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New species of ancient cynodont, 220 million years old, discovered

A Photoshop-created image of how Kataigidodon venetus may have looked, illustrated by Ben Kligman, a Ph.D. student in the Department of Geosciences and Hannah R. Kligman. Credit: Virginia Tech
A Photoshop-created image of how Kataigidodon venetus may have looked, illustrated by Ben Kligman, a Ph.D. student in the Department of Geosciences and Hannah R. Kligman. Credit: Virginia Tech

Fossilized jaw bone fragments of a rat-like creature found at the Petrified Forest National Park in Arizona last year by a Virginia Tech College of Science Ph.D. candidate are in fact a newly discovered 220-million-year-old species of cynodont or stem-mammal, a precursor of modern-day mammals.

The finding of this new species, Kataigidodon venetus, has been published today in the journal Biology Letters by lead author Ben Kligman, a doctoral student in the Department of Geosciences.

“This discovery sheds light on the geography and environment during the early evolution of mammals,” Kligman said. “It also adds to evidence that humid climates played an important role in the early evolution of mammals and their closest relatives. Kataigidodon was living alongside dinosauromorphs and possibly early dinosaurs related to Coelophysis—a small bipedal predator—and Kataigidodon was possibly prey of these early dinosaurs and other predators like crocodylomorphs, small coyote-like quadrupedal predators related to living crocodiles.”

Kligman added that finding a fossil that is part of Cynodontia, which includes close cousins of mammals, such as Kataigidodon, as well as true mammals, from Triassic rocks is an extremely rare event in North America. Prior to Kligman’s discovery, the only other unambiguous cynodont fossil from the Late Triassic of western North America was the 1990 discovery of a braincase of Adelobasileus cromptoni in Texas. Note that 220 million years ago, modern day Arizona and Texas were located close to the equator, near the center of the supercontinent Pangaea. Kataigidodon would have been living in a lush tropical forest ecosystem.

Kligman made the discovery while working as a seasonal paleontologist at Petrified Forest National Park in 2019. The two fossil lower jaws of Kataigidodon were found in the Upper Triassic Chinle Formation. Because only the lower jaws were discovered and are quite small—half an inch, the size of a medium grain of rice—Kligman only has a semi-picture of how the creature looked, roughly 3.5 inches in total body size, minus the tail.

Along with the jawbone fossils, Kligman found incisor, canine, and complex-postcanine teeth, similar to modern day mammals. Given the pointed shape of its teeth and small body size, it likely fed on a diet of insects, Kligman added. (Why are jaw fossils commonly found, even among small specimens? According to Kligman, the fossil record is “biased” toward only preserving the largest and most robust bones in a skeleton. The other smaller or more fragile bones—ribs, arms, feet—disappear.)

Kligman carried out field work, specimen preparation, CT scanning, conception, and design of the studyand drafting of the manuscript. He added that he and his collaborators only discovered the fossils were of a new species after reviewing the CT scan dataset of the jaws and comparing it to other related species.

“It likely would have looked like a small rat or mouse. If you were to see it in person you would think it is a mammal,” Kligman added. Does it have fur? Kligman and the researchers he worked with to identify and name the creature actually don’t know. “Triassic cynodonts have not been found from geological settings which could preserve fur if it was there, but later nonmammalian cynodonts from the Jurassic had fur, so scientists assume that Triassic ones did also.”

The name Kataigidodon venetus derives from the Greek words for thunderstorm, “kataigidos,” and tooth, “odon,” and the Latin word for blue, “venetus,” all referring to the discovery location of Thunderstorm Ridge, and the blue color of the rocks at this site. Kligman didn’t name the creature, though. That task fell to Hans Dieter-Sues, coauthor and curator of vertebrate paleontology at the Smithsonian National Museum.

Additional collaborators include Adam Marsh, park paleontologist at Petrified Forest National Park, who found the jaw fossils with Kligman, and Christian Sidor, an associate professor at the University of Washington’s Department of Biology. The research was funded by the Petrified Forest Museum Association, the Friends of Petrified Forest National Park, and the Virginia Tech Department of Geosciences.

“This study exemplifies the idea that what we collect determines what we can say,” said Michelle Stocker, an assistant professor of geosciences and Kligman’s doctoral advisor. “Our hypotheses and interpretations of past life on Earth depend on the actual fossil materials that we have, and if our search images for finding fossils only focuses on large-bodied animals, we will miss those important small specimens that are key for understanding the diversification of many groups.”

With Kataigidodon being only the second other unambiguous cynodont fossil from the Late Triassic found in western North America, could there be more new species out there waiting to be found?

Kligman said most likely. “We have preliminary evidence that more species of cynodonts are present in the same site as Kataigidodon, but we are hoping to find better fossils of them,” he added.

Reference:
A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record, Biology Letters (2020). royalsocietypublishing.org/doi … .1098/rsbl.2020.0631

Note: The above post is reprinted from materials provided by Virginia Tech.

Lizard skull fossil is new and ‘perplexing’ extinct species

Kopidosaurus perplexus skull in left lateral view. Credit: Simon Scarpetta
Kopidosaurus perplexus skull in left lateral view. Credit: Simon Scarpetta

In 2017, while browsing the fossil collections of Yale’s Peabody Museum of Natural History, University of Texas at Austin graduate student Simon Scarpetta came across a small lizard skull, just under an inch long.

The skull was beautifully preserved, with a mouth full of sharp teeth — including some with a distinctive curve.

Much to Scarpetta’s surprise, no one had studied it. Since being discovered in 1971 on a museum fossil hunting trip to Wyoming, the 52 million-year-old skull had sat in the specimen drawer.

“Lizards are small and prone to breaking apart, so you mostly get these individual, isolated fragmented bones,” said Scarpetta, who is studying paleontology at the UT Jackson School of Geosciences. “Anytime you find a skull, especially when you’re trying to figure out how things are related to each other, it’s always an exciting find.”

Scarpetta decided to bring the skull back to the Jackson School for a closer look. And on September 2020, the journal Scientific Reports published a study authored by Scarpetta describing the lizard as a new species, which he named Kopidosaurus perplexus.

The first part of the name references the lizard’s distinct teeth; a “kopis” is a curved blade used in ancient Greece. But the second part is a nod to the “perplexing” matter of just where the extinct lizard should be placed on the tree of life. According to an analysis conducted by Scarpetta, the evidence points to a number of plausible spots.

The spots can be divided into two groups of lizards, representing two general hypotheses of where the new species belongs. But adding to the uncertainty is that how those two groups relate to one another can shift depending on the particular evolutionary tree that’s examined. Scarpetta examined three of these trees — each one built by other researchers studying the evolutionary connections of different reptile groups using DNA — and suggests that there could be a forest of possibilities where the ancient lizard could fit.

The case of where exactly to put the perplexing lizard highlights an important lesson for paleontologists: just because a specimen fits in one place doesn’t mean that it won’t fit equally well into another.

“The hypothesis that you have about how different lizards are related to each other is going to influence what you think this one is,” Scarpetta said.

Paleontologists use anatomical details present in bones to discern the evolutionary relationships of long-dead animals. To get a close look at the lizard skull, Scarpetta created a digital scan of it in the Jackson School’s High-Resolution X-Ray CT Lab. However, while certain details helped identify the lizard as a new species, other details overlapped with features from a number of different evolutionary groups.

All of these groups belonged to a larger category known as Iguania, which includes a number of diverse species, including chameleons, anoles and iguanas. To get a better idea of where the new species might fit into the larger Iguania tree, Scarpetta compared the skull data to evolutionary trees for Iguania that were compiled by other researchers based on DNA evidence from living reptiles.

On each tree, the fossil fit equally well into two general spots. What’s more, the lizard groupings in each spot varied from tree to tree. If Scarpetta had just stopped at one spot or one tree, he would have missed alternative explanations that appear just as plausible as the others.

Scarpetta said that Kopidosaurus perplexus is far from the only fossil that could easily fit onto multiple branches on the tree of life. Paleontologist Joshua Lively, a curator at the Utah State University Eastern Prehistoric Museum, agrees and said that this study epitomizes why embracing uncertainty can lead to better, more accurate science.

“Something that I think the broader scientific community should pull from this is that you have to be realistic about your data and acknowledge what we can actually pull from our results and conclude and where there are still uncertainties,” Lively said. “Simon’s approach is the high bar, taking the high road. It’s acknowledging what we don’t know and really embracing that.”

The research was funded by the Jackson School of Geosciences and the Geological Society of America.

Reference:
Simon G. Scarpetta. Effects of phylogenetic uncertainty on fossil identification illustrated by a new and enigmatic Eocene iguanian. Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-72509-2

Note: The above post is reprinted from materials provided by University of Texas at Austin.

New fault zone measurements could help us to understand subduction earthquakes

The outcrop of the pseudotachylyte-bearing fault zone in pelagic sedimentary rocks.
The outcrop of the pseudotachylyte-bearing fault zone in pelagic sedimentary rocks.

A research team from the University of Tsukuba has conducted detailed structural analyses of a fault zone located in central Japan, with the aim to help identify the specific conditions that lead to earthquake faulting, a hazard that can cause enormous social damage. Subduction is a geological process that takes place in areas where two tectonic plates meet, such as the Japan Trench, in which one plate moves under another and is forced to sink.

Regions in which this process occurs are known as subduction zones and the seismic activity that they produce causes devastating damage through ground shaking and tsunamis. However, understanding these seismic processes can be difficult because of the problems associated with taking measurements from their deepest sections, where much of the activity occurs.

“To overcome this problem, we examined fault rocks exhumed from source depths of subduction earthquakes, which are now exposed at the land surface at the Jurassic accretionary complex in central Japan,” explains study lead author Professor Kohtaro Ujiie. “At this complex, we were able to examine pseudotachylyte, a solidified frictional melt produced during subduction earthquakes, to help us to infer what may occur in the subduction zones deep beneath the oceans.”

The exposed fault zone was characterized through a range of measurements such as scanning electron microscope and Raman spectroscopy to provide a detailed picture of the pseudotachylytes and make some constraints about the heating conditions at the time of formation.

“The pseudotachylyte at the site derived from the frictional melting of black carbonaceous mudstone together with chert, which accumulated under low-oxygen conditions,” says Ujiie. “Thermal fracturing tends to occur along slip zones flanked by rocks with high thermal diffusivities such as chert, and may happen during seismic slip within the Jurassic accretionary complex. This thermal fracturing could lead to a fluid pressure drop in the slip zone and reduction in stiffness of surrounding rocks, potentially contributing to the generation of frictional melt and acceleration of seismic slip.”

The seismic slip processes recorded in the studied complex may be applicable to other fault zones with similar rock layers, such as the Japan Trench subduction zone. Therefore, the data gathered from this area could be useful in future attempts to describe or model the subduction earthquakes that lead to ground shaking and tsunami risk.

Reference:
Kohtaro Ujiie, Keisuke Ito, Ayaka Nagate, Hiroki Tabata. Frictional melting and thermal fracturing recorded in pelagic sedimentary rocks of the Jurassic accretionary complex, central Japan. Earth and Planetary Science Letters, 2020; 116638 DOI: 10.1016/j.epsl.2020.116638

Note: The above post is reprinted from materials provided by University of Tsukuba.

Magma ‘conveyor belt’ fuelled world’s longest erupting supervolcanoes

Representative Image : Lava "Volcanic Eruption"
Representative Image : Lava “Volcanic Eruption”

International research led by geologists from Curtin University has found that a volcanic province in the Indian Ocean was the world’s most continuously active — erupting for 30 million years — fuelled by a constantly moving ‘conveyor belt’ of magma.

It’s believed this magma ‘conveyor belt,’ created by shifts in the seabed, continuously made space available for the molten rock to flow for millions of years, beginning around 120 million years ago.

Research lead Qiang Jiang, a PhD candidate from Curtin’s School of Earth and Planetary Sciences, said the studied volcanoes were in the Kerguelen Plateau, located in the Indian Ocean, about 3,000 kilometres south west of Fremantle, Western Australia.

“Extremely large accumulations of volcanic rocks — known as large volcanic provinces — are very interesting to scientists due to their links with mass extinctions, rapid climatic disturbances, and ore deposit formation,” Mr Jiang said.

“The Kerguelen Plateau is gigantic, almost the size of Western Australia. Now imagine this area of land covered by lava, several kilometres thick, erupting at a rate of about 20 centimetres every year.

“Twenty centimetres of lava a year may not sound like much but, over an area the size of Western Australia, that’s equivalent to filling up 184,000 Olympic-size swimming pools to the brim with lava every single year. Over the total eruptive duration, that’s equivalent to 5.5 trillion lava-filled swimming pools!

“This volume of activity continued for 30 million years, making the Kerguelen Plateau home to the longest continuously erupting supervolcanoes on Earth. The eruption rates then dropped drastically some 90 million years ago, for reasons that are not yet fully understood.

“From then on, there was a slow but steady outpouring of lava that continued right to this day, including the 2016 eruptions associated with the Big Ben volcano on Heard Island, Australia’s only active volcano.”

Co-researcher Dr Hugo Olierook, also from Curtin’s School of Earth and Planetary Sciences, explained such a long eruption duration requires very peculiar geological conditions.

“After the partial breakup of the supercontinent Gondwana, into the pieces now known as Australia, India and Antarctica, the Kerguelen Plateau began forming on top of a mushroom-shaped mantle upwelling, called a mantle plume, as well as along deep sea, mid-oceanic mantle ridges,” Dr Olierook said.

“The volcanism lasted for so long because magmas caused by the mantle plume were continuously flowing out through the mid-oceanic ridges, which successively acted as a channel, or a ‘magma conveyor belt’ for more than 30 million years.

“Other volcanoes would stop erupting because, when temperatures cooled, the channels became clogged by ‘frozen’ magmas.

“For the Kerguelen Plateau, the mantle plume acts as a Bunsen burner that kept allowing the mantle to melt, resulting in an extraordinarily long period of eruption activity.”

Research co-author, Professor Fred Jourdan, Director of the Western Australia Argon Isotope Facility at Curtin University, said the team used an argon-argon dating technique to date the lava flows, by analysing a range of black basaltic rocks taken from the bottom of the sea floor.

“Finding this long, continuous eruption activity is important because it helps us to understand what factors can control the start and end of volcanic activity,” Professor Jourdan said.

“This has implications for how we understand magmatism on Earth, and on other planets as well.”

The Curtin-led research was a collaboration with Uppsala University in Sweden and the University of Tasmania.

Reference:
Qiang Jiang, Fred Jourdan, Hugo K.H. Olierook, Renaud E. Merle, Joanne M. Whittaker. Longest continuously erupting large igneous province drivenby plume-ridge interaction. Geology, 2020; DOI: 10.1130/G47850.1

Note: The above post is reprinted from materials provided by Curtin University.

These two bird-sized dinosaurs evolved the ability to glide, but weren’t great at it

This illustration shows a reconstruction of Ambopteryx in a glide. Credit: Gabriel Ugueto
This illustration shows a reconstruction of Ambopteryx in a glide. Credit: Gabriel Ugueto

Despite having bat-like wings, two small dinosaurs, Yi and Ambopteryx, struggled to fly, only managing to glide clumsily between the trees where they lived, researchers report October 22 in the journal iScience. Unable to compete with other tree-dwelling dinosaurs and early birds, they went extinct after just a few million years. The findings support that dinosaurs evolved flight in several different ways before modern birds evolved.

“Once birds got into the air, these two species were so poorly capable of being in the air that they just got squeezed out,” says first author Thomas Dececchi, Assistant Professor of Biology at Mount Marty University. “Maybe you can survive a few million years underperforming, but you have predators from the top, competition from the bottom, and even some small mammals adding into that, squeezing them out until they disappeared.”

Yi and Ambopteryx were small animals from Late Jurassic China, living about 160 million years ago. Weighing in at less than two pounds, they are unusual examples of theropod dinosaurs, the group that gave rise to birds. Most theropods were ground-loving carnivores, but Yi and Ambopteryx were at home in the trees and lived on a diet of insects, seeds, and other plants.

Curious about how these animals fly, Dececchi and his collaborators scanned fossils using laser-stimulated fluorescence (LSF), a technique that uses laser light to pick up soft-tissue details that can’t be seen with standard white light. Later, the team used mathematical models to predict how they might have flown, testing many different variables like weight, wingspan, and muscle placement.

“They really can’t do powered flight. You have to give them extremely generous assumptions in how they can flap their wings. You basically have to model them as the biggest bat, make them the lightest weight, make them flap as fast as a really fast bird, and give them muscles higher than they were likely to have had to cross that threshold,” says Dececchi. “They could glide, but even their gliding wasn’t great.”

While gliding is not an efficient form of flight, since it can only be done if the animal has already climbed to a high point, it did help Yi and Ambopteryx stay out of danger while they were still alive.

“If an animal needs to travel long distances for whatever reason, gliding costs a bit more energy at the start, but it’s faster. It can also be used as an escape hatch. It’s not a great thing to do, but sometimes it’s a choice between losing a bit of energy and being eaten,” says Dececchi. “Once they were put under pressure, they just lost their space. They couldn’t win on the ground. They couldn’t win in the air. They were done.”

The researchers are now looking at the muscles that powered Yi and Ambopteryx to construct an accurate image of these bizarre little creatures. “I’m used to working with the earliest birds, and we sort of have an idea of what they looked like already,” Dececchi says. “To work where we’re just trying to figure out the possibilities for a weird creature is kind of fun.”

The authors were supported by Mount Marty University and The University of Hong Kong.

Reference:
Dececchi et al. Aerodynamics show membranous-winged theropods were a poor gliding dead-end. iScience, 2020 DOI: 10.1016/j.isci.2020.101574

Note: The above post is reprinted from materials provided by Cell Press.

A new way of looking at the Earth’s interior

Structure layers of the earth.
Structure layers of the earth.

There are places that will always be beyond our reach. The Earth’s interior is one of them. But we do have ways of gaining an understanding of this uncharted world. Seismic waves, for instance, allow us to put important constraints about the structure of our planet and the physical properties of the materials hidden deep within it. Then there are the volcanic rocks that emerge in some places on the Earth’s surface from deep within and provide important clues about the chemical composition of the mantle. And finally there are lab experiments that can simulate the conditions of the Earth’s interior on a small scale.

A new publication by Motohiko Murakami, Professor of Experimental Mineral Physics, and his team was featured recently in the journal PNAS and shows just how illuminating such experiments can be. The researchers’ findings suggest that many geoscientists’ understanding of the Earth’s interior may be too simplistic.

Dramatic change

Below the Earth’s crust, which is only a few kilometres thick, lies its mantle. Also made of rock, this surrounds the planet’s core, which begins some 2,900 kilometres below us. Thanks to seismic signals, we know that a dramatic change occurs in the mantle at a depth of around 660 kilometres: this is where the upper mantle meets the lower mantle and the mechanical properties of the rock begin to differ, which is why the propagation velocity of seismic waves changes dramatically at this border.

What is unclear is whether this is merely a physical border or whether the chemical composition of the rock also changes at this point. Many geoscientists presume that the Earth’s mantle as a whole is composed relatively consistently of magnesium-rich rock, which in turn has a composition similar to that of peridotite rock found on the Earth’s surface. These envoys from the upper mantle, which arrive on the Earth’s surface by way of events like volcanic eruptions, exhibit a magnesium-silicon ratio of ~1.3.

“The presumption that the composition of the Earth’s mantle is more or less homogeneous is based on a relatively simple hypothesis,” Murakami explains. “Namely that the powerful convection currents within the mantle, which also drive the motion of the tectonic plates on the Earth’s surface, are constantly mixing it through. But it’s possible that this view is too simplistic.”

Where’s the silicon

There really is a fundamental flaw in this hypothesis. It is generally agreed that the Earth was formed around 4.5 billion years ago through the accretion of meteorites that emerged from the primordial solar nebula, and as such has the same overall composition of those meteorites. The differentiation of the Earth into core, mantle and crust happened as part of a second step.

Leaving aside the iron and nickel, which are now part of the planet’s core, it becomes apparent that the mantle should actually contain more silicon than the peridotite rock. Based on these calculations, the mantle should have a magnesium-silicon ratio closer to ~1 rather than ~1.3.

This moves geoscientists to ask the following question: where is the missing silicon And there is an obvious answer: the Earth’s mantle contains so little silicon because it is in the Earth’s core. But Murakami reaches a different conclusion, namely that the silicon is in the lower mantle. This would mean that the composition of the lower mantle differs to that of the upper mantel.

Winding hypothesis

Murakami’s hypothesis takes a few twists and turns: First, we already know precisely how fast seismic waves travel through the mantle. Second, lab experiments show that the lower mantle is made mostly of the siliceous mineral bridgmanite and the magnesium-rich mineral ferropericlase. Third, we know that the speed the seismic waves travel depends on the elasticity of the minerals that make up the rock. So if the elastic properties of the two minerals are known, it is possible to calculate the proportions of each mineral required to correlate with the observed speed of the seismic waves. It is then possible to derive what the chemical composition of the lower mantle must be.

While the elastic properties of ferropericlase are known, those of bridgmanite are as yet not. This is because this mineral’s elasticity depends greatly on its chemical composition; more specifically, it varies according to how much iron the bridgmanite contains.

Time-consuming measurements

In his lab, Murakami and his team have now conducted high-pressure tests on this mineral and experimented with different compositions. The researchers began by clamping a small specimen between two diamond tips and using a special device to press them together. This subjected the specimen to extremely high pressure, similar to that found in the lower mantle.

The researchers then directed a laser beam at the specimen and measured the wave spectrum of the light dispersed on the other side. Using the displacements in the wave spectrum, they were able to determine the mineral’s elasticity at different pressures. “It took a very long time to complete the measurements,” Murakami reports. “Since the more iron bridgmanite contains the less permeable to light it becomes, we needed up to fifteen days to complete each individual measurement.”

Silicon discovered

Murakami then used the measurement values to model the composition that best correlates with the dispersal of seismic waves. The results confirm his theory that the composition of the lower mantle differs to that of the upper mantel. “We estimate that bridgmanite makes up 88 to 93 percent of the lower mantle,” Murakami says, “which gives this region a magnesium-silicon ratio of approximately 1.1.” Murakami’s hypothesis solves the mystery of the missing silicon.

But his findings raise new questions. We know for instance that within certain subduction zones, the Earth’s crust gets pushed deep into the mantle — sometimes even as far as the border to the core. This means that the upper and lower mantles are actually not hermetically separated entities. How the two areas interact and exactly how the dynamics of the Earth’s interior work to produce chemically different regions of mantle remains to be seen.

Reference:
Izumi Mashino, Motohiko Murakami, Nobuyoshi Miyajima, Sylvain Petitgirard. Experimental evidence for silica-enriched Earth’s lower mantle with ferrous iron dominant bridgmanite. Proceedings of the National Academy of Sciences, 2020; 201917096 DOI: 10.1073/pnas.1917096117

Note: The above post is reprinted from materials provided by ETH Zurich. Original written by Felix Würsten.

Deep magma facilitates the movement of tectonic plates

Three-dimensional visualisation of partial melting at the base of tectonic plates. The orange iso-surfaces show the regions where, at a depth of between 100 and 300 km, the quantity of molten rock is greater than 0.2%. The white sphere in the centre of the globe represents the Earth’s core. Credit © Stéphanie Durand, Laboratoire de géologie de Lyon: Terre, planètes et environnement (CNRS/ENS de Lyon/Université Claude Bernard Lyon 1).
Three-dimensional visualisation of partial melting at the base of tectonic plates. The orange iso-surfaces show the regions where, at a depth of between 100 and 300 km, the quantity of molten rock is greater than 0.2%. The white sphere in the centre of the globe represents the Earth’s core. Credit © Stéphanie Durand, Laboratoire de géologie de Lyon: Terre, planètes et environnement (CNRS/ENS de Lyon/Université Claude Bernard Lyon 1).

A small amount of molten rock located under tectonic plates encourages them to move. This is what scientists from the Laboratoire de géologie de Lyon: Terre, planètes et environnement (CNRS/ENS de Lyon/Université Claude Bernard Lyon 1) have recently discovered. Their new model takes into account not only the velocity of seismic waves but also the way in which they are attenuated by the medium they pass through. The velocity of tectonic plates near the surface is thus directly correlated with the quantity of magma present. This research is published on October 21, 2020 in Nature.

The lithosphere, the outer part of the Earth, is made up of the crust and part of the upper mantle. It is subdivided into rigid plates, known as tectonic or lithospheric plates. These move on a more fluid layer of the mantle, the asthenosphere. The lower viscosity of the asthenosphere allows the tectonic plates to move around on the underlying mantle, but until today the origin of this low viscosity remained unknown.

Seismic tomography produces three-dimensional images of the Earth’s interior by analysing millions of seismic waves recorded at seismological stations spread across the surface of the globe. Since the 1970s, seismologists have analysed these waves with a view to identifying a single parameter: their propagation speed. This parameter varies with temperature (the colder the medium, the faster the waves arrive), composition, and the possible presence of molten rocks in the medium the waves pass through. Seismologists from the Laboratoire de géologie de Lyon: Terre, planètes et environnement (CNRS/ENS de Lyon/Université Claude Bernard Lyon 1) instead studied another parameter, wave attenuation, alongside the variation in wave propagation speeds. This analysis, which provides new information on the temperature of the medium traversed by the waves, makes it possible to ascertain the quantity of molten rock in the medium the waves pass through.

Their new model made it possible, for the first time, to map the amount of molten rock under tectonic plates. This work reveals that a small amount of molten rock (less than 0.7% by volume) is present in the asthenosphere under the oceans, not only where this was expected, i.e. under ocean ridges and some volcanoes such as Tahiti, Hawaii or Reunion, but also under all oceanic plates. The low percentage of molten rock observed is enough to reduce the viscosity by one or two orders of magnitude underneath the tectonic plates, thus “decoupling” them from the underlying mantle. Moreover, the seismologists from Lyon observed that the amount of molten rock is higher under the fastest-moving plates, such as the Pacific plate. This suggests that the melting of the rocks encourages the plates to move and the deformation at their bases. This research improves our understanding of plate tectonics and how it works.

Reference:
Eric Debayle, Thomas Bodin, Stéphanie Durand, et Yanick Ricard. Seismic evidence for partial melt below tectonic plates. Nature, October 21, 2020 DOI: 10.1038/s41586-020-2809-4

Note: The above post is reprinted from materials provided by CNRS.

Lost and found: Geologists ‘resurrect’ missing tectonic plate

A 3D block diagram across North America showing a mantle tomography image reveals the Slab Unfolding method used to flatten the Farallon tectonic plate. By doing this, Fuston and Wu were able to locate the lost Resurrection plate.
A 3D block diagram across North America showing a mantle tomography image reveals the Slab Unfolding method used to flatten the Farallon tectonic plate. By doing this, Fuston and Wu were able to locate the lost Resurrection plate.

The existence of a tectonic plate called Resurrection has long been a topic of debate among geologists, with some arguing it was never real. Others say it subducted — moved sideways and downward — into the earth’s mantle somewhere in the Pacific Margin between 40 and 60 million years ago.

A team of geologists at the University of Houston College of Natural Sciences and Mathematics believes they have found the lost plate in northern Canada by using existing mantle tomography images — similar to a CT scan of the earth’s interior. The findings, published in Geological Society of America Bulletin, could help geologists better predict volcanic hazards as well as mineral and hydrocarbon deposits.

“Volcanoes form at plate boundaries, and the more plates you have, the more volcanoes you have,” said Jonny Wu, assistant professor of geology in the Department of Earth and Atmospheric Sciences. “Volcanoes also affect climate change. So, when you are trying to model the earth and understand how climate has changed since time, you really want to know how many volcanoes there have been on earth.”

Wu and Spencer Fuston, a third-year geology doctoral student, applied a technique developed by the UH Center for Tectonics and Tomography called slab unfolding to reconstruct what tectonic plates in the Pacific Ocean looked like during the early Cenozoic Era. The rigid outermost shell of Earth, or lithosphere, is broken into tectonic plates and geologists have always known there were two plates in the Pacific Ocean at that time called Kula and Farallon. But there has been discussion about a potential third plate, Resurrection, having formed a special type of volcanic belt along Alaska and Washington State.

“We believe we have direct evidence that the Resurrection plate existed. We are also trying to solve a debate and advocate for which side our data supports,” Fuston said.

Using 3D mapping technology, Fuston applied the slab unfolding technique to the mantle tomography images to pull out the subducted plates before unfolding and stretching them to their original shapes.

“When ‘raised’ back to the earth’s surface and reconstructed, the boundaries of this ancient Resurrection tectonic plate match well with the ancient volcanic belts in Washington State and Alaska, providing a much sought after link between the ancient Pacific Ocean and the North American geologic record,” explained Wu.

This study is funded by a five-year, $568,309 National Science Foundation CAREER Award led by Wu.

Reference:
Spencer Fuston, Jonny Wu. Raising the Resurrection plate from an unfolded-slab plate tectonic reconstruction of northwestern North America since early Cenozoic time. GSA Bulletin, 2020; DOI: 10.1130/B35677.1

Note: The above post is reprinted from materials provided by University of Houston. Original written by Sara Tubbs.

African crocodiles lived in Spain six million years ago

A crocodile next to a mastodon of the genus Anancus and primitive horses of the genus Hipparion in a similar environment to what could have been Valencia six million years ago. Credit: José Antonio Peñas (SINC)
A crocodile next to a mastodon of the genus Anancus and primitive horses of the genus Hipparion in a similar environment to what could have been Valencia six million years ago. Credit: José Antonio Peñas (SINC)

Millions of years ago, several species of crocodiles of different genera and characteristics inhabited Europe and sometimes even coexisted. But among all these species, it was thought unlikely that crocodiles of the genus Crocodylus, of African origin, had ever lived in the Mediterranean basin. The remains found in the Italian regions of Gargano, Tuscany and Scontrone over the last few decades confirm that they did.

Now, a study published in the Journal of Paleontology corroborates this with the fossils of two crocodiles measuring about three meters in length that were discovered in the Valencian Venta del Moro site -excavated by researchers from the University of Valencia between 1995 and 2006-, and which were ascribed at the time to the Crocodylus checchiai species . This new work describes the remains more than 14 years after they were found for the first time.

“Our comparisons indicate that this material clearly does not belong to the Diplocynodon genera -an extinct genus of alligatoroid, similar to today’s caimans- or Tomistoma -similar to gavials-, the only other two crocodilians described so far for the late European Miocene,” as Ángel Hernández Luján, a palaeontologist at the Miquel Crusafont Catalan Institute of Palaeontology (ICP) and co-author of the work, has explained to Sinc.

However, as the remains are too fragmented, an analysis of the cranial bones, isolated teeth and osteoderms (bone plaque on the skin) suggests that they could belong to the C. checchiai species, as assigned at the time of their discovery, but their taxonomy is still not completely clear and hinders a more precise specific identification. In any case, “the morphology of the Venta del Moro crocodile remains is congruent with the Crocodylus genus,” the researcher states.

Swimming from Africa to Europe

The fossil remains of this Valencian site, which are the first Crocodylus in the Iberian Peninsula, “unequivocally” support the non-occasional dispersion of this genus from Africa to Europe during the late Miocene, according to palaeontologists. The discovery of two partial individuals, instead of just one, could indicate that a whole population was present in this area.

During their ‘colonization,’ these reptiles spread more significantly in the southern areas of Mediterranean Europe, as suggested by the Italian and Spanish areas where the fossils have been found. “All European localities with late Miocene crocodilians, including Venta del Moro, were at that time close to the northern Mediterranean coast and therefore easily accessible thanks to specimens that became scattered in the seawater,” the authors stress in the study.

“What is most certain is that it would have also inhabited the coasts of Murcia and Andalusia, although we cannot rule out that it would also have become dispersed along the coast of Catalonia and the Balearic Islands,” Hernández Luján has pointed out to SINC. But how could they have got there from the African coasts?

The researchers’ hypothesis is that these crocodiles swam from one continent to another in the sea before a land connection was established between Africa and Europe. This idea would be supported by the behavior of modern crocodiles, which are good swimmers and can even reach 32 km/h in the water.

An example of this is the current saltwater crocodile (Crocodylus porosus), which can make significant forays into the open sea to colonize other islands or other continents between Oceania and South-East Asia. “You only have to look at how easily it moves in the open sea to be seen in the waters of the Solomon Islands or even in French Polynesia,” says the palaeontologist.

But there are more examples that reinforce this hypothesis. Because of its anatomical similarity to American crocodiles, the extinct species Crocodylus checchiai, which originated in Libya and Kenya, could well be its ancestor. This suggests that crocodiles were able to cross the Atlantic Ocean during the Miocene, which would explain the appearance of the genus in America.

Therefore, in the case of the specimens found in Venta del Moro, swimming from the African to the European continent “must not have meant a great effort for them before they reached the Peninsula,” the researcher concludes.

Reference:
Massimo Delfino et al, Late Miocene remains from Venta del Moro (Iberian Peninsula) provide further insights on the dispersal of crocodiles across the late Miocene Tethys, Journal of Paleontology (2020). DOI: 10.1017/jpa.2020.62

Note: The above post is reprinted from materials provided by Spanish Foundation for Science and Technology (FECYT).

Tooth marks and lost teeth offer insights into dinosaur feeding behavior

Teeth of a large dinosaur, possibly Metriacanthosauridae, from the Liuhuanggou site in the southern Junggar basin. Scale: 1 cm. Credit: University of Tübingen
Teeth of a large dinosaur, possibly Metriacanthosauridae, from the Liuhuanggou site in the southern Junggar basin. Scale: 1 cm. Credit: University of Tübingen

The carcass of a large long-necked dinosaur in the Junggar Basin in northwestern China served as food for several other dinosaurs, Tübingen paleontologists say, citing tooth marks on the bones and several dinosaur teeth, which matched the tooth marks perfectly. A research team from the Geoscience Department at the University of Tübingen found that the large number of bite marks on the 20-meter carcass showed that other animals fed on it for a long period of time. The bones and teeth were preserved in situ by favorable climatic and geological conditions for more than 160 million years. For the paleontologists this is a rare stroke of luck, as little is known about the feeding behavior of large predatory dinosaurs. The team’s study has been published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

At least one large carnivorous dinosaur of approximately 7.5 meters length and a smaller one some three meters long gnawed on the carcass of the long-necked mamenchisaur, says Felix Augustin, the study’s lead author. Four of the teeth found nearby, and most of the bite marks on the bones, were from the large dinosaur, a carnosaur. “Sometimes the teeth fit exactly into the holes in the bone,” Augustin reports. Another tooth found at the site enabled the researchers to identify a smaller coelurosaur, a diverse group of dinosaurs found the world over. The team believes the teeth fell out while the dinosaurs were eating. In an earlier study, the research team described much smaller tooth marks on the same skeleton as the earliest known evidence that mammals ate dinosaur meat (press release of July 31, 2020).

Trampled bones

The finds originate from today’s Junggar Basin in the province of Xinjiang in northwest China. There, researchers on a Chinese-German expedition in 2000 excavated numerous fossils of vertebrates such as turtles and crocodiles, dinosaurs and mammals from the Jurassic period, the time about 160 million years before today. The bones and teeth are currently being stored in Tübingen, where experts in vertebrate paleontology have been reviewing them since last year.

Many of the mamenchisaurus’ bones were broken in many places or even shattered. “One or more large animals must have trampled the bones when visiting the feeding place; probably it was the large carnivorous dinosaurs,” says Augustin. Some of the bones themselves appear to have been partially or completely eaten. “This is rare in carnivorous dinosaurs. So far, it has mainly been documented in tyrannosaurs.”

Reference:
Felix J. Augustin et al. A theropod dinosaur feeding site from the Upper Jurassic of the Junggar Basin, NW China, Palaeogeography, Palaeoclimatology, Palaeoecology (2020). DOI: 10.1016/j.palaeo.2020.109999

Note: The above post is reprinted from materials provided by University of Tübingen.

Chrysoberyl : One of the world’s most expensive Gemstone

Chrysoberyl
Chrysoberyl, Locality: Governador Valadares, Doce valley, Minas Gerais, BrazilOriginal description: 7.33 mm Chrysoberyl specimen with ” star ” form. Collection: D.Preite, Photo: M.Chinellato

The mineral or gemstone chrysoberyl is a beryllium aluminate with the formula BeAl2O4. The name chrysoberyl is derived from the Greekwords χρυσός chrysos and βήρυλλος beryllos, meaning “a gold-white spar”. Despite the similarity of their names, chrysoberyl and beryl are two entirely different gemstones, although they both contain beryllium. Chrysoberyl is the third hardest commonly encountered natural gemstone and lies at 8.5 on the Mohs scale of mineral hardness, between corundum (9) and topaz (8).

The ordinary chrysoberyl is yellowish-green and transparent to translucent. When the mineral has a good pale green to yellow colour and is transparent, it is used as a gemstone. The three main varieties of chrysoberyl are: ordinary yellow-green chrysoberyl, cat’s eye or cymophane, and alexandrite. Yellow-green chrysoberyl was referred to as “chrysolite” during the Victorian and Edwardian eras, which caused confusion since that name was also used for mineral olivine (‘peridot’ as a gemstone); this name is no longer used in the gemological nomenclature.

Chrysoberyl Occurrence

Chrysoberyl forms as a result of pegmatic processes. Melting in Earth’s crust produces relatively low-density molten magma, which can rise up to the surface. As the main magma body cools, the water initially present at low concentrations became more concentrated in the molten rock because it could not be incorporated into the crystallisation of solid minerals. The remaining magma thus becomes richer in water, and also in rare elements that similarly do not fit into the crystal structures of the major rock-forming minerals. Water extends the temperature range downwards before the magma becomes completely solid, allowing the concentration of rare elements to proceed to the point where they produce their own distinctive minerals. The resulting rock is igneous in appearance but formed at a low temperature by a water-rich melt, with large crystals of common minerals such as quartz and feldspar, but also with elevated concentrations of rare elements such as beryllium, lithium or niobium, often forming their own minerals; this is called pegmatite. The high water content of the magma made it possible for the crystals to grow rapidly, so that the pegmatite crystals are often quite large, increasing the likelihood of gems forming.

Chrysoberyl may also grow in country rocks near pegmatites, when pegmatite-rich be-and al-rich fluids react with surrounding minerals. It can therefore be found in mica shales and in contact with the metamorphic deposits of dolomitic marble. Because it is a hard , dense mineral that is resistant to chemical alteration, it can be wetted out of rocks and deposited in river sands and gravels in alluvial deposits with other gem minerals such as diamonds, corundum, topaz, spinel, granite and tourmaline. When found in such pleasures, there will be rounded edges instead of sharp, wedge-shaped shapes. Much of the chrysoberyl mined in Brazil and Sri Lanka is recovered from pleasure, as the host rocks have been severely weathered and eroded.

If the pegmatite fluid is rich in beryllium, beryllium or chrysoberyl crystals may form. Beryl has a high ratio of beryllium to aluminium, while the opposite is true of chrysoberyl. Both are stable with a common quartz mineral. Some chromium would also have had to be present to form alexandrite. However, beryllium and chromium do not tend to occur in the same rock types. Chromium is most common in mafic and ultramafic rocks where beryllium is extremely rare. Beryllium is concentrated in felsic pegmatites where chromium is almost absent. Therefore, the only situation where alexandrite can grow is when Be-rich pegmatite fluids react with Cr-rich country rock. This unusual requirement explains the rareness of this chrysoberyl variety.

Physical Properties of Chrysoberyl

Cleavage: {110} Distinct, {010} Imperfect, {???} Imperfect
Color: Blue green, Brown, Brownish green, Green, Gray.
Density: 3.5 – 3.84, Average = 3.67
Diaphaneity: Transparent to translucent
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Habit: Prismatic – Crystals Shaped like Slender Prisms (e.g. tourmaline).
Habit: Tabular – Form dimensions are thin in one direction.
Habit: Twinning Common – Crystals are usually twinned.
Hardness: 8.5 – Chrysoberyl
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Streak: white

What is chrysoberyl used for?

Chrysoberyl is not present in large deposits to be used as a beryllium ore. Its only used as a gemstone due to its very high hardness and its unique properties.

How much is chrysoberyl worth?

Chrysoberyl has recently been marketed for tens of thousands of dollars, with alexandrite chrysoberyl often hitting over $100,000.

Related Article: Top 10 World’s Rarest & Valuable Gems

Natural nanodiamonds in oceanic rocks

The fluid inclusions inside the olivine contain nanodiamonds, apart from serpentine, magnetite, metallic silicon and pure methane. Credit: University of Barcelona
The fluid inclusions inside the olivine contain nanodiamonds, apart from serpentine, magnetite, metallic silicon and pure methane. Credit: University of Barcelona

Natural diamonds can form through low pressure and temperature geological processes on Earth, as stated in an article published in the journal Geochemical Perspectives Letters. The newfound mechanism, far from the classic view on the formation of diamonds under ultra-high pressure, is confirmed in the study, which draws on the participation of experts from the Mineral Resources Research Group of the Faculty of Earth Sciences of the University of Barcelona (UB).

Other participants in the study are the experts from the Institute of Nanoscience and Nanotechnology of the UB (IN2UB), the University of Granada (UGR), the Andalusian Institute of Earth Sciences (IACT), the Institute of Ceramics and Glass (CSIC), and the National Autonomous University of Mexico (UNAM). The study has been carried out within the framework of the doctoral thesis carried out by researcher Núria Pujol-Solà (UB), first author of the article, under the supervision of researchers Joaquín A. Proenza (UB) and Antonio García-Casco (UGR).

Diamond: The toughest of all minerals

A symbol of luxury and richness, the diamond (from the Greek αδ?μας, “invincible”) is the most valuable gem and the toughest mineral (value of 10 in Mohs scale). It is formed by chemically pure carbon, and according to the traditional hypothesis, it crystalizes the cubic system under ultra-high-pressure conditions at great depths in the Earth’s mantle.

The study confirms for the first time the formation of the natural diamond under low pressures in oceanic rocks in the Moa-Baracoa Ophiolitic Massif, in Cuba. This great geological structure is in the north-eastern side of the island and is formed by ophiolites, representative rocks of the Oceanic lithosphere.

These oceanic rocks were deposited on the continental edge of North America during the collision of the Caribbean oceanic island arch, between 70 and 40 million years ago. “During its formation in the abysmal marine seafloors, in the cretaceous period—about 120 million years ago—these oceanic rocks underwent mineral alterations due to marine water infiltrations, a process that led to small fluid inclusions inside the olivine, the most common mineral in this kind of rock,” notes Joaquín A. Proenza, member of the Department of Mineralogy, Petrology and Applied Geology at the UB and principal researcher of the project in which the article appears, and Antonio García-Casco, from the Department of Mineralogy and Petrology of the UGR.

“These fluid inclusions contain nanodiamonds of about 200 and 300 nanometres, apart from serpentine, magnetite, metallic silicon and pure methane. All these materials have formed under low pressure (<200 MPa) and temperature (<350 ºC), during the olivine alteration that contains fluid inclusions,” add the researchers.

“Therefore, this is the first description of ophiolitic diamond formed under low pressure and temperature, whose formation under natural processes does not bear any doubts,” they highlight.

Diamonds formed under low pressure and temperature

It is notable to bear in mind that the team published, in 2019, a first description of the formation of ophiolitic diamonds under low pressure conditions (Geology), a study carried out as part of the doctoral thesis by the UB researcher Júlia Farré de Pablo, supervised by Joaquín A. Proenza and the UGR professor José María González Jiménez. This study was highly debated among the members of the international scientific community.

In the current article in Geochemical Perspectives Letters, a journal of the European Association of Geochemistry, the experts detected the nanodiamonds in small fluid inclusions under the surface of the samples. The finding was carried out by using confocal Raman maps and using focused ion beams (FIB), combined with transmission electron microscopy (FIB-TEM). This is how they could confirm the presence of the diamond in the depth of the sample, and therefore, the formation of a natural diamond under low pressure in exhumed oceanic rocks. The Scientific and Technological Centres of the UB (CCiTUB) have taken part in this study, among other infrastructures supporting the country.

In this case, the study focuses its debate on the validity of some geodynamic models that, based on the presence of ophiolite diamonds, imply circulation in the mantle and large-scale lithosphere recycling. For instance, the ophiolitic diamond was thought to reflect the passing of ophiolitic rocks over the deep earth’s mantle up to the transition area (210-660 km deep) before settling into a normal ophiolite formed under low pressure (~10 km deep).

According to the experts, the low state of oxidation in this geological system would explain the formation of nano-diamonds instead of graphite, which would be expected under physical and chemical formation conditions of fluid inclusions.

Reference:
N. Pujol-Solà et al, Diamond forms during low pressure serpentinisation of oceanic lithosphere, Geochemical Perspectives Letters (2020). DOI: 10.7185/geochemlet.2029

Note: The above post is reprinted from materials provided by University of Barcelona.

Volcanic eruptions may explain Denmark’s giant mystery crystals

Photo of a glendonite. Credit: Bo Schultz
Photo of a glendonite. Credit: Bo Schultz

Researchers have long been stumped for an explanation of how tens of millions of years-old giant crystals known as glendonites came to be on the Danish islands of Fur and Mors. A recent study from the University of Copenhagen offers a possible explanation to the conundrum: major volcanic eruptions resulted in episodes of much cooler prehistoric climates than once thought.

Some of the world’s largest specimens of rare calcium carbonate crystals, known as glendonites, are found in Denmark.

The crystals were formed between 56 and 54 million years ago, during a period that is known to have had some of the highest temperatures in Earth’s geologic history. Their presence has long stirred wonder among researchers the world over.

“Why we find glendonites from a hot period, when temperatures averaged above 35 degrees, has long been a mystery. It shouldn’t be possible,” explains Nicolas Thibault, an associate professor at the University of Copenhagen’s Department of Geosciences and Natural Resource Management.

This is because glendonites are composed of ikaite, a mineral that is only stable, and can therefore only crystallize, at temperatures of less than four degrees Celsius.

Volcanoes responsible for cold intervals

In their new study, Nicolas Thibault, along with department colleagues Madeleine Vickers, Christian Bjerrum and Christoph Korte, performed chemical analyses of the Danish glendonites.

Their work reveals that the early Eocene Epoch, between 56 and 48 million years ago, was not at all as uniformly warm as once thought.

“Our study proves that there must have been periods of cold during the Eocene Epoch. Otherwise, these crystals couldn’t exist—they would have simply melted. We also propose a suggestion for how this cooling might have happened, and in doing so, potentially solve the mystery of how glendonites in Denmark and the rest of the world came to be,” says Nicolas Thibault. He adds:

“There were probably a large number of volcanic eruptions in Greenland, Iceland and Ireland during this period. These released sulphuric acid droplets into the stratosphere, which could have remained there for years, shading the planet from the sun and reflecting sunlight away. This helps to explain how regionally cold areas were possible, which is what affected the climate in early Eocene Denmark.”

Layers of volcanic ash in rock

The presence of volcanic activity is revealed by, among other things, sedimentary layers visible on Fur, where layers of volcanic ash are clearly visible as bands in the coastal bluffs.

“Our study helps solve a mystery about glendonites, as well as demonstrating that cooler episodes are possible during otherwise warmer climates. The same can be said for today, as we wise up to the possibility of abrupt climate change,” concludes Nicolas Thibault.

Reference:
Madeleine L. Vickers et al, Cold spells in the Nordic Seas during the early Eocene Greenhouse, Nature Communications (2020). DOI: 10.1038/s41467-020-18558-7

Note: The above post is reprinted from materials provided by University of Copenhagen.

World’s greatest mass extinction triggered switch to warm-bloodedness

The origin of endothermy in synapsids, including the ancestors of mammals. The diagram shows the evolution of main groups through the Triassic, and the scale from blue to red is a measure of the degree of warm-bloodedness reconstructed based on different indicators of bone structure and anatomy. Credit: Mike Benton, University of Bristol. Animal images are by Nobu Tamura, Wikimedia
The origin of endothermy in synapsids, including the ancestors of mammals. The diagram shows the evolution of main groups through the Triassic, and the scale from blue to red is a measure of the degree of warm-bloodedness reconstructed based on different indicators of bone structure and anatomy. Credit: Mike Benton, University of Bristol. Animal images are by Nobu Tamura, Wikimedia

Mammals and birds today are warm-blooded, and this is often taken as the reason for their great success.

University of Bristol palaeontologist Professor Mike Benton, identifies in the journal Gondwana Research that the ancestors of both mammals and birds became warm-blooded at the same time, some 250 million years ago, in the time when life was recovering from the greatest mass extinction of all time.

The Permian–Triassic mass extinction killed as much as 95 per cent of life, and the very few survivors faced a turbulent world, repeatedly hit by global warming and ocean acidification crises. Two main groups of tetrapods survived, the synapsids and archosaurs, including ancestors of mammals and birds respectively.

Palaeontologists had identified indications of warm-bloodedness, or technically endothermy, in these Triassic survivors, including evidence for a diaphragm and possible whiskers in the synapsids.

More recently, similar evidence for early origin of feathers in dinosaur and bird ancestors has come to light. In both synapsids and archosaurs of the Triassic, the bone structure shows characteristics of warm-bloodedness. The evidence that mammal ancestors had hair from the beginning of the Triassic has been suspected for a long time, but the suggestion that archosaurs had feathers from 250 million years ago is new.

But a strong hint for this sudden origin of warm-bloodedness in both synapsids and archosaurs at exactly the time of the Permian-Triassic mass extinction was found in 2009. Tai Kubo, then a student studying the Masters in Palaeobiology degree at Bristol and Professor Benton identified that all medium-sized and large tetrapods switched from sprawling to erect posture right at the Permian-Triassic boundary.

Their study was based on fossilised footprints. They looked at a sample of hundreds of fossil trackways, and Kubo and Benton were surprised to see the posture shift happened instantly, not strung out over tens of millions of years, as had been suggested. It also happened in all groups, not just the mammal ancestors or bird ancestors.

Professor Benton said: “Modern amphibians and reptiles are sprawlers, holding their limbs partly sideways.

“Birds and mammals have erect postures, with the limbs immediately below their bodies. This allows them to run faster, and especially further. There are great advantages in erect posture and warm-bloodedness, but the cost is that endotherms have to eat much more than cold-blooded animals just to fuel their inner temperature control.”

The evidence from posture change and from early origin of hair and feathers, all happening at the same time, suggested this was the beginning of a kind of ‘arms race’. In ecology, arms races occur when predators and prey have to compete with each other, and where there may be an escalation of adaptations. The lion evolves to run faster, but the wildebeest also evolves to run faster or twist and turn to escape.

Something like this happened in the Triassic, from 250 to 200 million years ago. Today, warm-blooded animals can live all over the Earth, even in cold areas, and they remain active at night. They also show intensive parental care, feeding their babies and teaching them complex and smart behaviour. These adaptations gave birds and mammals the edge over amphibians and reptiles and in the present cool world allowed them to dominate in more parts of the world.

Professor Benton added: “The Triassic was a remarkable time in the history of life on Earth. You see birds and mammals everywhere on land today, whereas amphibians and reptiles are often quite hidden.

“This revolution in ecosystems was triggered by the independent origins of endothermy in birds and mammals, but until recently we didn’t realise that these two events might have been coordinated.

“That happened because only a tiny number of species survived the Permian-Triassic mass extinction — who survived depended on intense competition in a tough world. Because a few of the survivors were already endothermic in a primitive way, all the others had to become endothermic to survive in the new fast-paced world.”

Reference:
Michael J. Benton. The origin of endothermy in synapsids and archosaurs and arms races in the Triassic. Gondwana Research, 2020; DOI: 10.1016/j.gr.2020.08.003

Note: The above post is reprinted from materials provided by University of Bristol.

Ancient tiny teeth reveal first mammals lived more like reptiles

Reconstruction of Morganucodon (left) and Kuehneotherium (right) hunting in Early Jurassic Wales 200 million years ago. Credit: Original painting by John Sibbick, 2013. Copyright: Pam Gill
Reconstruction of Morganucodon (left) and Kuehneotherium (right) hunting in Early Jurassic Wales 200 million years ago. Credit: Original painting by John Sibbick, 2013. Copyright: Pam Gill

Pioneering analysis of 200 million-year-old teeth belonging to the earliest mammals suggests they functioned like their cold-blooded counterparts — reptiles, leading less active but much longer lives.

The research, led by the University of Bristol, UK and University of Helsinki, Finland, published today in Nature Communications, is the first time palaeontologists have been able to study the physiologies of early fossil mammals directly, and turns on its head what was previously believed about our earliest ancestors.

Fossils of teeth, the size of a pinhead, from two of the earliest mammals, Morganucodon and Kuehneotherium, were scanned for the first time using powerful X-rays, shedding new light on the lifespan and evolution of these small mammals, which roamed the earth alongside early dinosaurs and were believed to be warm-blooded by many scientists. This allowed the team to study growth rings in their tooth sockets, deposited every year like tree rings, which could be counted to tell us how long these animals lived. The results indicated a maximum lifespan of up to 14 years — much older than their similarly sized furry successors such as mice and shrews, which tend to only survive a year or two in the wild.

“We made some amazing and very surprising discoveries. It was thought the key characteristics of mammals, including their warm-bloodedness, evolved at around the same time,” said lead author Dr Elis Newham, Research Associate at the University of Bristol, and previously PhD student at the University of Southampton during the time when this study was conducted.

“By contrast, our findings clearly show that, although they had bigger brains and more advanced behaviour, they didn’t live fast and die young but led a slower-paced, longer life akin to those of small reptiles, like lizards.”

Using advanced imaging technology in this way was the brainchild of Dr Newham’s supervisor Dr Pam Gill, Senior Research Associate at the University of Bristol and Scientific Associate at the Natural History Museum London, who was determined to get to the root of its potential.

“A colleague, one of the co-authors, had a tooth removed and told me they wanted to get it X-rayed, because it can tell all sorts of things about your life history. That got me wondering whether we could do the same to learn more about ancient mammals,” Dr Gill said.

By scanning the fossilised cementum, the material which locks the tooth roots into their socket in the gum and continues growing throughout life, Dr Gill hoped the preservation would be clear enough to determine the mammal’s lifespan.

To test the theory, an ancient tooth specimen belonging to Morganucodon was sent to Dr Ian Corfe, from the University of Helsinki and the Geological Survey of Finland, who scanned it using high-powered Synchrotron X-ray radiation.

“To our delight, although the cementum is only a fraction of a millimetre thick, the image from the scan was so clear the rings could literally be counted,” Dr Corfe said.

It marked the start of a six-year international study, which focused on these first mammals, Morganucodon and Kuehneotherium, known from Jurassic rocks in South Wales, UK, dating back nearly 200 million years.

“The little mammals fell into caves and holes in the rock, where their skeletons, including their teeth, fossilised. Thanks to the incredible preservation of these tiny fragments, we were able to examine hundreds of individuals of a species, giving greater confidence in the results than might be expected from fossils so old,” Dr Corfe added.

The journey saw the researchers take some 200 teeth specimens, provided by the Natural History Museum London and University Museum of Zoology Cambridge, to be scanned at the European Synchrotron Radiation Facility and the Swiss Light Source, among the world’s brightest X-ray light sources, in France and Switzerland, respectively.

In search of an exciting project, Dr Newham took this up for the MSc in Palaeobiology at the University of Bristol, and then a PhD at the University of Southampton.

“I was looking for something big to get my teeth into and this more than fitted the bill. The scanning alone took over a week and we ran 24-hour shifts to get it all done. It was an extraordinary experience, and when the images started coming through, we knew we were onto something,” Dr Newham said.

Dr Newham was the first to analyse the cementum layers and pick up on their huge significance.

“We digitally reconstructed the tooth roots in 3-D and these showed that Morganucodon lived for up to 14 years, and Kuehneotherium for up to nine years. I was dumbfounded as these lifespans were much longer than the one to three years we anticipated for tiny mammals of the same size,” Dr Newham said.

“They were otherwise quite mammal-like in their skeletons, skulls and teeth. They had specialised chewing teeth, relatively large brains and probably had hair, but their long lifespan shows they were living life at more of a reptilian pace than a mammalian one. There is good evidence that the ancestors of mammals began to become increasingly warm-blooded from the Late Permian, more than 270 million years ago, but, even 70 million years later, our ancestors were still functioning more like modern reptiles than mammals”

While their pace-of-life remained reptilian, evidence for an intermediate ability for sustained exercise was found in the bone tissue of these early mammals. As a living tissue, bone contains fat and blood vessels. The diameter of these blood vessels can reveal the maximum possible blood flow available to an animal, critical for activities such as foraging and hunting.

Dr Newham said: “We found that in the thigh bones of Morganucodon, the blood vessels had flow rates a little higher than in lizards of the same size, but much lower than in modern mammals. This suggests these early mammals were active for longer than small reptiles but could not live the energetic lifestyles of living mammals.”

Reference:
Elis Newham, Pamela G. Gill, Philippa Brewer, Michael J. Benton, Vincent Fernandez, Neil J. Gostling, David Haberthür, Jukka Jernvall, Tuomas Kankaanpää, Aki Kallonen, Charles Navarro, Alexandra Pacureanu, Kelly Richards, Kate Robson Brown, Philipp Schneider, Heikki Suhonen, Paul Tafforeau, Katherine A. Williams, Berit Zeller-Plumhoff, Ian J. Corfe. Reptile-like physiology in Early Jurassic stem-mammals. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-18898-4

Note: The above post is reprinted from materials provided by University of Bristol.

Beak bone reveals pterosaur like no other

An artist's impression of Leptostomia begaaensis Credit: Megan Jacobs, University of Portsmouth
An artist’s impression of Leptostomia begaaensis Credit: Megan Jacobs, University of Portsmouth

A new species of small pterosaur — similar in size to a turkey — has been discovered, which is unlike any other pterosaur seen before due to its long slender toothless beak.

The fossilised piece of beak was a surprising find and was initially assumed to be part of the fin spine of a fish, but a team of palaeontologists from the universities of Portsmouth and Bath spotted the unusual texture of the bone — seen only in pterosaurs — and realised it was a piece of beak.

Professor David Martill of the University of Portsmouth, who co-authored the study, said: “We’ve never seen anything like this little pterosaur before. The bizarre shape of the beak was so unique, at first the fossils weren’t recognised as a pterosaur.”

Careful searching of the late Cretaceous Kem Kem strata of Morocco, where this particular bone was found, revealed additional fossils of the animal, which led to the team concluding it was a new species with a long, skinny beak, like that of a Kiwi.

Lead author of the project, University of Portsmouth PhD student Roy Smith, said: “Just imagine how delighted I was, while on field work in Morocco, to discover the lower jaw to match the upper jaw found by Dr Longrich of this utterly unique fossil animal.”

The new species, Leptostomia begaaensis, used its beak to probe dirt and mud for hidden prey, hunting like present-day sandpipers or kiwis to find worms, crustaceans, and perhaps even small hard-shelled clams.

Pterosaurs are the less well-known cousins of dinosaurs. Over 100 species of these winged-reptiles are known, some as large as a fighter jet and others as small as a sparrow.

Professor Martill said: “The diets and hunting strategies of pterosaurs were diverse — they likely ate meat, fish and insects. The giant 500-pound pterosaurs probably ate whatever they wanted.

“Some species hunted food on the wing, others stalked their prey on the ground. Now, the fragments of this remarkable little pterosaur show a lifestyle previously unknown for pterosaurs.”

The scientists used a computerised tomography (CT) scan to reveal an incredible network of internal canals for nerves that helped detect the prey underground.

Dr Nick Longrich, from the Milner Centre for Evolution at the University of Bath, said: “Leptostomia may actually have been a fairly common pterosaur, but it’s so strange — people have probably been finding bits of this beast for years, but we didn’t know what they were until now.”

Long, slender beaks evolved in many modern birds. Those most similar to Leptostomia are probing birds — like sandpipers, kiwis, curlews, ibises and hoopoes. Some of these birds forage in earth for earthworms while others forage along beaches and tidal flats, feeding on bristle worms, fiddler crabs, and small clams.

Leptostomia could probably have done either, but its presence in the Cretaceous age Kem Kem strata of Africa — representing a rich ecosystem of rivers and estuaries — suggests it was drawn there to feed on aquatic prey.

“You might think of the pterosaur as imitating the strategy used successfully by modern birds, but it was the pterosaur that got there first,” said Dr Longrich. “Birds just reinvented what pterosaurs had already done tens of millions of years earlier.”

Dr Longrich suggests the new species shows how, more than a century after pterosaurs were first discovered, there’s still so much to learn about them. He said: “We’re underestimating pterosaur diversity because the fossil record gives us a biased picture.

“Pterosaur fossils typically preserve in watery settings — seas, lakes, and lagoons — because water carries sediments to bury bones. Pterosaurs flying over water to hunt for fish tend to fall in and die, so they’re common as fossils. Pterosaurs hunting along the margins of the water will preserve more rarely, and many from inland habitats may never preserve as fossils at all.

“There’s a similar pattern in birds. If all we had of birds was their fossils, we’d probably think that birds were mostly aquatic things like penguins, puffins, ducks and albatrosses. Even though they’re a minority of the species, their fossil record is a lot better than for land birds like hummingbirds, hawks, and ostriches.”

Over time, more and more species of pterosaurs with diverse lifestyles have been discovered. That trend, the new pterosaur suggests, is likely to continue.

The paper was published today in Cretaceous Research.

Reference:
Roy E. Smith, David M. Martill, Alexander Kao, Samir Zouhri, Nicholas Longrich. A long-billed, possible probe-feeding pterosaur (Pterodactyloidea: ?Azhdarchoidea) from the mid-Cretaceous of Morocco, North Africa. Cretaceous Research, 2020; 104643 DOI: 10.1016/j.cretres.2020.104643

Note: The above post is reprinted from materials provided by University of Portsmouth.

Researchers discover fossils of new species in Arizona

Representative Image

Researchers have discovered fossils of a tiny burrowing reptile among a vast expanse of petrified wood in eastern Arizona.

The new species has been named Skybalonyx skapter, a part of a group known as drepanosaurs from the Triassic Period, about 220 million years ago.

Petrified Forest National Park outside Holbrook is considered one of the premier places to study plants and animals from that period, sometimes known as the dawning age of dinosaurs.

The researchers say the ancient reptiles are strange because of morphologies that include enlarged second claws, bird-like beaks and tails with claws. They likely looked like a cross between an anteater and a chameleon.

They say the new species could be even stranger because it has claws that allow it to burrow, rather than climb into and live in trees, more like a mole or mole-rat.

The fossils were discovered by a team of researchers from the park, Virginia Tech, the University of Washington, Arizona State University, Idaho State University and the Virginia Museum of Natural History. They published their findings earlier this month in the Journal of Vertebrate Paleontology.

They found the fossils in the summers of 2018 and 2019 using a screen-washing technique.

Note: The above post is reprinted from materials provided by The Associated Press. All rights reserved.

Earth grows fine gems in minutes

Brazilian emeralds in a quartz-pegmatite matrix. (Photo courtesy of Madereugeneandrew/Wikimedia Commons)
Brazilian emeralds in a quartz-pegmatite matrix. (Photo courtesy of Madereugeneandrew/Wikimedia Commons)

Rome wasn’t built in a day, but some of Earth’s finest gemstones were, according to new research from Rice University.

Aquamarine, emerald, garnet, zircon and topaz are but a few of the crystalline minerals found mostly in pegmatites, veinlike formations that commonly contain both large crystals and hard-to-find elements like tantalum and niobium. Another common find is lithium, a vital component of electric car batteries.

“This is one step towards understanding how Earth concentrates lithium in certain places and minerals,” said Rice graduate student Patrick Phelps, co-author of a study published online in Nature Communications. “If we can understand the basics of pegmatite growth rates, it’s one step in the direction of understanding the whole picture of how and where they form.”

Pegmatites are formed when rising magma cools inside Earth, and they feature some of Earth’s largest crystals. South Dakota’s Etta mine, for example, features log-sized crystals of lithium-rich spodumene, including one 42 feet in length in weighing an estimated 37 tons. The research by Phelps, Rice’s Cin-Ty Lee and Southern California geologist Douglas Morton attempts to answer a question that has long vexed mineralogists: How can such large crystals be in pegmatites?

“In magmatic minerals, crystal size is traditionally linked to cooling time,” said Lee, Rice’s Harry Carothers Wiess Professor of Geology and chair of the Department of Earth, Environmental and Planetary Sciences at Rice. “The idea is that large crystals take time to grow.”

Magma that cools rapidly, like rock in erupted lavas, contains microscopic crystals, for example. But the same magma, if cooled over tens of thousands of years, might feature centimeter-sized crystals, Lee said.

“Pegmatites cool relatively quickly, sometimes in just a few years, and yet they feature some of the largest crystals on Earth,” he said. “The big question is really, ‘How can that be?'”

When Phelps began the research, his most immediate questions were about how to formulate a set of measurements that would allow him, Lee and Morton to answer the big question.

“It was more a question of, ‘Can we figure out how fast they actually grow?'” Phelps said. “Can we use trace elements — elements that don’t belong in quartz crystals — to figure out the growth rate?”

It took more than three years, a field trip to gather sample crystals from a pegmatite mine in Southern California, hundreds of lab measurements to precisely map the chemical composition of the samples and a deep dive into some 50-year-old materials science papers to create a mathematical model that could transform the chemical profiles into crystal growth rates.

“We examined crystals that were half an inch wide and over an inch long,” Phelps said. “We showed those grew in a matter of hours, and there is nothing to suggest the physics would be different in larger crystals that measure a meter or more in length. Based on what we found, larger crystals like that could grow in a matter of days.”

Pegmatites form where pieces of Earth’s crust are drawn down and recycled in the planet’s molten mantle. Any water that’s trapped in the crust becomes part of the melt, and as the melt rises and cools, it gives rise to many kinds of minerals. Each forms and precipitates out of the melt at a characteristic temperature and pressure. But the water remains, making up a progressively higher percentage of the cooling melt.

“Eventually, you get so much water left over that it becomes more of a water-dominated fluid than a melt-dominated fluid,” Phelps said. “The leftover elements in this watery mixture can now move around a lot faster. Chemical diffusion rates are much faster in fluids and the fluids tend to flow more quickly. So when a crystal starts forming, elements can get to it faster, which means it can grow faster.”

Crystals are ordered arrangement of atoms. They form when atoms naturally fall into that arranged pattern based on their chemical properties and energy levels. For example, in the mine where Phelps collected his quartz samples, many crystals had formed in what appeared to be cracks that had opened while the pegmatite was still forming.

“You see these pop up and go through the layers of pegmatite itself, almost like veins within veins,” Phelps said. “When those cracks opened, that lowered the pressure quickly. So the fluid rushed in, because everything’s expanding, and the pressure dropped dramatically. All of a sudden, all the elements in the melt are now confused. They don’t want to be in that physical state anymore, and they rapidly start coming together in crystals.”

To decipher how quickly the sample crystals grew, Phelps used both cathodoluminescence microscopy and laser ablation with mass spectrometry to measure the precise amount of trace elements that had been incorporated into the crystal matrix at dozens of points during growth. From experimental work done by materials scientists in the mid-20th century, Phelps was able to decipher the growth rates from these profiles.

“There are three variables,” he said. “There’s the likelihood of things getting brought in. That’s the partition coefficient. There’s how fast the crystal is growing, the growth rate. And then there’s the diffusivity, so how quickly elemental nutrients are brought to the crystal.”

Phelps said the fast growth rates were quite a surprise.

“Pegmatites are pretty short-lived, so we knew they had to grow relatively fast,” he said. “But we were showing it was a few orders of magnitude faster than anyone had predicted.

“When I finally got one of these numbers, I remember going into Cin-Ty’s office, and saying, ‘Is this feasible? I don’t think this is right.'” Phelps recalled. “Because in my head, I was still kind of thinking about a thousand-year time scale. And these numbers were meaning days or hours.

“And Cin-Ty said, ‘Well, why not? Why can’t it be right?'” Phelps said. “Because we’d done the math and the physics. That part was sound. While we didn’t expect it to be that fast, we couldn’t come up with a reason why it wasn’t plausible.”

The research was supported by the National Science Foundation.

Reference:
Patrick R. Phelps, Cin-Ty A. Lee, Douglas M. Morton. Episodes of fast crystal growth in pegmatites. Nature Communications, 2020; 11 (1) DOI: 10.1038/s41467-020-18806-w

Note: The above post is reprinted from materials provided by Rice University.

Diamonds found with gold in Canada’s Far North offer clues to Earth’s early history

A sample of pebbly rock that U of A researchers took from an outcrop in Nunavut. The rock was found to contain both gold and diamonds—a rare combination similar to that found in the world's richest gold deposit in South Africa. (Photo: Supplied)
A sample of pebbly rock that U of A researchers took from an outcrop in Nunavut. The rock was found to contain both gold and diamonds—a rare combination similar to that found in the world’s richest gold deposit in South Africa. (Photo: Supplied)

The presence of diamonds in an outcrop atop an unrealized gold deposit in Canada’s Far North mirrors the association found above the world’s richest gold mine, according to University of Alberta research that fills in blanks about the thermal conditions of Earth’s crust three billion years ago.

“The diamonds we have found so far are small and not economic, but they occur in ancient sediments that are an exact analog of the world’s biggest gold deposit — the Witwatersrand Goldfields of South Africa, which has produced more than 40 per cent of the gold ever mined on Earth,” said Graham Pearson, researcher in the Faculty of Science and Canada Excellence Research Chair Laureate in Arctic Resources.

“Diamonds and gold are very strange bedfellows. They hardly ever appear in the same rock, so this new find may help to sweeten the attractiveness of the original gold discovery if we can find more diamonds.”

Pearson explained that ex-N.W.T. Geological Survey scientist Val Jackson alerted his group to an unusual outcropping on the Arctic coast that has close similarities to the Witwatersrand gold deposits.

Pearson said this outcrop of rocks, known as conglomerates, are basically the erosion product of old mountain chains that get deposited in braided river channels.

“They’re high-energy deposits that are good at carrying gold, and they’re good at carrying diamonds,” he said. “Our feeling was if the analogies are that close, then maybe there are diamonds in the Nunavut conglomerate also.”

Pearson said finding new diamond deposits in Canada’s North is critical in Canada continuing to host a $2.5-billion-per-year diamond mining industry.

So, on a hunch, Pearson used the last of his Canada Excellence Research Chair funding that brought him to the U of A, along with funding from the Metal Earth Project and the National Science Foundation, and — accompanied by post-doctoral diamond researcher Adrien Vizinet and former U of A grad student Jesse Reimink, now a professor at Penn State University — travelled to Nunavut.

Once at the site, the group — with the assistance of Silver Range Resources, whose CEO Mike Power is also a U of A alumnus — bashed off a modest 15 kilograms of the conglomerate and dated these rocks using the state-of-the-art mass spectrometry equipment at the U of A, which established their deposition to be about three billion years ago.

The group promptly delivered their samples to the Saskatchewan Research Council, the world leader in quantifying how many diamonds are in a rock.

Pearson remembers the precise moment about a year later, when the council’s Cristiana Mircea, who visits Edmonton to teach Diamond Exploration Research Training School (DERTS) students about diamond indicator mineral identification, matter-of-factly told him the sample produced three diamonds.

“My jaw hit the floor,” said Pearson. “Normally people would take hundreds of kilograms, if not tons of samples, to try and find that many diamonds. We managed to find diamonds in 15 kilos of rock that we sampled with a sledgehammer on a surface outcrop.”

Though the diamonds found are quite small — less than a millimetre in diameter — he said the geologic implications are immense.

First, Pearson said there must have been kimberlite or rock like kimberlite present to carry diamonds to the Earth’s surface in the ancient Earth — a notion many people have doubted.

Kimberlite pipes are the passageways that allow magma to erupt diamonds and other rocks and minerals from the mantle through the crust and onto the Earth’s surface.

It also helps us understand under what conditions these peculiar kimberlite rocks can form.

Pearson said an Italian collaborator, Fabrizio Nestola from the University of Padua, managed to find an inclusion — a non-diamond mineral — in one of the diamond samples. From that, Suzette Timmerman, a researcher in the Canadian Centre for Isotopic Microanalysis and a Banting Postdoctoral Fellowship recipient, began building a theory that the diamonds had to be derived from a small, deep but cool lithospheric root, which is the thickest part of the continental plate.

“This is something completely unexpected from what we think conditions were like three billion years ago on Earth,” said Pearson.

He explained that stable diamonds exist only in cool parts of the mantle, so it suggests there must have been very deep, perhaps 200-kilometre-thick cold roots beneath parts of the continent very early in Earth’s history.

Pearson said despite the U of A’s expertise in dating diamonds around the world, there’s always an argument about the relationship between the inclusion and the diamond deposit.

“Here, there’s no argument because we know when those rocks were eroded onto the Earth’s surface,” he said.

“It tells us there’s an older source, a primary source of diamonds that must have been eroded to form this diamond-plus-gold deposit,” he said.

This also means mining diamonds in the area would not necessarily require very deep mines, if more economic outcrops of these rocks can be found.

“We went up there on a float plane, bashed a piece of rock off with a sledgehammer and found three diamonds,” he said. “That’s actually one of the most astounding parts of this discovery.”

He added that the provincial government, through Alberta Innovates, clearly realized universities can help a lot in expanding and diversifying Alberta’s economy into the mining sector.

“The government’s investment enables us to chase hunches that might otherwise be difficult for industry to go and look at.”

Pearson pointed to the Collaborative Research and Training Experience grant from the Natural Sciences and Engineering Research Council of Canada, which almost instantly turned the U of A into the world’s leading diamond research institution thanks to the formation of DERTS.

“Alberta has several potential diamond deposits and areas ripe for further exploration,” he said. “I believe the University of Alberta can play a key role in helping to find and establish diamond and other mineral mines in Alberta.”

Pearson said more research is continuing on similar nearby outcrops being developed by Silver Range Resources in collaboration with the Metal Earth Project, the Nunavut government and Penn State University, to establish the extent of the diamonds and gold in these rocks, and the possible primary sources of these minerals.

The studies, “Mesoarchean Deposition Age for Diamond-Bearing Metasediment of the Northwestern Slave Craton, Nunavut Territory (Canada)” and “Diamond-Bearing Metasediments Point to Thick, Cool Lithospheric Root Established by the Mesoarchean Beneath Parts of the Slave Craton (Canada),” will be presented at the virtual fall meeting of the American Geophysical Union this December.

Note: The above post is reprinted from materials provided by University of Alberta. Original written by Michael Brown.

Paleontologists identify new species of mosasaur

Artist's rendering of Gavialimimus almaghribensis, a newly discovered species of mosasaur that ruled the seas of what is now Morocco some 72 to 66 million years ago. Credit: Tatsuya Shinmura
Artist’s rendering of Gavialimimus almaghribensis, a newly discovered species of mosasaur that ruled the seas of what is now Morocco some 72 to 66 million years ago. Credit: Tatsuya Shinmura

A new species of an ancient marine reptile evolved to strike terror into the hearts of the normally safe, fast-swimming fish has been identified by a team of University of Alberta researchers, shedding light on what it took to survive in highly competitive ecosystems.

Gavialimimus almaghribensis, a new type of mosasaur, was catalogued and named by an international research team led by master’s student Catie Strong, who performed the research a year ago as part of an undergrad honours thesis guided by vertebrate paleontologist Michael Caldwell, professor in the Faculty of Science, along with collaborators from the University of Cincinnati and Flinders University.

More than a dozen types of mosasaur — which can reach 17 metres in length and resemble an overgrown komodo dragon — ruled over the marine environment in what is now Morocco at the tail end of the Late Cretaceous period between 72 and 66 million years ago.

What differentiates Strong’s version, however, is that it features a long, narrow snout and interlocking teeth — similar to the crocodilian gharials, a relative of crocodiles and alligators.

Strong said this discovery adds a layer of clarity to a diverse picture seemingly overcrowded with mega-predators all competing for food, space and resources.

“Its long snout reflects that this mosasaur was likely adapted to a specific form of predation, or niche partitioning, within this larger ecosystem.”

Strong explained there is evidence that each species of the giant marine lizard shows adaptations for different prey items or styles of predation.

“For some species, these adaptations can be very prominent, such as the extremely long snout and the interlocking teeth in Gavialimimus, which we hypothesized as helping it to catch rapidly moving prey,” she said.

She added another distinctive species would be Globidens simplex — described last year by the Caldwell lab — which has stout, globular teeth adapted for crushing hard prey like shelled animals.

“Not all of the adaptations in these dozen or so species are this dramatic, and in some cases there may have been some overlap in prey items, but overall there is evidence that there’s been diversification of these species into different niches,” Strong noted.

Alternatively, the main contrasting hypothesis would be a scenario of more direct competition among species. Strong said given the anatomical differences among these mosasaurs, though, the idea of niche partitioning seems more consistent with the anatomy of these various species.

“This does help give another dimension to that diversity and shows how all of these animals living at the same time in the same place were able to branch off and take their own paths through evolution to be able to coexist like that,” she said.

The remains of the G. almaghribensis included a metre-long skull and some isolated bones. There was nothing to explain the cause of death of the specimen, which was uncovered in a phosphate mine in Morocco that is rich in fossils.

“Morocco is an incredibly good place to find fossils, especially in these phosphate mines,” Strong said. “Those phosphates themselves reflect sediments that would have been deposited in marine environments, so there are a lot of mosasaurs there.”

Reference:
Catherine R. C. Strong, Michael W. Caldwell, Takuya Konishi, Alessandro Palci. A new species of longirostrine plioplatecarpine mosasaur (Squamata: Mosasauridae) from the Late Cretaceous of Morocco, with a re-evaluation of the problematic taxon ‘Platecarpus’ ptychodon. Journal of Systematic Palaeontology, 2020; 1 DOI: 10.1080/14772019.2020.1818322

Note: The above post is reprinted from materials provided by University of Alberta. Original written by Michael Brown.

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