Diverse fossil flora from 400 million year ago

The analysis of very old plant fossils discovered in South Africa and dating from the Lower Devonian period documents the transition from barren continents to the green planet we know today. Cyrille Prestianni, a palaeobotanist at the EDDy Lab at the University of Liège (Belgium), participated in this study, the results of which have just been published in the journal Scientific Reports.

The greening of continents — or terrestrialisation — is undoubtedly one of the most important processes that our planet has undergone. For most of the Earth’s history, the continents were devoid of macroscopic life, but from the Ordovician period (480 million years ago) green algae gradually adapted to life outside the aquatic environment. The conquest of land by plants was a very long process during which plants gradually acquired the ability to stand upright, breathe in the air or disperse their spores. Plant fossils that document these key transitions are very rare. In 2015, during the expansion of the Mpofu Dam (South Africa), researchers discovered numerous plant fossils in geological strata dated to the Lower Devonian (420 — 410 million years ago), making this a truly exceptional discovery.

Cyrille Prestianni, a palaeobotanist at the EDDy Lab (Evolution and Diversity Dynamics Lab) at the University of Liège, explains: “The discovery quickly proved to be extraordinary, since we are in the presence of the oldest fossil flora in Africa and it is very diversified and of exceptional quality. It is thanks to a collaboration between the University of Liège, the IRSNB (Royal Belgian Institute of Natural Sciences) and the New Albany Museum (South Africa) that this incredible discovery could be studied. The study, which has just been published in the journal Scientific Reports, describes this particularly diverse fossil flora with no less than fifteen species analysed, three of which are new to science. Dr. Prestianni adds : ” This flora is also particularly interesting because of the quantity of complete specimens that have been discovered,” says the researcher. These plants are small, with the largest specimens not exceeding 10 cm in height. They are simple plants, consisting of axes that divide two or three times and end in reproductive structures called sporangia. “

The fossil flora of Mpofu allows us today to imagine what the world might have been like when the largest plants were no taller than our ankle and almost no animals had yet been able to free themselves from the aquatic environment. It gives us a better understanding of how our Earth went from a red rock devoid of life to the green planet we know today. These plants, simple as they are, are a crucial step in the construction of the environments that hosted the first land animals, arthropods. They form the basis of the long history of life on Earth, which continues today from dense tropical forests to the arid tundra of the north.

Story Source:

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

Journal Reference:

1. Robert W. Gess, Cyrille Prestianni. An early Devonian flora from the Baviaanskloof Formation (Table Mountain Group) of South Africa. Scientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-90180-z

School lesson gone wrong leads to new, bigger megalodon size estimate

A more reliable way of estimating the size of megalodon shows the extinct shark may have been bigger than previously thought, measuring up to 65 feet, nearly the length of two school buses. Earlier studies had ball-parked the massive predator at about 50 to 60 feet long.

The revised estimate is the result of new equations based on the width of megalodon’s teeth — and began with a high school lesson that went awry.

Victor Perez, then a doctoral student at the Florida Museum of Natural History, was guiding students through a math exercise that used 3D-printed replicas of fossil teeth from a real megalodon and a set of commonly used equations based on tooth height to estimate the shark’s size. But something was off: Students’ calculations ranged from about 40 to 148 feet for the same shark. Perez snapped into trouble-shooting mode.

“I was going around, checking, like, did you use the wrong equation? Did you forget to convert your units?” said Perez, the study’s lead author and now the assistant curator of paleontology at the Calvert Marine Museum in Maryland. “But it very quickly became clear that it was not the students that had made the error. It was simply that the equations were not as accurate as we had predicted.”

Although the equations have been widely used by scientists since their publication in 2002, the classroom exercise revealed they generate varying size estimates for a single shark, depending on which tooth is measured.

“I was really surprised,” Perez said. “I think a lot of people had seen that study and blindly accepted the equations.”

For more than a century, scientists have attempted to calculate the size of megalodon, whose name means “big tooth.” But the only known remains of the fearsome shark that dominated oceans from about 23 to 3.6 million years ago are fossilized teeth and a few, rare vertebrae. Like other sharks, the rest of megalodon’s skeleton, including its jaw, was composed of lightweight cartilage that decomposed quickly after death. Tooth enamel, however, “preserves really well,” Perez said. “It’s probably the most structurally stable thing in living organisms.” Megalodon sharks shed thousands of teeth over a lifetime, leaving abundant traces of the species in the fossil record.

The most accepted methods for estimating the length of megalodon have used great white sharks as a modern proxy, relying on the relationship between tooth size to total body length. While great white sharks and megalodon belong to different families, they share similar predatory lifestyles and broad, triangular teeth serrated like steak knives — ideal adaptations for hunting large, fleshy marine mammals such as whales and dolphins, Perez said.

But these methods also present a challenge: To generate body length estimates, they require the researcher to correctly identify a fossil tooth’s former position in a megalodon jaw. As in humans, the size and shape of shark teeth vary depending on where they’re located in the mouth, and megalodon teeth are most often found as standalone fossils.

So, Perez was ecstatic when fossil collector Gordon Hubbell donated a nearly complete set of teeth from the same megalodon shark to the Florida Museum in 2015, reducing the guesswork. After museum researchers CT scanned the teeth and made them available online, Perez collaborated with teacher Megan Higbee Hendrickson on a plan to incorporate them into her middle school curriculum at the Academy of the Holy Names school in Tampa.

“We decided to have the kids 3D-print the teeth, determine the size of the shark and build a replica of its jaw for our art show,” Hendrickson said.

Perez and Hendrickson co-designed a lesson for students based on the then-most popular method for estimating shark size: Match the tooth to its position in the shark jaw, look up the corresponding equation, measure the tooth from the tip of the crown to the line where root and crown meet and plug the number into the equation.

After a successful pilot test of a few teeth with Hendrickson’s students, he expanded the lesson plan to include the whole set of megalodon teeth for high school students at Delta Charter High School in Aptos, California. Perez expected a slight variability of a couple millimeters in their results, but this time, variations in students’ estimates shot to more than 100 feet. The farther a tooth position was from the front of the jaw, the larger the size estimate.

After Perez detailed the lesson’s results in a fossil community newsletter, he received an email from Teddy Badaut, an avocational paleontologist in France. Badaut suggested a different approach. Why not measure tooth width instead of height? Previous research had suggested tooth width was limited by the size of a shark’s jaw, which would be proportional to its body length.

Ronny Maik Leder, then a postdoctoral researcher at the Florida Museum, worked with Perez to develop a new set of equations based on tooth width.

By measuring the set of teeth from Hubbell, “we could actually sum up the width of the teeth and get an even better approximation of the jaw width,” Perez said.

The researchers analyzed sets of fossil teeth from 11 individual sharks, representing five species, including megalodon, its close relatives and modern great white sharks.

By measuring the combined width of each tooth in a row, they developed a model for how wide an individual tooth was in relation to the jaw for a given species. Now when a paleontologist unearths a lone megalodon tooth the size of their hand, they can compare its width to the average obtained in the study and get an accurate estimate of how big the shark was.

“I was quite surprised that indeed no one had thought of this before,” said Leder, now director of the Natural History Museum in Leipzig, Germany. “The simple beauty of this method must have been too obvious to be seen. Our model was much more stable than previous approaches. This collaboration was a wonderful example of why working with amateur and hobby paleontologists is so important.”

Perez cautioned that because individual sharks vary in size, the team’s methods still have a range of error of about 10 feet when applied to the largest individuals. It’s also unclear exactly how wide megalodon’s jaw was and difficult to guess based on teeth alone — some shark species have gaps between each tooth while the teeth in other species overlap.

“Even though this potentially advances our understanding, we haven’t really settled the question of how big megalodon was. There’s still more that could be done, but that would probably require finding a complete skeleton at this point,” he said.

Perez continues to teach the megalodon tooth lesson, but its focus has changed.

“Since then, we’ve used the lesson to talk about the nature of science — the fact that we don’t know everything. There are still unanswered questions,” he said.

For Hendrickson, the lesson sparked her students’ enthusiasm for science in ways that textbooks could not.

“Victor was an amazing role model for the kids. He is the personification of a young scientist that followed his childhood interest and made a career out of it. So many of these kids had never worked with or spoken to a scientist who respected their point of view and was willing to answer their questions.”

Leder and Badaut co-authored the study.

Story Source:

Materials provided by Florida Museum of Natural History. Original written by Natalie van Hoose and Jerald B Pinson. Note: Content may be edited for style and length.

Journal Reference:

1. Victor Perez, Ronny Leder, Teddy Badaut. Body length estimation of Neogene macrophagous lamniform sharks (Carcharodon and Otodus) derived from associated fossil dentitions. Palaeontologia Electronica, 2021; DOI: 10.26879/1140

New ancient shark discovered

This rare fossil find comes from the Kimmeridge Clay Formation in England, a series of sedimentary rocks that was formed in a shallow, tropical-subtropical sea during the Upper Jurassic, about 150 million years ago. The fossil shark skeleton was found more than 20 years ago on the southern coast of England and is now held in the Etches Collection. Additional fossil shark specimens from it will be investigated in the years to come.

Due to their life-long tooth replacement shark teeth are among the most common vertebrate finds encountered in the fossil record. The low preservation potential of their poorly mineralized cartilaginous skeletons, on the other hand, prevents fossilization of completely preserved specimens in most cases.

The new study published in the journal PeerJ and led by Sebastian Stumpf from the University of Vienna now presents the fossil skeleton of a new ancient shark from the Kimmeridge Clay Formation of England, a fossiliferous rock sequence that was formed during the Late Jurassic in a shallow, tropical-subtropical sea.

The new shark fossil, which is about 150 million years old, is assigned to a previously unknown genus and species of hybodontiform sharks named Durnonovariaodus maiseyi. This extremely rare fossil find was made almost 20 years ago on the southern coast of England and is now held and curated in the Etches Collection, which houses one of the most scientifically significant fossil collections in England.

Hybodontiform sharks are one of the most species-rich groups of extinct sharks and represent the closest relatives to modern sharks. They first appeared during the latest Devonian, about 361 million years ago, and went extinct together with dinosaurs at the end of the Cretaceous, about 66 million years ago. The new genus and species Durnonovariaodus maiseyi differs from all other previously described hybodontiform sharks, including those that are characterized by having similarly shaped teeth. “Durnonovariaodus maiseyi represents an important source of information for better understanding the diversity of sharks in the past as well as for new interpretations of the evolution of hybodontiform sharks, whose relationships are still poorly understood, even after more than 150 years of research,” says Stumpf.

The scientific importance of the Kimmeridge Clay Formation is underlined by additional, but still undescribed hybodontiform shark skeletons, which are also held in the Etches Collection. The research of fossil sharks from the Kimmeridge Clay Formation of England, which will be continued in the years to come, will certainly contain further surprises to be yet discovered.

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

Journal Reference:

1. Sebastian Stumpf, Steve Etches, Charlie J. Underwood, Jürgen Kriwet. Durnonovariaodus maiseyi gen. et sp. nov., a new hybodontiform shark-like chondrichthyan from the Upper Jurassic Kimmeridge Clay Formation of England. PeerJ, 2021; 9: e11362 DOI: 10.7717/peerj.11362

Newly described horned dinosaur from New Mexico was the earliest of its kind

A newly described horned dinosaur that lived in New Mexico 82 million years ago is one of the earliest known ceratopsid species, a group known as horned or frilled dinosaurs. Researchers reported their find in a publication in the journal PalZ (Paläontologische Zeitschrift).

Menefeeceratops sealeyi adds important information to scientists’ understanding of the evolution of ceratopsid dinosaurs, which are characterized by horns and frills, along with beaked faces. In particular, the discovery sheds light on the centrosaurine subfamily of horned dinosaurs, of which Menefeeceratops is believed to be the oldest member. Its remains offer a clearer picture of the group’s evolutionary path before it went extinct at the end of the Cretaceous.

Steven Jasinski, who recently completed his Ph.D. in Penn’s Department of Earth and Environmental Science in the School of Arts & Sciences, and Peter Dodson of the School of Veterinary Medicine and Penn Arts & Sciences, collaborated on the work, which was led by Sebastian Dalman of the New Mexico Museum of Natural History and Science. Spencer Lucas and Asher Lichtig of the New Mexico Museum of Natural History and Science in Albuquerque were also part of the research team.

“There has been a striking increase in our knowledge of ceratopsid diversity during the past two decades,” says Dodson, who specializes in the study of horned dinosaurs. “Much of that has resulted from discoveries farther north, from Utah to Alberta. It is particularly exciting that this find so far south is significantly older than any previous ceratopsid discovery. It underscores the importance of the Menefee dinosaur fauna for the understanding of the evolution of Late Cretaceous dinosaur faunas throughout western North America.”

The fossil specimen of the new species, including multiple bones from one individual, was originally discovered in 1996 by Paul Sealey, a research associate of the New Mexico Museum of Natural History and Science, in Cretaceous rocks of the Menefee Formation in northwestern New Mexico. A field crew from the New Mexico Museum of Natural History and Science collected the specimen. Tom Williamson of the New Mexico Museum of Natural History and Science briefly described it the following year, and recent research on other ceratopsid dinosaurs and further preparation of the specimen shed important new light on the fossils.

Based on the latest investigations, researchers determined the fossils represent a new species. The genus name Menefeeceratops refers to the rock formation in which it was discovered, the Menefee Formation, and to the group of which the species is a part, Ceratopsidae. The species name sealeyi honors Sealey, who unearthed the specimen.

Menefeeceratops is related to but predates Triceratops, another ceratopsid dinosaur. However Menefeeceratops was a relatively small member of the group, growing to around 13 to 15 feet long, compared to Triceratops, which could grow to up to 30 feet long.

Horned dinosaurs were generally large, rhinoceros-like herbivores that likely lived in groups or herds. They were significant members of Late Cretaceous ecosystems in North America. “Ceratopsids are better known from various localities in western North America during the Late Cretaceous near the end of the time of dinosaurs,” says Jasinski. “But we have less information about the group, and their fossils are rarer, when you go back before about 79 million years ago.”

Although bones of the entire dinosaur were not recovered, a significant amount of the skeleton was preserved, including parts of the skull and lower jaws, forearm, hindlimbs, pelvis, vertebrae, and ribs. These bones not only show the animal is unique among known dinosaur species but also provide additional clues to its life history. For example, the fossils show evidence of a potential pathology, resulting from a minor injury or disease, on at least one of the vertebrae near the base of its spinal column.

Some of the key features that distinguish Menefeeceratops from other horned dinosaurs involve the bone that make up the sides of the dinosaur’s frill, known as the squamosal. While less ornate than those of some other ceratopsids, Menefeeceratops’ squamosal has a distinct pattern of concave and convex parts.

Comparing features of Menefeeceratops with other known ceratopsid dinosaurs helped the research team trace its evolutionary relationships. Their analysis places Menefeeceratops sealeyi at the base of the evolutionary tree of the centrosaurines subfamily, suggesting that not only is Menefeeceratops one of the oldest known centrosaurine ceratopsids, but also one of the most basal evolutionarily.

Menefeeceratops was part of an ancient ecosystem with numerous other dinosaurs, including the recently recognized nodosaurid ankylosaur Invictarx and the tyrannosaurid Dynamoterror, as well as hadrosaurids and dromaeosaurids.

“Menefeeceratops was part of a thriving Cretaceous ecosystem in the southwestern United States with dinosaurs that predated a lot of the more well-known members closer to end of the Cretaceous,” says Jasinski.

While relatively less work has been done collecting dinosaurs in the Menefee Formation to date, the researchers hope that more field work and collecting in these areas, together with new analyses, will turn up more fossils of Menefeeceratops and ensure a better understanding of the ancient ecosystem of which it was part.

Peter Dodson is a professor of anatomy in the School of Veterinary Medicine and a professor of earth and environmental science in the School of Arts & Sciences at the University of Pennsylvania.

Steven E. Jasinski is a curator of paleontology and geology at the State Museum of Pennsylvania and corporate faculty at Harrisburg University of Science and Technology. He earned his doctoral degree in the Department of Earth and Environmental Science in the University of Pennsylvania’s School of Arts & Sciences.

Sebastian G. Dalman is a research associate at the New Mexico Museum of Natural History and Science in Albuquerque.

Spencer G. Lucas is a curator of paleontology at the New Mexico Museum of Natural History and Science in Albuquerque.

Asher J. Lichtig is a research associate at the New Mexico Museum of Natural History and Science in Albuquerque.

Jasinski was supported by Geo. L. Harrison and Benjamin Franklin fellowships while attending the University of Pennsylvania. The research was also partially funded by a Walker Endowment Research Grant and a University of Pennsylvania Paleontology Research Grant.

Story Source:

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

Journal Reference:

1. Sebastian G. Dalman, Spencer G. Lucas, Steven E. Jasinski, Asher J. Lichtig, Peter Dodson. The oldest centrosaurine: a new ceratopsid dinosaur (Dinosauria: Ceratopsidae) from the Allison Member of the Menefee Formation (Upper Cretaceous, early Campanian), northwestern New Mexico, USA. PalZ, 2021; DOI: 10.1007/s12542-021-00555-w

18.5 million year old vine fossil identified as new species

An 18.5 million-year-old fossil found in Panama provides evidence of a new species and is the oldest reliable example of a climbing woody vine known as a liana from the soapberry family. The discovery sheds light on the evolution of climbing plants.

The new species, named Ampelorhiza heteroxylon, belongs to a diverse group of tropical lianas called Paullinieae, within the soapberry family (Sapindaceae). More than 475 species of Paullinieae live in the tropics today.

Researchers identified the species from fossilized roots that revealed features known to be unique to the wood of modern climbing vines, adaptations that allow them to twist, grow and climb.

The study, “Climbing Since the Early Miocene: The Fossil Record of Paullinieae (Sapindaceae),” was published April 7 in the journal PLOS ONE.

“This is evidence that lianas have been creating unusual wood, even in their roots, as far back as 18 million years ago,” said wood anatomist Joyce Chery ’13, assistant research professor in the School of Integrative Plant Science, Plant Biology Section, in the College of Agriculture and Life Sciences, and a corresponding author of the paper.

“Before this discovery, we knew almost nothing about when or where these lianas evolved or how rapidly they diversified,” said first author Nathan Jud, assistant professor of plant biology at William Jewell College and a former Cornell postdoctoral researcher.

Panama was a peninsula 18.5 to 19 million years ago, a volcanic landscape covered with tropical forest in North America and separated from South America by a Central American seaway. While these forests contained North American animals, the plants mostly descended from South American tropical plants that had dispersed across the seaway, Jud said.

“The fossil we described is the oldest macrofossil of these vines,” he said, “and they were among the plants that made it to North America long before the Great American Biotic Interchange when large animals moved between the continents some 3 million years ago.”

In the study, the researchers made thin slices of the fossil, examined the arrangements and dimensions of tissues and water conducting vessels under a microscope and created a database of all the features. They then studied the literature to see how these features matched up with the living and fossil records of plants.

“We were able to say, it really does look like it’s a fossil from the Paullinieae group, given the anatomical characteristics that are similar to species that live today,” Chery said.

During their analyses, the researchers identified features that are characteristic of lianas. Most trees and shrubs have water-conducting tissues (which transport water and minerals from roots to leaves) that are all roughly the same size when viewed in a cross-section; in vines, these conduits come in two sizes, big and small, which is exactly what the researchers discovered in the fossil.

“This is a feature that is pretty specific to vines across all sorts of families,” Chery said.

The two vessel sizes provide insurance for a twisting and curving plant, as large vessels provide ample water flow, but are also vulnerable to collapse and develop cavities that disrupt flow. The series of smaller vessels offers a less vulnerable backup water transport system, Chery said.

Also, cross-sections of the wood in trees and shrubs are circular, but in the fossil, and in many living vines, such cross-sections are instead irregular and lobed.

Thirdly, on the walls of those vascular vessels, they found long horizontal perforations that allow for water to flow in lateral directions. That is a distinguishing feature of lianas in the soapberry family, Chery said.

In future work, now that they can place the lianas of Sapindaceae to 18.5 million years ago, the researchers intend to continue their investigation of the evolutionary history and diversification of this family. Chery also plans to investigate how wood has evolved in this group of vines, including identifying the genes that contribute to lobe-shaped stems.

The study was partly funded by the National Science Foundation.

Story Source:

Materials provided by Cornell University. Original written by Krishna Ramanujan. Note: Content may be edited for style and length.

Journal Reference:

1. Nathan A. Jud, Sarah E. Allen, Chris W. Nelson, Carolina L. Bastos, Joyce G. Chery. Climbing since the early Miocene: The fossil record of Paullinieae (Sapindaceae). PLOS ONE, 2021; 16 (4): e0248369 DOI: 10.1371/journal.pone.0248369

Fat-footed tyrannosaur parents could not keep up with their skinnier adolescent offspring

New research by the University of New England’s Palaeoscience Research Centre suggests juvenile tyrannosaurs were slenderer and relatively faster for their body size compared to their multi-tonne parents.

The research, published in the Journal of Vertebrate Paleontology, analysed a collection of fossilised tyrannosaur footprints to learn more about the way these animals aged and how they moved.

UNE PhD student and study leader, Nathan Enriquez — in international collaboration with the Philip J. Currie Dinosaur Museum, University of Alberta, Royal Ontario Museum, University of Bologna and the Grande Prairie Regional College — believes the findings contribute a new line of evidence to previous findings based on bone anatomy and computer models of muscle masses.

“The results suggest that as some tyrannosaurs grew older and heavier, their feet also became comparably more bulky,” Mr Enriquez said.

“Fully grown tyrannosaurs were believed to be more robust than younger individuals based on their relatively shorter hind limbs and more massive skulls, but nobody had explored this growth pattern using fossil footprints, which are unique in that they can provide a snapshot of the feet as they appeared in life, with outlines of the soft, fleshy parts of the foot that are rarely preserved as fossils.

Footprints can be ambiguous and hard to interpret correctly — the shape of a footprint may be influenced by the type of ground surface that is stepped on and the motions of the animal making the footprints. In addition, the exact identity of the animal may not always be clear. These challenges have previously limited the use of fossil footprints in understanding dinosaur growth.

The answer lay in the Grande Prairie region of Northern Alberta, Canada, where the research team worked with well-preserved samples of footprints of different sizes that are suggested to belong to the same type of animal.

“We explored a remote dinosaur footprint site where we discovered a new set of large carnivorous dinosaur footprints within very similar rocks to those which have produced tyrannosaur tracks in the past,” Mr Enriquez said.

“Based on the relatively close proximity between these discoveries and their nearly equivalent ages — about 72.5 million years old — we suggest they may indeed belong to the same species.

“We were also careful to assess the quality of preservation in each footprint, and only considered specimens which were likely to reflect the shape of the actual feet that produced them.”

Once the team had a suitable sample, they analysed the outlines of each specimen using a method called geometric morphometrics. This process removes the effect of overall size differences between each footprint and shows what the most important differences in track shape are.

“The greatest difference in shape was found to be the relative width and surface area of the heel impression, which significantly increased in size between smaller and larger footprints,” Mr Enriquez said.

“The smaller tracks are comparably slender, while the biggest tyrannosaur tracks are relatively broader and had much larger heel areas. This makes sense for an animal that is becoming larger and needs to support its rapidly increasing body weight. It also suggests the relative speed of these animals decreased with age.

“Increasingly bulky feet in the adults aligns with previous suggestions that juvenile tyrannosaurs would have been faster and more agile for their body size in comparison to their parents, and means that we can add footprints as another line of evidence in the debate over tyrannosaur growth.

“Lastly, it demonstrates the usefulness of footprints for investigating a potentially wider range of ideas about the lives of extinct species than has been considered previously.”

Story Source:

Materials provided by Taylor & Francis Group. Note: Content may be edited for style and length.

Journal Reference:

1. Nathan J. Enriquez, Nicolás E. Campione, Tom Brougham, Federico Fanti, Matt A. White, Robin L. Sissons, Corwin Sullivan, Matthew J. Vavrek, Phil R. Bell. Exploring possible ontogenetic trajectories in tyrannosaurids using tracks from the Wapiti Formation (upper Campanian) of Alberta, Canada. Journal of Vertebrate Paleontology, 2021; e1878201 DOI: 10.1080/02724634.2021.1878201

New duckbilled dinosaur discovered in Japan

Paleontologists find second hadrosaurid species

An international team of paleontologists has identified a new genus and species of hadrosaur or duck-billed dinosaur, Yamatosaurus izanagii, on one of Japan’s southern islands.

The fossilized discovery yields new information about hadrosaur migration, suggesting that the herbivors migrated from Asia to North America instead of vice versa. The discovery also illustrates an evolutionary step as the giant creatures evolved from walking upright to walking on all fours. Most of all, the discovery provides new information and asks new questions about dinosaurs in Japan.

The research, “A New Basal Hadrosaurid (Dinosauria: Ornithischia) From the latest Cretaceous Kita-ama Formation in Japan implies the origin of Hadrosaurids,” was recently published in Scientific Reports. Authors include Yoshitsugu Kobayashi of Hokkaido University Museum, Ryuji Takasaki of Okayama University of Science, Katsuhiro Kubota of Museum of Nature and Human Activities, Hyogo and Anthony R. Fiorillo of Southern Methodist University.

Hadrosaurs, known for their broad, flattened snouts, are the most commonly found of all dinosaurs. The plant-eating dinosaurs lived in the Late Cretaceous period more than 65 million years ago and their fossilized remains have been found in North America, Europe, Africa and Asia.

Uniquely adapted to chewing, hadrosaurs had hundreds of closely spaced teeth in their cheeks. As their teeth wore down and fell out, new teeth in the dental battery, or rows of teeth below existing teeth, grew in as replacements. Hadrosaurs’ efficient ability to chew vegetation is among the factors that led to its diversity, abundance and widespread population, researchers say.

The Yamatosaurus’ dental structure distinguishes it from known hadrosaurs, says Fiorillo, senior fellow at SMU’s Institute for the Study of Earth and Man. Unlike other hadrosaurs, he explains, the new hadrosaur has just one functional tooth in several battery positions and no branched ridges on the chewing surfaces, suggesting that it evolved to devour different types of vegetation than other hadrosaurs.

Yamatosaurus also is distinguished by the development of its shoulder and forelimbs, an evolutionary step in hadrosaurid’s gait change from a bipedal to a quadrupedal dinosaur, he says.

“In the far north, where much of our work occurs, hadrosaurs are known as the caribou of the Cretaceous,” says Fiorillo. They most likely used the Bering Land Bridge to cross from Asia to present-day Alaska and then spread across North America as far east as Appalachia, he says. When hadrosaurs roamed Japan, the island country was attached to the eastern coast of Asia. Tectonic activity separated the islands from the mainland about 15 million years ago, long after dinosaurs became extinct.

The partial specimen of the Yamatosaurus was discovered in 2004 by an amateur fossil hunter in an approximately 71- to 72-million-year-old layer of sediment in a cement quarry on Japan’s Awaji Island. The preserved lower jaw, teeth, neck vertebrae, shoulder bone and tail vertebra were found by Mr. Shingo Kishimoto and given to Japan’s Museum of Nature and Human Activities in the Hyogo Prefecture, where they were stored until studied by the team.

“Japan is mostly covered with vegetation with few outcrops for fossil-hunting,” says Yoshitsugu Kobayashi, professor at Hokkaido University Museum. “The help of amateur fossil-hunters has been very important.”

Kobayashi has worked with SMU paleontologist Tony Fiorillo since 1999 when he studied under Fiorillo as a Ph.D. student. They have collaborated to study hadrosaurs and other dinosaurs in Alaska, Mongolia and Japan. Together they created their latest discovery’s name. Yamato is the ancient name for Japan and Izanagi is a god from Japanese mythology who created the Japanese islands, beginning with Awaji Island, where Yamatosaurus was found.

Yamatosaurus is the second new species of hadrosaurid that Kobayashi and Fiorillo have identified in Japan. In 2019 they reported the discovery of the largest dinosaur skeleton found in Japan, another hadrosaurid, Kamuysaurus, discovered on the northern Japanese island of Hokkaido.

“These are the first dinosaurs discovered in Japan from the late Cretaceous period,” Kobayashi says. “Until now, we had no idea what dinosaurs lived in Japan at the end of the dinosaur age,” he says. “The discovery of these Japanese dinosaurs will help us to fill a piece of our bigger vision of how dinosaurs migrated between these two continents,” Kobayashi says.

Story Source:

Materials provided by Southern Methodist University. Note: Content may be edited for style and length.

Journal Reference:

1. Yoshitsugu Kobayashi, Ryuji Takasaki, Katsuhiro Kubota, Anthony R. Fiorillo. A new basal hadrosaurid (Dinosauria: Ornithischia) from the latest Cretaceous Kita-ama Formation in Japan implies the origin of hadrosaurids. Scientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-87719-5

Fearsome tyrannosaurs were social animals

The fearsome tyrannosaur dinosaurs that ruled the northern hemisphere during the Late Cretaceous period (66-100 million years ago) may not have been solitary predators as popularly envisioned, but social carnivores similar to wolves, according to a new study.

The finding, based on research at a unique fossil bone site inside Utah’s Grand Staircase-Escalante National Monument containing the remains of several dinosaurs of the same species, was made by a team of scientists including Celina Suarez, University of Arkansas associate professor of geosciences.

“This supports our hypothesis that these tyrannosaurs died in this site and were all fossilized together; they all died together, and this information is key to our interpretation that the animals were likely gregarious in their behavior,” Suarez said.

The research team also include scientists from the U.S. Bureau of Land Management, Denver Museum of Nature and Science, Colby College of Maine and James Cook University in Australia. The study examines a unique fossil bone site inside Grand Staircase-Escalante National Monument called the “Rainbows and Unicorns Quarry” that they say exceeded the expectations raised even from the site’s lofty nickname.

“Localities [like Rainbows and Unicorns Quarry] that produce insights into the possible behavior of extinct animals are especially rare, and difficult to interpret,” said tyrannosaur expert Philip Currie in a press release from the BLM. “Traditional excavation techniques, supplemented by the analysis of rare earth elements, stable isotopes and charcoal concentrations convincingly show a synchronous death event at the Rainbows site of four or five tyrannosaurids. Undoubtedly, this group died together, which adds to a growing body of evidence that tyrannosaurids were capable of interacting as gregarious packs.”

In 2014, BLM paleontologist Alan Titus discovered the Rainbows and Unicorns Quarry site in Grand Staircase-Escalante National Monument and led the subsequent research on the site, which is the first tyrannosaur mass death site found in the southern United States. Researchers ran a battery of tests and analyses on the vestiges of the original site, now preserved as small rock fragments and fossils in their final resting place, and sandbar deposits from the ancient river.

“We realized right away this site could potentially be used to test the social tyrannosaur idea. Unfortunately, the site’s ancient history is complicated,” Titus said. “With bones appearing to have been exhumed and reburied by the action of a river, the original context within which they lay has been destroyed. However, all has not been lost.” As the details of the site’s history emerged, the research team concluded that the tyrannosaurs died together during a seasonal flooding event that washed their carcasses into a lake, where they sat, largely undisturbed until the river later churned its way through the bone bed.

“We used a truly multidisciplinary approach (physical and chemical evidence) to piece the history of the site together, with the end-result being that the tyrannosaurs died together during a seasonal flooding event,” said Suarez.

Using analysis of stable carbon and oxygen isotopes and concentrations of rare earth elements within the bones and rock, Suarez and her then-doctoral student, Daigo Yamamura, were able to provide a chemical fingerprint of the site. Based on the geochemical work, they were able to conclusively determine that the remains from the site all fossilized in the same environment and were not the result of an attritional assemblage of fossils washed in from a variety of areas.

“None of the physical evidence conclusively suggested that these organisms came to be fossilized together, so we turned to geochemistry to see if that could help us. The similarity of rare earth element patterns is highly suggestive that these organisms died and were fossilized together,” said Suarez.

Excavation of the quarry site has been ongoing since its discovery in 2014 and due to the size of the site and volume of bones found there the excavation will probably continue into the foreseeable future. In addition to tyrannosaurs, the site has also yielded seven species of turtles, multiple fish and ray species, two other kinds of dinosaurs, and a nearly complete skeleton of a juvenile (12-foot-long) Deinosuchus alligator, although they do not appear to have all died together like the tyrannosaurs.

“The new Utah site adds to the growing body of evidence showing that tyrannosaurs were complex, large predators capable of social behaviors common in many of their living relatives, the birds,” said project contributor, Joe Sertich, curator of dinosaurs at the Denver Museum of Nature & Science. “This discovery should be the tipping point for reconsidering how these top carnivores behaved and hunted across the northern hemisphere during the Cretaceous.”

Future research plans for the Rainbows and Unicorns Quarry fossils include additional trace element and isotopic analysis of the tyrannosaur bones, which paleontologists hope will determine with a greater degree of certainty the mystery of Teratophoneus’ social behavior.

In stark contrast to the social interaction between humans and among many species of animals, paleontologists have long debated whether tyrannosaurs lived and hunted alone or in groups.

Based on findings at a site in Alberta, Canada, with over 12 individuals, the idea that tyrannosaurs were social with complex hunting strategies was first formulated by Philip Currie over 20 years ago. This idea has been widely debated, with many scientists doubting the giant killing machines had the brainpower to organize into anything more complex than what is observed in modern crocodiles. Because the Canadian site appeared to be an isolated case, skeptics claimed it represented unusual circumstances that did not reflect normal tyrannosaur behavior. Discovery of a second tyrannosaur mass death site in Montana again raised the possibility of social tyrannosaurs, but this site was still not widely accepted by the scientific community as evidence for social behavior. The researcher’s findings at the Unicorns and Rainbows Quarry provides even more compelling evidence that tyrannosaurs may have habitually lived in groups.

Story Source:

Materials provided by University of Arkansas. Original written by Bob Whitby. Note: Content may be edited for style and length.

Journal Reference:

1. Alan L. Titus, Katja Knoll, Joseph J.W. Sertich, Daigo Yamamura, Celina A. Suarez, Ian J. Glasspool, Jonathan E. Ginouves, Abigail K. Lukacic, Eric M. Roberts. Geology and taphonomy of a unique tyrannosaurid bonebed from the upper Campanian Kaiparowits Formation of southern Utah: implications for tyrannosaurid gregariousness. PeerJ, 2021; 9: e11013 DOI: 10.7717/peerj.11013

Tiny cat-sized stegosaur leaves its mark

A single footprint left by a cat-sized dinosaur around 100 million years ago has been discovered in China by an international team of palaeontologists.

University of Queensland researcher Dr Anthony Romilio was part of the team that investigated the track, originally found by Associate Professor Lida Xing from the China University of Geosciences (Beijing).

“This footprint was made by a herbivorous, armoured dinosaur known broadly as a stegosaur — the family of dinosaurs that includes the famed stegosaurus,” Dr Romilio said.

“Like the stegosaurus, this little dinosaur probably had spikes on its tail and bony plates along its back as an adult.

“With a footprint of less than six centimetres, this is the smallest stegosaur footprint known in the world.

“It’s in strong contrast with other stegosaur prints found at the Chinese track site which measured up to 30 centimetres, and prints found in places like Broome in Western Australia where they can be up to 80 centimetres.”

The tiny footprint has similar characteristics of other stegosaur footprints with three short, wide, round toe impressions.

However researchers found the print wasn’t elongated like larger counterpart prints discovered at the track sites, which suggests the young stegosaur had a different behaviour.

“Stegosaurs typically walked with their heels on the ground, much like humans do, but on all fours which creates long footprints,” Dr Romilio said.

“The tiny track shows that this dinosaur had been moving with its heel lifted off the ground, much like a bird or cat does today.

“We’ve only previously seen shortened tracks like this when dinosaurs walked on two legs.”

Associate Professor Xing said that it was plausible young stegosaurs were toe-walkers.

“This could be possible as this is the ancestral condition and a posture of most dinosaurs, but the stegosaur could also have transitioned to heel-walking as it got older,” Dr Xing said.

“A complete set of tracks of these tiny footprints would provide us with the answer to this question, but unfortunately we only have a single footprint.”

Finding the tiny tracks on crowded track sites will be challenging for the researchers.

“The footprints made by tiny armoured dinosaur are much rarer than those formed by other groups of dinosaurs,” Associate Professor Xing said.

“Now that our study has identified nine different dinosaur track sites from this locality, we will look even closer to see if we can find more of these tiny tracks.”

Story Source:

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

How many T. rexes were there? Billions

Analysis of what’s known about the dinosaur leads to conclusion there were 2.5 billion over time

How many Tyrannosaurus rexes roamed North America during the Cretaceous period?

That’s a question Charles Marshall pestered his paleontologist colleagues with for years until he finally teamed up with his students to find an answer.

What the team found, to be published this week in the journal Science, is that about 20,000 adult T. rexes probably lived at any one time, give or take a factor of 10, which is in the ballpark of what most of his colleagues guessed.

What few paleontologists had fully grasped, he said, including himself, is that this means that some 2.5 billion lived and died over the approximately 2 1/2 million years the dinosaur walked the earth.

Until now, no one has been able to compute population numbers for long-extinct animals, and George Gaylord Simpson, one of the most influential paleontologists of the last century, felt that it couldn’t be done.

Marshall, director of the University of California Museum of Paleontology, the Philip Sandford Boone Chair in Paleontology and a UC Berkeley professor of integrative biology and of earth and planetary science, was also surprised that such a calculation was possible.

“The project just started off as a lark, in a way,” he said. “When I hold a fossil in my hand, I can’t help wondering at the improbability that this very beast was alive millions of years ago, and here I am holding part of its skeleton — it seems so improbable. The question just kept popping into my head, ‘Just how improbable is it? Is it one in a thousand, one in a million, one in a billion?’ And then I began to realize that maybe we can actually estimate how many were alive, and thus, that I could answer that question.”

Marshall is quick to point out that the uncertainties in the estimates are large. While the population of T. rexes was most likely 20,000 adults at any give time, the 95% confidence range — the population range within which there’s a 95% chance that the real number lies — is from 1,300 to 328,000 individuals. Thus, the total number of individuals that existed over the lifetime of the species could have been anywhere from 140 million to 42 billion.

“As Simpson observed, it is very hard to make quantitative estimates with the fossil record,” he said. “In our study, we focused in developing robust constraints on the variables we needed to make our calculations, rather than on focusing on making best estimates, per se.”

He and his team then used Monte Carlo computer simulation to determine how the uncertainties in the data translated into uncertainties in the results.

The greatest uncertainty in these numbers, Marshall said, centers around questions about the exact nature of the dinosaur’s ecology, including how warm-blooded T. rex was. The study relies on data published by John Damuth of UC Santa Barbara that relates body mass to population density for living animals, a relationship known as Damuth’s Law. While the relationship is strong, he said, ecological differences result in large variations in population densities for animals with the same physiology and ecological niche. For example, jaguars and hyenas are about the same size, but hyenas are found in their habitat at a density 50 times greater than the density of jaguars in their habitat.

“Our calculations depend on this relationship for living animals between their body mass and their population density, but the uncertainty in the relationship spans about two orders of magnitude,” Marshall said. “Surprisingly, then, the uncertainty in our estimates is dominated by this ecological variability and not from the uncertainty in the paleontological data we used.”

As part of the calculations, Marshall chose to treat T. rex as a predator with energy requirements halfway between those of a lion and a Komodo dragon, the largest lizard on Earth.

The issue of T. rex‘s place in the ecosystem led Marshall and his team to ignore juvenile T. rexes, which are underrepresented in the fossil record and may, in fact, have lived apart from adults and pursued different prey. As T. rex crossed into maturity, its jaws became stronger by an order of magnitude, enabling it to crush bone. This suggests that juveniles and adults ate different prey and were almost like different predator species.

This possibility is supported by a recent study, led by evolutionary biologist Felicia Smith of the University of New Mexico, which hypothesized that the absence of medium-size predators alongside the massive predatory T. rex during the late Cretaceous was because juvenile T. rex filled that ecological niche.

What the fossils tell us

The UC Berkeley scientists mined the scientific literature and the expertise of colleagues for data they used to estimate that the likely age at sexual maturity of a T. rex was 15.5 years; its maximum lifespan was probably into its late 20s; and its average body mass as an adult — its so-called ecological body mass, — was about 5,200 kilograms, or 5.2 tons. They also used data on how quickly T. rexes grew over their life span: They had a growth spurt around sexual maturity and could grow to weigh about 7,000 kilograms, or 7 tons.

From these estimates, they also calculated that each generation lasted about 19 years, and that the average population density was about one dinosaur for every 100 square kilometers.

Then, estimating that the total geographic range of T. rex was about 2.3 million square kilometers, and that the species survived for roughly 2 1/2 million years, they calculated a standing population size of 20,000. Over a total of about 127,000 generations that the species lived, that translates to about 2.5 billion individuals overall.

With such a large number of post-juvenile dinosaurs over the history of the species, not to mention the juveniles that were presumably more numerous, where did all those bones go? What proportion of these individuals have been discovered by paleontologists? To date, fewer than 100 T. rex individuals have been found, many represented by a single fossilized bone.

“There are about 32 relatively well-preserved, post-juvenile T. rexes in public museums today,” he said. “Of all the post-juvenile adults that ever lived, this means we have about one in 80 million of them.”

“If we restrict our analysis of the fossil recovery rate to where T. rex fossils are most common, a portion of the famous Hell Creek Formation in Montana, we estimate we have recovered about one in 16,000 of the T. rexes that lived in that region over that time interval that the rocks were deposited,” he added. “We were surprised by this number; this fossil record has a much higher representation of the living than I first guessed. It could be as good as one in a 1,000, if hardly any lived there, or it could be as low as one in a quarter million, given the uncertainties in the estimated population densities of the beast.”

Marshall expects his colleagues will quibble with many, if not most, of the numbers, but he believes that his calculational framework for estimating extinct populations will stand and be useful for estimating populations of other fossilized creatures.

“In some ways, this has been a paleontological exercise in how much we can know, and how we go about knowing it,” he said. “It’s surprising how much we actually know about these dinosaurs and, from that, how much more we can compute. Our knowledge of T. rex has expanded so greatly in the past few decades thanks to more fossils, more ways of analyzing them and better ways of integrating information over the multiple fossils known.”

The framework, which the researchers have made available as computer code, also lays the foundation for estimating how many species paleontologists might have missed when excavating for fossils, he said.

“With these numbers, we can start to estimate how many short-lived, geographically specialized species we might be missing in the fossil record,” he said. “This may be a way of beginning to quantify what we don’t know.”

Story Source:

Materials provided by University of California – Berkeley. Original written by Robert Sanders. Note: Content may be edited for style and length.

Journal Reference:

1. Charles R. Marshall, Daniel V. Latorre, Connor J. Wilson, Tanner M. Frank, Katherine M. Magoulick, Joshua B. Zimmt, Ashley W. Poust. Absolute abundance and preservation rate of Tyrannosaurus rex. Science, 2021 DOI: 10.1126/science.abc8300