Scientists have named a unique, two-fingered therizinosaur species.  The fossils of Duonychus tsogtbaatari come from the Upper Cretaceous Bayanshiree Formation of the Gobi Desert (Mongolia).  This is the first time that a reduction of the digits on the manus has been recorded within the Therizinosauridae family.  All other therizinosaurs possessed three fingers on each hand.  Moreover, each finger ended in a curved claw.  Some of the claws of therizinosaurs were huge.  For example, one of the largest, Therizinosaurus cheloniformis had finger claws over a metre in length.

A life reconstruction of Duonychus tsogtbaatari. This dinosaur had two fingers on each hand. Although the fossils from which this new species has been described represent a subadult. Scientists have calculated that It weighed approximately 260 kilograms and was around three metres in length. Picture credit: Tim Bollinger.

Picture credit: Tim Bollinger

Duonychus tsogtbaatari

Duonychus (pronounced due-oh-ny-kus) translates from the Greek as “two claws”.  The species name honours the Mongolian palaeontologist Khishigjav Tsogtbaatar.  The discovery of this therizinosaur is doubly unique.  One of the sheaths on a fossil claw (digit I) has been preserved.  The sheath made from the protein keratin (same as our hair and fingernails), reveals that the claw was much longer than the underlying bone.  It was forty percent longer than the claw’s bony core.  It is the largest claw of its kind found fully preserved in this way.  The total claw length has been estimated at around thirty centimetres.

Duonychus tsogtbaatari was not carnivorous.  These long claws were probably not used to attack other dinosaurs.  Although, they could have had a defensive function or have been used in intraspecific combat.  The researchers studying the fossil material believe the long, curved claws and the ability of Duonychus to flex them would have helped this animal to grasp vegetation.

Duonychus tsogtbaatari data card. Picture credit: Tim Bollinger.

Picture credit: Tim Bollinger

Digit Reduction in Theropod Dinosaurs

The most famous two-fingered theropod dinosaur is Tyrannosaurus rex.  Duonychus is not closely related to T. rex.  However, both these dinosaurs evolved from ancestors that had three digits on each hand.  So, why did some theropod dinosaurs lose digits?  It is likely that the outer fingers of the hand became less useful and so they were gradually reduced over the time.  An evolutionary pathway led to the outer fingers becoming redundant, then vestigial, before finally disappearing altogether. Alternatively, digits I and II became increasingly dominant and thus enlarged.  This led to the eventual reduction and elimination of digit III.

Intriguingly, the hand claws of Duonychus were highly curved.  The researchers conclude that the extremely curved claws were adaptations to help this animal to “hook” branches and pull them within easy reach.  In essence, the reduction of digits was an evolutionary adaptation towards more efficient feeding.

Potential Niche Partitioning?

The sediments of the Bayanshiree Formation preserve a diverse dinosaur biota.  For example, there were at least three other therizinosaurs that were likely coeval with Duonychus.  All the other Bayanshiree Formation therizinosaurs described to date had three fingers on each hand.  With so many therizinosaurs in the same environment, it is possible that Duonychus evolved reduced digits to permit it to feed on different types of vegetation.  The reduced fingers could represent evidence of niche partitioning within the Therizinosauridae associated with these strata.

The four therizinosaurs described from the Bayanshiree Formation to date:

• Segnosaurus (S. galbinensis) named in 1979. One of the largest therizinosaurs known with a length of around seven metres.
• Erlikosaurus (E. andrewsi) named in 1980.  Measuring around three and half metres in length it had a robust beak suggesting a diet of mainly vegetation.
• Enigmosaurus (E. mongoliensis) named in 1983.  Some scientists consider Enigmosaurus a junior synonym of Erlikosaurus.  Although, the discovery of Duonychus lends support to the idea that several different types of therizinosaur were present.
• Duonychus (D. tsogtbaatari) named in 2025.  The first didactyl therizinosaur, possessing only two manual digits. In addition, the keratinous sheath on digit I provides a rare insight into theropod claw structure.

It is also worth noting that several other potential therizinosaur fossil specimens have been excavated from the Bayanshiree Formation.  These have yet to be formally named and described.

Our thanks to Tim Bollinger for permission to use his Duonychus illustrations in the compilation of this article.

Take a look at Tim Bollinger’s work under the moniker UnexpectedDinoLesson:

Instagram – @unexpecteddinolesson
Facebook – @UnexpectedDinoLesson
X (Twitter) – @Dino_Lesson

The scientific paper: “Didactyl therizinosaur with a preserved keratinous claw from the Late Cretaceous of Mongolia” by Yoshitsugu Kobayashi, Darla K. Zelenitsky, Anthony R. Fiorillo and Tsogtbaatar Chinzorig published in the journey iScience.

Recently published temnospondyl research suggests that adopting a generalist feeding ecology helped these ancient amphibians to survive the end-Permian mass extinction event.  The study published this week in the journal “Royal Society Open Science”, concludes temnospondyl’s success lay in their generalist feeding ecology. The temnospondyls consist of an extinct clade comprising around three hundred known species.  They evolved in the Early Carboniferous and persisted until the Early Cretaceous.  This represents a timespan of around two hundred and thirty million years.  Temnospondyls were traditionally classified as amphibians, although their taxonomic affinity with the Amphibia remains controversial.  It is more technically correct to refer to these vertebrates as anamniote tetrapods.

A dorsal view of the CollectA Deluxe Koolasuchus a late surviving temnospondyl from the Early Cretaceous of Australia. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The photograph (above) shows a dorsal view of Koolasuchus cleelandi model. It is the youngest temnospondyl described to date.  Fragmentary fossils are thought to be around 125-120 million years old (Barremian – Aptian faunal stages of the Cretaceous).  The model is from the CollectA Deluxe range of scale prehistoric animal figures.

To view this range of prehistoric animal models: CollectA Deluxe Prehistoric Life Models.

A Mystery of the end-Permian Mass Extinction Event

One of the mysteries of the end-Permian mass extinction was the subsequent success of temnospondyls. This catastrophic global event occurred approximately 252 million years ago.  It was the largest extinction event in the Phanerozoic, marked by the loss of as many as 90% of all species.  Although many types of temnospondyl died out, following this mass extinction temnospondyls diversified rapidly during the Early Triassic.  Numerous lineages arose.  These lineages continued, although with diminishing diversity throughout the remainder of the Triassic.  A few taxa survived into the Jurassic before the temnospondyls are thought to have finally become extinct during the Early Cretaceous.

Researchers led by scientists from the University of Bristol propose that these animals thrived after the mass extinction event by feeding on freshwater prey that evaded terrestrial predators.

By adopting a generalist feeding ecology, these predators could consume a wide variety of prey despite all the environmental changes going on during the Triassic. A broader examination of Triassic ecosystems also indicates that the freshwater habitats temnospondyls preferred provided them with a relatively stable variety of food resources.  This allowed them to thrive while strictly terrestrial predators made do with meagre, unstable resource availability on land.

A Mastodonsaurus rises out of the depths to ambush a small, archiosauriform (Jaxtasuchus). Picture credit: Mark Witton.

Picture credit: Mark Witton

Mastodonsaurus (see image above), is known from the Middle Triassic of Europe.  It was one of the largest temnospondyls, with an estimated body length of more than five metres.

Lead author of the study Aamir Mehmood (University of Bristol School of Biological Sciences), commented:

“One of the great mysteries has been the survival and flourishing of a major group of amphibians called the temnospondyls.  These were predatory animals that fed on fishes and other prey, but were primarily linked to the water, just like modern amphibians such as frogs and salamanders. We know that climates then were hot, and especially so after the extinction event. How could these water-loving animals have been so successful?”

The Triassic “Tropical Dead Zone”

The Early Triassic was a time of repeated volcanic activity leading to long phases of global warming, aridification, reductions in atmospheric oxygen, acid rain and widespread wildfires, creating conditions so hostile that the tropics became devoid of animal life. This “tropical dead zone” drastically impacted the distributions of both marine and terrestrial organisms.

Co-author Dr Suresh Singh said:

“We collected data on a hundred temnospondyls that lived throughout the Triassic and wanted to look at how their ecologies changed. We measured their body sizes and features of the skulls and teeth that tell us about function.”

Dr Armin Elsler another co-author of the temnospondyl research paper added:

“Much to our surprise, we found that they did not change much through the crisis. The temnospondyls showed the same range of body sizes as in the Permian, some of them small and feeding on insects, and others larger. These larger forms included long-snouted animals that trapped fishes and broad-snouted generalist feeders. What was unusual though was how their diversity of body sizes and functional variety expanded about five million years after the crisis and then dropped back.”

Due to the intense global warming of the first five million years of the Triassic, there is evidence that life on land and in the sea moved away from the tropics to avoid the heat.

Professor Mike Benton (University of Bristol) explained:

“Our work shows that the temnospondyls, unexpectedly, were able to cross the tropical dead zone. Fossils are known from South Africa and Australia in the south, as well as North America, Europe and Russia in the north. The temnospondyls must have been able to criss-cross the tropical zone during cooler episodes.”

An exhibit featuring a reconstruction of the skeleton of the giant Permian temnospondyl Eyrops. New research suggests that temnospondyl’s success during the Early Triassic lay in their generalist feeding ecology. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The Decline of the Temnospondyls

Aamir summarised the team’s findings stating:

“Their burst of success in the Early Triassic was not followed up. They coped with the hot conditions probably by having a low requirement for food, by being able to eat most prey animals, and by hiding in sparse water bodies. But when the ancestors of dinosaurs and of mammals began to diversify in the Middle Triassic, the temnospondyls began their long decline.”

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

The scientific paper: “The ecology and geography of temnospondyl recovery after the Permian – Triassic mass extinction” by Aamir Mehmood, Dr Suresh Singh, Dr Armin Elsler and Professor Michael Benton published in Royal Society Open Science.

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

A jumbled set of bones first spotted on a beach on the southern portion of the Isle of Skye in 1973 have been identified as a probable ornithopod.  The Elgol dinosaur fossil is Scotland’s earliest recorded dinosaur fossil discovery.  A research team led by Dr Elsa Panciroli (NERC Independent Research Fellow at National Museums Scotland), visited the site in 2018 and began the challenging process of extracting the fossil specimen from the surrounding boulders.

A specialist Canadian company was invited to supervise the extraction of the rare fossil.  Once the difficult task of releasing the fossil slab was completed, it was carefully loaded onto an inflatable dingy and piloted safely back to port by a local crew from Elgol’s Bella Jane Boat Trips.  The researchers were so worried about the fossil block sinking that they tied several buoys to it in the hope that if the boat should capsize, the rare fossil could still be located.

Lead author Dr Elsa Panciroli with the Elgol dinosaur fossil. The jumbled bones have proved difficult to identify. Picture credit: Neil Hanna.

Picture credit: Neil Hanna

The Dinosaur Fossil Record of Scotland

The fossil record of dinosaurs in Scotland mostly comprises isolated highly fragmentary bones from the Great Estuarine Group in the Inner Hebrides.  These sediments were deposited in the Middle Jurassic (Bajocian–Bathonian faunal stage).  The Elgol dinosaur fossil is estimated to be around 166 million years old. It is the first and most complete partial dinosaur skeleton currently known from Scotland. The material has been assigned a specimen number (NMS G.2023.19.1).

After manual preparation, the scientists were able to identify part of the spine, ribs and elements from the hips (a partial ilium).  Unfortunately, micro-CT scanning failed to help with fossil identification.  However, the team are confident that the material does represent a dinosaur, an ornithischian and most likely an ornithopod.  If it does prove to be an ornithopod, then it would be one of the world’s oldest ornithopod body fossils described to date.

The Elgol dinosaur fossil has been interpreted to represent an early ornithopod. Picture credit: Maija Karala.

Picture credit: Maija Karala

Lead author of the study, Dr Elsa Panciroli stated:

“This was a really challenging extraction, in fact we’d previously felt was too difficult to collect the fossil, but I thought it was really important to study it. I was able to persuade the team to give it a try. It took a lot of hard work from a lot of people, but we did it: finally we can confirm and publish Scotland’s first recorded and most complete dinosaur, and that makes it all worthwhile”.

Cerapodan or Ornithopod Dinosaur

The ornithischian (bird-hipped) clade of the Dinosauria has been subdivided into several groups.  Although the exact taxonomy remains undetermined, most palaeontologists distinguish two main groups. Firstly, there is the Thyreophora which comprises the armoured dinosaurs. In addition, there is the Cerapoda which can be further divided into the Ornithopoda and the Marginocephalia (ceratopsids and pachycephalosaurs).

The partial ilium and a histological analysis of fossil bone led the team to conclude that NMS G.2023.19.1 was definitely ornithischian and probably an early ornithopod. Ornithopods were much more common in the Early and Late Cretaceous.  Famous ornithopods such as Iguanodon, Hypsilophodon and Mantellisaurus are associated with Lower Cretaceous deposits.

A Mantellisaurus scale drawing.  An illustration of an Early Cretaceous ornithopod.  Picture credit: Everything Dinosaur

Picture credit: Everything Dinosaur

The ornithopod illustration (above) is based on the CollectA Age of Dinosaurs Mantellisaurus model that was introduced in 2018.  This was the same year when the fossil was removed from its difficult to access location.

To view the range of CollectA Age of Dinosaur figures, including many ornithopods: CollectA Age of Dinosaurs Figures.

Late Cretaceous ornithopods were extremely successful.  Hadrosaurs became the dominant herbivores in many ecosystems.  The Hadrosauridae family (duck-billed dinosaurs) had a global distribution. Some of these dinosaurs were enormous.  For example, Shantungosaurus from the Late Cretaceous of China reached lengths in excess of fourteen metres.

The Elgol Dinosaur Fossil

The Elgol fossils suggest an animal about the size of a pony.  Histological analysis concluded that the animal was at least eight years of age when it died. The new description of the Elgol dinosaur is published in the Earth and Environmental Science Transactions of the Royal Society of Edinburgh. If the fossil material does represent an ornithischian, as tentatively suggested from the partial ilium and histological sectioning, it represents the geologically youngest known occurrence in Scotland, and first from the Kilmaluag Formation.  This adds to the diversity of dinosaurs known from the Middle Jurassic of the Isle of Skye.

To read an article about the types of dinosaurs that lived in this part of the world during the Middle Jurassic: Tracks of Middle Jurassic Dinosaurs.

A close-up view of the 166-million-year-old Elgol dinosaur fossil. Dr Elsa Panciroli carefully examines the fossil material. Picture credit: Neil Hanna.

Picture credit: Neil Hanna

Co-author of the study, Dr Stig Walsh (National Museums Scotland) said:

“This is a wonderful addition to the rapidly growing set of Jurassic finds from the Isle of Skye which are enabling us to learn more and more about the rich ecosystem of the time. We’ve known there were dinosaurs there for a while, most obviously from the famous footprints at An Corran, Brother’s Point and Duntulm and from individual bones, but it’s exciting to see a more complete, if still partial, skeleton. We’re delighted to add it to the other amazing finds now in the National Collection”.

Other recent Jurassic discoveries from Skye include the description of adult and juvenile mammals of the same species, Krusatodon, which revealed that these mammals grew more slowly than mammals today, and possibly one of the world’s largest Jurassic pterosaurs, Dearc sgiathanach.

To read Everything Dinosaur’s article about the Krusatodon fossils: Providing an Insight into Krusatodon Ontogeny.

To read about the discovery of D. sgiathanach: Fantastic Pterosaur from the Isle of Skye.

More Dinosaur Fossils?

Fellow author Professor Susie Maidment of the London Natural History Museum and the University of Birmingham, added:

“The Elgol dinosaur was a challenge to collect, and has proven perhaps an even bigger challenge to identify. Some aspects of the bones indicate that the specimen may be an ornithopod, a group of plant-eating dinosaurs that are best known from the Cretaceous. This specimen, however, would already have been a fossil by the time that the better-known ornithopods like Iguanodon and Hypsilophodon were walking the Earth. Recent research on the fossils of Elgol has revealed a diverse ecosystem of extraordinarily preserved Middle Jurassic animals, and I’m sure there are more exciting discoveries to come.”

The other authors on the paper were Professor Roger Benson (American Museum of Natural History), Professor Richard Butler (University of Birmingham), Brett Crawford (Research Casting International – RCI), Matt Fear (RCI), Dr Nick Fraser (National Museums Scotland) and Dr Gregory Funston (Royal Ontario Museum).

With the description of the Elgol dinosaur fossil, the significance of the Isle of Skye is once again emphasised.  Furthermore, it demonstrates the importance of this part of Scotland in terms of learning more about the dinosaur biota from the Middle Jurassic.

Everything Dinosaur acknowledges the assistance of a media release downloaded from National Museums Scotland.

The scientific paper: “The first and most complete dinosaur skeleton from the Middle Jurassic of Scotland” by Elsa Panciroli, Gregory F. Funston, Susannah C. R. Maidment, Richard J. Butler, Roger B. J. Benson, Brett L. Crawford, Matt Fair, Nicholas C. Fraser and Stig Walsh published in the Earth and Environmental Science Transactions of The Royal Society of Edinburgh.

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

A newly published scientific paper highlights the uniqueness and diversity of Australian theropods.  The research, published in the Journal of Vertebrate Paleontology identifies the world’s oldest known megaraptorid.  In addition, the study provides the first evidence of the presence of carcharodontosaurs in Australia.  These fossil discoveries are rewriting the evolutionary history of theropod dinosaurs.  Furthermore, they highlight a unique predator hierarchy in Australia during the Early Cretaceous.

The research was led by Museums Victoria Research Institute and Monash University PhD student Jake Kotevski. The scientists describe five new theropod specimens. Three tibiae, and a fossil consisting of two articulated caudal vertebrae with haemal arches, from the upper Strzelecki Group. In addition, the study includes a single tibia from the slightly younger Eumeralla Formation.

Unenlagiinae left tibia (front). Carcharodontosauria left tibia (middle) and Megaraptoridae right tibia (rear). New research highlights the diversity of Early Cretaceous Australian theropods. Picture credit: Nadir Kinani/Museums Victoria.

Picture credit: Nadir Kinani/Museums Victoria

Describing the Theropod Fossils

The five specimens included in the study are:

• Articulated Megaraptoridae caudal vertebrae (NMV P257414) – from upper Strzelecki Group exposures from the Twin Reefs locality.
• A partial right tibia (Megaraptoridae) specimen number NMV P257415 also from upper Strzelecki Group exposures at the Twin Reefs locality.
• Carcharodontosauria indet. left tibia (NMV P186143). A fragmentary fossil collected from the Lesley’s Lair site by Patricia Vickers-Rich in 1988 (upper Strzelecki Group).
• NMV P221042 a Carcharodontosauria indet. right tibia from the Point Lewis locality of the Eumeralla Formation.
• NMV P257601 a crushed left tibia assigned to Unenlagiinae indet. This fossil was found at Eagles Nest, near Inverloch, (upper Strzelecki Group).

For context, the upper Strzelecki Group deposits are dated from 121.4 to 118 million years ago.  Whilst the geologically younger Eumeralla Formation dates from 113 to 108 million years ago.

Fragmentary fossil material found in Australia has been assigned to the Megaraptoridae family previously.  However, these megaraptorid fossils from the upper Strzelecki Group are several million years older.  As such, they are the oldest assigned Megaraptoridae fossil material known to science.  Previously, Everything Dinosaur has reported on the discovery of Australian megaraptor fossil material that dates from approximately 110 million years ago.

To read more about this research: Australian Theropod Bone Challenges Gondwana Break-up Theory.

Megaraptoridae right tibia. Picture credit: Nadir Kinani/Museums Victoria.

Picture credit: Nadir Kinani/Museums Victoria

A Fresh Perspective on Australian Theropods

These newly described theropod fossils offer insights into Victoria’s dinosaur dominated, Early Cretaceous ecosystem.  The fossils suggest that the apex predators were megaraptorids.  In contrast, the coeval carcharodontosaurs were much smaller and lighter.  For example, the partial tibia and articulated caudal vertebrae indicate the presence of megaraptorids that were around six to seven metres in length.  The fossils assigned to carcharodontosaurs indicate much smaller theropods.  A size estimate for the carcharodontosaurs of two to four metres in length has been proposed.

One of the authors of the study, PhD student Jake Kotevski commented:

“The discovery of carcharodontosaurs in Australia is ground-breaking. It’s fascinating to see how Victoria’s predator hierarchy diverged from South America, where carcharodontosaurs reached Tyrannosaurus rex-like sizes up to 13 metres, towering over megaraptorids. Here, the roles were reversed, highlighting the uniqueness of Australia’s Cretaceous ecosystem.”

Two Megaraptoridae caudal (tail) vertebrae and haemal arches. Picture credit: Nadir Kinani/Museums Victoria.

Picture credit: Nadir Kinani/Museums Victoria

Numerous small ornithopods are known from the Early Cretaceous of Victoria.  However, sauropod remains are absent.  This may have favoured the evolution of smaller, cursorial predators such as megaraptors.  Whereas, in South America large carcharodontosaurs were the apex predators.  They probably hunted the abundant sauropods.  This suggests the composition of the herbivorous dinosaurs in each region led to different theropods dominating the ecosystem.

To read a blog post from 2019 about the discovery of a new ornithopod from Victoria: A New Early Cretaceous Ornithopod from Australia is Described (Galleonosaurus).

Evidence of Faunal Interchange

Co-author Dr Thomas Rich (Museums Victoria) added:

“The findings not only expand Australia’s theropod fossil record but offer compelling evidence of faunal interchange between Australia and South America through Antarctica during the Early Cretaceous. The findings also challenge previous assumptions about body-size hierarchies in Gondwanan predator ecosystems highlighting Victoria’s unique Cretaceous fauna.”

Specimen number NMV P257601 has been referred to the Unenlagiinae.  Their taxonomic position within the Theropoda remains controversial.  For example, some palaeontologists consider unenlagiines to be a subfamily of the Dromaeosauridae.  However, other scientists consider, these small, long-snouted dinosaurs as a separate family (Unenlagiidae). Most unenlagiine fossil remains have been found in South America. Historically, Australia had limited evidence for their presence.  Nevertheless, the crushed tibia (NMV P257601) provides further robust evidence for a faunal interchange between South America and Australia across Antarctica.

Jake Kotevski (left) holding Unenlagiinae left tibia and Tim Ziegler (right) holding Megaraptoridae right tibia. Picture credit: Nadir Kinani/Museums Victoria.

Picture credit: Nadir Kinani/Museums Victoria

The Importance of Museum Collections

Co-author Tim Ziegler (Museums Victoria) highlighted the importance of access to museum collections to foster scientific breakthroughs.

He stated:

“Museum collections are crucial to advancing our understanding of prehistoric life. Specimens preserved in the State Collection for decades – unidentifiable until now – are providing new insights into the evolution of dinosaur ecosystems.”

Three of the fossils, uncovered between 2022 and 2023, were first identified by Museums Victoria volunteer Melissa Lowery. This discovery highlights the essential contributions of community members working alongside seasoned researchers to further our understanding of Australia’s Cretaceous past.

An aerial view of Twin Reefs, Bunurong Coastal Reserve (Victoria), the area where some of the dinosaur fossils were found. Picture credit John Broomfield/Museums Victoria.

Picture credit: John Broomfield/Museums Victoria

Everything Dinosaur acknowledges the assistance of a media release from Museums Victoria in the compilation of this article.

The scientific paper: “Evolutionary and paleobiogeographic implications of new carcharodontosaurian, megaraptorid, and unenlagiine theropod remains from the upper Lower Cretaceous of Victoria, southeast Australia” by Jake Kotevski, Ruairidh J. Duncan, Tim Ziegler, Joseph J. Bevitt, Patricia Vickers-Rich, Thomas H. Rich, Alistair R. Evans and Stephen F. Poropat published in the Journal of Vertebrate Paleontology.

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

A scientific paper was published earlier this week that announced two new Hateg Basin sauropod taxa.  These dinosaurs were named Petrustitan hungaricus and Uriash kadici.  At least four sauropod taxa are known from the Hateg Basin.  However, as the sediments in this region cover several million years, it is likely that these four taxa were not contemporaneous.  It is also likely that additional sauropod genera are represented in the fossil deposits.

To read Everything Dinosaur’s earlier blog post about this new study: New Hateg Basin Sauropods are Described.

We have been asked to provide a little more information on the largest of these four sauropod taxa. As this area consisted of a series of large islands at the end of the Cretaceous, it was thought that the dinosaur fauna in this region consisted mostly of dwarf forms.  However, this idea of the Hateg Basin dinosaur fauna representing examples of “island dwarfism” has been challenged.  For example, the newly described U. kadici is thought to amongst the biggest European Late Cretaceous sauropods know to science.

The Hateg Basin Sauropod Fauna – A Complex Picture

The first sauropod to be named and described from this region of western Romania was Magyarosaurus. The German palaeontologist Friedrich von Huene erected this genus in 1932.  He assigned three species to this genus.

1. Magyarosaurus dacus – now recognised as the only valid species.
2. The nomen dubium Magyarosaurus transsylvanicus – a nomen dubium with assigned fossil material thought to represent more than one species of sauropod.
3. Magyarosaurus hungaricus – renamed in 2025 as Petrustitan hungaricus (Verónica Díez Díaz et al).

It is likely that the substantial number of fossils, often isolated and fragmentary remains found in western Romania represent several more, as yet undescribed sauropod taxa.

The Wild Past Magyarosaurus dinosaur model, a replica of this dwarf titanosaur taxon. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture shows a model of the dwarf titanosaur Magyarosaurus sent to Everything Dinosaur by Wild Past.

To view the range of Wild Past models and figures in stock: Wild Past Prehistoric Animal Figures.

Uriash kadici – A Giant Amongst Hateg Basin Sauropods

The second, newly described Hateg Basin sauropod is an outlier in terms of size.  Whilst three of the four Hateg Basin sauropod taxa described to date were relatively small, Uriash kadici was much larger. Size estimates vary but it could have had a body length of around twelve metres.

Mike from Everything Dinosaur explained that three of the four known Hateg Basin sauropod taxa were relatively small.  Although size estimates vary, it is possible to compare these four taxa and to produce a scale drawing.

• Magyarosaurus dacus – 3 metres (<1 tonne).
• Paludititan nalatzensis – 6 metres (2 tonnes).
• Petrustitan hungaricus – 6-7 metres (2 tonnes+).
• Uriash kadici – 12 metres (5-8 tonnes).

Comparing the size of Hateg Island sauropods. Uriash kadici is the biggest taxon described to date. Picture credit: Everything Dinosaur from Brian Cooley/Dan Horatiu Popa/Hateg County UNESCO Global Geopark.

Picture credit: Everything Dinosaur from Brian Cooley/Dan Horatiu Popa/Hateg County UNESCO Global Geopark

Uriash kadici is the largest titanosaurian taxon described to date from the Hateg Basin.  It is larger than most of the other Late Cretaceous European titanosaurs.  Its size is only surpassed by Abditosaurus (A. kuehnei).  Abditosaurus fossils come from southern Pyrenees of Spain.  It was formally described in 2022 (Vila et al).  Abditosaurus is thought to have measured around seventeen metres long.

To read a blog post about this dinosaur: Abditosaurus – The First New Dinosaur of 2022.

What’s in a Name?

The genus name comes from the Romanian word ‘uriaș’ (pronounced ‘uriash’). It refers to gigantic humanoid characters from Romanian folklore. The species name honours Ottokár Kadić (1876–1957), a geologist and palaeontologist of the Royal Geological Survey of Hungary and discoverer of several continental vertebrate-bearing fossil localities in the north-western Hateg Basin, including the type locality of Uriash.

Mike from Everything Dinosaur explained that the recent study focusing on the Hateg Basin sauropods had expanded knowledge about European titanosaurs.  However, much remains to be discovered.  New fossil quarries will be opened, and new material will help to fill in the gaps and provide palaeontologists with a better understanding of Late Cretaceous sauropod evolution.

Visit the award-winning Everything Dinosaur website: Dinosaur Toys and Models.

Two new species of Hateg Basin sauropods have been identified.  Their fossils come from the Upper Cretaceous deposits of the Hateg Basin in western Romania.  The discovery of these new taxa can help palaeontologists to better understand dinosaur populations across the planet prior to the end-Cretaceous extinction event. The study led by Verónica Díez Díaz from the Museum für Naturkunde Berlin (Germany) demonstrates how important Europe’s fossils are when it comes to providing a more complete picture of dinosaur extinction.

Scientists from the University College London and the University of Bucharest collaborated in this research.

Hateg Basin Sauropods

The researchers report two new sauropod taxa from the Hateg Basin.  They have been named Petrustitan hungaricus and Uriash kadici. During the Late Cretaceous, much of the Europe was covered by water. However, an archipelago existed in what is known today as eastern Europe. The largest island (Hateg Island) was approximately 120 miles (200 km) from the nearest landmass. Size estimates vary, but it has been suggested that by the very end of the Cretaceous (Maastrichtian faunal stage), Hateg Island covered an area of around thirty thousand square miles. It was roughly the size of the Japanese island Hokkaido.

The archipelago was home to several different sauropod taxa.  The diversity of sauropods in the Late Cretaceous of Europe is much greater than previously thought.  Fifteen years ago, only five sauropod species were known from the Late Cretaceous of Europe.  Today, at least eleven taxa have been identified.  In contrast, only a single sauropod species is known from the Late Cretaceous of America (Alamosaurus sanjuanensis).

Commenting on the significance of this new study into Hateg Basin sauropods, corresponding author Verónica Díez Díaz (Museum für Naturkunde Berlin) stated:

“The extraordinary diversity in a small geographical area like Hațeg Island surprises us. Sauropods of different sizes lived side by side here: from giants over 10 metres long and weighing eight tonnes to dwarfs of just 2.5 metres and weighing less than a tonne. This provides exciting insights into the environmental conditions and the coexistence of different species.”

The researchers propose the presence of three additional, but only partly contemporaneous taxa in the Hateg Basin. These are Paludititan nalatzensis, Petrustitan (‘Magyarosaurus’) hungaricus and the much larger Uriash kadici. U. kadici is amongst the biggest known sauropods of the Late Cretaceous European Archipelago. Picture credit: Brian Cooley/Dan Horatiu Popa/Hațeg County UNESCO Global Geopark.

Picture credit: Brian Cooley/Dan Horatiu Popa/Hațeg County UNESCO Global Geopark

Giants and Dwarf Sauropods

Traditionally, the fauna of Hateg Island was thought to consist mainly of smaller relatives of dinosaur genera found on larger landmasses.  It had been assumed that the dinosaurs of Hateg Island became smaller due to the limited amount of resources on the island.  This biological phenomenon is known as island dwarfism (insular dwarfism).  This idea was postulated by the famous 20th Century polymath Baron Franz Nopcsa von Felső-Szilvás. He argued that the limited resources such as food, water and space on islands would result in a reduction of the size of animals that lived there. These island dwelling populations would become smaller over many generations when compared to their continental counterparts.

For example, the ornithopod Tethyshadros (T. insularis) was once thought to be a dwarf hadrosauroid.  However, subsequent analysis indicates that it was around twenty-five percent larger than previously thought.

To read more about this 2021 study: Sizing up Tethyshadros.

The biota of the Hateg Basin seems to be much more complicated and diverse.  For instance, whilst a number of Hateg Basin sauropods are relatively small, the newly described Uriash kadici may have been more than eleven metres in length.

Co-author Zoltán Csiki-Sava (University of Bucharest) added:

“Local evolution was more complex than expected and shows that not all species reduced their size.”

European Dinosaurs Linked to Gondwanan Lineages

This study also highlights the links between European dinosaur taxa and their relatives in Asia, Africa and South America.  The team’s findings strengthen the hypothesis that Late Cretaceous European titanosaurs belonged to Gondwanan lineages that invaded the former area during the Barremian–Albian faunal stages of the Early Cretaceous.  Paul Upchurch (University College London) explained that Gondwanan sauropods migrated into Europe over land bridges that existed in the Early Cretaceous.  However, sauropods were probably very capable swimmers and may have traversed distances in excess of three hundred miles (500 kilometres) to reach distant islands.

Co-author Philip Mannion (University College London) commented:

“Some of these dinosaurs were descendants of earlier faunas, while others arrived in the region late.”

Why were Large Hateg Island Sauropods Present?

The researchers interpret the presence of body-size disparity as either evidence that large-bodied taxa were ecologically excluded from body-size reduction by competition with small-bodied titanosaurs, or that dwarfing occurred stratigraphically earlier among several lineages and the small-bodied titanosaurs on Hațeg Island are the descendants of existing dwarfed ancestors. In addition, the team report that they found no indication of a body size-related titanosaurian turnover in the uppermost Cretaceous of the Transylvanian area.

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

The scientific paper: “Revision of Romanian sauropod dinosaurs reveals high titanosaur diversity and body-size disparity on the latest Cretaceous Haţeg Island, with implications for titanosaurian biogeography” by Verónica Díez Díaz, Philip D. Mannion, Zoltán Csiki-Sava and Paul Upchurch published in the Journal of Systematic Palaeontology.

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

A new study suggests that pterosaur anatomy could inspire the next generation of aeroplanes.  The microarchitecture of fossilised pterosaur bones could hold the key to lighter, stronger materials that can be used to make new types of aircraft.  This is the remarkable conclusion made by scientists from the University of Manchester.  Advanced and extremely powerful X-ray imaging techniques were utilised to reveal a complex network of microscopic canals inside the preserved bones of ancient flying reptiles.  These structures make the bones exceptionally light but incredibly strong.  They are ideal material properties for use in the aviation industry.

Pterosaur anatomy could inspire the next generation of aeroplane designs according to a new study. Picture credit: Nathan Pili, The University of Manchester.

Picture credit: Nathan Pili, The University of Manchester

Examining Pterosaur Anatomy at the Microscopic Level

The researchers claim that these pterosaur adaptations could have the potential to start a “palaeo-biomimetics” revolution using the biological designs of prehistoric creatures to develop new materials for use in the aeronautics industry. The paper has been published in the journal “Scientific Reports”.

Lead author of the study, Nathan Pili, a PhD student at the University of Manchester commented:

“For centuries, engineers have looked to nature for inspiration, like how the burrs from plants led to the invention of Velcro. But we rarely look back to extinct species when seeking inspiration for new engineering development, but we should. We are so excited to find and map these microscopic interlocking structures in pterosaur bones, we hope one day we can use them to reduce the weight of aircraft materials, thereby reducing fuel consumption and potentially making planes safer.”

Pterosaurs first evolved in the Triassic. They were close relatives of the dinosaurs and members of the Archosauria clade. Pterosaurs were the first vertebrates to achieve powered flight. Whilst many Triassic and Jurassic taxa typically had wingspans of less than two metres, many Cretaceous pterosaurs were giants.

A model of the giant pterosaur Quetzalcoatlus.

The picture (above) shows a replica of the giant azhdarchid pterosaur Quetzalcoatlus. The figure is from the Wild Safari Prehistoric World range.

To view this range of prehistoric animal figures: Wild Safari Prehistoric World Figures.

Quetzalcoatlus lived during the Late Cretaceous and it had a wingspan of around ten metres. This huge size meant that these reptiles had to solve multiple engineering challenges to get their enormous bodies airborne.  For example, their huge wing membrane was supported predominantly from a single, elongated finger.

X-ray Computed Tomography

The researchers used advanced X-ray Computed Tomography (XCT) to scan the pterosaur anatomy at the molecular level.  The technique enabled the team to examine complex structures approximately twenty times smaller than the width of a human hair. Three-dimensional mapping of the internal structures permeating the wing bones of pterosaurs has never been achieved at these high resolutions (~0.002 mm).

The team discovered that the unique network of tiny canals and pores with the bones, once used for nutrient transfer, growth, and maintenance, also helped to protect against microfractures by deflecting cracks, serving both biological and mechanical functions. By replicating these natural designs, engineers could not only create lightweight, robust components but could also incorporate sensors and self-healing materials, opening up new possibilities for more complex and efficient aircraft designs.

The team propose that advancements in metal 3D printing could turn these ideas into reality.  Pterosaur anatomy could permit an exciting new avenue for further research.

Nathan Pilli added:

“This is an incredible field of research, especially when working at the microscopic scale. Of all the species that have ever lived, most are extinct, though many died out due to rapid environmental changes rather than ‘poor design’. These findings are pushing our team to generate even higher-resolution scans of additional extinct species. Who knows what hidden solutions we might find!”

Learning from Darwinian Natural Selection

Senior author of the study, Professor Phil Manning (University of Manchester), explained:

“There is over four billion years of experimental design that were a function of Darwinian natural selection. These natural solutions are beautifully reflected by the same iterative processes used by engineers to refine materials. It is highly likely that among the billions of permutations of life on Earth, unique engineering solutions have evolved but were lost to the sands of time. We hope to unlock the potential of ancient natural solutions to create new materials but also help build a more sustainable future. It is wonderful that life in the Jurassic might make flying in the 21st century more efficient and safer.”

We need to develop stronger, lighter and more fuel-efficient materials. Pterosaurs may hold the key to the future of powered flight.  By examining the first vertebrates to achieve powered flight we might be able to pave the way for a new generation of aviation technology.

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

The scientific paper: “Harnessing 3D microarchitecture of pterosaur bone using multi-scale X-ray CT for aerospace material design” published in Scientific Reports.

The Everything Dinosaur website: Prehistoric Animal Models and Figures.

Scientists have analysed the soft tissue preserved in a nearly complete Jurassic plesiosaur fossil. This is the first in-depth study of plesiosaur soft tissues to be published.  The study has been published in the journal “Current Biology”.  The research was led by scientists from Lund University (Sweden).  The results show that some plesiosaurs had smooth skin on the body and small scales on the flippers.  This integumentary covering permitted maximum swimming efficiency by reducing drag.  The scales on the flippers are reminiscent of modern reptile scales.  They may have played a role in flipper hydrodynamics and/or provided protection and traction as these marine reptiles moved across rough seabeds in search of food (benthic feeding).

Reconstruction of the new plesiosaur with scales on the flipper and smooth scale-less skin along the body as informed by this new plesiosaur fossil. This is a significant update to how we reconstruct plesiosaurs which has otherwise not change substantially since their initial discovery more than 200 years ago. Picture credit: Joschua Knüppe.

Picture credit: Joschua Knüppe

Studying a Remarkable Jurassic Plesiosaur

Plesiosaurs are an iconic group of Mesozoic marine reptiles with an evolutionary history spanning over 140 million years Their skeletal remains have been discovered worldwide. However, accompanying fossilised soft tissues are exceptionally rare. Only eight instances of plesiosaur soft tissue preservation have been reported to date. The research team examined a beautifully preserved fossil specimen from the Lower Jurassic Posidonia Shale (Posidonienschiefer Formation) of southern Germany.  The fossil is estimated to be around 183 million years old.  It dates from the Toarcian faunal stage of the Early Jurassic.

Skeleton of the new plesiosaur at the Urwelt-Museum Hauff in Holzmaden, Germany. Picture credit: Klaus Nilkens/Urwelt-Museum Hauff.

Picture credit: Klaus Nilkens/Urwelt-Museum Hauff

Until now, little was known about the external anatomy of plesiosaurs.  For example, considerable debate has occurred in regards to whether plesiosaurs had tail flukes, and if they did, what shape they were.  In 2021, CollectA introduced a replica of the Late Cretaceous derived plesiosaur Elasmosaurus.  This model had a diamond-shaped tail fluke.  In Everything Dinosaur’s video review of this figure, the controversy over the tail fluke was highlighted.

To read more about this and to view Everything Dinosaur’s video review: New for 2021 CollectA Figures Including a New Interpretation of Elasmosaurus.

The specimen (MH 7) was excavated from a quarry near the town of Holzmaden in 1940. More complete preparation undertaken in 2020 revealed traces of soft tissue preservation. The soft tissue was associated with the tail and the trailing edge of the right forelimb.

Skin from the bottom half of the tail in the new plesiosaur. The skin as preserved is beige in colour with some parts showing a pitted surface. This pitted surface represents the underside of the skin, with the outer surface facing into the rock matrix. Picture credit: Klaus Nilkens/Urwelt-Museum Hauff.

Picture credit: Klaus Nilkens/Urwelt-Museum Hauff

What Does Specimen MH 7 Reveal?

The scientists utilised a variety of techniques, including transmitted light microscopy (TLM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), examining specimen MH 7 in unprecedented detail. In addition, the researchers used electron backscatter diffraction (EBSD), infrared (IR) microspectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to reveal details of the integumentary covering including the identification of potential melanosomes.

Their research indicates that plesiosaurs had both smooth and scaly skin.

The tip of the right flipper with two scales along the trailing edge. Picture credit: Klaus Nilkens/Urwelt-Museum Hauff.

Picture credit: Klaus Nilkens/Urwelt-Museum Hauff

Lead author of the study into this remarkable Jurassic plesiosaur fossil, Miguel Marx, a PhD student in geology at Lund University commented:

“Fossilised soft tissue, such as skin and internal organs, is exceptionally rare. We used a broad range of techniques to identify smooth skin in the tail region as well as scales along the rear edge of the flippers. This provided us with unparalleled insights into the appearance and biology of these long-extinct reptiles.”

Smooth and Scaly Skin

An unusual combination of smooth and scaly skin on different parts of the body was revealed.  The scientists conclude that this variation related to different functions.  For example, the plesiosaur needed to be streamlined so that it could swim efficiently.  Moreover, the smooth and hydrodynamic skin would have reduced drag and helped the animal to use less energy as it swam after prey.  However, it also needed to move across rough seafloors, the scaly flippers would have likely allowed it to do so with maximum efficiency and without damaging its skin.

Miguel Marx added:

“Our findings help us create more accurate life reconstructions of plesiosaurs, something that has been extremely difficult since they were first studied over 200 years ago. Also, the well-preserved German fossil really highlights the potential for soft tissue in providing valuable insights into the biology of these long-extinct animals.”

A close-up image of the two scales from the right flipper. Note the triangular shape of the scale remnants that are distinct from the skin found on the tail of this plesiosaur.
Picture credit: Klaus Nilkens/Urwelt-Museum Hauff.

Picture credit: Klaus Nilkens/Urwelt-Museum Hauff

Reconstructing the Appearance of an Ancient Marine Reptile

With a better understanding of the anatomy and adaptations of extinct creatures palaeontologists can develop an improved understanding of macroevolution.  Furthermore, in recreating the past, scientists can make better predictions about future events.

Summarising the importance of this study, Miguel Marx stated:

“Apart from the mosaic of smooth skin and scales, it was an incredible moment to visualize the cells in thin sections of the fossilized plesiosaur’s skin. I was shocked when I saw skin cells that had been preserved for 183 million years. It was almost like looking at modern skin.”

In addition to Lund University, collaborators from Uppsala University, RISE (Research Institutes of Sweden), Naturkunde-Museum Bielefeld, and Urwelt-Museum Hauff took part in this research.

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

The scientific paper: “Skin, scales, and cells in a Jurassic plesiosaur” by Miguel Marx, Peter Sjövall, Benjamin P. Kear, Martin Jarenmark, Mats E. Eriksson, Sven Sachs, Klaus Nilkens, Michiel Op De Beeck and Johan Lindgren published in Current Biology.

The award-winning Everything Dinosaur website: Models of Prehistoric Animals.

A newly published scientific paper demonstrates that an Edmontosaurus fossil contains collagen. The study confirms fossils can retain original organic materials.  The discovery of hydroxyproline, a unique collagen-indicator amino acid, in acid-digested samples resolves a long-standing debate amongst palaeontologists.  Identifying organic materials in dinosaur bones could provide a new perspective on the Dinosauria.

Reports of proteins in fossilised bones have been a subject of controversy in the scientific literature.  It is assumed that fossilisation results in the destruction of all organic components.  However, this new research adds weight to the theory that in exceptional circumstances traces of organic materials can persist for tens of millions of years.  Research led by scientists from the University of Liverpool suggests that Mesozoic fossils could still preserve remnants of original organic materials.

A view of the inside of the Edmontosaurus fossil bone. An exceptionally well-preserved Edmontosaurus sacrum excavated from the Upper Cretaceous strata of the South Dakota Hell Creek Formation is demonstrated to preserve evidence of hydroxyproline. Hydroxyproline is a unique collagen-indicator amino acid. Picture credit: University of Liverpool.

Picture credit: University of Liverpool

Edmontosaurus Fossil Contains Collagen

The research team used mass spectrometry and other advanced techniques to tease out traces of preserved collagen within the sacrum of an Edmontosaurus.  Edmontosaurus is a duck-billed dinosaur (family Hadrosauridae).  Fossils of these taxon come from Upper Cretaceous deposits of North America. It was a large, herbivorous dinosaur. Some specimens indicate a body length in excess of thirteen metres.

The CollectA Deluxe 1:40 scale Edmontosaurus dinosaur model. A detailed analysis of Edmontosaurus hip bone fossils (sacrum) reveals evidence of collagen.

The picture (above) shows a model of Edmontosaurus.  This figure is from the CollectA Deluxe series.

To view the range of CollectA Deluxe prehistoric animal models: CollectA Deluxe Prehistoric Animal Figures.

Writing in the journal “Analytical Chemistry” the researchers outline several techniques, including protein sequencing that led to the detection of collagen in the fossilised bone. The specimen (a sacrum), was excavated from Hell Creek Formation deposits located in South Dakota. It is part of the University of Liverpool’s collections and offered a unique opportunity for cutting-edge analyses.

The Implications of this Research

Commenting on the significance of this study, co-author Professor Steve Taylor (chair of the Mass Spectrometry Research Group at the University of Liverpool), stated:

“This research shows beyond doubt that organic biomolecules, such as proteins like collagen, appear to be present in some fossils. Our results have far-reaching implications. Firstly, it refutes the hypothesis that any organics found in fossils must result from contamination. Secondly, it suggests that cross-polarised light microscopy images of fossil bones, collected for a century, should be revisited. These images may reveal intact patches of bone collagen, potentially offering a ready-made trove of fossil candidates for further protein analysis. This could unlock new insights into dinosaurs. For example, revealing connections between dinosaur species that remain unknown. Lastly, the findings inform the intriguing mystery of how these proteins have managed to persist in fossils for so long.”

Researchers from the University of California were also involved in this study.  Mass spectrometry was used to detect and quantify, for the first time, the amino acid hydroxyproline, which is specific to collagen when found in bone, thus confirming the presence of decayed collagen.

Edmontosaurus fossil specimen used in collagen study. Picture credit: University of Liverpool.

Picture credit: University of Liverpool

The researchers conclude that their study demonstrated the presence of identical collagen peptide sequences previously discovered in another hadrosaur and a T. rex sample.

Links to Other Blog Posts

To read an article from 2017 about a study that identified fragments of collagen in the femur of a hadrosaur (Brachylophosaurus):Researchers Confirm the Presence of Dinosaur Collagen.

Traces of organic material discovered in a juvenile hadrosaur fossil: Has Dinosaur DNA Been Found?

Research from 2008 outlining the search for organic materials in a femur of Tyrannosaurus rex: Are You Going to Call the “Tyrant Lizard King” Chicken?

This newly published research opens further avenues for studying ancient life, offering a glimpse into the biochemical preservation of fossils of extinct creatures.

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

The scientific paper: “Evidence for Endogenous Collagen in Edmontosaurus Fossil Bone” by Lucien Tuinstra, Brian Thomas, Steven Robinson, Krzysztof Pawlak, Gazmend Elezi, Kym Francis Faull, and Stephen Taylor published in Analytical Chemistry.

The award-winning Everything Dinosaur website: Dinosaur Toys and Models.

Researchers have described a new theropod dinosaur from the Cerro del Pueblo Formation (Coahuila, northern Mexico).  The dinosaur has been named Mexidracon longimanus.  It is the first ornithomimid to be named from fossils associated with the Cerro del Pueblo Formation. The most conspicuous characteristics of this new taxon are the exceptionally long metacarpal bones.  These are the bones that form the palm of the hand.  The hands of Mexidracon longimanus were long and slender.  Furthermore, the hands were longer than the humerus (upper arm bone).  It is not known what these slender hands were used for, although it has been speculated that they helped this toothless dinosaur forage for food.

A scale drawing of the newly described ornithomimid dinosaur from the Cerro del Pueblo Formation (Mexico). Although known from only fragmentary remains it is thought this dinosaur was feathered. It is estimated to have stood around one metre tall and measured two and half metres long. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Mexidracon longimanus – the first ornithomimid formally described from Coahuila

In 2014, Professor Claudio de León-Dávila collected postcranial ornithomimid remains from a deposit representing an estuary environment.  These fossils are currently housed in the collection of the Benemérita Escuela Normal de Coahuila (BENC), a teacher training institution in Coahuila state. Ornithomimosaur remains are relatively common in the Campanian Cerro del Pueblo Formation, although most of the material is highly fragmentary.

To date only one other ornithomimosaur has been described from the region. Paraxenisaurus normalensis was scientifically described in 2020 (Serrano-Brañas et al).  It is represented by elements from the hands, limbs, including the distal end of a femur, and caudal vertebrae.  P. normalensis is thought to be much larger than the newly described Mexidracon.  Moreover, it has been tentatively assigned to the Deinocheiridae family within the Ornithomimosauria clade. Whereas, Mexidracon longimanus has been assigned to another family, the Ornithomimidae.

A model of Deinocheirus.  The figure is from the CollectA Age of Dinosaurs Popular range.

The image (above) shows the CollectA Age of Dinosaurs Popular Deinocheirus figure.  It is thought that Paraxenisaurus normalensis may have been related to this Asian deinocheirid.

To view the CollectA Age of Dinosaurs Popular range available from Everything Dinosaur: CollectA Prehistoric Animal Models.

The Etymology of a Dinosaur Name

The genus name is derived from the prefix “Mexi”, a reference to Mexico and the suffix “dracon”.  This is from the Greek, and it means serpent or dragon.  The species or trivial name translates as “long hands”.  So, this new theropod’s name translates as “long-handed Mexican dragon.”

The researchers conclude that the discovery of the first ornithomimid in this region of Mexico suggests that during the Campanian faunal stage of the Cretaceous there was a large number of different ornithomimosaurs present.

The scientific paper: “A long-handed new ornithomimid dinosaur from the Campanian (Upper Cretaceous) Cerro del Pueblo Formation, Coahuila, Mexico” by Claudia Inés Serrano-Brañas, Belinda Espinosa-Chávez, Claudio de León-Dávila, S. Augusta Maccracken, Daniela Barrera-Guevara, Esperanza Torres-Rodríguez and Albert Prieto-Márquez published in Cretaceous Research.

Visit the Everything Dinosaur website: Dinosaur Toys.