Permian-Triassic mass extinction, caused by volcanoes?


This 15 September 2015 video from the USA says about itself:

Around 252 millions years ago life on Earth collapsed in a unprecedented fashion as more than 96 percent of marine species and 70 percent of land species disappeared.

The cause of this severe extinction has been a mystery, until now. (Learn more here. MIT researchers have now determined the Siberian Traps erupted at the right time and for the right duration to have been a likely trigger for the end-Permian extinction.

Video produced and edited by Melanie Gonick/MIT

Additional footage and stills: Henrik Svensen, Scott Simper and Seth Burgess

Music sampled from “Out” by Ryan Cross

From the University of Cincinnati in the USA:

New evidence suggests volcanoes caused biggest mass extinction ever

Mercury found in ancient rock around the world supports theory that eruptions caused ‘Great Dying’ 252 million years ago.

April 15, 2019

Researchers say mercury buried in ancient rock provides the strongest evidence yet that volcanoes caused the biggest mass extinction in the history of the Earth.

The extinction 252 million years ago was so dramatic and widespread that scientists call it “the Great Dying.” The catastrophe killed off more than 95 percent of life on Earth over the course of hundreds of thousands of years.

Paleontologists with the University of Cincinnati and the China University of Geosciences said they found a spike in mercury in the geologic record at nearly a dozen sites around the world, which provides persuasive evidence that volcanic eruptions were to blame for this global cataclysm.

The study was published this month in the journal Nature Communications.

The eruptions ignited vast deposits of coal, releasing mercury vapor high into the atmosphere. Eventually, it rained down into the marine sediment around the planet, creating an elemental signature of a catastrophe that would herald the age of dinosaurs.

“Volcanic activities, including emissions of volcanic gases and combustion of organic matter, released abundant mercury to the surface of the Earth,” said lead author Jun Shen, an associate professor at the China University of Geosciences.

The mass extinction occurred at what scientists call the Permian-Triassic Boundary. The mass extinction killed off much of the terrestrial and marine life before the rise of dinosaurs. Some were prehistoric monsters in their own right, such as the ferocious gorgonopsids that looked like a cross between a sabre-toothed tiger and a Komodo dragon.

The eruptions occurred in a volcanic system called the Siberian Traps in what is now central Russia. Many of the eruptions occurred not in cone-shaped volcanoes but through gaping fissures in the ground. The eruptions were frequent and long-lasting and their fury spanned a period of hundreds of thousands of years.

“Typically, when you have large, explosive volcanic eruptions, a lot of mercury is released into the atmosphere,” said Thomas Algeo, a professor of geology in UC’s McMicken College of Arts and Sciences.

“Mercury is a relatively new indicator for researchers. It has become a hot topic for investigating volcanic influences on major events in Earth’s history,” Algeo said.

Researchers use the sharp fossilized teeth of lamprey-like creatures called conodonts to date the rock in which the mercury was deposited. Like most other creatures on the planet, conodonts were decimated by the catastrophe.

The eruptions propelled as much as 3 million cubic kilometers of ash high into the air over this extended period. To put that in perspective, the 1980 eruption of Mount St. Helens in Washington sent just 1 cubic kilometer of ash into the atmosphere, even though ash fell on car windshields as far away as Oklahoma.

In fact, Algeo said, the Siberian Traps eruptions spewed so much material in the air, particularly greenhouse gases, that it warmed the planet by an average of about 10 degrees centigrade.

The warming climate likely would have been one of the biggest culprits in the mass extinction, he said. But acid rain would have spoiled many bodies of water and raised the acidity of the global oceans. And the warmer water would have had more dead zones from a lack of dissolved oxygen.

“We’re often left scratching our heads about what exactly was most harmful. Creatures adapted to colder environments would have been out of luck,” Algeo said. “So my guess is temperature change would be the No. 1 killer. Effects would exacerbated by acidification and other toxins in the environment.”

Stretching over an extended period, eruption after eruption prevented the Earth’s food chain from recovering.

“It’s not necessarily the intensity but the duration that matters,” Algeo said. “The longer this went on, the more pressure was placed on the environment.”

Likewise, the Earth was slow to recover from the disaster because the ongoing disturbances continued to wipe out biodiversity, he said.

Earth has witnessed five known mass extinctions over its 4.5 billion years.

Scientists used another elemental signature — iridium — to pin down the likely cause of the global mass extinction that wiped out the dinosaurs 65 million years ago. They believe an enormous meteor struck what is now Mexico.

The resulting plume of superheated earth blown into the atmosphere rained down material containing iridium that is found in the geologic record around the world.

Shen said the mercury signature provides convincing evidence that the Siberian Traps eruptions were responsible for the catastrophe. Now researchers are trying to pin down the extent of the eruptions and which environmental effects in particular were most responsible for the mass die-off, particularly for land animals and plants.

Shen said the Permian extinction could shed light on how global warming today might lead to the next mass extinction. If global warming, indeed, was responsible for the Permian die-off, what does warming portend for humans and wildlife today?

“The release of carbon into the atmosphere by human beings is similar to the situation in the Late Permian, where abundant carbon was released by the Siberian eruptions,” Shen said.

Algeo said it is cause for concern.

“A majority of biologists believe we’re at the cusp of another mass extinction — the sixth big one. I share that view, too,” Algeo said. “What we should learn is this will be serious business that will harm human interests so we should work to minimize the damage.”

People living in marginal environments such as arid deserts will suffer first. This will lead to more climate refugees around the world.

“We’re likely to see more famine and mass migration in the hardest hit places. It’s a global issue and one we should recognize and proactively deal with. It’s much easier to address these problems before they reach a crisis.”

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Swiss Triassic fossil fish, new study


Fossil Fish Eosemionotus diskosomus. Credit: A. López-Arbarello

From the Ludwig-Maximilians-Universität München in Germany:

Paleontology: Diversification after mass extinction

March 1, 2019

A team led by Ludwig-Maximilians-Universitaet (LMU) in Munich paleontologist Adriana López-Arbarello has identified three hitherto unknown fossil fish species in the Swiss Alps, which provide new insights into the diversification of the genus Eosemionotus.

Monte San Giorgio in the Swiss canton of Ticino is one of the most important known sources of marine fossils from the Middle Triassic Period (around 240 million years ago). The new and exquisitely preserved fossil fish specimens, which Dr. Adriana López-Arbarello (a member of the Institute of Paleontology and Geobiology and of the Geobiocenter at LMU) has been studying in collaboration with colleagues based in Switzerland were also discovered in these dolomites and limestones. As the researchers now report in the online journal Palaeontologia Electronica, the specimens represent three previously unknown species of Eosemionotus, a genus of ray-finned fishes. “The largest episode of mass extinction in the history of the Earth took place about 250 million years ago,” as López-Arbarello explains. “Our finds now provide further evidence that after this catastrophic event, the biosphere recovered relatively fast and went through a period of rapid diversification and the emergence of numerous new species during the Middle Triassic.”

The first member of the genus Eosemionotus was discovered in the vicinity of Berlin in 1906, and was named E. vogeli. Almost a century later, in 2004, a second species was described from Monte San Giorgio as E. ceresiensis. Detailed anatomical studies of new material from this locality, carried out by López-Arbarello, have now enabled the recognition of three further species that can be assigned to same genus — E. diskosomus, E. sceltrichensis and E. minutus. All five species are small in size, but they can be clearly distinguished from each other on the basis of the relative proportions of their bodies, the position of the fins, the morphology of the skull, and the disposition of teeth and scales. “These differences indicate that each species was adapted to different ecological niches,” López-Arbarello concludes.

These findings provide new insights into the evolution of the genus. “Our phylogenetic analyses demonstrate that Eosemionotus is the oldest known member of an extinct family within the Order Semionotiformes. Although the Semionotiformes were a species-rich and highly diversified clade during the Mesozoic Era, the order died out in the Cretaceous. Only a few members of its sister group have survived down to the present day, and this ancient lineage is now represented by a single family, the gars,” says López-Arbarello.

Triassic fossil frogs discovery in Arizona, USA


This June 2016 video from the USA says about itself:

In this episode of the Rocks of Utah we explore the Triassic Chinle River Formation. The Rocks of Utah is a YouTube series that explores the unique geology of Utah, and hosted by Benjamin Burger, a geology professor at Utah State University Uintah Basin Campus in Vernal, Utah.

No fossils were collected in this episode, rocks and fossils can not be collected from Dinosaur National Monument, and vertebrate fossils require a permit to collect from Bureau of Land Management Lands in Utah.

From Virginia Tech in the USA:

Oldest frog relative found in North America

February 27, 2019

A team of paleontologists led by Virginia Tech’s Michelle Stocker and Sterling Nesbitt of the Department of Geosciences have identified fossil fragments of what are thought to be the oldest known frogs in North America.

The fossils are comprised of several small pieces of hip bone, called an ilium, from Chinle frogs, a distant long-extinct branch of, but not a direct ancestor of, modern frogs. The fragments are packed into rock and are smaller than a pinky nail. They represent the first known and earliest equatorial remains of a salientian — the group containing living frogs, and their most-closely related fossil relatives — from the Late Triassic, roughly 216 million years ago.

The name of the fossil derives from where they were found, the Chinle Formation of Arizona.

Stocker, an assistant professor of geosciences in the Virginia Tech College of Science, says the fossils, discovered in May 2018, underscore the importance of microfossil collection and analysis for understanding extinct species whose total length is under three feet in length.

“This new find highlights just how much there is still to learn about the Late Triassic ecosystem, and how much we find when we just look a little closer,” Stocker said. “We’re familiar with the charismatic archosaurs from the Chinle Formation, but we know that based on other ecosystems, they should make up a small percentage of the animals that lived together. With this new focus we’re able to fill in a lot of those missing smaller components with new discoveries.”

Coming from multiple individuals, the hip bones are long and hollow, with a hip socket offset rather than centered. The bones of the frogs show how tiny they were: Just a bit over half-an-inch long. “The Chinle frog could fit on the end of your finger,” Stocker added.

Stocker and her team include researchers from Virginia Tech, Arizona’s Petrified Forest National Park, and the University of Florida’s Museum of Natural History, with the findings published today in the online journal Biology Letters. Even though the fossils are part of the Chinle frog family, they are not yet naming the specific fossils.

“We refrain from naming this Chinle frog because we are continuing to process microvertebrate matrix that will likely yield additional skull and postcranial material that has the potential to be even more informative,” Stocker added.

The Chinle frog shares more features with living frogs and Prosalirus, an Early Jurassic frog found in sediments from the present-day Navajo Nation, than to Triadobatrachus, an Early Triassic frog found in modern day Madagascar in Africa. “These are the oldest frogs from near the equator,” Stocker added. “The oldest frogs overall are roughly 250 million years old from Madagascar and Poland, but those specimens are from higher latitudes and not equatorial.”

Added Nesbitt, also an assistant professor of geosciences, “Now we know that tiny frogs were present approximately 215 million years ago from North America, we may be able to find other members of the modern vertebrate communities in the Triassic Period.”

(During the Triassic, the separate continents we recognize today formed the single landmass named Pangaea. Present-day Arizona was located roughly 10 degrees north of the equator.)

The team added this discovery also marks the first time that frog fossils have been found directly with phytosaurs, and … early dinosaurs.

The Virginia Tech team included both undergraduate and graduate students from across the university, using fossils found in the field and dousing additional rock samples repeatedly in water buckets. Further study of the fossils was completed by CT scans. The undergraduates who accompanied Stocker and Nesbitt on the spring 2018 expedition to Arizona included Elizabeth Evans, a major in the School of Performing Arts; Rebecca Hawkins, majoring in the Department of Fish and Wildlife Conservation; and Hector Lopez, majoring in biological sciences.

“Through my internship with Drs. Stocker and Nesbitt in Arizona, I learned firsthand the hard work that paleontologists put into finding fossils,” said Hawkins, a sophomore in the College of Natural Resources and Environment. “Every day you have to brave long treks, heavy loads, scorching heat, and more. But, with just the right combination of patience and luck, you can find something truly amazing that makes the toil worth it, like a tiny frog hip that tells a big story.”

“Our development of methods that recover delicate bones from small-bodied vertebrates enabled this exciting discovery,” said Ben Kligman, a Ph.D. student in Geosciences from Philadelphia, Pennsylvania. “Our aim is to use similar techniques in the Chinle Formation to uncover the early history of other small-bodied animals including lizards, salamanders, turtles, and mammals.”

Funding for the study came from the National Science Foundation, the National Geographic Society, the David B. Jones Foundation, the Petrified Forest Museum Association, and the Friends of Petrified Forest National Park

Triassic tuatara ancestor reptiles, new research


This 5 February 2018 video from England says about itself:

New small reptile species that lived 205 million years ago discovered in a quarry in South Wales

Fossils discovered in a quarry in South Wales have been identified as a new small species of reptile that lived 205 million years ago. The species has been called Clevosaurus cambrica, the second part is Latin and refers to the fact that it comes from Wales.

They belong to a new species of Clevosaurus (Gloucester lizard), named in 1939 after Clevum, the Latin name of Gloucester.

The new species, Clevosaurus cambrica lived side by side with a small dinosaur, Pantydraco, and a crocodile-like animal, Terrestrisuchus.

We compared it with other examples of Clevosaurus from places around Bristol and South Gloucestershire, but our new beast is quite different in the arrangement of its teeth. In the Late Triassic period, the foothills of south Wales and southwest England formed an archipelago that was inhabited by small dinosaurs and relatives of the tuatara, a reptilian ‘living fossil’ from New Zealand. The limestone quarries of the region have many caves or fissures that contain sediments filled with bones of small species of reptiles that collapsed at the feet of dinosaurs.

From the University of Bristol in England:

Skulls of 2 species of ancient reptile reconstructed

February 25, 2019

Using two partially fragmented fossil skulls, a student at the University of Bristol has digitally reconstructed, in three-dimensions, the skulls of two species of ancient reptile that lived in the Late Triassic, one of which had been previously known only from its jaws.

The research was completed by Sofia Chambi-Trowell, an undergraduate in Bristol’s School of Earth Sciences, as part of her final-year project for her degree in Palaeobiology.

Clevosaurus was a lizard-like reptile that was first named back in 1939 from specimens found at Cromhall Quarry, near Bristol.

Since then, similar beasts have been found elsewhere around Bristol and in South Wales, as well as in China and North America. Clevosaurus was an early representative of an ancient group of reptiles called Rhynchocephalia, which today is represent only by the tuatara of New Zealand.

In her project, Sofia worked on new fossils of Clevosaurus hudsoni, the first species to be named, and Clevosaurus cambrica, which was named from a quarry site in South Wales in 2018.

She used CT scans of both skulls to reconstruct their original appearance, and she found evidence that the two species, which lived at the same time in the Late Triassic, some 205 million years ago, showed significant differences.

Sofia said: “I found that Clevosaurus cambrica was smaller overall and had a narrower snout than Clevosaurus hudsoni.

“Other differences include the number, shape and size of the teeth in the jaws, suggesting the two species fed on different food.”

Clevosaurus probably ate insects. Clevosaurus cambrica has corkscrew-shaped teeth which suggests it was able to shred the insect carcass by the natural twist as it drove its teeth through the hard carapace.

Clevosaurus hudsoni had teeth more adapted for simply slicing the prey. This might suggest that Clevosaurus cambrica ate larger or harder-shelled insects like beetles or cockroaches, while Clevosaurus hudsoni ate worms or millipedes which were less tough.

Professor Mike Benton, one of Sofia’s project supervisors, added: “Sofia’s work is a great example of how modern technology like CT scanning can open up information we would not know about.

“It took a lot of work, but Sofia has uncovered a good explanation of how many species of Clevosaurus could live side by side without competing over food.”

Her other supervisor, Dr David Whiteside, said: “Two hundred million years ago, Bristol lay much further south than it does today — about the same latitude as Morocco.

“Also, sea level was higher, so the peaks of limestone hills south of Bristol and in South Wales were islands, like Florida today [?].

“They were full of dinosaurs, early mammals, and rhynchocephalians feeding on the rich, tropical plants and insects. Sofia’s work helps us understand so much about this extraordinary time when dinosaurs were just taking over the world.”

This November 2017 video from England says about itself:

Computed tomography derived surface models of a left hind limb of Clevosaurus hudsoni

Sample: partially complete, left hind limb of Clevosaurus hudsoni (NMHUK PV R36846)

Sample composition: Fossilised bone

Facility: µ-VIS X-Ray Imaging Centre, Southampton

Researchers: Aileen O’Brien (University of Southampton), David I. Whiteside (University of Bristol),John E. A. Marshall (University of Southampton)

µ-CT images of a partially complete, left hind limb of Clevosaurus hudsoni (NMHUK PV R36846) were obtained at µ-VIS X-Ray Imaging Centre, Southampton and the data processed using Avizo 3D visualisation software, in the µ-VIS visualisation suite. The surface models created from the µ-CT scans provide a more complete picture of the morphology of the hind limb, including non-visible parts of the bones concealed within the matrix. Features of the bones such as compression in a particular plane, grooves, processes, facets and projections are often disguised by matrix, or are hidden by adjacent bones. Surface modelling of µ-CT data has highlighted these characters and yielded insights into the ontogeny and age of the animal from which the specimen came.

The authors would like to thank Sandra Chapman (NHMUK) for arranging the loan of Clevosaurus hudsoni.

Triassic turtle had bone cancer


This July 2015 video says about itself:

Resembling a broad-bodied, short-snouted lizard, Pappochelys appears to be an ancestor of modern turles.

By Aimee Cunningham, 6:00am, February 11, 2019:

A rare, ancient case of bone cancer has been found in a turtle ancestor

A 240-million-year-old fossil is the oldest known example of this disease in amniotes

A 240-million-year-old case of bone cancer has turned up in a fossil of an extinct ancestor of turtles. Dating to the Triassic Period, the fossil is the oldest known example of this cancer in an amniote, a group that includes mammals, birds and reptiles, researchers report online February 7 in JAMA Oncology.

The fossilized left femur from the shell-less stem-turtle Pappochelys rosinae was recovered in southwestern Germany in 2013. A growth on the leg bone prompted a team of paleontologists and physicians to analyze the fossil with a micro CT scan, an imaging technique that provides a detailed, three-dimensional view inside an object.

“When we saw that this was not a break or an infection, we started looking at other growth-causing diseases,” says Yara Haridy, a paleontologist at the Museum für Naturkunde in Berlin. The verdict? Periosteal osteosarcoma, a malignant bone tumor. “It looks almost exactly like human periosteal osteosarcoma,” Haridy says.

“It is almost obvious that ancient animals would have cancer, but it is so very rare that we find evidence of it,” she says. The discovery of this tumor from the Triassic offers evidence that cancer is “a vulnerability to mutation deeply rooted in our DNA.”

Cancer genes in mucosal melanoma, a rare and poorly understood subtype of melanoma, have been compared in humans, dogs and horses for the first time. Researchers sequenced the genomes of the same cancer across different species to pinpoint key cancer genes. The results give insights into how cancer evolves across the tree of life and could guide the development of new therapies: here.

Triassic dinosaur relative discovered in Antarctica


This 31 January 2019 video says about itself:

Before There Were Dinosaurs, This Triassic ‘Lizard King’ Ruled Antarctica

From the Field Museum in the USA:

Iguana-sized dinosaur cousin discovered in Antarctica

‘Antarctic king’ shows how life at the South Pole bounced back after mass extinction

January 31, 2019

Summary: Scientists have discovered the fossils of an iguana-sized reptile, which they named ‘Antarctic king’, that lived at the South Pole 250 million years ago (it used to be warmer). Antarctanax was an early cousin of the dinosaurs, and it shows how life bounced back after the world’s biggest mass extinction.

Antarctica wasn’t always a frozen wasteland — 250 million years ago, it was covered in forests and rivers, and the temperature rarely dipped below freezing. It was also home to diverse wildlife, including early relatives of the dinosaurs. Scientists have just discovered the newest member of that family — an iguana-sized reptile whose name means “Antarctic king.”

“This new animal was an archosaur, an early relative of crocodiles and dinosaurs,” says Brandon Peecook, a Field Museum researcher and lead author of a paper in the Journal of Vertebrate Paleontology describing the new species. “On its own, it just looks a little like a lizard, but evolutionarily, it’s one of the first members of that big group. It tells us how dinosaurs and their closest relatives evolved and spread.”

The fossil skeleton is incomplete, but paleontologists still have a good feel for the animal, named Antarctanax shackletoni (the former means “Antarctic king”, the latter is a nod to polar explorer Ernest Shackleton). Based on its similarities to other fossil animals, Peecook and his coauthors (Roger Smith of the University of Witwatersrand and the Iziko South African Museum and Christian Sidor of the Burke Museum and University of Washington) surmise that Antarctanax was a carnivore that hunted bugs, early mammal relatives, and amphibians.

The most interesting thing about Antarctanax, though, is where it lived, and when. “The more we find out about prehistoric Antarctica, the weirder it is,” says Peecook, who is also affiliated with the Burke Museum. “We thought that Antarctic animals would be similar to the ones that were living in southern Africa, since those landmasses were joined back then. But we’re finding that Antarctica’s wildlife is surprisingly unique.”

About two million years before Antarctanax lived — the blink of an eye in geologic time — Earth underwent its biggest-ever mass extinction. Climate change, caused by volcanic eruptions, killed 90% of all animal life. The years immediately after that extinction event were an evolutionary free-for-all — with the slate wiped clean by the mass extinction, new groups of animals vied to fill the gaps. The archosaurs, including dinosaurs, were one of the groups that experienced enormous growth. “Before the mass extinction, archosaurs were only found around the Equator, but after it, they were everywhere,” says Peecook. “And Antarctica had a combination of these brand-new animals and stragglers of animals that were already extinct in most places — what paleontologists call ‘dead clades walking.’ You’ve got tomorrow’s animals and yesterday’s animals, cohabiting in a cool place.”

The fact that scientists have found Antarctanax helps bolster the idea that Antarctica was a place of rapid evolution and diversification after the mass extinction. “The more different kinds of animals we find, the more we learn about the pattern of archosaurs taking over after the mass extinction,” notes Peecook.

“Antarctica is one of those places on Earth, like the bottom of the sea, where we’re still in the very early stages of exploration,” says Peecook. “Antarctanax is our little part of discovering the history of Antarctica.”

Triassic dinosaur relative fed like hyena


This September 2015 video says about itself:

“Smok” is an extinct genus of large carnivorous archosaur. It lived during the latest Triassic period.

Its remains have been found in Lisowice, southern Poland. The type species is “Smok wawelski” and was named in 2011. It is larger than any other known predatory archosaur from the Late Triassic or Early Jurassic of central Europe. The relation of “Smok” to other archosaurs has not yet been thoroughly studied; it may be a rauisuchid, prestosuchid or ornithosuchid crurotarsan or a theropod dinosaur.

From Uppsala University in Sweden:

The 210-million-year-old Smok was crushing bones like a hyena

January 30, 2019

Coprolites, or fossil droppings, of the dinosaur-like archosaur Smok wawelski contain lots of chewed-up bone fragments. This led researchers at Uppsala University to conclude that this top predator was exploiting bones for salt and marrow, a behavior often linked to mammals but seldom to archosaurs.

Most predatory dinosaurs used their blade-like teeth to feed on the flesh of their prey, but they are commonly not thought to be much of bone crushers. The major exception is seen in the large tyrannosaurids, such as Tyrannosaurus rex, that roamed North America toward the end of the age of dinosaurs. The tyrannosaurids are thought to have been osteophagous (voluntarily exploiting bone) based on findings of bone-rich coprolites, bite-marked bones, and their robust teeth being commonly worn.

In a study published in Scientific Reports, researchers from Uppsala University were able to link ten large coprolites to Smok wawelski, a top predator of a Late Triassic (210 million year old) assemblage unearthed in Poland. This bipedal, 5-6 meters long animal lived some 140 million years before the tyrannosaurids of North America and had a T. rex-like appearance, although it is not fully clear whether it was a true dinosaur or a dinosaur-like precursor.

Three of the coprolites were scanned using synchrotron microtomography. This method has just recently been applied to coprolites and works somewhat like a CT scanner in a hospital, with the difference that the energy in the x-ray beams is much stronger. This makes it possible to visualize internal structures in fossils in three dimensions.

The coprolites were shown to contain up to 50 percent of bones from prey animals such as large amphibians and juvenile dicynodonts. Several crushed serrated teeth, probably belonging to the coprolite producer itself, were also found in the coprolites. This means that the teeth were repeatedly crushed against the hard food items (and involuntarily ingested) and replaced by new ones.

Further evidence for a bone-crushing behaviour can also be found in the fossils from the same bone beds in Poland. These include worn teeth and bone-rich fossil regurgitates from Smok wawelski, as well as numerous crushed or bite-marked bones.

Several of the anatomical characters related to osteophagy, such as a massive head and robust body, seem to be shared by S. wawelski and the tyrannosaurids, despite them being distantly related and living 140 million years apart. These large predators therefore seem to provide evidence of similar feeding adaptations being independently acquired at the beginning and end of the age of dinosaurs.