New species of Allosaurus discovered in Utah

A remarkable new species of meat-eating dinosaur has been unveiled at the Natural History Museum of Utah. Paleontologists unearthed the first specimen in early 1990s in Dinosaur National Monument in northeastern Utah. The huge carnivore inhabited the flood plains of western North America during the Late Jurassic Period, between 157-152 million years ago, making it the geologically oldest species of Allosaurus, predating the more well-known state fossil of Utah, Allosaurus fragilis. The newly named dinosaur Allosaurus jimmadseni, was announced today in the open-access scientific journal PeerJ.

The species belongs to the allosauroids, a group of small to large-bodied, two-legged carnivorous dinosaurs that lived during the Jurassic and Cretaceous periods. Allosaurus jimmadseni, possesses several unique features, among them a short narrow skull with low facial crests extending from the horns in front of the eyes forward to the nose and a relatively narrow back of the skull with a flat surface to the bottom of the skull under the eyes. The skull was weaker with less of an overlapping field of vision than its younger cousin Allosaurus fragilis. Allosaurus jimmadseni evolved at least 5 million years earlier than fragilis, and was the most common and the top predator in its ecosystem. It had relatively long legs and tail, and long arms with three sharp claws. The name Allosaurus translates as “different reptile,” and the second part, jimmadseni, honors Utah State Paleontologist James H. Madsen Jr.

Following an initial description by Othniel C. Marsh in 1877, Allosaurus quickly became the best known — indeed the quintessential — Jurassic theropod. The taxonomic composition of the genus has long been a debate over the past 130 years. Paleontologists argue that there are anywhere between one and 12 species of Allosaurus in the Morrison Formation of North America. This study recognizes only two species — A. fragilis and A. jimmadseni.

“Previously, paleontologists thought there was only one species of Allosaurus in Jurassic North America, but this study shows there were two species — the newly described Allosaurus jimmadseni evolved at least 5 million years earlier than its younger cousin, Allosaurus fragilis,” said co-lead author Mark Loewen, research associate at the Natural History Museum of Utah, and associate professor in the Department of Geology and Geophysics at the University of Utah led the study. “The skull of Allosaurus jimmadseni is more lightly built than its later relative Allosaurus fragilis, suggesting a different feeding behavior between the two.”

George Engelmann of the University of Nebraska, Omaha initially discovered the initial skeleton of the new species within Dinosaur National Monument in 1990. In 1996, several years after the headless skeleton was collected, the radioactive skull belonging to the skeleton using a radiation detector by Ramal Jones of the University of Utah. Both skeleton and skull were excavated by teams from Dinosaur National Monument.

“Big Al,” another specimen belonging to the new species, was discovered in Wyoming on United States Bureau of Land Management (BLM) land in 1991 and is housed in the collections of the Museum of The Rockies in Bozeman, Montana. Previously thought to belong to Allosaurus fragilis, “Big Al” was featured in the BBC’s 2001 “Walking with Dinosaurs: Ballad of Big Al” video. Over the last 30 years, crews from various museums have collected and prepared materials of this new species. Other specimens include “Big Al Two” at the Saurier Museum Aathal in Switzerland and Allosaurus material from the Dry Mesa Quarry of Colorado at Brigham Young University.

Early Morrison Formation dinosaurs were replaced by some of the most iconic dinosaurs of the Late Jurassic

Allosaurus jimmadseni lived on the semi-arid Morrison Formation floodplains of the interior of western North America. The older rocks of the Morrison Formation preserve a fauna of dinosaurs distinct from the iconic younger Morrison Formation faunas that include Allosaurus fragilis, Diplodocus and Stegosaurus. Paleontologists have recently determined that specimens of this new species of dinosaur lived in several places throughout the western interior of North America (Utah, Colorado and Wyoming).

Study summary

Dinosaurs were the dominant members of terrestrial ecosystems during the Mesozoic. However, the pattern of evolution and turnover of ecosystems during the middle Mesozoic remains poorly understood. The authors report the discovery of the earliest member of the group of large-bodied allosauroids in the Morrison Formation ecosystem that was replaced by Allosaurus fragilis and illustrate changes acquired in the genus over time. The study includes an in-depth description of every bone of the skull and comparisons with the cranial materials of other carnivorous dinosaurs. Finally, the study recognizes just two species of Allosaurus in North America with Allosaurus fragilis replacing its earlier relative Allosaurus jimmadseni.

Fact sheet: Major points of the paper

• A remarkable new species of meat-eating dinosaur, Allosaurus jimmadseni, is described based on two spectacularly complete skeletons. The first specimen was unearthed in Dinosaur National Monument, in northeastern Utah.
• Allosaurus jimmadseni is distinguished by a number of unique features, including low crests running from above the eyes to the snout and a relatively narrow back of the skull with a flat surface to the bottom of the upper skull under the eyes. The skull was weaker with less of an overlapping field of vision than its younger cousin Allosaurus fragilis.
• At 155 million years old, Allosaurus jimmadseni is the geologically-oldest species of Allosaurus predating the more well-known State Fossil of Utah Allosaurus fragilis.
• Allosaurus jimmadseni was the most common and the top predator in its ecosystem. It had relatively long legs and tail, and long arms with three sharp claws.

Study design

• Comparison of the bones with all other known allosauroid dinosaurs indicate that the species possessed unique features of the upper jaw and cheeks (maxilla and jugal) and a decorative crest stretching from just in front of the eyes to the nose.
• Many of the comparisons were made with the thousands of bones of Allosaurus fragilis collected from the famous Cleveland-Lloyd Dinosaur Quarry administered by the Bureau of Land Management that are housed in the collections of the Natural History Museum of Utah.
• On the basis of these features, the scientific team named it a new genus and species of dinosaur, Allosaurus jimmadseni (translating to “Jim Madsen’s different reptile”).
• Allosaurus jimmadseni is particularly notable for its slender, narrow skull with short sharp nasal crests compared to its close relative and successor Allosaurus fragilis.
• The study was funded in part by the University of Utah, the National Park Service and the National Science Foundation.

New dinosaur name: Allosaurus jimmadseni

• The first part of the name, Allosaurus, (a·luh·SAW·ruhs) can be translated from Greek as the “other,” “strange” or “different” and “lizard” or “reptile” literally to “different reptile.” The second part of the name jimmadseni (gym-MAD-sehn-eye) honors the late Utah State Paleontologist James Madsen Jr. who excavated and studied tens of thousands of Allosaurus bones from the famous Cleveland-Lloyd Dinosaur Quarry in central Utah and contributed greatly to the knowledge of Allosaurus.

Size

• Allosaurus jimmadseni was approximately 26 to 29 feet (8-9 meters) long.
• Allosaurus jimmadseni weighed around 4000 lbs. (1.8 metric tonnes).

Relationships

• Allosaurus jimmadseni belongs to a group of carnivorous dinosaurs called “allosauroids,” the same group as the famous Allosaurus fragilis.
• Other dinosaurs found in rocks containing Allosaurus jimmadseni include the carnivorous theropods Torvosaurus and Ceratosaurus; the long-necked sauropods Haplocanthosaurus and Supersaurus; and the plate-backed stegosaur Hesperosaurus.
• Allosaurus jimmadseni is closely related to the State Fossil of Utah, Allosaurus fragilis.

Anatomy

• Allosaurus jimmadseni was a two-legged carnivore, with long forelimbs and sharp, recurved claws that were likely used for grasping prey.
• Like other allosauroid dinosaurs, Allosaurus jimmadseni had a large head full of 80 sharp teeth. It was also the most common carnivore in its ecosystem.

Age and geography

• Allosaurus jimmadseni lived during the Kimmeridgian stage of the Late Jurassic period, which spanned from approximately 157 million to 152 million years ago.
• Allosaurus jimmadseni lived in a semi-arid inland basin filled with floodplains, braided stream systems, lakes, and seasonal mudflats along the western interior of North America.
• Allosaurus jimmadseni represents the earliest species of Allosaurus in the world.

Discovery

• Allosaurus jimmadseni can be found in a geologic unit known as the Salt Wash Member of the Morrison Formation and its equivalents exposed in Colorado, Wyoming, and Utah.
• The first specimen of Allosaurus jimmadseni was discovered in the National Park Service administered by Dinosaur National Monument in Uintah County, near Vernal, Utah.
• Allosaurus jimmadseni was first discovered by George Engelmann of the University of Nebraska, Omaha on July 15, 1990 during a contracted paleontological inventory of the Morrison Formation of Dinosaur National Monument.
• Another specimen of Allosaurus jimmadseni known as “Big Al,” was found on land administered by the U.S. Department of the Interior’s Bureau of Land Management in Wyoming.
• Further specimens of Allosaurus jimmadseni have been subsequently recognized in the collections of various museums.
• Allosaurus jimmadseni specimens are permanently housed in the collections of Dinosaur National Monument, Utah; the Museum of the Rockies, Bozeman, Montana; the Saurier Museum of Aathal, Switzerland; the South Dakota School of Mines, Rapid City, South Dakota; Brigham Young University’s Museum of Paleontology, Provo, Utah; and the United States National Museum (Smithsonian) Washington D.C.
• These discoveries are the result of a continuing collaboration between the Natural History Museum of Utah, the National Park Service, and the Bureau of Land Management.

Excavation

• The first skeleton of Allosaurus jimmadseni was excavated during the summers of 1990 to 1994 by staff of the National Park Service’s Dinosaur National Monument. The skeleton block was so heavy it required the use of explosives to remove surrounding rock and a helicopter to fly out the 2700 kg block. The head of the skeleton was missing
• The first bones of Allosaurus jimmadseni discovered included toes and some tail vertebrae. Later excavation revealed most of an articulated skeleton missing the head and part of the tail.
• The radioactive skull of the first specimen of Allosaurus jimmadseni, which had previously eluded discovery, was found in 1996 by Ramal Jones of the University of Utah using a radiation detector.

Preparation

• It required seven years to fully prepare all of the bones of Allosaurus jimmadseni.
• Much of the preparation was done by then Dinosaur National Monument employees Scott Madsen and Ann Elder, with some assistance from Dinosaur National Monument volunteers and students at Brigham Young University.

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Materials provided by University of Utah. Note: Content may be edited for style and length.

Journal Reference:

1. Daniel J. Chure, Mark A. Loewen. Cranial anatomy of Allosaurus jimmadseni, a new species from the lower part of the Morrison Formation (Upper Jurassic) of Western North America. PeerJ, 2020; 8: e7803 DOI: 10.7717/peerj.7803

100 million years in amber: Researchers discover oldest fossilized slime mold

Most people associate the idea of creatures trapped in amber with insects or spiders, which are preserved lifelike in fossil tree resin. An international research team of palaeontologists and biologists from the Universities of Göttingen and Helsinki, and the American Museum of Natural History in New York has now discovered the oldest slime mould identified to date. The fossil is about 100 million years old and is exquisitely preserved in amber from Myanmar. The results have been published in the journal Scientific Reports.

Slime moulds, also called myxomycetes, belong to a group known as ‘Amoebozoa’. These are microscopic organisms that live most of the time as single mobile cells hidden in the soil or in rotting wood, where they eat bacteria. However, they can join together to form complex, beautiful and delicate fruiting bodies, which serve to make and spread spores.

Since fossil slime moulds are extremely rare, studying their evolutionary history has been very difficult. So far, there have only been two confirmed reports of fossils of fruiting bodies and these are just 35 to 40 million years old. The discovery of fossil myxomycetes is very unlikely because their fruiting bodies are extremely short-lived. The researchers are therefore astounded by the chain of events that must have led to the preservation of this newly identified fossil. “The fragile fruiting bodies were most likely torn from the tree bark by a lizard, which was also caught in the sticky tree resin, and finally embedded in it together with the reptile,” says Professor Jouko Rikkinen from the University of Helsinki. The lizard detached the fruiting bodies at a relatively early stage when the spores had not yet been released, which now reveals valuable information about the evolutionary history of these fascinating organisms.

The researchers were surprised by the discovery that the slime mould can easily be assigned to a genus still living today. “The fossil provides unique insights into the longevity of the ecological adaptations of myxomycetes,” explains palaeontologist Professor Alexander Schmidt from the University of Göttingen, lead author of the study.

“We interpret this as evidence of strong environmental selection. It seems that slime moulds that spread very small spores using the wind had an advantage,” says Rikkinen. The ability of slime moulds to develop long-lasting resting stages in their life cycle, which can last for years, probably also contributes to the remarkable similarity of the fossil to its closest present-day relatives.make a difference: sponsored opportunity

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Huge dinosaurs evolved different cooling systems to combat heat stroke

Different dinosaur groups independently evolved gigantic body sizes, but they all faced the same problems of overheating and damaging their brains. Researchers from Ohio University’s Heritage College of Osteopathic Medicine show in a new article in the Anatomical Record that different giant dinosaurs solved the problem in different ways, evolving different cooling systems in different parts of the head.

“The brain and sense organs like the eye are very sensitive to temperature,” said Ruger Porter, Assistant Professor of Anatomical Instruction and lead author of the study. “Animals today often have elaborate thermoregulatory strategies to protect these tissues by shuttling hot and cool blood around various networks of blood vessels. We wanted to see if dinosaurs were doing the same things.”

Many of the famous gigantic dinosaurs — such as the long-necked sauropods or armored ankylosaurs — actually evolved those big bodies independently from smaller-bodied ancestors. “Small dinosaurs could have just run into the shade to cool off,” said study co-author Professor Lawrence Witmer, “but for those giant dinosaurs, the potential for overheating was literally inescapable. They must have had special mechanisms to control brain temperature, but what were they?”

The answer turned out to be based in physics, but still part of our everyday experience. “One of the best ways to cool things down is with evaporation,” Porter said. “The air-conditioning units in buildings and cars use evaporation, and it’s the evaporative cooling of sweat that keeps us comfortable in summer. To cool the brain, we looked to the anatomical places where there’s moisture to allow evaporative cooling, such as the eyes and especially the nasal cavity and mouth.”

To test that idea, the team looked to the modern-day relatives of dinosaurs — birds and reptiles — where studies indeed showed that evaporation of moisture in the nose, mouth, and eyes cooled the blood on its way to the brain.

Porter and Witmer obtained carcasses of birds and reptiles that had died of natural causes from zoos and wildlife rehabilitation facilities. Using a technique developed in Witmer’s lab that allows arteries and veins to show up in CT scans, they were able to trace blood flow from the sites of evaporative cooling to the brain. They also precisely measured the bony canals and grooves that conveyed the blood vessels.

“The handy thing about blood vessels is that they basically write their presence into the bones,” Porter said. “The bony canals and grooves that we see in modern-day birds and reptiles are our link to the dinosaur fossils. We can use this bony evidence to restore the patterns of blood flow in extinct dinosaurs and hopefully get a glimpse into their thermal physiology and how they dealt with heat.”

“The discovery that different dinosaurs cooled their brains in a variety of ways not only provides a window into the everyday life of dinosaurs, it also serves as an exemplar of how the physical constraints imposed by specific environmental conditions have shaped the evolution of this diverse and unique group,” said Sharon Swartz, a program director at the National Science Foundation, which funded the research. “Using a combination of technological innovation and biological expertise, these researchers were able to take a direct reading from the fossil record that provides new clues about how dinosaur skeletal form and function evolved.”

This team of current and former members of WitmerLab at Ohio University has previously looked at other cases of dinosaur physiology. In 2014 and 2018, former doctoral student Jason Bourke led projects involving Porter and Witmer on breathing and heat exchange in pachycephalosaurs and ankylosaurs, respectively. Most recently, former lab doctoral student Casey Holliday led a project with Porter and Witmer that explored blood vessels on the skull roof of T. rex and other dinosaurs that also might have had a thermoregulatory function.

The new study by Porter and Witmer is a more expansive, quantitative study that shows that “one size didn’t fit all” with regard to how large-bodied dinosaurs kept their brains cool. That is, they had different thermoregulatory strategies. The researchers looked at bony canal sizes in the dinosaurs to assess the relative importance of the different sites of evaporative cooling based on how much blood was flowing through them.

A key factor turned out to be body size. Smaller dinosaurs such as the goat-sized pachycephalosaur Stegoceras had a very balanced vascular pattern with no single cooling region being particularly emphasized. “That makes physiological sense because smaller dinosaurs have less of a problem with overheating,” Porter said. “But giants like sauropods and ankylosaurs increased blood flow to particular cooling regions of the head far beyond what was necessary to simply nourish the tissues.” This unbalanced vascular pattern allowed the thermal strategies of large dinosaurs to be more focused, emphasizing one or more cooling regions.

But although sauropods like Diplodocus and Camarasaurus and ankylosaurs like Euoplocephalus all had unbalanced vascular patterns emphasizing certain cooling regions, they still differed. Sauropods emphasized both the nasal cavity and mouth as cooling regions whereas ankylosaurs only emphasized the nose. “It’s possible that sauropods were so large — often weighing dozens of tons — that they needed to recruit the mouth as a cooling region in times of heat stress,” Porter said. “Panting sauropods may have been a common sight!”

One problem that the researchers encountered was that many of the theropod dinosaurs — such as the 10-ton T. rex — were also gigantic, but the quantitative analysis showed that they had a balanced vascular pattern, like the small-bodied dinosaurs.

“This finding had us scratching our heads until we noticed the obvious difference — theropods like Majungasaurus and T. rex had a huge air sinus in their snouts,” Witmer said. Looking closer, the researchers discovered bony evidence that this antorbital air sinus was richly supplied with blood vessels. Witmer had previously shown that air circulated through the antorbital air sinus like a bellows pump every time the animal opened and closed its mouth. “Boom! An actively ventilated, highly vascular sinus meant that we had another potential cooling region. Theropod dinosaurs solved the same problem…but in a different way,” concluded Witmer.

The researchers are now expanding the project to include other dinosaur groups such as duck-billed hadrosaurs and horned ceratopsians like Triceratops to explore how thermoregulatory strategies varied among other dinosaurs and how these strategies may have influenced their behavior and even their preferred habitats.

The research was funded by National Science Foundation (NSF) grants to Witmer (part of the Visible Interactive Dinosaur Project), as well as by the Ohio University Heritage College of Osteopathic Medicine.

Arthropods formed orderly lines 480 million years ago

Researchers studied fossilized Moroccan Ampyx trilobites, which lived 480 million years ago and showed that the trilobites had probably been buried in their positions — all oriented in the same direction. Scientists deduced that these Ampyx processions may illustrate a kind of collective behavior adopted in response to cyclic environmental disturbances.

Though our understanding of the anatomy of the earliest animals is growing ever more precise, we know next to nothing about their behaviour. Did group behaviour arise recently or is it primeval? To answer this question, researchers from the CNRS, the University of Poitiers, UBO, Claude Bernard Lyon 1 University*, Cadi Ayyad University (Marrakech, Morocco), and the University of Lausanne (Switzerland) studied fossilized Moroccan Ampyx trilobites, which lived 480 million years ago. They showed that the trilobites had probably been buried in their positions — all oriented in the same direction, in orderly lines, maintaining close contact with each other through their long spines — during storms.

By comparing this observation with the behaviour of living animals such as North American spiny lobsters, the scientists deduced that these Ampyx processions may illustrate a similar kind of collective behaviour — adopted in response to cyclic environmental disturbances like storms or to chemical signals associated with reproduction.

This example would seem to suggest that group behaviour is of ancient origin and, from an early date, likely conferred an evolutionary advantage on the first animals, allowing them to survive environmental stress and improve their reproductive chances.

*- From the Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement (CNRS / ENS de Lyon / Université Claude Bernard Lyon 1), the Laboratoire Géosciences Océan (CNRS / Université Bretagne Occidentale / Université Bretagne Sud), and the Institute of Chemistry of Materials and Media of Poitiers (IC2MP (CNRS / Université de Poitiers).

Paleontologists discover complete Saurornitholestes langstoni specimen

The discovery of a nearly complete dromaeosaurid Saurornitholestes langstoni specimen is providing critical information for the evolution of theropod dinosaurs, according to new research by a University of Alberta paleontologist.

The 76-million-year-old species was long thought to be so closely related to Velociraptor from Mongolia that some researchers even called it Velociraptor langstoni — until now.

The landmark discovery was made by paleontologists Philip Currie and Clive Coy from the University of Alberta and David Evans, James and Louise Temerty Endowed Chair of Vertebrate Palaeontology at the Royal Ontario Museum. The research illustrates how Saurornitholestes differs from Velociraptor. Importantly, the research also identifies a unique tooth evolved for preening feathers and provides new evidence that the dromaeosaurid lineage from North America that includes Saurornitholestes is distinct from an Asian lineage that includes the famous Velociraptor.

“Palaeontology in general is a gigantic puzzle where most of the pieces are missing. The discovery and description of this specimen represents the recovery of many pieces of the puzzle,” said Currie, professor in the Department of Biological Sciences and Canada Research Chair in Dinosaur Paleobiology. “This ranks in the top discoveries of my career. It is pretty amazing.”

Another piece of the puzzle

Saurornitholestes is a small, feathered carnivorous dinosaur within the dromaeosaurid family (also known as “raptors”) that was previously known from fragmentary remains. Discovered by Coy in Dinosaur Provincial Park in 2014, the new skeleton is remarkably complete and exquisitely preserved, with all the bones (except for the tail) preserved in life position. The new research, which focuses on the skull, shows that the North American form has a shorter and deeper skull than the Velociraptor. At the front of the skull’s mouth, the researchers also discovered a flat tooth with long ridges, which was likely used for preening feathers. The same tooth has since been identified in Velociraptor and other dromaeosaurids.

“Because of their small size and delicate bones, small meat-eating dinosaur skeletons are exceptionally rare in the fossil record. The new skeleton is by far the most complete and best-preserved raptor skeleton ever found in North America. It’s a scientific goldmine,” said Evans.

The study also establishes a distinction between dromaeosaurids in North America and Asia. “The new anatomical information we have clearly shows that the North American dromaeosaurids are a separate lineage from the Asian dromaeosaurids, although they do have a common ancestor,” said Currie. “This changes our understanding of intercontinental movements of these animals and ultimately will help us understand their evolution.”

Future research will investigate the remainder of the skeleton as well as additional analyses on the relationships between dromaeosaurids.

T. rex used a stiff skull to eat its prey

A Tyrannosaurus rex could bite hard enough to shatter the bones of its prey. But how it accomplished this feat without breaking its own skull bones has baffled paleontologists. That’s why scientists at the University of Missouri are arguing that the T. rex’s skull was stiff much like the skulls of hyenas and crocodiles, and not flexible like snakes and birds as paleontologists previously thought.

“The T. rex had a skull that’s 6 feet long, 5 feet wide and 4 feet high, and bites with the force of about 6 tons,” said Kaleb Sellers, a graduate student in the MU School of Medicine. “Previous researchers looked at this from a bone-only perspective without taking into account all of the connections — ligaments and cartilage — that really mediate the interactions between the bones.”

Using a combination of imaging, anatomy and engineering analysis, the team observed how the roof of the mouth of the T. rex reacted to the stresses and strains from chewing by applying models of how two present day relatives of T. rex — a gecko and a parrot — chew to how the T. rex skull worked.

“Dinosaurs are like modern-day birds, crocodiles and lizards in that they inherited particular joints in their skulls from fish — ball and socket joints, much like people’s hip joints — that seem to lend themselves, but not always, to movement like in snakes,” said Casey Holliday, an associate professor of anatomy in the MU School of Medicine. “When you put a lot of force on things, there’s a tradeoff between movement and stability. Birds and lizards have more movement but less stability. When we applied their individual movements to the T. rex skull, we saw it did not like being wiggled in ways that the lizard and bird skulls do, which suggests more stiffness.”

In addition to helping paleontologists with a detailed study of the anatomy of fossilized animals, researchers believe their findings can help advance human and animal medicine by providing better models of how joints and ligaments interact.

“In humans, this can also be applied to how people’s jaws work, such as studying how the jaw joint is loaded by stresses and strains during chewing,” said Ian Cost, the lead researcher on the study. Cost is an assistant professor at Albright College and a former doctoral student in the MU School of Medicine. “In animals, understanding how those movements occur and joints are loaded will, for instance, help veterinarians better understand how to treat exotic animals such as parrots, which suffer from arthritis in their faces.”

Materials provided by University of Missouri-Columbia. Note: Content may be edited for style and length.

Journal Reference:

1. Ian N. Cost, Kevin M. Middleton, Kaleb C. Sellers, Michael Scott Echols, Lawrence M. Witmer, Julian L. Davis, Casey M. Holliday. Palatal Biomechanics and Its Significance for Cranial Kinesis in Tyrannosaurus rex. The Anatomical Record, 2019; DOI: 10.1002/ar.24219

Dinosaur brains from baby to adult

New research by a University of Bristol palaeontology post-graduate student has revealed fresh insights into how the braincase of the dinosaur Psittacosaurus developed and how this tells us about its posture.

Psittacosaurus was a very common dinosaur in the Early Cretaceous period — 125 million years ago — that lived in eastern Asia, especially north-east China.

Hundreds of samples have been collected which show it was a beaked plant-eater, an early representative of the Ceratopsia, which had later relatives with great neck frills and face horns, such as Triceratops.

The babies hatched out as tiny, hamster-sized beasts and grew to two metres long as adults.

As they grew, the brain changed in shape, from being crammed into the back of the head, behind the huge eyes in the hatchling, to being longer, and extending under the skull roof in the adults.

The braincase also shows evidence for a change in posture as the animals grew. There is good evidence from the relative lengths of the arms and legs, that baby Psittacosaurus scurried about on all fours, but by the age of two or three, they switched to a bipedal posture, standing up on their elongate hind legs and using their arms to grab plant food.

Claire Bullar from the University of Bristol’s School of Earth Sciences led the new research which has been published this week in PeerJ.

She said: “I was excited to see that the orientation of the semi-circular canals changes to show this posture switch.

“The semi-circular canals are the structures inside our ears that help us keep balance, and the so-called horizontal semi-circular canal should be just that — horizontal — when the animal is standing in its normal posture.

“This is just what we see, with the head of Psittacosaurus pointing down and forwards when it was a baby — just right for moving on all-fours. Then, in the teen or adult, we see the head points exactly forwards, and not downwards, just right for a biped.”

Co-supervisor Dr Qi Zhao from the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) in Beijing, where the specimens are housed, added: “It’s great to see our idea of posture shift confirmed, and in such a clear-cut way, from the orientation of the horizontal ear canal.

“It’s also amazing to see the results of high-quality CT scanning in Beijing and the technical work by Claire to get the best 3D models from these scan data.”

Professor Michael Ryan of Carleton University, Ottawa, Canada, another collaborator, said: “This posture shift during growth from quadruped to biped is unusual for dinosaurs, or indeed any animal. Among dinosaurs, it’s more usual to go the other way, to start out as a bipedal baby, and then go down on all fours as you get really huge.

“Of course, adult Psittacosaurus were not so huge, and the shift maybe reflects different modes of life: the babies were small and vulnerable and so probably hid in the undergrowth, whereas bipedalism allowed the adults to run faster and escape their predators.”

Professor Michael Benton, also from the University of Bristol’s School of Earth Sciences and another collaborator, added: “This is a great example of classic, thorough anatomical work, but also an excellent example of international collaboration.

“The Bristol Palaeobiology Research Group has a long-standing collaboration with IVPP, and this enables the mix of excellent specimens and excellent research.

“Who would have imagined we could reconstruct posture of dinosaurs from baby to adult, and with multiple lines of evidence to confirm we got it right.”

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Extinct Caribbean bird yields DNA after 2,500 years in watery grave

Scientists have recovered the first genetic data from an extinct bird in the Caribbean, thanks to the remarkably preserved bones of a Creighton’s caracara from a flooded sinkhole on Great Abaco Island.

Studies of ancient DNA from tropical birds have faced two formidable obstacles. Organic material quickly degrades when exposed to heat, light and oxygen. And birds’ lightweight, hollow bones break easily, accelerating the decay of the DNA within.

But the dark, oxygen-free depths of a 100-foot blue hole known as Sawmill Sink provided ideal preservation conditions for the bones of Caracara creightoni, a species of large carrion-eating falcon that disappeared soon after humans arrived in the Bahamas about 1,000 years ago.

Florida Museum of Natural History postdoctoral researcher Jessica Oswald extracted and sequenced genetic material from a 2,500-year-old C. creightoni femur from the blue hole. Because ancient DNA is often fragmented or missing, Oswald had modest expectations for what she would find — maybe one or two genes. But instead, the bone yielded 98.7% of the bird’s mitochondrial genome, the set of DNA that most living things inherit only from their mothers.

“I was super excited. I would have been happy to get that amount of coverage from a fresh specimen,” said Oswald, lead author of a study describing the work and also a postdoctoral researcher at the University of Nevada, Reno. “Getting DNA from an extinct bird in the tropics is significant because it hasn’t been successful in many cases or even tried.”

The mitochondrial genome showed that C. creightoni is closely related to the two remaining caracara species alive today: the crested caracara, Caracara cheriway, and the southern caracara, Caracara plancus. The three species last shared a common ancestor between 1.2 and 0.4 million years ago.

At least six species of caracara once cleaned carcasses and picked off small prey in the Caribbean. But the retreat of glaciers 15,000 years ago and the resulting rise in sea levels triggered extinctions of many birds, said David Steadman, Florida Museum curator of ornithology.

C. creightoni managed to survive the sweeping climatic changes, but the arrival of people on the islands ultimately heralded the species’ demise, as the tortoises, crocodiles, iguanas and rodents that the caracara depended on for food swiftly disappeared.

“This species would still be flying around if it weren’t for humans,” Steadman said. “We’re using ancient DNA to study what should be modern biodiversity.”

Today, the islands host only a fraction of the wildlife that once flourished in the scrubland, forests and water. But blue holes like Sawmill Sink can offer a portal into the past. Researchers have collected more than 10,000 fossils from the sinkhole, representing nearly 100 species, including crocodiles, tortoises, iguanas, snakes, bats and more than 60 species of birds.

Sawmill Sink’s rich store of fossils was discovered by cave diver Brian Kakuk in 2005 in his quest for horizontal passages in the limestone. The hole was not a popular diving spot: Thirty feet below the surface lay a 20-foot-thick layer of saturated hydrogen sulfide, an opaque mass that not only smells of rotten egg, but also reacts with the freshwater above it to form sulfuric acid, which causes severe chemical burns.

After multiple attempts, Kakuk, outfitted with a rebreather system and extra skin protection, punched through the hydrogen sulfide. His lamp lit up dozens of skulls and bones on the blue hole’s floor.

Soon after, Kakuk and fellow cave diver Nancy Albury began an organized diving program in Sawmill Sink.

“This was found by someone who recognized what it was and never moved anything until it was all done right,” Steadman said.

Though the hydrogen sulfide layer presented a foul problem for divers, it provided excellent insulation for the fossils below, blocking UV light and oxygen from reaching the lower layer of water. Among the crocodile skulls and tortoise shells were the C. creightoni bones, including an intact skull.

“For birds, having an entire head of an extinct species from a fossil site is pretty mind-blowing,” Oswald said. “Because all the material from the blue hole is beautifully preserved, we thought at least some DNA would probably be there.”

Since 2017, Oswald has been revitalizing the museum’s ancient DNA laboratory, testing methods and developing best practices for extracting and analyzing DNA from fossils and objects that are hundreds to millions of years old.

Ancient DNA is a challenging medium because it’s in the process of degradation. Sometimes only a minute quantity of an animal’s original DNA — or no DNA at all — remains after bacteria, fungi, light, oxygen, heat and other environmental factors have broken down an organism.

“With ancient DNA, you take what you can get and see what works,” Oswald said. “Every bone has been subjected to slightly different conditions, even relative to other ones from the same site.”

To maximize her chance of salvaging genetic material, Oswald cleans a bone, freezes it with liquid nitrogen and then pulverizes it into powder with a rubber mallet.

“It’s pretty fun,” she said.

While previous studies required large amounts of bone, Oswald’s caracara work showed ancient DNA could be successfully recovered at a smaller scale.

“This puts an exclamation point on what’s possible with ancient DNA,” said Robert Guralnick, Florida Museum curator of bioinformatics. “We have new techniques for looking at the context of evolution and extinction. Beyond the caracara, it’s cool that we have an ancient DNA lab that’s going to deliver ways to look at questions not only from the paleontological perspective, but also at the beginnings of a human-dominated planet.”

Steadman, who has spent decades researching modern and extinct biodiversity in the Caribbean, said some questions can only be answered with ancient DNA.

“By understanding species that weren’t able to withstand human presence, it helps us better appreciate what we have left — and not just appreciate it, but understand that when these species evolved, there were a lot more things running and flying around than we have today.”

Other co-authors are Julia Allen of the University of Nevada, Reno; Kelsey Witt of the University of California, Merced; Ryan Folk of the Florida Museum and Nancy Albury of the National Museum of the Bahamas.

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Researchers discover oldest fossil forest in Asia

The Devonian period, which was 419 million to 359 million years ago, is best known for Tiktaalik, the lobe-finned fish that is often portrayed pulling itself onto land. However, the “age of the fishes,” as the period is called, also saw evolutionary progress in plants. Researchers reporting August 8 in the journal Current Biology describe the largest example of a Devonian forest, made up of 250,000 square meters of fossilized lycopsid trees, which was recently discovered near Xinhang in China’s Anhui province. The fossil forest, which is larger than Grand Central Station, is the earliest example of a forest in Asia.

Lycopsids found in the Xinhang forest resembled palm trees, with branchless trunks and leafy crowns, and grew in a coastal environment prone to flooding. These lycopsid trees were normally less than 3.2 meters tall, but the tallest was estimated at 7.7 meters, taller than the average giraffe. Giant lycopsids would later define the Carboniferous period, which followed the Devonian, and become much of the coal that is mined today. The Xinhang forest depicts the early root systems that made their height possible. Two other Devonian fossil forests have been found: one in the United States, and one in Norway.

“The large density as well as the small size of the trees could make Xinhang forest very similar to a sugarcane field, although the plants in Xinhang forest are distributed in patches,” says Deming Wang, a professor in the School of Earth and Space Sciences at Peking University, co-first author on the paper along with Min Qin of Linyi University. “It might also be that the Xinhang lycopsid forest was much like the mangroves along the coast, since they occur in a similar environment and play comparable ecologic roles.”

The fossilized trees are visible in the walls of the Jianchuan and Yongchuan clay quarries, below and above a four-meter thick sandstone bed. Some fossils included pinecone-like structures with megaspores, and the diameters of fossilized trunks were used to estimate the trees’ heights. The authors remarked that it was difficult to mark and count all the trees without missing anything.

“Jianchuan quarry has been mined for several years and there were always some excavators working at the section. The excavations in quarries benefit our finding and research. When the excavators stop or left, we come close to the highwalls and look for exposed erect lycopsid trunks,” says Wang, who, with Qin, found the first collection of fossil trunks in the mine in 2016. “The continuous finding of new in-situ tree fossils is fantastic. As an old saying goes: the best one is always the next one.”

This work was supported by The National Natural Science Foundation of China.

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