred during episodes of marine transgression in the Lochkovian-Pragian, when the sea flooded parts of Gondwana.
“The dispersal of Metacryphaeus trilobites during the Lochkovian occurred from Bolivia and Peru to Brazil — to the Paraná basin, now in the South region, and the Parnaíba basin, on the North-Northeast divide — and on toward the Malvinas/Falklands, while the Pragian dispersal occurred toward South Africa,” he said.
Fossil trilobites have been found continuously in the Paraná basin in recent decades. Trilobites collected in the late nineteenth century in the Parnaíba basin were held by Brazil’s National Museum in Rio de Janeiro, which was destroyed by fire in September 2018.
“These fossils haven’t yet been found under the rubble and it’s likely that nothing is left of them. They were mere shell impressions left in the ancient seabed. Even in petrified form, they must have dissolved in the blaze,” Ghilardi said.
Reference:
Fábio Augusto Carbonaro, Max Cardoso Langer, Silvio Shigueo Nihei, Gabriel de Souza Ferreira, Renato Pirani Ghilardi. Inferring ancestral range reconstruction based on trilobite records: a study-case on Metacryphaeus (Phacopida, Calmoniidae). Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-33517-5
Part of a quilted Ediacaran fossil is partly covered by ancient wind-drift from Namibia. Image courtesy of Greg Retallack.
New clues emerging from fossils found in the oldest soils on Earth suggest that multicellular, land-dwelling organisms possibly emerged much earlier than thought.
The evidence for such a conclusion emerged from fossil assemblages, previously considered to be ocean organisms, found in thin layers of silt and sand located between thicker sandstone beds in South Australia. The sediments date to between 542 million to 635 million years ago – during a geological period known as the Ediacaran.
“These Ediacaran organisms are one of the enduring mysteries of the fossil record,” said Greg Retallack, fossil collections director at the University of Oregon’s Museum of Natural and Cultural History. “Were they worms, sea jellies, sea pens, amoebae, algae? They are notoriously difficult to classify, but conventional wisdom has long held that they were marine organisms.”
Retallack’s new study, published online in November and in the January issue of the journal Sedimentary Geology, suggests otherwise based on a geochemical and microscopic re-examination of both the age and environmental associations in the thin, silty-to-sandy layers.
The sediments, known as interflag sandstone laminae, reveal telltale marks of ancient wind erosion—phenomena more closely associated with modern river banks than with oceans or seas. These thin, alternating layers, which are light in color and rich in fine grain sizes, appear similar to sheets of white paper between books bound in brown and red, Retallack noted.
“Such wind-drifted layers are widespread on river levees and sandbars today. They are present throughout the Flinders Ranges of South Australia and also in Ediacaran rocks of southern Namibia,” he said.
The emergence of multicellular life on land dates to about 565 million years ago, although there is debate on whether Ediacaran fossils of that age originated from organisms in the sea or on land, Retallack said.
If the sediments themselves were deposited on dry land, it would follow that the organisms fossilized there were land dwellers, said Retallack, who also is a professor in the UO’s Department of Earth Sciences. The organisms that left the fossils, he said, would have been from multicellular organisms visible with the naked eye. Such life would have preceded the emergence of green plant vegetation, which is believed to have started between 470 million and 583 million years ago.
Last November, Retallack and Nora Noffke of Old Dominion University had reported on traces of life left in 3.7 billion-year-old soils in a metamorphic rock formation in southwestern Greenland. In the journal Palaeogeography, Palaeoclimatology, Palaeoecology, they identified isotopic ratios of carbon potentially indicative of early land-dwelling microbes.
While the Ediacaran organisms remain enigmatic when it comes to biological classification, Retallack’s new study offers some important clues.
“The investigation points to a terrestrial habitat for some of these organisms, and combined with growing evidence from studies of fossil soils and biological soil crust features, it suggests that they may have been land creatures such as lichens,” Retallack said.
For the paper, Retallack also re-examined well-known interflag sandstone laminae at four southern Indiana locations, which date to the Pennsylvanian period, and a central Colorado site from the Eocene epoch. These locations and examination of modern rivers showed the same sedimentary processes seen in Ediacaran rocks of South Australia and Africa.
Reference:
Gregory J. Retallack. Interflag sandstone laminae, a novel sedimentary structure, with implications for Ediacaran paleoenvironments, Sedimentary Geology (2018). DOI: 10.1016/j.sedgeo.2018.11.003
Gregory J. Retallack et al. Multiple Early Triassic greenhouse crises impeded recovery from Late Permian mass extinction, Palaeogeography, Palaeoclimatology, Palaeoecology (2010). DOI: 10.1016/j.palaeo.2010.09.022
Life reconstruction of ichthyosaur skull. Credit: Bob Nicholls (Thinktank, Birmingham Science Museum)
A nearly metre-long skull of a giant fossil marine ichthyosaur found in a farmer’s field more than 60 years ago has been studied for the first time.
Using cutting-edge computerised tomography (CT) scanning technology, the research reveals new information including details of the rarely preserved braincase.
The almost 200 million year old fossil, which was found in 1955 at Fell Mill Farm in Warwickshire, had never formally been studied prior to this research.
Now, thanks to data collected from CT scans, the research team were able to digitally reconstruct the entire skull in 3D. It is the first time a digital reconstruction of a skull and mandible of a large marine reptile has ever been made available for research purposes and to the public.
Although thousands of ichthyosaur fossils have been unearthed in the UK, this specimen is particularly important and unusual because it is three-dimensionally preserved and contains bones of the skull that are rarely exposed.
In 2014, as part of a project at Thinktank Science Museum, Birmingham, palaeontologists Dean Lomax, from The University of Manchester, and Nigel Larkin began to study the skull and its incomplete skeleton for the first time and were soon convinced of its importance.
Dean, the lead author and one of the world’s leading ichthyosaur experts, explains: “The first time I saw this specimen I was puzzled by its excellent preservation.
Ichthyosaurs of this age (Early Jurassic) are usually ‘pancaked’, meaning that they are squished so that the original structure of the skull is either not preserved or is distorted or damaged. So to have a skull and portions of the skeleton of an ichthyosaur of this age preserved in three dimensions, and without any surrounding rock obscuring it, is something quite special.”
The ichthyosaur was originally identified as a common species called Ichthyosaurus communis, but after studying it closer, Dean was convinced it was a rarer species. Based on various features of the skull, he identified it as an example of an ichthyosaur called Protoichthyosaurus prostaxalis. With a skull almost twice as long as any other specimen of Protoichthyosaurus, this is the largest specimen so far known of the species.
Co-author Nigel Larkin added: “Initially, the aim of the project was to clean and conserve the skull and partially dismantle it to rebuild it more accurately, ready for redisplay at the Thinktank Museum. But we soon realised that the individual bones of the skull were exceptionally well preserved in three dimensions, better than in any other ichthyosaur skull we’d seen. Furthermore, that they would respond well to CT scanning, enabling us to capture their shape digitally and to see their internal details. This presented an opportunity that couldn’t be missed”
The skull isn’t quite complete, but several bones of the braincase — which are rarely preserved in ichthyosaurs — are present. To unlock information contained in the skull, these bones were micro-CT scanned at Cambridge University in 2015 by expert palaeontologist and co-author, Dr Laura Porro of University College London (UCL).
The fossil only preserved bones from the left side of the braincase; however, using CT scans these elements were digitally mirrored and 3D printed at life size to complete the braincase. Finally, the entire skull was CT scanned at the Royal Veterinary College (RVC) using a scanner typically reserved for horses and other large animals.
Dr Porro added: “CT scanning allows us to look inside fossils — in this case, we could see long canals within the skull bones that originally contained blood vessels and nerves. Scans also revealed the curation history of the specimen since its discovery in the ’50s. There were several areas reconstructed in plaster and clay, and one bone was so expertly modelled that only the scans revealed part of it was a fake. Finally there is the potential to digitally reconstruct the skull in 3D. This is hard (and risky) to do with the original, fragile and very heavy fossil bones; plus, we can now make the 3D reconstruction freely available to other scientists and for education.”
The use of modern technologies, such as medical scanners, have revolutionised the way in which palaeontologists are able to study and describe fossils.
Dean added: “It’s taken more than half a century for this ichthyosaur to be studied and described, but it has been worth the wait. Not only has our study revealed exciting information about the internal anatomy of the skull of this animal, but our findings will aid other palaeontologists in exploring its evolutionary relationship with other ichthyosaurs.”
Reference:
Dean R. Lomax, Laura B. Porro, Nigel R. Larkin. Descriptive anatomy of the largest known specimen of Protoichthyosaurus prostaxalis (Reptilia: Ichthyosauria) including computed tomography and digital reconstruction of a three-dimensional skull. PeerJ, 2019; 7: e6112 DOI: 10.7717/peerj.6112
Map of the locations and depths of the deep low-frequency (DLF) earthquakes beneath the Laacher See Volcano (“Lake Laach Volcano”) in Germany. Brittle earthquakes are marked as circles, DLF events as stars. Credit: Hensch et al.
Magma could rise from the upper mantle into the middle and upper crust beneath the Laacher See Volcano (Rhineland-Palatinate). This is the result of a study conducted by the Seismological Survey of Southwest Germany (Erdbebendienst Südwest), together with GFZ German Research Centre for Geosciences, Karlsruhe Institute of Technology (KIT) and the Seismological Survey of North Rhine-Westphalia. For the first time, the scientists present evidence of deep and low-frequency earthquakes caused by magma movements under the Laacher See Volcano. However, there are presently no signs of any upcoming volcanic activity in the near future. The researchers report their findings in Geophysical Journal International.
“The detected earthquakes are generated at large depths and are characterized by unusually low frequencies. Their magnitudes are below the limit of human perception,” explains Professor Joachim Ritter of the Geophysical Institute (GPI) at KIT. The scientists speak of “deep low-frequency” (DLF) earthquakes. They are generated at depths between ten and over forty kilometres, i.e. in the Earth’s crust and upper mantle. Their dominant oscillation frequencies are between one and ten Hertz, which is significantly lower than tectonic earthquakes of comparable magnitude.
“DLF earthquakes are regarded worldwide as an indication of the movement of magmatic fluids at great depths,” explains Professor Torsten Dahm, head of the GFZ section Physics of Earthquakes and Volcanoes. “Such earthquakes can be observed regularly beneath active volcanoes, for example in Iceland, Japan or Kamchatka.” The results of the study in the East Eifel region suggest that magmatic fluids from the upper mantle of the Earth could rise into the Earth’s crust under the Laacher See Volcano. This can be interpreted as an indication for the existence and ongoing slow recharge of magma chambers in the crust beneath the volcano.
In their study, the scientists of KIT, GFZ, Erdbebendienst Südwest — the joint seismological services of Rhineland-Palatinate and Baden-Württemberg — and the State Seismological Service of North Rhine-Westphalia determined that these earthquakes occur episodically in groups that are narrowly limited in time and space and line up along a line between 10 and 45 kilometres depth The scientists conclude that fluids and magmas, i.e. molten rock, could rise from the upper mantle into the middle and upper crust of the earth beneath the Laacher See Volcano.
“Due to extensive improvements of the seismological monitoring networks in Rhineland-Palatinate and the adjacent regions, deep low-frequency earthquakes could be registered beneath the Laacher See Volcano for the first time in 2013,” says Dr. Martin Hensch, head of the study at the Erdbebendienst Südwest. “In the past five years, a total of four spatially well constrained clusters of such DLF earthquakes have been detected in the East Eifel region.” The clusters align along an approximately 80° southeast dipping line south of the Laacher See Volcano. In addition to the spatial separation, the temporal occurrence of the DLF earthquakes is also sharply limited: So far, the experts have observed eight episodes of DLF earthquakes lasting between 40 seconds and eight minutes.
However, the researchers do not interpret the observed DLF earthquakes as an immediate precursor signal of any upcoming volcanic activity in the near future. “The rise of magma into the shallow crust is usually accompanied by swarms of high-frequency earthquakes. Such activity has not yet been observed in the Eastern Eifel,” reports Joachim Ritter. “Further, there is no sign of deformation at the Earth’s surface, which should be clearly detectable during massive magma ascents,” adds Torsten Dahm. Dating of the magma produced during the last eruption 12,900 years ago show that the filling and differentiation of the upper magma chamber under Laacher See Volcano could have taken about 30,000 years before the actual eruption took place. This means that the magmatic processes take an extremely long time before an eruption occurs. As the technical requirements for the detection and localization of DLF earthquakes in the East Eifel region have only reached a sufficient quality in the last few years, it is not possible to determine retrospectively since when DLF earthquakes have occurred in the region. It can be assumed that this was already the case before 2013. Following the first observation of deep earthquakes in 2013, KIT, GFZ and Erdbebendienst Südwest installed a seismological research network. The joint use of seismic registrations now allows detailed scientific analysis of microseismicity.
In order to better investigate the interrelation of DLF earthquakes and possible magmatic activity beneath the East Eifel region, the researchers recommend to intensify geochemical monitoring to analyse emitted gases, as well as repeated geodetic measurements to detect possible deformations of the earth’s surface. Specific geophysical investigations should also be conducted to map and characterize possible magma reservoirs under the Laacher See Volcano. Further, the scientists advise a reassessment of the volcanic hazard of the Eifel.
Reference:
Martin Hensch, Torsten Dahm, Joachim Ritter, Sebastian Heimann, Bernd Schmidt, Stefan Stange, Klaus Lehmann. Deep low-frequency earthquakes reveal ongoing magmatic recharge beneath Laacher See Volcano (Eifel, Germany). Geophysical Journal International, 2019; DOI: 10.1093/gji/ggy532
Doctoral students Daniel Miller, in the water, with Helen Habicht and Benjamin Keisling, handle two recaptured sediment traps from an unusually deep lake in central Maine, where they collected 136 sediment samples spanning the 900-year time span to reconstruct the longest and highest-resolution climate record for the Northeastern United States to date. Credit: UMass Amherst
Deploying a new technique for the first time in the region, geoscientists at the University of Massachusetts Amherst have reconstructed the longest and highest-resolution climate record for the Northeastern United States, which reveals previously undetected past temperature cycles and extends the record 900 years into the past, well beyond the previous early date of 1850.
First author Daniel Miller, with Helen Habicht and Benjamin Keisling, conducted this study as part of their doctoral programs with advisors geosciences professors Raymond Bradley and Isla Castañeda. As Miller explains, they used a relatively new quantitative method based on the presence of chemical compounds known as branched glycerol dialkyl glycerol tetra ethers (branched GDGTs) found in lakes, soils, rivers and peat bogs around the world. The compounds can provide an independent terrestrial paleo-thermometer that accurately assesses past temperature variability.
Miller says, “This is the first effort using these compounds to reconstruct temperature in the Northeast, and the first one at this resolution.” He and colleagues were able to collect a total of 136 samples spanning the 900-year time span, many more than would be available with more traditional methods and from other locations that typically yield just one sample per 30-100 years.
In their results, Miller says, “We see essentially cooling throughout most of the record until the 1900s, which matches other paleo-records for North America. We see the Medieval Warm Period in the early part and the Little Ice Age in the 1800s.” An unexpected observation was 10, 50-to-60-year temperature cycles not seen before in records from Northeast U.S., he adds, “a new finding and surprising. We’re trying to figure out what causes that. It may be caused by changes in the North Atlantic Oscillation or some other atmospheric patterns. We’ll be looking further into it.”
He adds, “We’re very excited about this. I think it’s a great story of how grad students who come up with a promising idea, if they have enough support from their advisors, can produce a study with really eye-opening results.” Details appear in a recent issue of the European Geophysical Union’s open-access online journal, Climate of the Past.
The authors point out that paleo-temperature reconstructions are essential for distinguishing human-made climate change from natural variability, but historical temperature records are not long enough to capture pre-human-impact variability. Further, using conventional pollen- and land-based sediment samples as climate proxies can reflect confounding parameters rather than temperature, such as precipitation, humidity, evapo-transpiration and vegetation changes.
Therefore, additional quantitative paleo-temperature records are needed to accurately assess past temperature variability in the Northeast United States, the researchers point out. An independent terrestrial paleo-thermometer that relies on measuring two byproducts of processes carried out in branched GDGTs in lake sediment, a method first introduced two decades ago by researchers in The Netherlands, offered a promising alternative, Miller says.
Source organisms are not known for branch GDGTs, he points out, but they are thought to be produced in part by Acidobacteria. “These are compounds likely produced by different algae and bacteria communities in the membrane, or skin,” he notes. “Just like for humans, the skin regulates the organism’s body temperature and these compounds change in response to temperature. So if they grow in summer, they reflect that and the compounds are different than if they were produced in winter. We record the compounds to get the temperature curves. We found there seems to be a huge bloom of these organisms in the fall. After they die, they settle into the lake bottom. We think it’s mainly a fall temperature that we’re detecting.”
For this work, Miller and colleagues constructed large plastic sediment traps and deployed them about ten feet below the surface of a small, 106-foot-deep lake in central Maine in May, 2014. They then dove under to collect a catchment bottle from the bottom of each trap every month in June, July, August and September, and the following May 2015.
Miller says, “This lake is very deep for its small area, with very steep sides. It doesn’t seem to have much mixing of water layers by surface winds. We think that has helped to preserve a bottom water layer with no oxygen year-round, known as anoxia, which helps in the preservation of annual layers in the sediments at the bottom of the lake. It’s rare for a lake to have such fine, thin lines that represent annual deposition, so all you have to do is count the lines to count the years. We double-checked our results with radiocarbon dating and other methods, and it turns out that reconstructing the temperature record this way was successful.”
Miller and colleagues say this project enjoyed notable support from many quarters, including the UMass Amherst Alumni Association supporting student field work and data collection in Maine; the geology department at Bates College; funding from the U.S. Geological Survey; and at UMass Amherst, sophisticated biogeochemistry laboratory equipment and the Joe Hartshorn Memorial Award from the geosciences department, and other assistance from the Northeast Climate Adaptation Science Center.
The researchers conclude that this first paleo-temperature reconstruction coupled with site-specific knowledge from Basin Pond “informs our understanding of climatic variability in the Northeast U.S. beyond the era of human influence” and “contributes to our understanding of the production and fate of brGDGTs” in lake systems.
Reference:
Daniel R. Miller, M. Helen Habicht, Benjamin A. Keisling, Isla S. Castañeda, Raymond S. Bradley. A 900-year New England temperature reconstruction from in situ seasonally produced branched glycerol dialkyl glycerol tetraethers (brGDGTs). Climate of the Past, 2018; 14 (11): 1653 DOI: 10.5194/cp-14-1653-2018
A snapshot of seismic data taken at a single station during the peak of an aftershock sequence. Credit: Zachary Ross/Caltech
Understanding earthquakes is a challenging problem—not only because they are potentially dangerous but also because they are complicated phenomena that are difficult to study. Interpreting the massive, often convoluted data sets that are recorded by earthquake monitoring networks is a herculean task for seismologists, but the effort involved in producing accurate analyses could significantly improve the development of reliable earthquake early-warning systems.
A promising new collaboration between Caltech seismologists and computer scientists using artificial intelligence (AI)—computer systems capable of learning and performing tasks that previously required humans—aims to improve the automated processes that identify earthquake waves and assess the strength, speed, and direction of shaking in real time. The collaboration includes researchers from the divisions of Geological and Planetary Sciences and Engineering and Applied Science, and is part of Caltech’s AI4Science Initiative to apply AI to the big-data problems faced by scientists throughout the Institute. Powered by advanced hardware and machine-learning algorithms, modern AI has the potential to revolutionize seismological data tools and make all of us a little safer from earthquakes.
Recently, Caltech’s Yisong Yue, an assistant professor of computing and mathematical sciences, sat down with his collaborators, Research Professor of Geophysics Egill Hauksson, Postdoctoral Scholar in Geophysics Zachary Ross, and Associate Staff Seismologist Men-Andrin Meier, to discuss the new project and future of AI and earthquake science.
What seismological problem inspired you to include AI in your research?
Meier: One of the things that I work on is earthquake early warning. Early warning requires us to try to detect earthquakes very rapidly and predict the shaking that they will produce later so that you can get a few seconds to maybe tens of seconds of warning before the shaking starts.
Hauksson: It has to be done very quickly—that’s the game. The earthquake waves will hit the closest monitoring station first, and if we can recognize them immediately, then we can send out an alert before the waves travel farther.
Meier: You only have a few seconds of seismogram to decide whether it is an earthquake, which would mean sending out an alert, or if it is instead a nuisance signal—a truck driving by one of our seismometers or something like that. We have too many false classifications, too many false alerts, and people don’t like that. This is a classic machine-learning problem: you have some data and you need to make a realistic and accurate classification. So, we reached out to Caltech’s computing and mathematical science (CMS) department and started working on it with them.
Why is AI a good tool for improving earthquake monitoring systems?
Yue: The reasons why AI can be a good tool have to do with scale and complexity coupled with an abundant amount of data. Earthquake monitoring systems generate massive data sets that need to be processed in order to provide useful information to scientists. AI can do that faster and more accurately than humans can, and even find patterns that would otherwise escape the human eye. Furthermore, the patterns we hope to extract are hard for rule-based systems to adequately capture, and so the advanced pattern-matching abilities of modern deep learning can offer superior performance than existing automated earthquake monitoring algorithms.
Ross: In a big aftershock sequence, for example, you could have events that are spaced every 10 seconds, rapid fire, all day long. We use maybe 400 stations in Southern California to monitor earthquakes, and the waves caused by each different earthquake will hit them all at different times.
Yue: When you have multiple earthquakes, and the sensors are all firing at different locations, you want to be able to unscramble which data belong to which earthquake. Cleaning up and analyzing the data takes time. But once you train a machine-learning algorithm—a computer program that learns by studying examples as opposed to through explicit programing—to do this, it could make an assessment really quickly. That’s the value.
How else will AI help seismologists?
Yue: We are not just interested in the occasional very big earthquake that happens every few years or so. We are interested in the earthquakes of all sizes that happen every day. AI has the potential to identify small earthquakes that are currently indistinguishable from background noise.
Ross: On average we see about 50 or so earthquakes each day in Southern California, and we have a mandate from the U.S. Geological Survey to monitor each one. There are many more, but they’re just too small for us to detect with existing technology. And the smaller they are, the more often they occur. What we are trying to do is monitor, locate, detect, and characterize each and every one of those events to build “earthquake catalogs.” All of this analysis is starting to reveal the very intricate details of the physical processes that drive earthquakes. Those details were not really visible before.
Why hasn’t anyone applied AI to seismology before?
Ross: Only in the last year or two has seismology started to seriously consider AI technology. Part of it has to do with the dramatic increase in computer processing power that we have seen just within the past decade.
What is the long-term goal of this collaboration?
Meier: Ultimately, we want to build an algorithm that mimics what human experts do. A human seismologist can feel an earthquake or see a seismogram and immediately tell a lot of things about that earthquake just from experience. It was really difficult to teach that to a computer. With artificial intelligence, we can get much closer to how a human expert would treat the problem. We are getting much closer to creating a “virtual seismologist.”
Why do we need a “virtual seismologist?”
Yue: Fundamentally both in seismology and beyond, the reason that you want to do this kind of thing is scale and complexity. If you can train an AI that learns, then you can take a specialized skill set and make it available to anyone. The other issue is complexity. You could have a human look at detailed seismic data for a long time and uncover small earthquakes. Or you could just have an algorithm learn to pick out the patterns that matter much faster.
Meier: The detailed information that we’re gathering helps us figure out the physics of earthquakes—why they fizzle out along certain faults and trigger big quakes along others, and how often they occur.
Will creating a “virtual seismologist” mean the end of human seismologists?
Ross: Having talked to a range of students, I can say with fairly high confidence that most of them don’t want to do cataloguing work. [Laughs.] They would rather be doing more exciting work.
Yue: Imagine that you’re a musician and before you can become a musician, first you have to build your own piano. So you spend five years building your piano, and then you become a musician. Now we have an automated way of building pianos—are we going to destroy musicians’ jobs? No, we are actually empowering a new generation of musicians. We have other problems that they could be working on.
Four complete Tragychrysa ovoruptora newborns preserved together with egg shell remains and one visible egg burster (right inset). Credit: Modified from the open access article published in Palaeontology: ‘The hatching mechanism of 130-million-year-old insects: an association of neonates, egg shells, and egg bursters in Lebanese amber’
Fossilised newborns, egg shells, and egg bursters preserved together in amber provide the first direct evidence of how insects hatched in deep time, according to a new article published today in the journal Palaeontology.
One of the earliest and toughest trials that all organisms face is birth. The new findings give scientists evidence on how tiny insects broke the barrier separating them from life and took their first steps into an ancient forest.
Trapped together inside 130 million-year-old Lebanese amber, or fossilised resin, researchers found several green lacewing newborn larvae, the split egg shells from where they hatched, and the minute structures the hatchlings used to crack the egg, known as egg bursters. The discovery is remarkable because no definitive evidence of these specialised structures had been reported from the fossil record of egg-laying animals, until now.
The fossil newborns have been described as the new species Tragichrysa ovoruptora, meaning ‘egg breaking’ and ‘tragic green lacewing’, after the fact that multiple specimens were ensnared and entombed in the resin simultaneously.
“Egg-laying animals such as many arthropods and vertebrates use egg bursters to break the egg surface during hatching; a famous example is the ‘egg tooth’ on the beak of newborn chicks,” explains Dr Ricardo Pérez-de la Fuente, a researcher at Oxford University Museum of Natural History and lead author of the work. “Egg bursters are diverse in shape and location. Modern green lacewing hatchlings split the egg with a ‘mask’ bearing a jagged blade. Once used, this ‘mask’ is shed and left attached to the empty egg shell, which is exactly what we found in the amber together with the newborns.”
Green lacewing larvae are small hunters which often carry debris as camouflage, and use sickle-shaped jaws to pierce and suck the fluids of their prey. Although the larvae trapped in amber differ significantly from modern-day relatives, in that they possess long tubes instead of clubs or bumps for holding debris, the studied egg shells and egg bursters are remarkably similar to those of today’s green lacewings. Altogether, they provide the full picture of how these fossil insects hatched like their extant counterparts, about 130 million years ago during the Early Cretaceous.
“The process of hatching is ephemeral and the structures that make it possible tend to disappear quickly once egg-laying animals hatch, so obtaining fossil evidence of them is truly exceptional,” remarks Dr Michael S. Engel, a co-author of the study from the University of Kansas.
The Tragichrysa ovoruptora larvae were almost certainly trapped by resin while clutching the eggs from which they had freshly emerged. Such behaviour is common among modern relatives while their body hardens and their predatory jaws become functional. The two mouthparts forming the jaws are not interlocked in most of the fossil larvae, which further suggests that they were recently born.
All the preparations studied were obtained from the same amber piece and are as thin as a pinhead, allowing a detailed account of the fossils and finding the tiny egg bursters, according to Dr Dany Azar, another co-author of the work, from the Lebanese University, who discovered and prepared the studied amber samples.
It would seem reasonable to assume that traits controlling a life event as crucial as hatching would have remained quite stable during evolution. However, as Dr Enrique Peñalver of the Spanish Geological Survey (IGME; Geomining Museum) and co-author of the work explains: “There are known instances in modern insects where closely related groups, even down to the species level, show different means of hatching that can entail the loss of egg bursters. So, the long-term stability of a hatching mechanism in a given animal lineage cannot be taken for granted.”
Nonetheless, this new discovery in fossil green lacewings shows the existence 130 million years ago of a sophisticated hatching mechanism which endures to this day.
Reference:
Ricardo Pérez-de la Fuente, Michael S. Engel, Dany Azar, Enrique Peñalver. The hatching mechanism of 130-million-year-old insects: an association of neonates, egg shells and egg bursters in Lebanese amber. Palaeontology, 2018; DOI: 10.1111/pala.12414
Researchers state that many mammals lineages coexisted with the dinosaurs before the end-Cretaceous mass extinction. Although many species of mammals also disappeared in the extinction event, several lineages survived (image: origination, extinction and diversification rates for the three mammalian clades in North America. Dotted lines denote the Cretaceous-Paleogene boundary/ Biology Letters)
Mass extinction typically conjures up a picture of a meteor falling to Earth and decimating the dinosaurs along with everything else. However, this is not exactly what happened. Different groups of living beings were affected differently by the various mass extinctions that have occurred during the planet’s history.
Consider mammals, a class of vertebrates that already existed during the dinosaur era and survived the mass extinction event in which almost all the dinosaurs were wiped out 66 million years ago, marking the end of the Cretaceous Period.
Four lineages of mammals were contemporaries of the giant reptiles. All four survived. Some were worse hit than others. In a study published in the journal Biology Letters, biologists Tiago Bosisio Quental of the University of São Paulo (USP) and Mathias Pires of the University of Campinas (UNICAMP), both from Brazil, set out to understand how the different groups of mammals made it through the end-Cretaceous mass extinction. Their research was supported by São Paulo Research Foundation — FAPESP.
“When people talk about a mass extinction, it’s assumed that they’re referring to a single extinction event of exceptional magnitude during which a large number of species became extinct in a relatively short time,” Pires said.
Another way of looking at mass extinctions consists of observing the number of species in the fossil record. It can be inferred that a mass extinction occurred in a given geological period when the total number of species that disappeared from the fossil record was much higher than the number of new species that emerged.
“In other words, the extinction rate — the speed at which species are lost — surpasses the speciation rate — the speed at which species are created. This makes the diversification rate negative, since the diversification rate is given by the difference between the extinction and speciation rates,” Pires said.
Five great mass extinctions have been identified in the fossil record in the last 500 million years (as well as many others on a smaller scale). They occurred for various reasons, such as magma spills lasting thousands or millions of years and releasing billions of tons of greenhouse gases that poisoned the atmosphere and blocked out the sun’s rays.
This is what caused the worst of all mass extinctions, in which over 90% of species vanished. It happened 252 million years ago, marking the boundary between the Permian and Triassic Periods (and between the Paleozoic and Mesozoic Eras).
Mass extinctions have also been caused by huge greenhouse effects due to the release of billions of tons of carbon gas (CO2) trapped under the seabed. One such episode is believed to have occurred at the end of the Triassic some 201 million years ago, killing 80% of all species.
The reverse has also happened, with billions of tons of CO2 being sequestered from the atmosphere and causing temperatures to crash and ice to cover the planet. This was the case 444 million years ago at the end of the Ordovician, when 86% of life forms disappeared.
The mass extinction that occurred 66 million years ago is known as the K-Pg event. The acronym refers to the end of the Cretaceous (Kreide in German) and the onset of the Paleogene (Pg).
On a larger time scale, the K-Pg event marks the boundary between the Mesozoic, the era dominated by dinosaurs, and the Cenozoic, the era extending from 66 million years ago to the present day during which mammals have been one of the dominant groups on the planet.
The K-Pg event was caused by a combination of two factors: devastating magma spills in what is now India and the impact of a comet or asteroid with a diameter of 10 km on the Yucatán peninsula in Mexico.
“All these mass extinction episodes are heterogeneous. They occurred for different reasons and unfolded in different ways. Their impact on life forms was not absolute but relative. Some groups suffered more, others less. Some disappeared, while others took advantage of the new environmental conditions after the catastrophe to diversify rapidly,” Pires said.
In the new study that was supported by FAPESP, the researchers set out to investigate how the different lineages of mammals that existed at the end of the Cretaceous succeeded in emerging from the biotic bottleneck represented by the K-Pg event. Daniele Silvestro of the University of Gothenburg (Sweden) and Brian Rankin of the University of California Berkeley (USA) also participated in the study.
The great class of mammals emerged in the Triassic at least 220 million years ago. This is the age of the oldest known fossil. At the end of the Cretaceous, mammalian species were highly diversified. There were the Eutheria or placental mammals, the clade to which Homo sapiens belongs, as do all primates, rodents, bats, cetaceans, and ungulates, among others.
In addition, there were Metatheria or marsupials, the clade to which today’s opossums, kangaroos, and koalas belong. They shared the planet with monotremes (egg-laying mammals) and multituberculates (an extinct taxon of rodent-like mammals named for the specific shape of their teeth, which had multiple tubercles).
The study by Pires and Quental stresses that mammals were particularly hard hit by the mass extinction in the Cretaceous. This does not mean that all four groups suffered equally. The mass extinction was more severe for some than for others.
During the Cretaceous, between 145 million and 66 million years ago, the multituberculates were the dominant and most diversified group of mammals. We know this because multituberculates are the vast majority in the fossil record prior to the K-Pg event. Fossils of placentals and marsupials are less numerous but also plentiful.
Monotremes are the exception. Today, they are few and far between. Indeed, they are comprised of just two families: one includes the duck-billed platypus while the other regards echidnas. Monotremes are also rare in the fossil record both before and after the Cretaceous, suggesting that the group has always been relatively marginal among mammals. For this reason, the researchers did not include monotremes in their study.
Given the knowledge that there were multituberculates, placentals, and marsupials, which group of mammals was most severely affected by the K-Pg event? Which had the most surviving genera? Which displayed the largest increase in diversity (or highest speciation rate) in the millions of years that followed the biotic bottleneck? Which group failed to recover from the cataclysm?
The only way to find answers to these questions is by analyzing the fossil record in a specific region of the planet to try to ensure that all groups of mammals were affected more or less to the same extent by the catastrophe 66 million years ago and in that region.
Quental and Pires chose North America as the focus for their study. One hundred and fifty years of continuous paleontological prospecting in the region have created a detailed picture of mammalian diversity before, during and after the K-Pg event.
“North America has a fossil record of sufficient quality for this kind of study. Other studies have been conducted to analyze how mammals as a whole survived the Cretaceous extinction, but as far we know, this is one of the first studies to analyze the dynamics of diversification in the different groups of mammals,” Quental said.
Distinct diversification patterns
The scientists used a dataset containing 188 recent fossil assemblages from the Cretaceous and Paleocene (spanning from 69.9 million to 55 million years ago) located in the western interior of North America.
“The North American mammal fossil record has the richest and most extensively studied assemblages near the K-Pg event. Fossil occurrences are relatively well resolved, minimizing taxonomic uncertainty. This dataset includes information on nearly 290 genera of mammals, including multituberculates, eutherians, and metatherians,” Quental said.
Several advanced statistical methods were used to estimate origination, extinction and diversification patterns before, during and after the K-Pg event. The results showed that the three groups emerged very differently from the mass extinction.
The origination rate for Methateria (marsupials), for example, remained approximately constant throughout the studied interval. However, a clear peak in extinction was identified during the K-Pg, generating a pulse of negative net diversification. After the K-Pg, the extinction rate gradually diminished, but negative net diversification persisted for more than 2 million years until approximately 64 million years ago.
Multituberculates were diversifying toward the end of the Cretaceous prior to the K-Pg boundary, showing high origination rates and relatively low extinction rates. Near the K-Pg boundary, the extinction rate remained low, but a drop in origination reduced the diversification of multituberculates to near zero. In other words, during the K-Pg, the diversification rate was in balance, as roughly the same number of genera were being created and becoming extinct.
According to the study, after the K-Pg boundary, the extinction rate for multituberculates continued to fall; however, the decrease in multituberculates’ origination rate was even sharper, hence leading to negative diversification. Thus, the number of genera continued to diminish throughout the rest of the period analyzed, until 55 million years ago. The decline appears to have persisted for a long time, given that the multituberculates steadily disappear from the world fossil record. The clade ends approximately 35 million years ago.
Scientists believe the reason for the disappearance of the multituberculates may have been growing competition with rodents, a new eutherian lineage that originated shortly after the K-Pg in the Paleogene.
Eutherians (placentals) display high origination and high extinction near the K-Pg, resulting in high diversity turnover. Originations were higher than extinctions, except between 66 million and 64 million years ago.
Not long after this, there was a second origination pulse accompanied by a drop in the extinction rate, evidencing a short burst in diversification. Around 62 million years ago origination decreased and diversification remained around zero, suggesting diversity equilibrium.
“We found three diversification patterns among the mammalian groups. Metatheria (marsupials) conformed to the classic mass extinction response, with several temporally clustered extinctions leading to a sharp drop in diversification,” Quental said.
Multituberculates underwent a reduction in diversity, with a decrease in diversification and subsequent diversity loss driven by declining origination rates rather than extinction. In other words, their diversity diminished because the creation of new species took a long time.
“Among eutherians there was a more complex rise-and-fall pattern due to rapid fluctuations in the speciation rate during and just after the K-Pg, while the extinction rate rose but not enough to cause negative diversification for long,” Quental said.
According to Pires, the study shows that the K-Pg mass extinction was ecologically selective among mammalian lineages. “Extinctions were concentrated among the specialized carnivorous metatherians and insectivorous eutherians, whereas more generalized eutherians and multituberculates survived and maintained higher diversity,” he said.
Although the results suggest eutherians suffered substantial losses at the K-Pg boundary, these losses were offset by increased origination. Diversification may have occurred among the survivors as other groups of eutherians came to North America from other continents.
“The dietary plasticity of multituberculates may have enabled some species to persist, explaining the low extinction rates. The ecological and taxonomic diversity of multituberculates increased during the late Cretaceous. However, our analysis shows that the multituberculates failed to offset extinction losses because they created less and less diversity, unlike the eutherians, whose losses were offset by high origination rates,” Pires said.
In their conclusion, the authors note that when clades are assessed individually, mass extinction events may be seen as shifts in extinction, in origination, or in both regimes.
“This means that studies of macroevolutionary phenomena focusing on broad taxonomic groups may miss a much richer macroevolutionary history, which can be perceived only at finer taxonomic scales,” Pires said.
Reference:
Mathias M. Pires, Brian D. Rankin, Daniele Silvestro, Tiago B. Quental. Diversification dynamics of mammalian clades during the K–Pg mass extinction. Biology Letters, 2018; 14 (9): 20180458 DOI: 10.1098/rsbl.2018.0458
Bone microstructure (A–B) and skeletal reconstruction (C) of Saltriovenator zanellai. Photos by M. Zilioli; drawing by M. Auditore.
Early Jurassic predatory dinosaurs are very rare, and mostly small in size. Saltriovenator zanellai, a new genus and species described in the peer-reviewed journal PeerJ — the Journal of Life and Environmental Sciences by Italian paleontologists, is the oldest known ceratosaurian, and the world’s largest (one ton) predatory dinosaur from the Lower Jurassic (Sinemurian, ~198 Mya).
This unique specimen, which also represents the first Jurassic dinosaur from Italy, was accidentally discovered in 1996 by a fossil amateur within a quarry near Saltrio, some 80 km N-E of Milan. Many bones of Saltriovenator bear feeding marks by marine invertebrates, which represent the first case on dinosaurian remains and indicate that the dinosaur carcass floated in a marine basin and then sunk, remaining on the sea bottom for quite a long time before burial.
Although fragmentary, “Saltriovenator shows a mosaic of ancestral and advanced anatomical features, respectively seen in the four-fingered dilophosaurids and ceratosaurians, and the three-fingered tetanuran theropods, such as allosaurids,” says first author Cristiano Dal Sasso, of the Natural History Museum of Milan, who reassembled and studied the fossil for several years.
“Paleohistological analysis indicates that Saltriovenator was a still growing subadult individual, therefore its estimated size is all the more remarkable, in the context of the Early Jurassic period,” says co-author Simone Maganuco.
“The evolutionary ‘arms race’ between stockier predatory and giant herbivorous dinosaurs, involving progressively larger species, had already begun 200 million of years ago.”
The evolution of the hand of birds from their dinosaurian ancestors is still hotly debated. “The grasping hand of Saltriovenator fills a key gap in the theropod evolutionary tree: predatory dinosaurs progressively lost the pinky and ring fingers, and acquired the three-fingered hand which is the precursor of the avian wing,” remarks co-author Andrea Cau.
Reference:
Cristiano Dal Sasso, Simone Maganuco, Andrea Cau. The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds. PeerJ, 2018; 6: e5976 DOI: 10.7717/peerj.5976
Note: The above post is reprinted from materials provided by PeerJ.
One of the newly discovered millipede fossilized in Cretaceous amber from Myanmar (Burma). Credit: Dr Thomas Wesener CC-BY 4.0
Since the success of the Jurassic Park film series, it is widely known that insects from the Age of the Dinosaurs can be found exceptionally well preserved in amber, which is in fact fossilised tree resin.
Especially diverse is the animal fauna preserved in Cretaceousamber from Myanmar (Burma). Over the last few years, the almost 100-million-year-old amber has revealed some spectacular discoveries, including dinosaur feathers, a complete dinosaur tail, unknown groups of spiders and several long extinct groups of insects.
However, as few as three millipede species, preserved in Burmese amber, had been found prior to the study of Thomas Wesener and his PhD student Leif Moritz at the Zoological Research Museum Alexander Koenig — Leibniz Institute for Animal Biodiversity (ZFMK). Their research was recently published in the open-access journal Check List.
Having identified over 450 millipedes preserved in the Burmese amber, the scientists confirmed species representing as many as 13 out of the 16 main orders walking the Earth today. The oldest known fossils for half of these orders were found within the studied amber.
The researchers conducted their analysis with the help of micro-computed tomography (micro-CT). This scanning technology uses omni-directional X-rays to create a 3D image of the specimen, which can then be virtually removed from the amber and digitally examined.
The studied amber is mostly borrowed from private collections, including the largest European one, held by Patrick Müller from Käshofen. There are thought to be many additional, scientifically important specimens, perhaps even thousands of them, currently inaccessible in private collections in China.
Over the next few years, the newly discovered specimens will be carefully described and compared to extant species in order to identify what morphological changes have occurred in the last 100 million years and pinpoint the speciation events in the millipede Tree of Life. As a result, science will be finally looking at solving long-standing mysteries, such as whether the local millipede diversity in the southern Alps of Italy or on the island of Madagascar is the result of evolutionary processes which have taken place one, ten or more than 100-million years ago.
According to the scientists, most of the Cretaceous millipedes found in the amber do not differ significantly from the species found in Southeast Asia nowadays, which is an indication of the old age of the extant millipede lineages.
On the other hand, the diversity of the different orders seems to have changed drastically. For example, during the Age of the Dinosaurs, the group Colobognatha — millipedes characterised by their unusual elongated heads which have evolved to suck in liquid food — used to be very common. In contrast, with over 12,000 millipede species living today, there are only 500 colobognaths.
Another curious finding was the discovery of freshly hatched, eight-legged juveniles, which indicated that the animals lived and reproduced in the resin-producing trees.
“Even before the arachnids and insects, and far ahead of the first vertebrates, the leaf litter-eating millipedes were the first animals to leave their mark on land more than 400-million-years ago,” explain the scientists. “These early millipedes differed quite strongly from the ones living today — they would often be much larger and many had very large eyes.”
The larger species in the genus Arthropleura, for example, would grow up to 2 m (6.5 ft) long and 50-80 cm (2-3 ft) wide — the largest arthropods to have ever crawled on Earth. Why these giants became extinct and those other orders survived remains unknown, partly because only a handful of usually badly preserved fossils from the whole Mesozoic era (252-66-million years ago) has been retrieved. Similarly, although it had long been suspected that the 16 modern millipede orders must be very old, a fossil record to support this assumption was missing.
Reference:
Thomas Wesener, Leif Moritz. Checklist of the Myriapoda in Cretaceous Burmese amber and a correction of the Myriapoda identified by Zhang (2017). Check List, 2018; 14 (6): 1131 DOI: 10.15560/14.6.1131
Note: The above post is reprinted from materials provided by Pensoft Publishers. The original story is licensed under a Creative Commons License.
Panoplosaurus mirus and Euoplocephalus tutus. Credit: Bourke et al, 2018.
Being a gigantic dinosaur presented some challenges, such as overheating in the Cretaceous sun and frying your brain. Researchers from Ohio University and NYITCOM at Arkansas State show in a new article in PLOS ONE that the heavily armored, club-tailed ankylosaurs had a built-in air conditioner in their snouts.
“The huge bodies that we see in most dinosaurs must have gotten really hot in warm Mesozoic climates,” said Jason Bourke, Assistant Professor at the New York Institute of Technology College of Osteopathic Medicine at Arkansas State and lead author of the study. “Brains don’t like that, so we wanted to see if there were ways to protect the brain from cooking. It turns out the nose may be the key.”
Bourke and the team used CT scanning and a powerful engineering approach called computational fluid dynamics to simulate how air moved through the nasal passages of two different ankylosaur species, the hippo-sized Panoplosaurus and larger rhino-sized Euoplocephalus, to test how well ankylosaur noses transferred heat from the body to the inhaled air.
“A decade ago, my colleague Ryan Ridgely and I published the discovery that ankylosaurs had insanely long nasal passages coiled up in their snouts,” said study co-author Lawrence Witmer, professor at the Ohio University Heritage College of Osteopathic Medicine. “These convoluted airways looked like a kid’s ‘crazy-straw!’ It was completely unexpected and cried out for explanation. I was thrilled when Jason took up the problem as part of his doctoral research in our lab.”
“This project is an excellent example of how advances in CT scanning, 3-D reconstruction, imaging, and computational fluid dynamics modeling can be used in biological research to test long-standing hypotheses,” said Kathy Dickson, a program officer at the National Science Foundation that funded the research. “From these new images and models, fossils can provide further insight into extinct organisms like the ankylosaur — in this case, offering an explanation of how unusual features actually function physiologically.”
Smell may be a primary function of the nose, but noses are also heat exchangers, making sure that air is warmed and humidified before it reaches our delicate lungs. To accomplish this effective air conditioning, birds and mammals, including humans, rely on thin curls of bone and cartilage within their nasal cavities called turbinates, which increase the surface area, allowing for air to come into contact with more of the nasal walls. “Ankylosaurs didn’t have turbinates, but instead made their noses very long and twisty,” said Bourke.
When the researchers compared their findings to data from living animals, they discovered that the dinosaurs’ noses were just as efficient at warming and cooling respired air. “This was a case of nature finding a different solution to the same problem,” said Bourke.
Just how long were these nasal passages? In Panoplosaurus, they were a bit longer than the skull itself and in Euoplocephalus they were almost twice as long as the skull, which is why they’re coiled up in the snout. To see if nasal passage length was the reason for this efficiency, Bourke ran alternative models with shorter, simpler nasal passages that ran directly from the nostril to the throat, as in most other animals. The results clearly showed that nose length was indeed the key to their air-conditioning ability. “When we stuck a short, simple nose in their snouts, heat-transfer rates dropped over 50 percent in both dinosaurs. They were less efficient and didn’t work very well,” said Bourke.
Another line of evidence that these noses were air conditioners that helped cool the brain came from analyses of blood flow.
“When we reconstructed the blood vessels, based on bony grooves and canals, we found a rich blood supply running right next to these convoluted nasal passages,” said Ruger Porter, lecturer at the Ohio University Heritage College of Osteopathic Medicine and one of the study’s co-authors. “Hot blood from the body core would travel through these blood vessels and transfer their heat to the incoming air. Simultaneously, evaporation of moisture in the long nasal passages cooled the venous blood destined for the brain.”
So why the need for such effective heat exchangers? The large bodies of Panoplosaurus and Euoplocephalus were really good at retaining heat, which is good for staying warm, but bad when the animals need to cool off. This heat-shedding problem would have put them at risk of overheating even on cloudy days. In the absence of some protective mechanism, the delicate neural tissue of the brain could be damaged by the hot blood from the body core.
“Sure, their brains were almost comically small,” Bourke said. “But they’re still their brains and needed protection.”
The complicated nasal airways of these dinosaurs were acting as radiators to cool down the brain with a constant flow of cooled venous blood, allowing them to keep a cool head at all times. This natural engineering feat also may have allowed the evolution of the great sizes of so many dinosaurs.
“When we look at the nasal cavity and airway in dinosaurs, we find that the most elaborate noses are found in the large dinosaur species, which suggests that the physiological stresses of large body size may have spurred some of these anatomical novelties to help regulate brain temperatures,” Witmer said.
The next step for the researchers is to examine other dinosaurs to determine when this nasal enlargement happened.
“We know that large dinosaurs had these crazy airways, but at exactly what size did this happen?” Bourke said. “Was this elaboration gradual as body size increased, or is there a threshold size where a run-of-the-mill nose can no longer do the job? We just don’t know yet.”
The research was funded by National Science Foundation (NSF) grants to Witmer (part of the Visible Interactive Dinosaur Project) and an NSF fellowship to Bourke, as well as by the Ohio University Heritage College of Osteopathic Medicine.
Reference:
Jason M. Bourke, Wm. Ruger Porter, Lawrence M. Witmer. Convoluted nasal passages function as efficient heat exchangers in ankylosaurs (Dinosauria: Ornithischia: Thyreophora). PLOS ONE, 2018; 13 (12): e0207381 DOI: 10.1371/journal.pone.0207381
Note: The above post is reprinted from materials provided by Ohio University.
First dinosaur ever found, the predatory Megalosaurus came from same location, in Oxfordshire Credit: MARK WITTON
Spectacular flying reptiles armed with long teeth and claws which once dominated the skies have been rediscovered, thanks to a palaeontology student’s PhD research.
Dr Michael O’Sullivan, at the University of Portsmouth, has uncovered evidence of well armed and substantial flying reptiles from historically important, but overlooked, British Jurassic fossils.
He’s also found a new species of pterosaur with a wingspan of two metres — as large as a modern mute swan, and a giant in its time.
Some 200 fossils of flying reptiles — pterosaurs — have been collected over the last two centuries from the Stonesfield Slate, but their significance has been long neglected by palaeontologists, probably because they are mere fragments.
Closer inspection has revealed evidence of multiple pterosaur lineages in the UK’s Jurassic past, including some unexpectedly large and formidably armed species.
The research is Published in Acta Palaeontologica Polonica where it is highlighted as ‘editor’s choice’.
Dr O’Sullivan, in the University’s School of Earth and Environmental Sciences, said: “It’s large fangs would have meshed together to form a toothy cage, from which little could escape once Klobiodon had gotten a hold of it.
“The excellent marine reptiles and ammonites of the UK’s Jurassic heritage are widely known, but we celebrate our Jurassic flying reptiles far less.
“The Stonesfield pterosaurs are rarely pretty or spectacular, but they capture a time in flying reptile evolution which is poorly represented globally. They have an important role to play in not only understanding the UK’s natural history, but help us understand the bigger global picture as well.”
He has named the new species Klobiodon rochei.
The generic name means ‘cage tooth’, in reference to its huge, fang-like teeth — up to 26mm long at a time when few pterosaurs had any teeth — and the species name honours comic book artist Nick Roche in recognition of the role popular media has in how extinct animals are portrayed.
Only the lower jaw of Klobiodon is known, but it has a unique dental configuration that allows it to be distinguished from other pterosaurs. It was likely a gull or tern-like creature — a coastal flier that caught fish and squid using its enormous teeth, swallowing them whole.
Much of Dr O’Sullivan’s research has involved untangling the messy science associated with these neglected specimens.
He said: “Klobiodon has been known to us for centuries, archived in a museum drawer and seen by dozens or hundreds of scientists, but it’s significance has been overlooked because it’s been confused with another species since the 1800s.”
Klobiodon and the other Stonesfield pterosaurs lived alongside one of the most famous and important dinosaurs in the world, the predatory Megalosaurus, the first dinosaur ever named. But as global sea levels were higher, and the world was much warmer, their Jurassic Britain was a series of large tropical islands.
Dr O’Sullivan was examining the Stonesfield pterosaur collections held in museums across the UK for his PhD studies when he found evidence of three distinct types of pterosaur, some of which are the oldest of their kind, as well as evidence of a new pterosaur species.
Stonesfield Slate, where the new pterosaur fossils were found, is a rich source of Jurassic fossils about 10 miles northwest of Oxford. It is where, in 1824, Britain’s first discovered dinosaur, the Megalosaurus, was found.
The quantity and quality of such fossils from the area might be why these fragments have until now been overlooked.
Reference:
Michael O’Sullivan, David Martill. Pterosauria of the Great Oolite Group (Middle Jurassic, Bathonian) of Oxfordshire and Gloucestershire, England.. Acta Palaeontologica Polonica, 2018; 63 DOI: 10.4202/app.00490.2018
Two large iguanodontian footprints with skin and claw impressions. Credit: Neil Davies
More than 85 well-preserved dinosaur footprints — made by at least seven different species — have been uncovered in East Sussex, representing the most diverse and detailed collection of these trace fossils from the Cretaceous Period found in the UK to date.
The footprints were identified by University of Cambridge researchers between 2014 and 2018, following periods of coastal erosion along the cliffs near Hastings. Many of the footprints — which range in size from less than 2 cm to over 60 cm across — are so well-preserved that fine detail of skin, scales and claws is easily visible.
The footprints date from the Lower Cretaceous epoch, between 145 and 100 million years ago, with prints from herbivores including Iguanodon, Ankylosaurus, a species of stegosaur, and possible examples from the sauropod group (which included Diplodocus and Brontosaurus); as well as meat-eating theropods. The results are reported in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.
Over the past 160 years, there have been sporadic reports of fossilised dinosaur footprints along the Sussex coast, but no new major discoveries have been described for the past quarter century and the earlier findings were far less varied and detailed than those described in the current research.
The area around Hastings is one of the richest in the UK for dinosaur fossils, including the first known Iguanodon in 1825, and the first confirmed example of fossilised dinosaur brain tissue in 2016. However, trace fossils such as footprints, which can help scientists learn more about the composition of dinosaur communities, are less common in the area.
“Whole body fossils of dinosaurs are incredibly rare,” said Anthony Shillito, a PhD student in Cambridge’s Department of Earth Sciences and the paper’s first author. “Usually you only get small pieces, which don’t tell you a lot about how that dinosaur may have lived. A collection of footprints like this helps you fill in some of the gaps and infer things about which dinosaurs were living in the same place at the same time.”
The footprints described in the current study, which Shillito co-authored with Dr Neil Davies, were uncovered during the past four winters, when strong storms and storm surges led to periods of collapse of the sandstone and mudstone cliffs.
In the Cretaceous Period, the area where the footprints were found was likely near a water source, and in addition to the footprints, a number of fossilised plants and invertebrates were also found.
“To preserve footprints, you need the right type of environment,” said Davies. “The ground needs to be ‘sticky’ enough so that the footprint leaves a mark, but not so wet that it gets washed away. You need that balance in order to capture and preserve them.”
“As well as the large abundance and diversity of these prints, we also see absolutely incredible detail,” said Shillito. “You can clearly see the texture of the skin and scales, as well as four-toed claw marks, which are extremely rare.
“You can get some idea about which dinosaurs made them from the shape of the footprints — comparing them with what we know about dinosaur feet from other fossils lets you identify the important similarities. When you also look at footprints from other locations you can start to piece together which species were the key players.”
As part of his research, Shillito is studying how dinosaurs may have affected the flows of rivers. In modern times, large animals such as hippopotamuses or cows can create small channels, diverting some of the river’s flow.
“Given the sheer size of many dinosaurs, it’s highly likely that they affected rivers in a similar way, but it’s difficult to find a ‘smoking gun’, since most footprints would have just washed away,” said Shillito. “However, we do see some smaller-scale evidence of their impact; in some of the deeper footprints you can see thickets of plants that were growing. We also found evidence of footprints along the banks of river channels, so it’s possible that dinosaurs played a role in creating those channels.”
It’s likely that there are many more dinosaur footprints hidden within the eroding sandstone cliffs of East Sussex, but the construction of sea defences in the area to slow or prevent the process of coastal erosion may mean that they remained locked within the rock.
The research was funded by the Natural Environment Research Council (NERC).
Reference:
Anthony P. Shillito, Neil S. Davies. Dinosaur-landscape interactions at a diverse Early Cretaceous tracksite (Lee Ness Sandstone, Ashdown Formation, southern England). Palaeogeography, Palaeoclimatology, Palaeoecology, 2019; 514: 593 DOI: 10.1016/j.palaeo.2018.11.018
Note: The above post is reprinted from materials provided by University of Cambridge. The original story is licensed under a Creative Commons License.
The high-density minerals in the Georgia kaolin mines are potential sources of rare-earth elements, including the heavy rare-earth elements that are in high demand for many important uses and are mostly imported to the United States from China, according to a study led by Georgia State University and Thiele Kaolin Co.
Rare-earth elements are used to make critical products, including magnetic resonance imaging (MRI) contrast agents, X-ray intensifying screens, portable X-ray machines, medical lasers, fiber optics, optical lenses, pressure sensors, monitors and television screens, fluorescent lamps, rechargeable battery electrodes and permanent magnets.
There are 17 rare-earth elements, which include the 15 elements of the lanthanide series (atomic numbers 57 to 71 on the periodic table), plus scandium (Sc) and yttrium (Y). The heavy rare-earth elements are from gadolinium (Gd) to lutetium (Lu), atomic numbers 64 to 71 on the periodic table.
Thiele Kaolin Co. mined for kaolin in two quarries near Sandersville, Ga., and provided Georgia State researchers with the leftover mineral samples, or grit, for analysis. The minerals present were identified using X-ray diffraction, scanning electron microscopy and chemical analysis. The findings, published in the journal Clays and Clay Minerals, suggest a new, potential source of rare-earth elements, including the less common heavy rare-earth elements.
“We were interested in looking at the very course, sand-sized material from the kaolin ore that they call grit. It accounts for about 10 percent of the mined material and is removed before they make finished kaolin products for a variety of applications, such as paper, paints, adhesives, plastics, ceramics, etc.,” said Dr. W. Crawford Elliott, senior author of the study and associate professor in the Department of Geosciences at Georgia State. “They gave us samples of the grit. When we processed these samples, we found a particular enrichment in the heavy rare-earth elements, gadolinium through lutetium. An enrichment in the heavy rare-earth elements is interesting and useful because in most cases, the Earth’s crust is enriched in the lighter rare-earth elements. The heavy rare-earth elements tend to be more technologically important.
“After we did a heavy liquid separation on that material, we found the Buffalo Creek Kaolin Member is about 100 times more enriched in the heavy rare-earth elements relative to concentrations in upper continental crust. Our work suggests a way to obtain heavy rare-earth elements from kaolin ore, which hasn’t been done before. This constitutes a new resource for the rare-earth elements, which we are getting all from China.”
Close-up of a looping millipede death-trail. Credit: Photo by Anthony Shillito
Our understanding of when the very first animals started living on land is helped by identifying trace fossils — the tracks and trails left by ancient animals — in sedimentary rocks that were deposited on the continents.
Geoscientists Anthony P. Shillito and Neil S. Davies of the University of Cambridge studied the site of what has widely been accepted as the earliest set of non-marine trackways, in Ordovician (ca. 455 million-year-old) strata from the Lake District, England.
What they discovered is that the trackways occur within volcanic ash that settled under water, and not within freshwater lake and sub-aerial sands (as previously thought). This means that the site is not the oldest evidence for animal communities on land, but instead “is actually a remarkable example of a ‘prehistoric Pompeii’,” says Shillito — a suite of rocks that preserve trails made by distressed and dying millipede-like arthropods as they were overcome by ash from volcanic events.
Shillito and Davies directed their research at this site in particular because it seemed unusual — at every other known trackway site in the world the evidence for when animals came onto land dates to the latest Silurian (ca. 420 million years ago), so something about the Borrowdale site didn’t seem right. Further investigation proved that this was the case. In the course of their study, they found 121 new millipede trackways, all within volcanic ash with evidence for underwater or shoreline deposition.
Volcanic ash is known to cause mass death in some modern arthropod communities, particularly in water, because ash is so tiny it can get inside arthropod exoskeletons and stick to their breathing and digestive apparatus. Shilllito and Davies noticed that most of the trails were extremely tightly looping — a feature which is commonly associated with “death dances” in modern and ancient arthropods.
This study, published in Geology, overturns what is known about the earliest life on land and casts new light onto one of the key evolutionary events in the history of life on Earth. Shillito notes, “It reveals how even surprising events can be preserved in the ancient rock record, but — by removing the ‘earliest’ outlier of evidence — suggests that the invasion of the continents happened globally at the same time.”
Understanding how life engineered major evolutionary advances within environments, and the rate and impact of these advances on the functioning of the Earth system, provides vital context for understanding global change at the present day, and underlines the inseparable relationship between life and the planet.
Reference:
Anthony P. Shillito, Neil S. Davies. Death near the shoreline, not life on land: Ordovician arthropod trackways in the Borrowdale Volcanic Group, UK. Geology, 2018; DOI: 10.1130/G45663.1
This is a Nanjinganthus fossil, showing its ovary (bottom centre), sepals and petals (on the sides) and a tree-shaped top. Credit: Fu et al., 2018
Scientists have described a fossil plant species that suggests flowers bloomed in the Early Jurassic, more than 174 million years ago, according to new research in the open-access journal eLife.
Before now, angiosperms (flowering plants) were thought to have a history of no more than 130 million years. The discovery of the novel flower species, which the study authors named Nanjinganthus dendrostyla, throws widely accepted theories of plant evolution into question, by suggesting that they existed around 50 million years earlier. Nanjinganthus also has a variety of ‘unexpected’ characteristics according to almost all of these theories.
Angiosperms are an important member of the plant kingdom, and their origin has been the topic of long-standing debate among evolutionary biologists. Many previously thought angiosperms could be no more than 130 million years old. However, molecular clocks have indicated that they must be older than this. Until now, there has been no convincing fossil-based evidence to prove that they existed further back in time.
“Researchers were not certain where and how flowers came into existence because it seems that many flowers just popped up in the Cretaceous from nowhere,” explains lead author Qiang Fu, Associate Research Professor at the Nanjing Institute of Geology and Paleontology, China. “Studying fossil flowers, especially those from earlier geologic periods, is the only reliable way to get an answer to these questions.”
The team studied 264 specimens of 198 individual flowers preserved on 34 rock slabs from the South Xiangshan Formation — an outcrop of rocks in the Nanjing region of China renowned for bearing fossils from the Early Jurassic epoch. The abundance of fossil samples used in the study allowed the researchers to dissect some of them and study them with sophisticated microscopy, providing high-resolution pictures of the flowers from different angles and magnifications. They then used this detailed information about the shape and structure of the different fossil flowers to reconstruct the features of Nanjinganthus dendrostyla.
The key feature of an angiosperm is ‘angio-ovuly’ — the presence of fully enclosed ovules, which are precursors of seeds before pollination. In the current study, the reconstructed flower was found to have a cup-form receptacle and ovarian roof that together enclose the ovules/seeds. This was a crucial discovery, because the presence of this feature confirmed the flower’s status as an angiosperm. Although there have been reports of angiosperms from the Middle-Late Jurassic epochs in northeastern China, there are structural features of Nanjinganthus that distinguish it from these other specimens and suggest that it is a new genus of angiosperms.
Having made this discovery, the team now wants to understand whether angiosperms are either monophyletic — which would mean Nanjinganthus represents a stem group giving rise to all later species — or polyphyletic, whereby Nanjinganthus represents an evolutionary dead end and has little to do with many later species.
“The origin of angiosperms has long been an academic ‘headache’ for many botanists,” concludes senior author Xin Wang, Research Professor at the Nanjing Institute of Geology and Paleontology. “Our discovery has moved the botany field forward and will allow a better understanding of angiosperms, which in turn will enhance our ability to efficiently use and look after our planet’s plant-based resources.”
Reference:
Qiang Fu, Jose Bienvenido Diez, Mike Pole, Manuel García Ávila, Zhong-Jian Liu, Hang Chu, Yemao Hou, Pengfei Yin, Guo-Qiang Zhang, Kaihe Du, Xin Wang. An unexpected noncarpellate epigynous flower from the Jurassic of China. eLife, 2018; 7 DOI: 10.7554/eLife.38827
Note: The above post is reprinted from materials provided by eLife.
Palentologists are announcing a new dinosaur discovery in the southwest United States. Crittendenceratops krzyzanowskii is a new ceratopsid (horned) dinosaur from 73-million-year-old (Late Cretaceous) rocks in southern Arizona. It is one of the few dinosaurs named from Arizona.
Crittendenceratops krzyzanowskii was named by Sebastian Dalman, John-Paul Hodnett, Asher Lichtig and Spencer Lucas, Ph.D, in an article recently published in the New Mexico Museum of Natural History & Science Bulletin.
Dalman and Lichtig are Research Associates of the New Mexico Museum of Natural History & Science (NMMNHS), Lucas is a curator at NMMNHS, and Hodnett is a paleontologist employed by the Maryland-National Capital Parks Commission.
The name Crittendenceratops is for the Fort Crittenden Formation (the rock formation that yielded the dinosaur fossils) and Greek ceratops, which means horned face. The species name krzyzanowskii is for the late Stan Krzyzanowski, a NMMNHS Research Associate who discovered the bones of the new dinosaur.
Crittendenceratops belongs to a group of horned dinosaurs called the centrosaurs, and can be distinguished from other centrosaurs by the unique shape of the bones in its frill (head shield). Crittendenceratrops was about 11 feet long and weighed an estimated three-quarters of a ton. Like other ceratopsids, Crittendenceratops was a plant eater.
The rocks that yielded the bones were deposited along the margins of a large lake that was present in an area southeast of Tucson, Arizona during the Late Cretaceous.
