A team of paleontologists from the University of Washington and its Burke Museum of Natural History and Culture excavated four dinosaurs in northeastern Montana this summer. All fossils will be brought back to the Burke Museum where the public can watch paleontologists remove the surrounding rock in the fossil preparation laboratory.

The four dinosaur fossils are: the ilium — or hip bones — of an ostrich-sized theropod, the group of meat-eating, two-legged dinosaurs that includes Tyrannosaurus rex and raptors; the hips and legs of a duck-billed dinosaur; a pelvis, toe claw and limbs from another theropod that could be a rare ostrich-mimic Anzu, or possibly a new species; and a Triceratops specimen consisting of its skull and other fossilized bones. Three of the four dinosaurs were all found in close proximity on Bureau of Land Management land that is currently leased to a rancher.

In July 2021, a team of volunteers, paleontology staff, K-12 educators who were part of the DIG Field School program and students from UW and other universities worked together to excavate these dinosaurs. The fossils were found in the Hell Creek Formation, a geologic formation that dates from the latest portion of Cretaceous Period, 66 to 68 million years ago. Typical paleontological digs involve excavating one known fossil. However, the Hell Creek Project is an ongoing research collaboration of paleontologists from around the world studying life right before, during and after the K-Pg mass extinction event that killed off all dinosaurs except birds. The Hell Creek Project is unique in that it is sampling all plant and animal life found throughout the rock formation in an unbiased manner.

“Each fossil that we collect helps us sharpen our views of the last dinosaur-dominated ecosystems and the first mammal-dominated ecosystems,” said Gregory Wilson Mantilla, a UW professor of biology and curator of vertebrate paleontology at the Burke Museum. “With these, we can better understand the processes involved in the loss and origination of biodiversity and the fragility, collapse and assembly of ecosystems.”

All of the dinosaurs except the Triceratops will be prepared in the Burke Museum’s fossil preparation laboratory this fall and winter. The Triceratops fossil remains on the site because the dig team continued to find more and more bones while excavating and needs an additional field season to excavate any further bones that may be connected to the surrounding rock. The team plans to finish excavation in the summer of 2022.

Called the “Flyby Trike” in honor of the rancher who first identified the dinosaur while he was flying his airplane over his ranch, the team has uncovered this dinosaur’s frill, horn bones, individual rib bones, lower jaw, teeth and the occipital condyle bone — nicknamed the “trailer hitch,” which is the ball on the back of the skull that connects to the neck vertebrae. The team estimates approximately 30% of this individual’s skull bones have been found to date, with more potential bones to be excavated next year.

The Flyby Trike was found in hardened mud, with the bones scattered on top of each other in ways that are different from the way the bones would be laid out in a living animal. These clues indicate the dinosaur likely died on a flood plain and then got mixed together after its death by being moved around by a flood or river system, or possibly moved around by a scavenger like a T. rex, before fossilizing. In addition, the Flyby Trike is one of the last Triceratops living before the K-Pg mass extinction. Burke paleontologists estimate it lived less than 300,000 years before the event.

“Previous to this year’s excavations, a portion of the Flyby Trike frill and a brow horn were collected and subsequently prepared by volunteer preparators in the fossil preparation lab. The frill was collected in many pieces and puzzled together fantastically by volunteers. Upon puzzling the frill portion together, it was discovered that the specimen is likely an older ‘grandparent’ Triceratops,” said Kelsie Abrams, the Burke Museum’s paleontology preparation laboratory manager who also participated in this summer’s field work. “The triangular bones along the frill, called ‘epi occipitals,’ are completely fused and almost unrecognizable on the specimen, as compared to the sharp, noticeable triangular shape seen in younger individuals. In addition, the brow horn curves downwards as opposed to upwards, and this feature has been reported to be seen in older animals as well.”

Amber and seed pods were also found with the Flyby Trike. These finds allow paleobotanists to determine what plants were living alongside Triceratops, what the dinosaurs may have eaten, and what the overall ecosystem was like in Hell Creek leading up to the mass extinction event.

“Plant fossil remains from this time period are crucial for our understanding of the wider ecosystem. Not only can plant material tell us what these dinosaurs were perhaps eating, but plants can more broadly tell us what their environment looked like,” said Paige Wilson, a UW graduate student in Earth and space sciences. “Plants are the base of the food chain and a crucial part of the fossil record. It’s exciting to see this new material found so close to vertebrate fossils!”

Museum visitors can now see paleontologists remove rock from the first of the four dinosaurs — the theropod hips — in the Burke’s paleontology preparation laboratory. Additional fossils will be prepared in the upcoming weeks. All four dinosaurs will be held in trust for the public on behalf of the Bureau of Land Management and become a part of the Burke Museum’s collections.

Note: The above post is reprinted from materials provided by University of Washington. Original written by Andrea Godinez.

Fossils trapped in amber provide a unique snapshot of the anatomy, biology, and ecology of extinct organisms. The most common fossils found in amber, which is formed from resin exuded from tree bark, are land-dwelling animals, mainly insects. But on very rare occasions scientists discover amber housing an aquatic organism.

In a study published October 20 in Science Advances an international team of researchers describe the first crab from the Cretaceous dinosaur era preserved in amber. The study used micro CT to examine and describe Cretapsara athanata, the oldest modern-looking crab (approximately 100 million years old) and the most complete fossil crab ever discovered. It is rivalled in completeness by the mysterious Callichimaera perplexa, a very distant relative nicknamed the platypus of the crab world. Callichimaera’s stunning preservation included soft tissues and delicate parts that rarely fossilize. Both Cretapsara and Callichimaera are new branches in the crab tree of life that lived during the Cretaceous Crab Revolution, a period when crabs diversified worldwide and the first modern groups originated while many others disappeared.

True crabs, or Brachyura, are an iconic group of crustaceans whose remarkable diversity of forms, species richness, and economic importance have inspired celebrations and festivals worldwide. They’ve even earned a special role in the pantheon of social media. True crabs are found all around the world, from the depths of the oceans, to coral reefs, beaches, rivers, caves, and even in trees as true crabs are among the few animal groups that have conquered land and freshwater multiple times.

The crab fossil record extends back into the early Jurassic, more than 200 million years ago. Unfortunately, fossils of nonmarine crabs are sparse and largely restricted to bits and pieces of the animals carapace — claws and legs found in sedimentary rocks. That is until now with the discovery of Cretapsara athanata. “The specimen is spectacular, it is one of a kind. It’s absolutely complete and is not missing a single hair on the body, which is remarkable,” said lead author Javier Luque, postdoctoral researcher in the Department of Organismic and Evolutionary Biology, Harvard University.

A group of scientists led by co-lead author Lida Xing, China University of Geosciences, Beijing, made micro CT scans of the fossil, which is housed in the Longyin Amber Museum in Yunnan, China. The scans created a full three-dimensional reconstruction of the exquisite preservation of the animal allowing Luque, Xing, and their team to see the complete body of the animal including delicate tissues, like the antennae and mouthparts lined with fine hairs. Shockingly they discovered the animal also had gills.

“The more we studied the fossil, the more we realized that this animal was very special in many ways,” said Luque. Cretapsara is remarkably modern-looking — superficially resembling some shore crabs found today — unlike most crabs during the mid-Cretaceous era which looked quite different from modern crabs. Yet, the animal was entombed in Cretaceous amber and the presence of well-developed gills indicated an aquatic to semi-aquatic animal. Aquatic animals are rarely preserved in tree resins that become amber. Crabs previously found in amber are by the handful and belong to a living group of tropical land and tree-dwelling crabs known as Sesarmidae from the Miocene (15 million years ago). How then, the researchers asked, did a 100 million year old aquatic animal become preserved in tree amber, which normally houses land-dwelling specimens?

Gills allow aquatic animals to breathe in water. But crabs have successfully and independently conquered land, brackish water, and fresh water at least twelve times since the dinosaur era. In doing so their gills evolved to include lung-like tissue allowing them to breathe both in and out of the water. Cretapsara however, had no lung tissue, only well-developed gills indicating the animal was not completely land dwelling. “Now we were dealing with an animal that is likely not marine, but also not fully terrestrial,” Luque said. “In the fossil record, nonmarine crabs evolved 50 million years ago, but this animal is twice that age.”

The team’s phylogenetic studies show that carcinization (the evolution of true crab-looking forms) had actually already occurred in the most recent common ancestor shared by all modern crabs more than 100 million years ago. Cretapsara bridges the gap in the fossil record and confirms that crabs actually invaded land and fresh water during the dinosaur era, not during the mammal era, pushing the evolution of nonmarine crabs much further back in time.

The researchers hypothesize that Cretapsara, measuring at five millimeters in leg span, was a juvenile crab of a freshwater to amphibious species. Or, that the animal is perhaps a semi-terrestrial juvenile crab migrating onto land from water as occurs to the iconic Christmas Island red crabs where land dwelling mother crabs release their babies into the ocean, which later swarm out of the water back onto land. They further hypothesize that like the crabs found in amber from the Miocene, Cretapsara could have been a tree climber. “These Miocene crabs are truly modern looking crabs and, as their extant relatives, they live in trees in little ponds of water,” said Luque, “these arboreal crabs can get trapped in tree resin today, but would it explain why Cretapsara is preserved in amber?”

Luque’s research is centered on understanding why things evolve into crabs, and their evolution and diversification over time leading to the modern forms seen today. “This study is pushing the timing of origin of many of these groups back in time. Every fossil we discover challenges our preconceptions about the time and place of origin of several organisms, often making us look further back in time,” Luque said.

The study is part of a National Science Foundation funded project with Luque, Professor Javier Ortega-Hernández and postdoctoral researcher Joanna Wolfe, both in the Department of Organismic and Evolutionary Biology, Harvard University, and Professor Heather Bracken-Grissom, Florida International University.

The researchers chose the name Cretapsara athanata, which means the immortal Cretaceous spirit of the clouds and waters, to honor the Cretaceous, during which this crab lived, and Apsara, a spirit of the clouds and waters in South and Southeast Asian mythology. The species name is based on “athanatos,” immortal, referring to its lifelike preservation as if ‘frozen in time’ in the time capsule that is amber.

Author’s Statement: The studied fossil, deposited in the Longyin Amber Museum (LYAM), Yunnan Province, China, comes from a batch of commercial “raw” (dull, unpolished) amber pieces collected by local miners and sold to a vendor at an amber jewelry market in Myitkyina on May 12, 2015. The polished piece containing the fossil studied was acquired by LYAM from the vendor’s mineral store in Tengchong, China, on 10 August 2015. We acknowledge the existence of a sociopolitical conflict in northern Myanmar and have limited our research to material predating the 2017 resumption of hostilities in the region. We hope that conducting research on specimens collected before the conflict and acknowledging the situation in the Kachin State will serve to raise awareness of the current conflict in Myanmar and the human cost behind it.

Reference:
Javier Luque, Lida Xing, Derek E. G. Briggs, Elizabeth G. Clark, Alex Duque, Junbo Hui, Huijuan Mai and Ryan C. McKellar. Crab in amber reveals an early colonization of nonmarine environments during the Cretaceous. Science Advances, 2021 DOI: 10.1126/sciadv.abj5689

Note: The above post is reprinted from materials provided by Harvard University, Department of Organismic and Evolutionary Biology.

A new study led by palaeontologists at the University of Southampton suggests that bones found on the Isle of Wight belong to two new species of spinosaurid, a group of predatory theropod dinosaurs closely related to the giant Spinosaurus. Their unusual, crocodile-like skulls helped the group expand their diets, allowing them hunt prey on both land and in the water.

The haul of bones was discovered on the beach near Brighstone over a period of several years. Keen-eyed fossil collectors initially found parts of two skulls, and a crew from Dinosaur Isle Museum recovered a large portion of a tail. In all, over 50 bones from the site have been uncovered from rocks that form part of the Wessex Formation, laid down over 125 million years ago during the Early Cretaceous.

The only spinosaurid skeleton previously unearthed in the UK belonged to Baryonyx, which was initially discovered in 1983 in a quarry in Surrey. Most other finds since have been restricted to isolated teeth and single bones.

Analysis of the bones carried out at the University of Southampton and published in Scientific Reports suggested they belonged to species of dinosaurs previously unknown to science.

Chris Barker, a PhD student at the University of Southampton and lead author of the study, said: “We found the skulls to differ not only from Baryonyx, but also one another, suggesting the UK housed a greater diversity of spinosaurids than previously thought.”

The discovery of spinosaurid dinosaurs on the Isle of Wight was a long time coming. “We’ve known for a couple of decades now that Baryonyx-like dinosaurs awaited discovered on the Isle of Wight, but finding the remains of two such animals in close succession was a huge surprise” remarked co-author Darren Naish, expert in British theropod dinosaurs.

The first specimen has been named Ceratosuchops inferodios, which translates as the “horned crocodile-faced hell heron.” With a series of low horns and bumps ornamenting the brow region the name also refers to the predator’s likely hunting style, which would be similar to that of a (terrifying) heron. Herons famously catch aquatic prey around the margins of waterways but their diet is far more flexible than is generally appreciated, and can include terrestrial prey too.

The second was named Riparovenator milnerae. This translates as “Milner’s riverbank hunter,” in honour of esteemed British palaeontologist Angela Milner, who recently passed away. Dr Milner had previously studied and named Baryonyx — a major palaeontological event whose discovery substantially improved our understanding of these distinctive predators.

Dr David Hone, co-author from Queen Mary University of London: “It might sound odd to have two similar and closely related carnivores in an ecosystem, but this is actually very common for both dinosaurs and numerous living ecosystems.”

Although the skeletons are incomplete, the researchers estimate that both Ceratosuchops and Riparovenator measured around nine metres in length, snapping up prey with their metre-long skulls. The study also suggested how spinosaurids might have first evolved in Europe, before dispersing into Asia, Africa and South America.

Dr Neil J. Gostling of the University of Southampton, who supervised the project, said: “This work has brought together universities, Dinosaur Isle museum and the public to reveal these amazing dinosaurs and the incredibly diverse ecology of the south coast of England 125 million years ago.”

The Early Cretaceous rocks on the Isle of Wight describe an ancient floodplain environment bathed in a Mediterranean-like climate. Whilst generally balmy, forest fires occasionally ravaged the landscape, and the remains of burnt wood can be seen throughout the cliffs today. With a large river and other bodies of water attracting dinosaurs and housing various fish, sharks and crocodiles, the habitat provided the newly discovered spinosaurids with plenty of hunting opportunities.

Fossil collector Brian Foster from Yorkshire, who made an important contribution to the finds and publication, said: “This is the rarest and most exciting find I’ve made in over 30 years of fossil collecting.” Fellow collector Jeremy Lockwood, who lives on the Isle of Wight and discovered several bones added, “we realised after the two snouts were found that this would be something rare and unusual. Then it just got more and more amazing as several collectors found and donated other parts of this enormous jigsaw to the museum.”

Dr Martin Munt, Curator of Dinosaur Isle Museum, noted how these new finds cement the Isle of Wight’s status as one of the top locations for dinosaur remains in Europe. The project also solidified how collectors, museums and universities can work together to bring fossil specimens to light.

Dr Munt added: “On behalf of the museum I wish to express our gratitude to the collectors, including colleagues at the museum, who have made these amazing finds, and made them available for scientific research. We also congratulate the team who have worked on these exciting finds and brought them to publication.”

Video illustrating newly discovered dinosaurs: https://www.youtube.com/watch?v=x3gUECD7axs&t=7s

The new fossils will go on display at Dinosaur Isle Museum at Sandown.

Reference:
Chris T. Barker, David W. E. Hone, Darren Naish, Andrea Cau, Jeremy A. F. Lockwood, Brian Foster, Claire E. Clarkin, Philipp Schneider, Neil J. Gostling. New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae. Scientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-97870-8

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

Fossil footprints found in an Australian coal mine around 50 years ago have long been thought to be that of a large ‘raptor-like’ predatory dinosaur, but scientists have in fact discovered they were instead left by a timid long-necked herbivore.

University of Queensland palaeontologist Dr Anthony Romilio recently led an international team to re-analyse the footprints, dated to the latter part of the Triassic Period, around 220 million-year-ago.

“For years it’s been believed that these tracks were made by a massive theropod predator that was part of the dinosaur family Eubrontes, with legs over two metres tall,” Dr Romilio said.

“This idea caused a sensation decades ago because no other meat-eating dinosaur in the world approached that size during the Triassic period.”

However, findings made by a team of international researchers, published today in the peer-reviewed journal Historical Biology, in fact shows the tracks were instead made by a dinosaur known as a Prosauropod – a vegetarian dinosaur that were smaller, with legs about 1.4 metres tall and a body length of six metres.

The research team suspected there was something not-quite-right with the original size estimates and there was a good reason for their doubts.

“Unfortunately, most earlier researchers could not directly access the footprint specimen for their study, instead relying on old drawings and photographs that lacked detail,” Dr Romilio said.

The dinosaur fossils were discovered more than half a century ago around 200 metres deep underground at an Ipswich coal mine, just west of Brisbane.

“It must have been quite a sight for the first miners in the 1960s to see big bird-like footprints jutting down from the ceiling,” Dr Romilio said.

Hendrik Klein, co-author and fossil expert from Saurierwelt Paläontologisches Museum in Germany, said the footprints — referred to as ‘Evazoum’, scientifically, the footprint type made by prosauropod dinosaurs — were made on the water-sodden layers of ancient plant debris with the tracks later in-filled by silt and sand.

“This explains why today they occur in an upside-down position right above our heads,” Mr Klein said.

“After millions of years, the plant material turned into coal which was extracted by the miners to reveal a ceiling of siltstone and sandstone, complete with the natural casts of dinosaur footprints.”

The mine has long since closed, but fortunately, in 1964, geologists and the Queensland Museum mapped the trackway and made plaster casts, now used in current research.

“We made a virtual 3D model of the dinosaur footprint that was emailed to team members across the world to study,” Mr Klein said.

“The more we looked at the footprint and toe impression shapes and proportions, the less they resembled tracks made by predatory dinosaurs — this monster dinosaur was definitely a much friendlier plant-eater.

“This is still a significant discovery even if it isn’t a scary Triassic carnivore.

“This is the earliest evidence we have for this type of dinosaur in Australia, marking a 50-million-year gap before the first quadrupedal sauropod fossils known.”

The dinosaur footprint is on display at the Queensland Museum, Brisbane.

Reference:
Anthony Romilio, Hendrik Klein, Andréas Jannel, Steven W. Salisbury. Saurischian dinosaur tracks from the Upper Triassic of southern Queensland: possible evidence for Australia’s earliest sauropodomorph trackmaker. Historical Biology, 2021; 1 DOI: 10.1080/08912963.2021.1984447

Note: The above post is reprinted from materials provided by Taylor & Francis Group.

To borrow a line from the movie “Jurassic Park:” Dinosaurs do move in herds. And a new study shows that the prehistoric creatures lived in herds much earlier than previously thought.

In a paper appearing in Scientific Reports, researchers from MIT, Argentina, and South Africa detail their discovery of an exceptionally preserved group of early dinosaurs that shows signs of complex herd behavior as early as 193 million years ago — 40 million years earlier than other records of dinosaur herding.

Since 2013, members of the team have excavated more than 100 dinosaur eggs (about the size of chicken eggs) and the partial skeletons of 80 juvenile and adult dinosaurs from a rich fossil bed in southern Patagonia.

Using X-ray imaging, they were able to examine the eggs’ contents without breaking them apart, and discovered preserved embryos within, which they used to confirm that the fossils were all members of Mussaurus patagonicus — a plant-eating dinosaur that lived in the early Jurassic period and is classified as a sauropodomorph, a predecessor of the massive, long-necked sauropods that later roamed the Earth.

Surprisingly, the researchers observed that the fossils were grouped by age: Dinosaur eggs and hatchlings were found in one area, while skeletons of juveniles were grouped in a nearby location. Meanwhile, remains of adult dinosaurs were found alone or in pairs throughout the field site.

This “age segregation,” the researchers believe, is a strong sign of a complex, herd-like social structure. The dinosaurs likely worked as a community, laying their eggs in a common nesting ground. Juveniles congregated in “schools,” while adults roamed and foraged for the herd.

“This may mean that the young were not following their parents in a small family structure,” says team member Jahandar Ramezani, a research scientist in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “There’s a larger community structure, where adults shared and took part in raising the whole community.”

Ramezani dated ancient sediments among the fossils and determined that the dinosaur herd dates back to around 193 million years ago, during the early Jurassic period. The team’s results represent the earliest evidence of social herding among dinosaurs.

Living in herds may have given Mussaurus and other social sauropodomorphs an evolutionary advantage. These early dinosaurs originated in the late Triassic, shortly before an extinction event wiped out many other animals. For whatever reason, sauropodomorphs held on and eventually dominated the terrestrial ecosystem in the early Jurassic.

“We’ve now observed and documented this earliest social behavior in dinosaurs,” Ramezani says. “This raises the question now of whether living in a herd may have had a major role in dinosaurs’ early evolutionary success. This gives us some clues to how dinosaurs evolved.”

A fossil flood

Since 2013, paleontologists on the team have worked in the Laguna Colorada Formation, a site in southern Patagonia that is known for bearing fossils of early sauropodomorphs. When scientists first discovered fossils within this formation in the 1970s, they named them Mussaurus for “mouse lizard,” as they assumed the skeletons were of miniature dinosaurs.

Only much later did scientists, including members of the Argentinian team, discover bigger skeletons, indicating Mussaurus adults were much larger than their rodent namesakes. The name stuck, however, and the team has continued to unearth a rich collection of Mussaurus fossils from a small, square kilometer of the formation.

The fossils they have identified so far were found in three sedimentary layers spaced close together, indicating that the region may have been a common breeding ground where the dinosaurs returned regularly, perhaps to take advantage of favorable seasonal conditions.

Among the fossils they uncovered, the team discovered a group of 11 articulated juvenile skeletons, intertwined and overlapping each other, as if they had been suddenly thrown together. In fact, judging from the remarkably preserved nature of the entire collection, the team believes this particular herd of Mussaurus died “synchronously,” perhaps quickly buried by sediments.

Based on evidence of ancient flora in the nearby outcrops, the Laguna Colorada Formation has long been assumed to be relatively old on the dinosaur timescale. The team wondered: Could these dinosaurs have been herding from early on?

“People already knew that in the late Jurassic and Cretaceous, the large herbivore dinosaurs exhibited social behavior — they lived in herds and had nesting spots,” Ramezani says. “But the question has always been, when was the earliest time for such herding behavior?”

A gregarious line

To find out, Diego Pol, a paleontologist at the Egidio Feruglio Paleontological Museum in Argentina who led the study, looked for samples of volcanic ash among the fossils to send to Ramezani’s lab at MIT. Volcanic ash can contain zircon — mineral grains contaning uranium and lead, the isotopic ratios of which Ramezani can precisely measure. Based on uranium’s half-life, or the time it takes for half of the element to decay into lead, he can calculate the age of the zircon and the ash in which it was found. Ramezani successfully identified zircons in two ash samples, all of which he dated to around 193 million years old.

Since the volcanic ash was found in the same sediment layers as the fossils, Ramezani’s analyses strongly suggest that the dinosaurs were buried at the same time the ash was deposited. A likely scenario may have involved a flash flood or windblown dust that buried the herd, while ash from a distant eruption happened to drift over and, luckily for science, deposit zircons in the sediments.

Taken together, the team’s results show that Mussaurus and possibly other dinosaurs evolved to live in complex social herds as early as 193 million years ago, around the dawn of the Jurassic period.

Scientists suspect that two other types of early dinosaurs — Massospondylus from South Africa and Lufengosaurus from China — also lived in herds around the same time, although the dating for these dinosaurs has been less precise. If multiple separate lines of dinosaurs lived in herds, the researchers believe the social behavior may have evolved earlier, perhaps as far back as their common ancestor, in the late Triassic.

“Now we know herding was going on 193 million years ago,” Ramezani says. “This is the earliest confirmed evidence of gregarious behavior in dinosaurs. But paleontological understanding says, if you find social behavior in this type of dinosaur at this time, it must have originated earlier.”

This research was supported, in part, by National Science Foundation in the U.S. and the National Scientific and Technical Research Council of Argentina.

Reference:
Pol, D., Mancuso, A.C., Smith, R.M.H. et al. Earliest evidence of herd-living and age segregation amongst dinosaurs. Sci Rep, 2021 DOI: 10.1038/s41598-021-99176-1

Note: The above post is reprinted from materials provided by Massachusetts Institute of Technology. Original written by Jennifer Chu.

The rise of dinosaurs coincided with environmental changes driven by major volcanic eruptions over 230 million years ago, a new study reveals.

The Late Triassic Carnian Pluvial Episode (CPE) saw an increase in global temperature and humidity — creating a major impact on the development of animal and plant life, coinciding with the establishment of modern conifers.

Researchers analysed sediment and fossil plant records from a lake in northern China’s Jiyuan Basin, matching pulses of volcanic activity with significant environmental changes, including the CPE’s ‘mega monsoon’ climate, some 234 million to 232 million years ago.

The international research team, including experts at the University of Birmingham, today published their findings in Proceedings of the National Academy of Sciences (PNAS) — revealing four distinct episodes of volcanic activity during this time period, with the most likely source being major volcanic eruptions from the Wrangellia Large Igneous Province, the remnants of which are preserved in western North America.

Co-author Jason Hilton, Professor of Palaeobotany and Palaeoenvironments at the University of Birmingham’s School of Geography, Earth and Environmental Sciences, commented: “Within the space of two million years the world’s animal and plant life underwent major changes including selective extinctions in the marine realm and diversification of plant and animal groups on land. These events coincide with a remarkable interval of intense rainfall known as the Carnian Pluvial Episode.

“Our research shows, in a detailed record from a lake in North China, that this period can actually be resolved into four distinct events, each one driven by discrete pulses of powerful volcanic activity associated with enormous releases of carbon dioxide into the atmosphere. These triggered an increase in global temperature and humidity.”

The researchers found that each phase of volcanic eruption coincided with large perturbation of the global Carbon cycle, major climatic changes to more humid conditions, as well the lake’s deepening with a corresponding decrease in oxygen and animal life.

Geological events from a similar timeframe in Central Europe, East Greenland, Morocco, North America, and Argentina, among other locations indicate that increased rainfall resulted in widespread expansion of drainage basins converging into lakes or swamps, rather than rivers or oceans.

“Our results show that large volcanic eruptions can occur in multiple, discrete pulses -demonstrating their powerful ability to alter the global carbon cycle, cause climate and hydrological disruption and drive evolutionary processes,” added co-author Dr Sarah Greene, Senior Lecturer also in the School of Geography, Earth and Environmental Sciences at the University of Birmingham.

Dr Emma Dunne, a Palaeobiologist also at the the University of Birmingham, who was not involved in the study, commented:

“This relatively long period of volcanic activity and environmental change would have had considerable consequences for animals on land. At this time, the dinosaurs had just begun to diversify, and it’s likely that without this event, they would never have reached their ecological dominance we see over the next 150 million years.”

Professor Hilton also added “In addition to dinosaurs, this remarkable period in Earth history was also important for the rise of modern conifer groups and had a major impact on the evolution of terrestrial ecosystems and animal and plant life — including ferns, crocodiles, turtles, insects and the first mammals.”

The research team investigated terrestrial sediments from the ZJ-1 borehole in the Jiyuan Basin of North China. They used uranium-lead zircon dating, high-resolution chemostratigraphy, palynological and sedimentological data to correlate terrestrial conditions in the region with synchronous large-scale volcanic activity in North America.

Reference:
Jing Lu, Peixin Zhang, Jacopo Dal Corso, Minfang Yang, Paul B. Wignall, Sarah E. Greene, Longyi Shao, Dan Lyu, Jason Hilton. Volcanically driven lacustrine ecosystem changes during the Carnian Pluvial Episode (Late Triassic). Proceedings of the National Academy of Sciences, 2021; 118 (40): e2109895118 DOI: 10.1073/pnas.2109895118

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

A new study suggests that all living snakes evolved from a handful of species that survived the giant asteroid impact that wiped out the dinosaurs and most other living things at the end of the Cretaceous. The authors say that this devastating extinction event was a form of ‘creative destruction’ that allowed snakes to diversify into new niches, previously filled by their competitors.

The research, published in Nature Communications, shows that snakes, today including almost 4000 living species, started to diversify around the time that an extra-terrestrial impact wiped out the dinosaurs and most other species on the planet.

The study, led by scientists at the University of Bath and including collaborators from Bristol, Cambridge and Germany, used fossils and analysed genetic differences between modern snakes to reconstruct snake evolution. The analyses helped to pinpoint the time that modern snakes evolved.

Their results show that all living snakes trace back to just a handful of species that survived the asteroid impact 66 million years ago, the same extinction that wiped out the dinosaurs.

The authors argue that the ability of snakes to shelter underground and go for long periods without food helped them survive the destructive effects of the impact. In the aftermath, the extinction of their competitors — including Cretaceous snakes and the dinosaurs themselves — allowed snakes to move into new niches, new habitats and new continents.

Snakes then began to diversify, producing lineages like vipers, cobras, garter snakes, pythons, and boas, exploiting new habitats, and new prey. Modern snake diversity — including tree snakes, sea snakes, venomous vipers and cobras, and huge constrictors like boas and pythons — emerged only after the dinosaur extinction.

Fossils also show a change in the shape of snake vertebrae in the aftermath, resulting from the extinction of Cretaceous lineages and the appearance of new groups, including giant sea snakes up to 10 metres long.

“It’s remarkable, because not only are they surviving an extinction that wipes out so many other animals, but within a few million years they are innovating, using their habitats in new ways,” said lead author and recent Bath graduate Dr Catherine Klein, who now works at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) in Germany.

The study also suggests that snakes began to spread across the globe around this time. Although the ancestor of living snakes probably lived somewhere in the Southern Hemisphere, snakes first appear to have spread to Asia after the extinction.

Dr Nick Longrich, from the Milner Centre for Evolution at the University of Bath and the corresponding author, said: “Our research suggests that extinction acted as a form of ‘creative destruction’- by wiping out old species, it allowed survivors to exploit the gaps in the ecosystem, experimenting with new lifestyles and habitats.

“This seems to be a general feature of evolution — it’s the periods immediately after major extinctions where we see evolution at its most wildly experimental and innovative.

“The destruction of biodiversity makes room for new things to emerge and colonize new landmasses. Ultimately life becomes even more diverse than before.”

The study also found evidence for a second major diversification event around the time that the world shifted from a warm ‘Greenhouse Earth’ into a cold ‘Icehouse’ climate, which saw the formation of polar icecaps and the start of the Ice Ages.

The patterns seen in snakes hint at a key role for catastrophes — severe, rapid, and global environmental disruptions — in driving evolutionary change.

Reference:
Catherine G. Klein, Davide Pisani, Daniel J. Field, Rebecca Lakin, Matthew A. Wills, Nicholas R. Longrich. Evolution and dispersal of snakes across the Cretaceous-Paleogene mass extinction. Nature Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-25136-y

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