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.

A remarkable, semi-articulated and near-complete ichthyosaur skeleton from the famous “Jurassic Coast” of Dorset helps to fill an important gap in the fossil record of ichthyosaurs.  Named Xiphodracon goldencapensis, this dolphin-sized marine reptile lived in the Early Jurassic.  Specifically, it lived during the Pliensbachian stage of the Early Jurassic.  The fossil material consisting of a stunning, three-dimensionally preserved skull along with extensive postcranial remains is around 186 to 184 million years old.  These fossils could represent the most complete reptile specimen known from the Pliensbachian.

Dr Dean Lomax and Professor Judy Massare study the skeleton of the newly named sword dragon ichthyosaur, Xiphodracon goldencapensis, at the Royal Ontario Museum, Toronto, Canada. Picture credit: Dr Dean Lomax.

Picture credit: Dr Dean Lomax

From Golden Cap

The fossils were discovered in the cliffs near Golden Cap between Bridport and Charmouth on the Dorset coast.  The material was found by fossil collector Chris Moore.  Chris has found several important marine reptile specimens, including other ichthyosaurs.  For example, in 2018 the BBC featured another ichthyosaur fossil discovery from Dorset in the documentary “Attenborough and the Sea Dragon”.  Ironically, the ichthyosaur featured in the television programme was probably killed by another ichthyosaur.  The newly named Xiphodracon goldencapensis may have suffered a similar grisly end.  The top of the skull bears evidence of a bite from a much larger marine reptile.

It has been postulated that the three-metre-long Xiphodracon may have been attacked by a Temnodontosaurus.  Temnodontosaurus is a genus of large, predatory ichthyosaurs, some of which could have reached lengths in excess of ten metres.

Ironically, the Temnodontosauridae persisted throughout the earlier Sinemurian stage of the Early Jurassic, through the Pliensbachian and into the Toarcian. However, the composition of the taxa represented by this period of time changed dramatically.

Ichthyosaur expert and co-author of the study, Professor Judy Massare, from the State University of NY at Brockport, (USA) stated:

“Thousands of complete or nearly complete ichthyosaur skeletons are known from strata before and after the Pliensbachian. The two faunas are quite distinct, with no species in common, even though the overall ecology is similar. Clearly, a major change in species diversity occurred sometime in the Pliensbachian. Xiphodracon helps to determine when the change occurred, but we still don’t know why.”

The skeleton and skull of the newly named sword dragon ichthyosaur, Xiphodracon goldencapensis. Picture credit: Dr Dean Lomax.

Picture credit: Dr Dean Lomax

Ichthyosaurs from the Pliensbachian are incredibly rare and this makes Xiphodracon a vital piece of evidence for scientists studying this critical but poorly understood time in ichthyosaurian evolution.

Xiphodracon goldencapensis – “Sword Dragon of Dorset”

The skull has an enormous eye socket. In addition, the rostrum is elongated.  Stomach contents may have been preserved, and they indicate that this ichthyosaur dined on fish and possibly squid. The study was undertaken by a trio of international palaeontologists led by ichthyosaur expert Dr Dean Lomax, an Honorary Research Fellow at The University of Manchester and an 1851 Research Fellow at the University of Bristol.

Dr Lomax has also played a crucial role in the development of Everything Dinosaur’s own range of prehistoric animal figures: Everything Dinosaur Evolution.

Dr Lomax commented:

“I remember seeing the skeleton for the first time in 2016. Back then, I knew it was unusual, but I did not expect it to play such a pivotal role in helping to fill a gap in our understanding of a complex faunal turnover during the Pliensbachian. This time is pretty crucial for ichthyosaurs as several families went extinct and new families emerged, yet Xiphodracon is something you might call a ‘missing piece of the ichthyosaur puzzle’. It is more closely related to species in the later Early Jurassic (in the Toarcian), and its discovery helps pinpoint when the faunal turnover occurred, being much earlier than expected.”

Dr Dean Lomax photographing the skeleton of the newly named sword dragon ichthyosaur, Xiphodracon goldencapensis, at the Royal Ontario Museum, Toronto, Canada. Picture credit: Dr Dean Lomax.

Picture credit: Dr Dean Lomax

Acquired by the Royal Ontario Museum (Toronto, Canada)

After its discovery in 2001, the skeleton was acquired by the Royal Ontario Museum, Canada.  It became part of their extensive collection of ichthyosaurs but had remained unstudied.

Co-author, Dr Erin Maxwell, (State Museum of Natural History Stuttgart, Germany) explained:

“This skeleton provides critical information for understanding ichthyosaur evolution, but also contributes to our understanding of what life must have been like in the Jurassic seas of Britain. The limb bones and teeth are malformed in such a way that points to serious injury or disease while the animal was still alive, and the skull appears to have been bitten by a large predator – likely another much larger species of ichthyosaur – giving us a cause of death for this individual. Life in the Mesozoic oceans was a dangerous prospect.”

Dr Dean Lomax with the skull of the newly named sword dragon ichthyosaur, Xiphodracon goldencapensis, at the Royal Ontario Museum, Toronto, Canada. Picture credit: Dr Dean Lomax.

Picture credit: Dr Dean Lomax

Collectively, the research team identified several unique features in Xiphodracon that have never been observed in any other ichthyosaur. The most peculiar (autapomorphy) is a strange and unique bone around the nostril (called a lacrimal) that has prong-like bony structures.

Dr Lomax added:

“One of the coolest things about identifying a new species is that you get to name it! We opted for Xiphodracon because of the long, sword-like snout (xipho from Greek xiphos for sword) and dracon (Greek and Latin for dragon) in reference to ichthyosaurs being referred to as ‘sea dragons’ for over two hundred years.”

There are plans to put this remarkable ichthyosaur specimen on display at the Royal Ontario Museum.

A close-up of the skull of the newly named sword dragon ichthyosaur, Xiphodracon goldencapensis. Picture credit: Dr Dean Lomax.

Picture credit: Dr Dean Lomax

“The Secret Lives of Dinosaurs”

October has been an exceptionally busy month for Dr Lomax.  In addition, to the publication of this new study he has recently published a new book.  Entitled “The Secret Lives of Dinosaurs” it highlights behaviours of long extinct prehistoric animals through a study of some of the most astonishing fossils ever found.

To learn more about this remarkable book, visit the publisher’s website: Columbia University Press and search for Dr Dean Lomax.

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

The scientific paper: “A new long and narrow-snouted ichthyosaur illuminates a complex faunal turnover during an undersampled Early Jurassic (Pliensbachian) interval” by Dean R. Lomax, Judy A. Massare and Erin E. Maxwell published in Papers in Palaeontology.

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

A fossil discovery made on the Isle of Skye reveals clues to the origins of modern snakes and lizards.  The animal, named Breugnathair elgolensis, lived during the Bathonian stage of the Middle Jurassic.  The fragmentary and disarticulated fossils are approximately 167 million years old.  The scientific paper has been published in the journal “Nature”.

Breugnathair elgolensis life reconstruction. Picture credit: Brennan Stokkermans (National Museums of Scotland).

Picture credit: Brennan Stokkermans (National Museums of Scotland)

Meet Breugnathair elgolensis

This reptile had the proportions and limbs of a lizard.  However, its jaws, lined with highly recurved teeth, were similar to the jaws of extant pythons.  The fossil specimen represents one of the oldest and most complete Jurassic lizards discovered to date. It has been classified as a member of the Squamata order.  The squamates include lizards and snakes. The evolutionary origins of the Squamata remain open to debate.  Although, many palaeontologists consider that the first squamates evolved in the Early Jurassic around 190 million years ago.

The fossil was discovered near Elgol by Dr Stig Walsh (National Museums Scotland). This rare fossil is now part of the Museum’s vertebrate fossil collection.

Dr Stig Walsh with a cast of the Breugnathair elgolensis fossil. Picture credit: Duncan McGlynn.

Picture credit: Duncan McGlynn

The fossil material and others like it will help palaeontologists to better understand the evolution of snakes and lizards.  For example, are snakes are early off-shoot from the lizard lineage or did snake-like characteristics evolve more than once in the Squamata?

The “False Snake of Elgol”

The fossils are exposed on a single limestone slab. The material includes caudal vertebrae, limb bones, ribs as well as bones from the skull.  The scientific name is taken from Gaelic. It translates as “false snake of Elgol”.  It has been placed in a newly created family, the Parviraptoridae. Until now, parviraptorids were known only from fragmentary remains. Some scientists thought they might represent basal snakes. In contrast, other scientists have proposed that parviraptorids were ancestors of all snakes and lizards.

An illustration of Breugnathair elgolensis swallowing a mammaliaform. We suspect that the unfortunate victim is the mammaliaform Krusatodon kirtlingtonensis, fossils of which are also known from the Isle of Skye. Picture credit: Mick Ellison (American Museum of Natural History).

Picture credit: Mick Ellison (American Museum of Natural History)

The illustration (above) depicts a Breugnathair swallowing an early mammaliaform.  The artist could be suggesting that Breugnathair is feeding on a Krusatodon (K. kirtlingtonensis). There have been many remarkable fossil discoveries made on the Isle of Skye.  The exposed strata were laid down in the Middle Jurassic.  Fossiliferous deposits from this time in Earth’s history are rare.

An article about Krusatodon fossils from the Isle of Skye: Providing an Insight into Mammaliaform Ontogeny.

To read an article about a large pterosaur fossil discovered on the Isle of Skye (Dearc sgiathanach): Fantastic Pterosaur Fossil from the Isle of Skye.

A Window into Evolution

Breugnathair elgolensis fossil material reveals a mosaic of primitive and more derived features. This mosaic of advanced traits combined with more primitive characteristics is found in other parviraptorids. The path taken by evolution is unpredictable.

A close view of the cast of the Breugnathair elgolensis fossil. Picture credit: Duncan McGlynn.

Picture credit: Duncan McGlynn

Mike from Everything Dinosaur commented:

“The Isle of Skye is recognised as one of the world’s most important Middle Jurassic fossil locations. Other discoveries include Scotland’s most complete dinosaur, ancient synapsids, and even flying reptiles. Breugnathair demonstrates the diverse palaeoenvironment represented by these deposits.”

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

The scientific paper: “Mosaic anatomy in an early fossil squamate” by Roger B. J. Benson, Stig A. Walsh, Elizabeth F. Griffiths, Zoe T. Kulik, Jennifer Botha, Vincent Fernandez, Jason J. Head and Susan E. Evans published in the journal Nature.

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

This week, the scientific paper announcing the discovery of a new megaraptor from South America was published.  The dinosaur has been named Joaquinraptor casali and it is probably the geologically youngest member of the Megataptoridae described to date.  In the media release there were several field photographs of the Joaquinraptor casali bones.  We were not able to use them all in our blog post about this new theropod. However, we wanted to share them with our readers, so we created a second article.

Joaquinraptor casali bones in the field (2019) shown with a skeletal reconstruction. Known fossil material is highlighted in blue. The photograph shows fossils of the new megaraptor dinosaur species Joaquinraptor casali in the quarry, laying in the positions they had laid for approximately 67 million years. A dentary, teeth, ribs, and several other bones are visible. Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco.

Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco

To read Everything Dinosaur’s earlier blog post about the discovery of Joaquinraptor: A New Species of Megaraptor from Patagonia.

Joaquinraptor casali Bones Photographed

When visitors view dinosaur fossils in a museum they appear, smooth, free from cracks and clean. The Joaquinraptor casali bones photographed at the dig site look different. Skilled technicians spend many hours preparing each fossil for display. They carefully remove rock, repair breaks, and restore missing areas. As a result, the finished fossils look polished and ready for study or exhibition. However, this final appearance is very different from how the bones first look when they are carefully excavated in the field.

Fossils of the new megaraptor species Joaquinraptor casali in the quarry. Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco.

Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco

The picture (above) shows the jumble of fossil bones in the quarry.  The field team take care to extract the fossils. In addition, they map their precise location and gather data on the fossil matrix.

Fragile Bones and Delicate Work in the Field

At the quarry, the Joaquinraptor casali bones are fragile, fragmented, and often extremely difficult to expose. Field team members work slowly with small tools to expose each piece. Dirt, dust, and natural cracks make the fossils appear rough and incomplete. Only after careful cleaning and conservation do these remains reveal their true form. This process highlights the remarkable journey from excavation site to museum gallery.

Mike from Everything Dinosaur commented:

“The media release we received contained some incredible photographs of the quarry.  We wanted to highlight the care and dedication it takes to extract fossils in the field.  Moreover, the fossil material comes from the uppermost part of the Lago Colhué Huapi Formation.  These field photographs are significant as the strata is most likely late Maastrichtian.  This suggests that Joaquinraptor lived close to the Cretaceous/Palaeogene boundary.  Therefore, the Megaraptoridae persisted until the end of the Age of Dinosaurs.”

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

The scientific paper: “Latest Cretaceous megaraptorid theropod dinosaur sheds light on megaraptoran evolution and palaeobiology” by Lucio M. Ibiricu, Matthew C. Lamanna, Bruno N. Alvarez, Ignacio A. Cerda, Julieta L. Caglianone, Noelia V. Cardozo, Marcelo Luna and Rubén D. Martínez published in Nature Communications.

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

A new species of Patagonian megaraptor has been described.  Joaquinraptor casali provides further insight into this enigmatic Cretaceous dinosaur family.  The fossil material casts light on these giant-clawed theropods, as this is only the second member of the Megaraptoridae family to have been discovered with extensive skull remains.  The study has been published in the journal “Nature Communications”.

Intriguingly, the field team found a crocodyliform humerus between the lower jaw bones of Joaquinraptor.  This suggests that that the new megaraptor may have been eating the crocodyliform when it died.  However, this is only an assertion, it is not definitive.  The limb bone could have ended up lodged between the dentaries as a result of being washed into the submerged mouth of the dinosaur’s carcase.

Joaquinraptor casali life reconstruction. The new megaraptor dinosaur species Joaquinraptor casali in what is now central Patagonia, Argentina roughly 67 million years ago. The carnivore holds a crocodyliform (= extinct crocodile relative) front leg in its mouth, in keeping with the discovery of a crocodyliform forelimb bone between the lower jaws. Picture credit: Andrew McAfee, Carnegie Museum of Natural History.

Picture credit: Andrew McAfee, Carnegie Museum of Natural History.

The upper arm bone of the crocodyliform bears tooth marks and the bone was touching some of the megaraptor’s teeth.  So, some kind of interspecific interaction seems likely. Perhaps, the theropod and the crocodyliform were fighting.  For example, the two predators could have been battling over a food resource.

Possible evidence of diet or predation in the new megaraptor dinosaur species Joaquinraptor casali. (a) Dentaries (= tooth-bearing lower jaw bones) of Joaquinraptor and an associated crocodyliform (= extinct crocodile relative) forelimb bone in the position in which they were found, prior to their separation in the laboratory. Detail (b) view showing a portion of the croc forelimb bone in contact with the teeth of Joaquinraptor. The croc bone (c) after its separation from the Joaquinraptor dentaries. Picture credit: Lucio M. Ibiricu et al.

Picture credit: Lucio M. Ibiricu et al

Joaquinraptor casali

Joaquinraptor seems to be quite typical for a megaraptor.  It had a long, low skull lined with serrated teeth and powerful forelimbs. The two innermost talons of the hand were tipped with large claws.  The genus name honours Joaquín, the son of the first author (Lucio M. Ibiricu) and the informal name given to the locality when the skeleton of the taxon was discovered (Valle Joaquín). Dr Gabriel Andrés Casal inspired the species epithet.  Dr Casal has made a significant contribution to our understanding of Cretaceous dinosaurs from Argentina.  In addition, he was responsible for the formal recognition and naming of the formation from which this megaraptorid was recovered (the Lago Colhué Huapi Formation).

A skeletal reconstruction of the new megaraptor dinosaur species Joaquinraptor casali showing the bones preserved (in blue). Other parts of the skeleton and body outline silhouette are based on closely related species. Photos of many of the preserved bones in various views surround the skeletal reconstruction. Skeletal reconstruction by T.K. Robinson and Andrew McAfee. Picture credit: Lucio M. Ibiricu et al.

Picture credit: Lucio M. Ibiricu et al

The Geologically Youngest Member of the Megaraptoridae

The researchers estimate that Joaquinraptor was around seven metres in length.  It probably weighed a tonne. This newly described theropod is also likely to be the geologically youngest megaraptor ever discovered.  Megaraptors survived until the end of the Cretaceous, 66 million years ago.  The partial, skeleton comes from the Chubut Province (southern Patagonia).  It was studied by Dr Lucio Ibiricu of Argentina’s Instituto Patagónico de Geología y Paleontología, and several other scientists including Dr Matt Lamanna of the Carnegie Museum of Natural History.

Dr Lamanna commented:

“At the Carnegie Museum of Natural History, we’re always seeking to better comprehend the history of life on our planet.  Every year, our team of experts conducts field work all over the world, helping to ensure that we’re on the cutting edge of research.  New revelatory dinosaur discoveries, like Joaquinraptor casali, deepen our understanding of how extraordinary creatures lived and advance understanding of the natural world, both past and present.”

Fossils of the new megaraptor dinosaur species J. casali in the quarry, laying in the positions they had laid for approximately 67 million years. A dentary, teeth, ribs, and several other bones are visible. Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr. Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco.

Picture credit: Everything Dinosaur

An analysis of a cross section of the tibia revealed that this dinosaur was at least nineteen years old when it perished. However, whilst the researchers considered the specimen to have been sexually mature, it was not fully grown.

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

The scientific paper: “Latest Cretaceous megaraptorid theropod dinosaur sheds light on megaraptoran evolution and palaeobiology” by Lucio M. Ibiricu, Matthew C. Lamanna, Bruno N. Alvarez, Ignacio A. Cerda, Julieta L. Caglianone, Noelia V. Cardozo, Marcelo Luna and Rubén D. Martínez published in Nature Communications.

The Everything Dinosaur website: Dinosaur Models.

The thick-skulled, dome-headed pachycephalosaurs are among the most enigmatic and yet, poorly known of all the Dinosauria.  For example, these ornithischians, with their elaborate cranial ornamentation are thought to have evolved complex social behaviours.  After all, the idea that those super thick skulls played a role in butting contests has been around for a long time.  The pachycephalosaurs have a new member.  The recently described Zavacephale rinpoche represents the oldest pachycephalosaur known to science.  It roamed Mongolia around 115 to 108 million years ago.  Its discovery helps palaeontologists to reconstruct the origins and the early evolution of the pachycephalosaurians.

The fossil represents a sub-adult, but the skull already has the distinctive dome. This indicates that pachycephalosaurs developed features relating to combat or display before they reached adulthood. Picture credit: Masato Hattori.

Picture credit: Masato Hattori

Zavacephale rinpoche

The fossil specimen, thought to represent a sub-adult, was discovered in the Khuren Dukh locality of the Eastern Gobi Basin. Not only is the specimen the oldest pachycephalosaur known to science, the skeleton is the most complete for this type of dinosaur found to date.

Corresponding author for the study, Lindsay Zanno, an associate research professor at North Carolina State University commented:

“Pachycephalosaurs are iconic dinosaurs, but they’re also rare and mysterious.”

The fossil material was found by Tsogtbaatar Chinzorig (Mongolian Academy of Sciences), the lead author of the study published in the journal “Nature”. The Z. rinpoche specimen was not fully grown when it died. However, it already bore a fully formed dome, though without much of the additional ornamentation found on other pachycephalosaur fossils.  The genus name is derived from zava which means “root” or “origin” in Tibetan and “cephal” which translates from Latin meaning head. The species name is derived from the Tibetan phrase for “precious one” as the domed skull was exposed on a cliff like a cabochon jewel.

Lindsay Zanno of the Department of Biological Sciences, (North Carolina State University), highlighting the morphology of the Zavacephale rinpoche skull. Picture credit: Alfio Alessandro Chiarenza.

Picture credit: Alfio Alessandro Chiarenza

Predating All Other Pachycephalosaur Fossils by at Least 14 Million Years

Zavacephale rinpoche pushes back fossil evidence of the frontoparietal dome by at least fourteen million years.  Furthermore, the skeleton, which is more than fifty percent complete, preserves regions of the body not scientifically described in any other pachycephalosaur.  For example, scientists could examine an almost complete tail covered in ossified tendons.  In addition, bones from the hand, a first for a pachycephalosaur, were found.

Intriguingly, the specimen had a gastrolith mass preserved in the stomach region.  These stomach stones suggest an omnivorous diet.  The stones ground up tough plant food to help with digestion.  It had been thought that these dinosaurs were herbivores.  However, recent discoveries such as fang-like teeth had led some researchers to speculate that they were carnivorous ornithischians.  The discovery of these stomach stones lends support to the theory that pachycephalosaurs probably ate both plants and animals, that they were omnivores.

To read a blog post from Everything Dinosaur: Pachycephalosaurus – Was it Carnivorous?

Highlighting the significance of Zavacephale rinpoche Tsogtbaatar Chinzorig stated:

“Z. rinpoche predates all known pachycephalosaur fossils to date by about 15 million years. It was a small animal – about three feet or less than one metre long, and the most skeletally complete specimen yet found.”

Chinzorig added:

“Z. rinpoche is an important specimen for understanding the cranial dome development of pachycephalosaurs, which has been debated for a long time due to the absence of early diverging or pre-Late Cretaceous species and the fragmentary nature of nearly all pachycephalosaurian fossils.”

Calculating the Age of a Dinosaur

A thin slice was carefully removed from a lower leg bone.  This slice was then subjected to histological analysis to calculate the dinosaur’s age when it died.  For the first time, palaeontologists had an almost complete pachycephalosaur skull with associated limb bones to help calculate the growth stage of the skeleton.

Lindsay Zanno explained:

“Pachycephalosaurs are all about the bling, but we can’t use flashy signalling structures alone to figure out what species they belong to or what growth stage they’re in because some cranial ornamentation changes as animals mature. We age dinosaurs by looking at growth rings in bones, but most pachycephalosaur skeletons are just isolated, fragmentary skulls. Z. rinpoche is a spectacular find because it has limbs and a complete skull, allowing us to couple growth stage and dome development for the first time.”

The fossil material has pushed back the fossil record of pachycephalosaurs by at least fourteen million years.  In addition, the research team have a much more complete fossil specimen to study.  Moreover, Zavacephale rinpoche demonstrates that dome heads developed in pachycephalosaurs before they reached adulthood.

Lindsay Zanno quipped:

“If you need to headbutt yourself into a relationship, it’s a good idea to start rehearsing early.”

Late Cretaceous Pachycephalosaurs

Most pachycephalosaur fossils are found in Upper Cretaceous deposits, primarily deposits laid down in the Campanian and Maastrichtian.

Austin the Pachycephalosaurus (P. wyomingensis).

Most specimens have been described based on cranial material.  These dinosaurs were bipedal.  Pachycephalosaurus had five fingers on each hand.  The image above of P. wyomingensis shows the PNSO model – Austin the Pachycephalosaurus.  This figure has been widely praised for its accuracy.

To view the range of PNSO models and figures in stock: PNSO Age of Dinosaurs Models.

An Important Discovery

The researchers stressed the significance of this fossil discovery.  Lindsay Zanno stated:

“This specimen is a once-in-a-lifetime discovery. It is remarkable for being the oldest definitive pachycephalosaur, pushing back the fossil record of this group by at least 15 million years, but also because of how complete and well-preserved it is. Z. rinpoche gives us an unprecedented glimpse into the anatomy and biology of pachycephalosaurs, including what their hands looked like and that they used stomach stones to grind food.”

Chinzorig added:

“The newly recovered materials of Z. rinpoche, such as the hand elements, the stomach stones (gastroliths), and an articulated tail with covered tendons, reshape our understanding of the paleobiology, locomotion, and body plan of these ‘mysterious’ dinosaurs.”

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

The scientific paper: “A domed pachycephalosaur from the early Cretaceous of Mongolia” by Tsogtbaatar Chinzorig, Ryuji Takasaki, Junki Yoshida, Ryan T. Tucker, Batsaikhan Buyantegsh, Buuvei Mainbayar, Khishigjav Tsogtbaatar and Lindsay E. Zanno published in the journal Nature.

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