The recent description of Utetitan zellaguymondeweyae marks a significant step forward in Late Cretaceous dinosaur research. This newly recognised titanosaurian sauropod lived during the Maastrichtian fauna stage in what is now Utah. Importantly, it challenges long-held assumptions about sauropod diversity in what we now know as North America.

For many years, palaeontologists believed that Alamosaurus sanjuanensis was the only sauropod present in North America during the final few million years of the Cretaceous. This idea always raised questions. After all, sauropods elsewhere often show multiple species living side by side. A single species persisting unchanged for such a long time seemed implausible.

The fossils that led to description of Utetitan come from the North Horn Formation, which dates to the very end of the Age of Dinosaurs. Although these remains were collected decades ago, they were historically placed within the Alamosaurus taxon. At the time, comparisons were difficult. Most sauropod fossils from the southwest and northern Mexico are fragmentary. Overlapping bones are rare. In addition, it is often difficult to compare fossil skeletons as they represent individuals at different growth stages.

A life reconstruction of Utetitan zellaguymondeweyae. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Utetitan zellaguymondeweyae

Recent re-examination of the material revealed something important. The Utah fossils differ consistently from Alamosaurus fossils found in New Mexico. These distinctions are anatomical, not simply related to ontogeny or taphonomy. As a result, the Utah skeleton was designated as the holotype of a new species, Utetitan zellaguymondeweyae.

The name Utetitan honours the native Ute peoples of the region. Whereas the species name honours the author’s (Gregory S. Paul) maternal grandmother Zella Guymon Dewey (1901–2002).

The holotype includes tail vertebrae, pelvic bones, limb elements, and a distinctive osteoderm. Consequently, Utetitan is one of the most informative Late Cretaceous sauropods known from North America. Its anatomy confirms its place within the Titanosauria clade.

Many Different Titanosaurs Lived in Late Cretaceous North America

Crucially, Utetitan changes how palaeontologists view Late Cretaceous ecosystems. Evidence now suggests that multiple titanosaurs lived in southwestern North America during the Campanian and Maastrichtian faunal stages of the Late Cretaceous. Furthermore, some fossils from Texas may belong to Utetitan. Other fossils do not. Older Campanian remains cannot be confidently assigned to either Alamosaurus or Utetitan. This suggests that there are many more titanosaur genera awaiting scientific description.

These titanosaurs may even represent a short-lived regional lineage. In semi-isolation, they could have evolved separately from titanosaurs elsewhere in the world. Interestingly, new skeletal reconstructions suggest that these animals were not as massive as earlier size estimates indicated.

Scale drawing of Alamosaurus.  Recent research suggests that Alamosaurus sanjuanensis may not have been as large as previously thought.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

From a biogeographical perspective, Utetitan supports the idea of late sauropod migrations into North America. Changing sea levels may have opened temporary land corridors. Through these routes, titanosaurs could disperse from other continents.

Ultimately, the Utetitan zellaguymondeweyae paper shows how revisiting old fossils can transform scientific understanding.

The scientific paper: “Stratigraphic and anatomical evidence for multiple titanosaurid dinosaur taxa in the Late Cretaceous (Campanian-Maastrichtian) of southwestern North America” by Gregory S. Paul published as an open-access paper in Geology of the Intermountain West.

For models of Alamosaurus and other titanosaurs: Dinosaur Models.

Palaeontologists have described two new species of azhdarchid pterosaurs from Mongolia’s Gobi Desert. The Gobi Desert is famous for its numerous dinosaur fossils. However, pterosaur remains are very rare in Mongolian Mesozoic deposits. Researchers writing in the academic journal “PeerJ” identified azhdarchid pterosaur fossils.

The material consists of bones from the neck, and from these specimens two new species have been erected. The fossils come from two different localities (Bayshin Tsav and Burkhant). Originally collected in the 1990s, the fossils were described in detail in 2009 (Watabe et al). Yet, at the time the pterosaurs were not named, just described as indeterminate azhdarchids.

Azhdarchid Pterosaur Fossils

Subsequently, knowledge of azhdarchid pterosaur anatomy has improved. As a result, two distinct species have been named.  In a paper published in the autumn, researchers identified diagnostic features permitting the establishment of these two new species. The paper was written by researchers from the Universidade de São Paulo (Brazil), Shihezi University (China) and Hokkaido University (Japan).

Azhdarchid pterosaur fossils lead to the naming of two new taxa. The two new Mongolian taxa are compared to two of the largest azhdarchid pterosaurs. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Gobiazhdarcho tsogtbaatari: A Medium-Sized Pterosaur

The first species is named Gobiazhdarcho tsogtbaatari. It comes from the Burkhant locality of the Bayanshiree Formation. This pterosaur had an estimated wingspan of three to three and a half metres. It has been described as a medium-sized azhdarchid, with a wingspan roughly comparable to an Andean Condor (Vultur gryphus).  Fossils associated with this taxon include an atlantoaxis (fused neck vertebrae) and other cervical bones. These show it belonged to a lineage related to giants such as Quetzalcoatlus and Arambourgiania. In evolutionary terms, Gobiazhdarcho is a basal member of this quetzalcoatlid group, bridging gaps in the fossil record.

Its name reflects both its origin and scientific heritage. “Gobi” refers to the desert where it was found. “Azhdarcho” comes from Persian for dragon. The species name honours Mongolian palaeontologist Khishigjav Tsogtbaatar.

Tsogtopteryx mongoliensis: A Small Azhdarchid Pterosaur

The second species named in the paper is Tsogtopteryx mongoliensis. This pterosaur is notably small for an azhdarchid. Its estimated wingspan was approximately two metres, making it one of the smallest members of the Azhdarchidae family.  A single, partial mid-cervical vertebra is known for this species. Despite the limited material, distinct features show it belongs to a different pterosaur lineage than Gobiazhdarcho.  It was related to Hatzegopteryx. This lineage includes robust-necked azhdarchids previously known only from Europe.

The genus name combines the Mongolian word “Tsogt” (meaning mighty hero) with the Greek word pteryx which means wing. The species name references its discovery in Mongolia.

Azhdarchids Occupied Diverse Ecological Niches

The coexistence of Gobiazhdarcho and Tsogtopteryx in the same geological formation emphasises that azhdarchids occupied diverse ecological niches. Different body sizes suggest varied foraging behaviours and diets. This pattern echoes findings from other Upper Cretaceous deposits.  This study sheds fresh light on the diversity and phylogeny of azhdarchid pterosaurs. It reinforces the reoccurring pattern of coexistence between multiple, differently-sized azhdarchid species within the same palaeoenvironment.

The scientific paper: “Azhdarchid pterosaur diversity in the Bayanshiree Formation, Upper Cretaceous of the Gobi Desert, Mongolia” by R. V. Pêgas, Xuanyu Zhou​ and Yoshitsugu Kobayashi published in PeerJ.

For pterosaur models and other prehistoric animal figures: Pterosaur Models and Prehistoric Animal Figures.

A new study published by the Royal Society Open Science reveals colour patterning in sauropod dinosaur skin.  Interpretation of the preserved integumentary covering has led scientists to suggest that the dull grey, elephant-like colouration of sauropods is probably inaccurate.  The peer-reviewed study was led by Tess Gallagher (Department of Palaeobiology, University of Bristol), and it provides exciting new information on the Sauropodomorpha.

This is the first reported evidence of colour patterning in a sauropod.  Exceptionally preserved juvenile diplodocid (Diplodocus) skin impressions from Montana formed the basis of this study. The fossils come from the Mother’s Day Quarry (Morrison Formation) and for the purposes of this study they were ascribed to Diplodocus. However, the taxonomic classification of these sauropods might change with future research.

Sauropod dinosaur skin speculative life reconstruction with graphic microscopy (inset). Picture credit: Tess Gallagher.

Picture credit: Tess Gallagher

Studying Sauropod Dinosaur Skin

One of the key conclusions from the research is the confirmation of the presence of two distinct microbody morphotypes associated with the integument. These structures have been identified as melanosomes.  Therefore, they are linked to pigmentation and colouration. The different shapes of these microbodies indicates that young sauropods may have displayed visual patterning rather than being a single uniform colour.

Elevation Science student holding a sample of Diplodocus fossilised skin. Picture credit: Joshua Levy.

Picture credit: Joshua Levy

It is possible that juvenile Diplodocus had complex colour patterning. Perhaps, these leviathans had similar colouration to extant archosaurs such as birds.

The new for 2020 CollectA rearing Diplodocus dinosaur model in the elephantine colour scheme. Many sauropods are depicted with a uniform colouration. This colouration has been inspired by large mammals alive today.  However, new research suggests that Diplodocus had complex colour patterning. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Difficult to Confirm the Exact Colours

The first sauropod to be scientifically described from fossilised bones was Cetiosaurus (1842 – Owen). Initially thought to be aquatic lizards, these animals were mainly terrestrial and some of them grew to enormous sizes.  Some taxa are regarded as the largest land animals that have ever existed.  Although dozens of genera have been named, evidence for their colouration is lacking.  This research provides a rare insight into the colouration of juvenile sauropods and opens new avenues for studying dinosaur biology and behaviour.

Commenting on the significance of the research, Tess Gallagher (University of Bristol) stated:

“This study investigates fossilised juvenile Diplodocus scales and marks the first instance of colour patterning found in a long-necked dinosaur. The skin is preserved 3-dimensionally as clay minerals with melanosome groups (melanin bearing organelles) dispersed throughout. Disk-shaped objects were found intermixed with the melanosomes. The disk-shaped objects are hypothesized to be melanosomes, though their bizarre shape makes it impossible to determine the true colour of the scales. Regardless, the results show juvenile sauropods could create more diverse melanosome morphologies than previously thought, akin to modern birds and mammals.”

Field photo of Tess Gallagher holding a preserved skin impression. Picture credit: Skye Walker/Elevation Science Institute.

Picture credit: Skye Walker/Elevation Science Institute.

The Significance of Integumentary Fossils

Remarkable, well-preserved integumentary fossils have the potential to help us learn more about dinosaur physiology. In addition, we can infer ecological niches and the appearance of dinosaurs in terms of their colouration.

Co-author of the paper, Jason Schein (Executive Director of Elevation Science for Natural History Exploration) added:

“It wasn’t that long ago when it seemed impossible that we could even really know what dinosaurs truly looked like. Technology and innovative scientists like Tess are pushing us into new frontiers, and showing us what is actually possible.”

Everything Dinosaur acknowledges the assistance of a media release from the Elevation Science Institute for Natural History Exploration in the compilation of this article.

The scientific paper: “Fossilized melanosomes reveal colour patterning of a sauropod dinosaur” by Tess Gallagher, Dan Folkes, Michael Pittman, Tom G. Kaye, Glenn W. Storrs and Jason Schein published in the Royal Society Open Science.

The multi-award-winning Everything Dinosaur website: Models of Sauropods and Other Prehistoric Animals.

A recently published paper highlights Australia’s oldest known crocodilian eggshells.  The study is helping researchers from the University of New South Wales to unlock clues to an ancient ecosystem that thrived before Australia became an island continent.  The eggshell fragments have been assigned to the oospecies Wakkaoolithus godthelpi.

The fossilised fragments of eggshell are approximately fifty-five million years old (Eocene Epoch).  The come from mekosuchine crocodiles.  These now extinct crocodiles dominated inland waters during the Eocene.  Modern saltwater and freshwater crocodiles only arrived in Australia around 3.8 million years ago.

Electron microscope scans of the eggshell fragments. Picture credit: Xavier Panadès.

Picture credit: Xavier Panadès

Field teams have been working in clay pit close to the small town of Murgon in southeast Queensland. The clay layers preserve evidence of when Australia was still connected to South America and Antarctica.  It is one of the oldest fossil sites in Australia.  An international research team led by the Institut Català de Paleontologia Miquel Crusafont (ICP) in collaboration with researchers from University New South Wales (UNSW) identified the mekosuchine fossil eggshells.

Commenting on the significance of the fossil finds, lead author of the study Xavier Panadès i Blas (El Museu de la Conca Dellà, Isona, Spain), stated:

“These eggshells have given us a glimpse of the intimate life history of mekosuchines. We can now investigate not only the strange anatomy of these crocs, but also how they reproduced and adapted to changing environments.”

A virtual reconstruction of the Murgon palaeoecosystem during the Early Eocene, featuring the oospecies Wakkaoolithus godthelpi. Also shown is one of the abundant giant soft-shell turtles, Murgonomys braithwaitei, an archaic marsupial, Djarthia murgonensis, and an unnamed ancestral songbird. The clays that form the fossil deposit were accumulated in this ancient lake. Image: generated with Google Gemini AI.

Picture credit: Google Gemini AI

Swimming and Tree Climbing Crocodiles

Unlike Australia’s crocodiles today, mekosuchines filled much more varied ecological niches.  For example, some species were almost entirely terrestrial and inhabited forests.  Others were at home in the river systems and grew to at least five metres in length.  Co-author of the paper, Professor Michael Archer (UNSW) has postulated that some species were at least partly arboreal, and these animals have been termed “drop crocs.”

Professor Archer added:

“They were perhaps hunting like leopards – dropping out of trees on any unsuspecting thing they fancied for dinner.”

The palaeontological team from UNSW excavating the Tingamarra fossil deposit at Murgon, Queensland, Australia. The hard clay is quarried, dried and then soaked in water to release the fossils it contains. Photo credit: Mina Bassarova.

Picture credit: Mina Bassarova

Delicate Time Capsules

The authors state that tiny, fossilised eggshells are an underused resource in vertebrate palaeontology.  They preserve microstructural and geochemical signals that provide information on the kinds of creatures that laid them but also where they nested and how they bred.

Xavier Panadès i Blas explained:

“Our study shows just how powerful these fragments can be.  Eggshells should be a routine, standard component of palaeontological research – collected curated and analysed alongside bones and teeth.”

The shell fragments from the clay pit were examined under optical and electron microscopes.  Their microstructure indicates that they were laid on the margins of a lake, with the reproductive strategy adapting to fluctuating conditions.

Co-author of the study, Dr Michael Stein (UNSW), commented that mekosuchine crocs may have lost much of their inland territory because of encroaching dry land.  These crocodiles eventually had to compete in the shrinking waterways not only with new crocodilian rivals arriving in Australia but also with dwindling numbers of prey.  As the climate became much drier, many of the large prey animals that these crocodiles hunted became rarer.

The researchers think that the lake was surrounded by a lush, tropical forest.

Dr Stein said:

“This forest was also home to the world’s oldest-known songbirds, Australia’s earliest frogs and snakes, a wide range of small mammals with South American links, as well as one of the world’s oldest bats.”

Wakkaoolithus godthelpi eggshell fragments shown in high magnification. Picture credit: Xavier Panadès.

Picture credit: Xavier Panadès

A Study with Teeth

The research into the Tingamarra deposits at Murgon is just part of a much bigger story.  Professor Archer recalls finding a bizarre crocodilian jaw fragment in 1975 in the Texas Caves of southeastern Queensland.  This jaw fossil has been confirmed to represent a mekosuchine crocodile.  The large teeth in situ were linked to another type of extinct crocodile known from South America.  This was the first evidence of crocodiles related to South American crocodiles being present in Australia during the Eocene.

Discoveries like this are more than just a glimpse into ancient history. They are reminders that Australia’s fossil record can provide important clues to help save today’s threatened species. For example, scientists have been working to help bring a small possum – Burramys parvus back from the brink of extinction.  Researchers discovered that the possum’s prehistoric relatives, evolving over the past twenty-five million years, have always thrived in temperate lowland rainforests.

This led to the theory that the immediate ancestors of B. parvus likely followed the rainforests as they moved up into the alpine areas during a warm, wet interval during the Pleistocene Epoch. However, when the climate in the alpine zone changed and became cooler, these small marsupials had to evolve evasive behaviours such as hibernation to escape the increasingly hostile conditions.

Based on the findings from the fossil record a breeding facility in an area of non-alpine rainforest was set up.  As a result, the numbers of Burramys parvus have increased.  The possums are flourishing in a non-alpine sanctuary, just as the fossil record predicted.

Wakkaoolithus godthelpi Fossils Provide Guidance to Conservationists

As climate change threatens Australia’s fauna today, the fossil record can provide important indicators to assist with the conservation of species.

Professor Archer stated:

“Clues from the fossil record matter.  Not just to understand the past, but also to help secure the future”.

The new crocodile species’ name, Wakkaoolithus godthelpi, acknowledges, with permission, the Wakka Wakka First Nations people, on whose Country the fossils were found. The second part of the name recognises Henk Godthelp, who was part of the UNSW palaeontologist crew along with Professor Archer, Professor Sue Hand and many other research staff and students.

Everything Dinosaur acknowledges the assistance of a media release from the University of New South Wales in the compilation of this article.

The scientific paper: “Australia’s oldest crocodylian eggshell: insights into the reproductive paleoecology of mekosuchines” by Xavier Panadès I Blas, Àngel Galobart, Michael Archer, Michael Stein, Suzanne Hand and Albert Sellés published in the Journal of Vertebrate Paleontology.

The award-winning Everything Dinosaur website: Prehistoric Animal Models.

A recently published scientific paper lends weight to the theory that Nanotyrannus is a valid taxon.  Writing in the journal “Science” a team of scientists, including researchers from the Cleveland Museum of Natural History used a novel approach to confirm that a skull does indeed represent skeletally mature adult.  Their evidence confirms that the fossil specimen, known as the “Cleveland skull” does not represent a juvenile Tyrannosaurus rex.  An often-overlooked bone helped make the breakthrough.  The Nanotyrannus hyoid bone provided the vital information.

Whether Nanotyrannus lancensis represents a distinct taxon or an immature T. rex is a decades-long controversy.  This new study comes shortly after a paper that concluded that Nanotyrannus was a valid taxon.  Indeed, this study claimed that there were two species of Nanotyrannus in the known fossil record.

To read Everything Dinosaur’s blog post about this earlier study: Nanotyrannus – A New Chapter in Tyrannosaur Evolution.

The “Cleveland skull” – Nanotyrannus lancensis fossil material. Picture credit: Cleveland Museum of Natural History.

Picture credit: Cleveland Museum of Natural History

The Cleveland Skull

The Cleveland skull lies at the heart of this long-running controversy. Discovered in 1942, the specimen consists almost entirely of a skull, with no associated postcranial bones. As a result, palaeontologists found it difficult to determine whether these fossils represented a juvenile tyrannosaur or an adult animal. If the fossil skull represented an adult, then this would indicate a new tyrannosaur genus present in Hell Creek. Hence, the erection of a new tyrannosaur species (Gorgosaurus lancensis) in a paper published posthumously in 1946 by the American palaeontologist Charles Whitney Gilmore.

Dr Caitlin Colleary (Department of Earth Sciences, Cleveland Museum of Natural History), examining the Nanotyrannus skull material. Picture credit: Cleveland Museum of Natural History.

Picture credit: Cleveland Museum of Natural History

The Nanotyrannus Hyoid Bone

One small bone proved vital when trying to assess the skull material. The Nanotyrannus hyoid bone had detached from the skull and was stored separately in the museum collection. This slender throat bone had gone largely unnoticed until a visiting researcher recognised its potential importance. The hyoid supports the tongue and airway in living animals. Crucially, it also records growth in a measurable way. The researchers were able to demonstrate that the histology preserved in this bone was useful for assessing the ontogeny of the fossils. The research team therefore applied histological analysis to the hyoid, an approach never used on this bone before.

Before examining the Cleveland specimen, the scientists validated their method. They studied hyoids from birds and crocodilians, which represent living dinosaur relatives. They then compared the Nanotyrannus hyoid bone with those from theropod dinosaurs including Tyrannosaurus rex, Allosaurus, and Coelophysis.

Thin sections viewed under a microscope revealed clear growth patterns. Most importantly, the hyoid contained an external fundamental system. This structure forms when growth has ceased. The team demonstrated that hyoid bone histology is useful for ontogenetic assessment in extant and extinct archosaur.

Senior author of the paper, Dr Caitlin Colleary (Department of Earth Sciences, Cleveland Museum of Natural History), explained:

“By applying a new technique to a specimen that’s been in the collection for nearly 80 years, we unlocked information that’s been there all along.”

The Cleveland Skull Material Represents a Fully Grown Animal

The presence of this feature confirms that the Cleveland skull fossils belonged to a fully grown individual. It did not represent a juvenile Tyrannosaurus rex. Instead, it supports the interpretation of Nanotyrannus lancensis as a distinct taxon coeval with T. rex.

A Nanotyrannus (N. lancensis) left, competes for food with a juvenile Tyrannosaurus rex, whilst an adult T. rex watches in the background. Picture credit: Andrey Atuchin.

Picture credit: Andrey Atuchin

Nanotyrannus Hyoid Bone Study – The Implications

This study has significant implications for tyrannosaur research. The holotype defines the species. Demonstrating adult status strengthens the case for Nanotyrannus beyond reasonable doubt. The study also highlights the enduring value of museum collections. A single overlooked bone provided the decisive evidence. Sometimes, the most important discoveries wait quietly in storage.

For the moment, the debate has shifted decisively. The Nanotyrannus hyoid bone offers direct proof of skeletal maturity. As a result, this small tyrannosaur finally steps out from the shadow of Tyrannosaurus rex.  This study and the earlier Nanotyrannus paper, indicate that the Hell Creek ecosystem was home to a wide assemblage of predatory dinosaurs.

Everything Dinosaur acknowledges the assistance of a media release from the Cleveland Museum of Natural History in the compilation of this article.

The scientific paper: “A diminutive tyrannosaur lived alongside Tyrannosaurus rex” by Christopher T. Griffin, Jeb Bugos, Ashley W. Poust, Zachary S. Morris, Riley S. Sombathy, Michael D. D’Emic, Patrick M. O’Connor, Holger Petermann, Matteo Fabbri and Caitlin Colleary published in the journal Science.

Visit the award-winning Everything Dinosaur website: Prehistoric Animal Models and Figures.

A new study by an international team of scientists shows that early amniotes – the ancestors of all modern reptiles, birds and mammals, developed significantly more diverse jaw shapes than amphibians (non-amniotes). This anatomical diversity enabled them to tap into new food sources and successfully adapt to life on land. The results of the study into early tetrapod jawbone evolution are published this week in the open-access journal PeerJ.

The research team included scientists from the Museum für Naturkunde Berlin and Humboldt University of Berlin.  In addition, researchers from the Staatliches Museum für Naturkunde Stuttgart, the Oertijdmuseum in Holland and the North Carolina Museum of Natural Sciences were involved in this study.

The Transition from Aquatic to Terrestrial Environments

The transition from aquatic fish to land-dwelling vertebrates is one of the most significant changes in the history of life. In the Devonian period around 370 million years ago, the first tetrapods – four-legged vertebrates – ventured onto land. This exposed them to new challenges: their bodies had to be stable enough to stand and walk without water to help support their bodyweight.  Furthermore, how they obtained food had to change.  Fish feed differently from other vertebrates.  For example, many fish suck in prey by opening their jaws rapidly.  This creates low pressure which sucks in water and any prey.  This method does not work when feeding on land.

Lead author of the study, Dr Jasper Ponstein, a former doctoral student at the Museum für Naturkunde Berlin stated:

“Many fish suck in their prey by opening their jaws at lightning speed. This method no longer works on land. There, animals have to actively grab their prey. This made changes to the jaw particularly important.”

Studying Early Tetrapod Jawbone Evolution

During the Carboniferous and later Permian periods, early land vertebrates diversified and spread into new habitats.  These animals adapted to different diets.  Some hunted the abundant arthropods such as insects, whilst others became herbivorous.  These diets required adaptations to the jaw and muscles associated with the jawbones.  This period in the history of vertebrates is extremely significant as back-boned animals adapted to non-aquatic environments on a large scale for the first time.

New research into early tetrapod jawbone evolution reveals that amniotes evolved diverse jawbones compared to non-amniotes. The image shows a jawbone of the reptiliomorph Diadectes absitus from the Early Permian. It was one of the first herbivorous tetrapods and one of the first terrestrial vertebrates to attain large size. Picture credit: Jasper Ponstein.

Picture credit: Jasper Ponstein

To find out how early tetrapods might have eaten, the team focused on the lower jaw – an element consisting of several bones whose shape reveals a lot about an animal’s diet. To this end, the researchers compiled the largest data set of fossil tetrapod jaws from the Carboniferous and Permian periods to date.  The research covers more than two hundred different species. A significant portion of the fossils studied came from the collection of the Museum für Naturkunde Berlin.

Two Key Findings

This in-depth analysis of early tetrapod jawbone evolution identified two key findings:

(1). Immediately after the transition to terrestrial habitats the jaw morphology of early tetrapods remained remarkable constant. Long, slender jaw types predominated.  It is likely that animals with this type of jaw fed on fish and/or insects.  Despite becoming much more terrestrial, the basic shape of the jawbone initially changed very little.

(2). With the emergence of the first amniotes (reptiliomorphs) jaw morphology evolved rapidly.

During the Early Permian (approximately 300 million years ago), amniotes developed a much wider range of jaw shapes than contemporary amphibians.  Their jaws became more robust, and the muscle attachment points more varied.  These adaptations enabled amniotes to feed on a greater variety of food resources.  For example, some amniotes such as Diadectes became herbivores.

 Other amniotes evolved into hypercarnivores, specialising in catching large prey.  Conversely, amphibians remained largely limited to a conservative jaw morphology that was simpler than those evolving in the Amniota.  Moreover, extant amphibians retain their simply jaw morphology with most feeding on small invertebrates.

The Basis for Modern Ecosystems and Terrestrial Animal Diversity

This research suggests that jaw development permitted the exploitation of new food resources by tetrapods.  It could be argued that these jawbone adaptations laid the foundations for modern ecosystems.  In addition, the ability to exploit new resources led to an increase in animal diversity during the Late Palaeozoic.

Jasper Ponstein added:

“The early diversity of jaw shapes probably enabled amniotes to exploit ecological niches that remained closed to amphibians. In doing so, they laid the foundation for the impressive diversity of reptiles, birds and mammals that we see around the world today.”

A close-up view of a jaw fragment from a Dimetrodon (Dimetrodon spp.). Early tetrapod jawbone evolution led to the emergence of hypercarnivores in the Early Permian such as Dimetrodon. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Today, the amniote group includes everything from turtles to birds to big cats – an enormous range of lifestyles. The study shows that this success is deeply rooted in Earth’s history: in the ability to adapt early and flexibly to exploit new food resources.

Everything Dinosaur acknowledges the assistance of a media release from the Museum für Naturkunde Berlin in the compilation of this article.

The scientific paper: “Mandibular form and function is more disparate in amniotes than in non-amniote tetrapods from the late Palaeozoic” by Jasper Ponstein​, Mark J. MacDougall, Joep Schaeffer, Christian F. Kammerer and Jörg Fröbisch published in PeerJ.

The multi-award-winning Everything Dinosaur website: Prehistoric Animal Models.

During Everything Dinosaur’s recent visit to the gardens of the London Natural History Museum, a very small statue was spotted. Hiding behind the huge Diplodocus was a life-size replica of Megazostrodon rudnerae, a tiny but hugely important early mammaliaform.

The tiny, life-size Megazostrodon rudnerae statue on display in the gardens of the London Natural History Museum. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Megazostrodon rudnerae

At first glance, the gold-coloured statue is easy to miss. However, that is rather fitting. Megazostrodon rudnerae was shrew-sized and probably nocturnal.  It lived millions of years before its giant garden neighbour Diplodocus evolved.  Fossils are known from strata laid down approximately 200 million years ago.  It is a mammaliaform from the Early Jurassic.  Whilst dinosaurs and other reptiles dominated terrestrial environments, mammaliaforms such as Megazostrodon scuttled in the shadows.

The nearby plaque provides helpful information. Furthermore, it explains that despite possessing fur and many mammal-like characteristics, such as endothermy, this little creature probably laid eggs like monotremes.

The Megazostrodon plaque on display at the London Natural History Museum gardens. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Two species are recognised.  In 1968, M. rudnerae was described from fossil remains found in Lesotho and South Africa. Then, in 2015 a second species (M. chenali) from Upper Triassic rocks in France was described.  These fossils provide a perspective on early mammal evolution. Furthermore, fossil evidence shows that Megazostrodon rudnerae had differentiated teeth. This feature allowed more efficient feeding. As a result, it represents a key step towards true mammals. Significantly, the structure of the jaw and ear bones hints at advanced hearing.

Therefore, this modest garden statue tells a powerful evolutionary story. It reminds visitors that mammal origins were humble. It also shows that success does not always come from size or strength.

The award-winning Everything Dinosaur website: Prehistoric Animal Models.

Discover why scientists now use Otodus megalodon instead of Carcharocles megalodon, and learn how this change reshapes our view of this giant shark.  As a boy, I read about the giant prehistoric shark Carcharocles megalodon – often referred to as megalodon.  However, research has led to a revision of this taxon.  The species is referred to as Otodus megalodon. This change reflects a deeper understanding of shark evolution and how this ancient lamniform fits into the fossil record.

The PNSO large megalodon model “Patton” being held by an Everything Dinosaur team member.  This giant member of the Lamniformes has inspired many model makers.  Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The image (above) shows an early prehistoric shark model from the Chinese company PNSO.

To view the range of PNSO prehistoric animal models in stock: PNSO Prehistoric Animal Models.

Otodus megalodon Instead of Carcharocles megalodon

The taxonomic history of this ancient shark is complicated. Fossil material was assigned to Carcharias megalodon by Louis Agassiz in 1835. Fossils, mainly teeth were subsequently assigned to Carcharodon, and this largely remained the case until some authors erected Carcharocles megalodon around fifteen years ago. Most of these studies placed megalodon within the same group as the great white shark, Carcharodon carcharias. Yet, new evidence tells a different story. Fossil teeth and jaw structures show that Otodus megalodon was part of the Otodontidae family, not directly related to modern great white sharks.

The Paleobiology Database resource records the use of O. megalodon in a paper published in 2015 (Reinecke and Radwanski).

This family line began with Otodus obliquus, a shark that lived more than 55 million years ago (Eocene Epoch). Over time, its descendants evolved larger, sharper teeth and greater size. Eventually, this lineage gave rise to Otodus megalodon, one of the largest marine predators known to science.

To read a blog post from 2018 about the ancestors of this shark lineage: On the Trail of Megalodon Ancestors.

Mike from Everything Dinosaur commented:

“The name changes, but the legend remains.  Fossilised teeth of this giant shark inspire fear and awe.  They remind us that there was a time when the oceans of the world were ruled by this enormous shark.”

The award-winning Everything Dinosaur website: Prehistoric Animal Figures.

A remarkable fossil discovery has been made in Wales. Palaeontologists have identified a new, Triassic dinosaur species named Newtonsaurus cambrensis. The fossil was first reported back in 1899, yet it was never properly studied until now.  The fossil material had been referred to in many scientific papers.  A scientific name had been erected – Zanclodon cambrensis by the British palaeontologist Edwin Tully Newton. This name is not valid, the genus name having been used previously to describe an archosauriform from southern Germany.

Using modern, digital scanning techniques researchers have been able to confirm that the fossil material represents a theropod dinosaur. Owain Evans, a student at Bristol University, created a three-dimensional digital reconstruction of the dentary material. The fossil is preserved as natural moulds, with the original bone lost. By digitally scanning and fusing the moulds, the team rebuilt the jaw in striking detail. Every ridge, groove, and serrated tooth was revealed.

The new name honours Edwin Newton.

A plaster cast of the left dentary of Newtonsaurus cambrensis. Picture credit: BGS NERC from “Dinosaurs of the British Isles” by Dean R. Lomax and Nobumichi Tamura.

Picture credit: BGS NERC

Newtonsaurus cambrensis

Writing in the Proceedings of the Geologists’ Association, the researchers suggest that the fossils represent a neotheropod similar to Liliensternus and Dilophosaurus. The jaw was over half a metre long. This suggests a theropod of approximately five to seven metres in length.  Poorly preserved bivalves in the matrix, enabled the scientists to confirm the age of the fossils (Rhaetian faunal stage of the Late Triassic).

Co-author of the study, Professor Michael Benton (University of Bristol), explained that the digital reconstruction gave scientists a much clearer idea of the anatomy.   This paper confirms the presence of large predatory dinosaurs in the area that was to become Wales around 200 million years ago. The research highlights the value of museum collections. Long-stored specimens can still yield significant results.

Part of the holotype (BGS GSM 6532 of Newtonsaurus. The right side of the left dentary, complete with teeth in situ. Picture credit: BCS NERC from “Dinosaurs of the British Isles” by Dean R. Lomax and Nobumichi Tamura.

Shares Characteristics with a European Coelophysoid

The detailed analysis of the digital images indicates that the dentary has characteristics with European coelophysoids of similar geological age (Liliensternus and Dracoraptor).  However, it was much larger.  The research team propose that Newtonsaurus was not a megalosauroid, as previously suggested.

Dracoraptor is also from Wales.  To read Everything Dinosaur’s blog post about the discovery of Dracoraptor: Wales Gets a New Dinosaur – Dracoraptor.

It is uncertain whether it might be an averostran or tetanuran. Its close similarity to Dilophosaurus suggests that this left dentary specimen represents a more derived basal neotheropod. Therefore, it is assigned as a new species (Newtonsaurus cambrensis).

Mike from Everything Dinosaur commented:

“This study shows the power of re-examining old fossils. Museum specimens can still reveal new dinosaurs and transform our understanding of the Dinosauria.”

The scientific paper: “Re-assessment of a large archosaur dentary from the Late Triassic of South Wales, United Kingdom” by Owain Evans, Cindy Howells, Nathan Wintle and Michael J. Benton published in the Proceedings of the Geologists’ Association.

The award-winning Everything Dinosaur website: Prehistoric Animal Models.