Jawbone Leads to an Isle of Wight Tapejarid Pterosaur

A single, fragmentary jawbone from the upper jaw of a pterosaur found on the Isle of Wight has demonstrated just how diverse and widespread the Tapejaridae family of pterosaurs were.  The fossil bone, a partial premaxilla from the Lower Cretaceous (Barremian) Wessex Formation of Yaverland (Isle of Wight), represents a new species, the first record of a tapejarid pterosaur from the Wessex Formation and one of the oldest examples of this pterosaur family to have been found outside of China.  The flying reptile has been named Wightia declivirostris.

A Life Reconstruction of Wightia declivirostris (Wessex Formation)

A life reconstruction of the newly described tapejarid from the Lower Cretaceous of the Isle of Wight (Wightia declivirostris).

Picture Credit: Megan Jacobs (University of Portsmouth)

Terrific Toothless Tapejarids

The terrific toothless tapejarids with their reputation for taking head crest development to the extreme, are known from relatively abundant fossil material associated with the Santana and Crato Formations of Brazil.  In addition, several members of the Tapejaridae family are associated with the Jiufotang Formation of China.  However, fragmentary fossils are known from elsewhere in the world such as Spain (Europejara olcadesorum) and a toothless, rather deep lower jaw tip along with other partial bones from the Kem Kem beds of Morocco suggests that these types of flying reptile may have persisted into the early Late Cretaceous.

Two of the authors associated with this scientific paper, Professor David Martill and Roy Smith (both from the University of Portsmouth), recently published a report on the discovery of a north African tapejarid which was named Afrotapejara zouhrii, one of a spate of recent Moroccan pterosaur discoveries.  To read Everything Dinosaur’s article about this: That Fourth Moroccan Pterosaur.  It seems that these fancy-crested, edentulous flying reptiles were much more geographically and temporally diverse than previously thought.

A Typical Illustration of a Tapejarid Pterosaur (Tupandactylus imperator)

A scale drawing of the tapejarid Pterosaur Tupandactylus imperator.  The Tapejaridae are thought to have all sported flamboyant head crests.

Picture Credit: Everything Dinosaur

The Isle of Wight Pterosaur is More Closely Related to Chinese Tapejarids

Amateur fossil hunter John Winch discovered a pterosaur snout near the cliff at Yaverland Point in Sandown Bay, in a fossil plant debris layer.  The unusual shape and thin bone walls suggested that it was from a pterosaur.  The fragment of jaw, although eroded, demonstrates the characteristic downturned tip, with numerous tiny holes (foramina), on the occulsal surface which indicate the presence of minute sensory organs for detecting food.

The Holotype Material Wightia declivirostris

The isolated, partial premaxilla of Wightia declivirostris.

Picture Credit: University of Portsmouth

The jaw fragment was passed to palaeontology student at Portsmouth University, Megan Jacobs, who confirmed it was a rare find and definitely pterosaurian.  Analysis of the specimen suggests that Wightia is more closely related to the older and more primitive tapejarid Sinopterus from Liaoning (Jiufotang Formation), than it is to Brazilian tapejarids.  The genus name of this newly described flying reptile honours the Isle of Wight, whilst the species (trivial) name means “slanting beak”, a reference to the typically tapejarid morphology of the partial premaxilla.

Both the Wealden Formation and the geologically younger Vectis Formation on the Isle of Wight have yielded pterosaur specimens, although they tend to consist of highly fragmentary remains.  The discovery of Wightia declivirostris demonstrates how significant the Lower Cretaceous Isle of Wight sediments are to palaeontologists as they try to plot the radiation of different types of flying reptile during the Early Cretaceous.

The scientific paper: “First tapejarid pterosaur from the Wessex Formation (Wealden Group: Lower Cretaceous, Barremian) of the United Kingdom” by David M. Martill,  Mick Green, Roy E. Smith,  Megan L. Jacobs and John Winch published in the journal Cretaceous Research.

Curious Cervical Leads to Startling Conclusion

Think of a theropod dinosaur and a ferocious carnivore with a large head and big teeth probably comes to mind.  However, the Theropoda is an extremely diverse clade within the Dinosauria, not all of them were big, particularly ferocious or even had teeth.   One group the elaphrosaurines, were very bizarre indeed and the discovery of a single neck bone in Victoria has led to the conclusion that these strange, light-weight dinosaurs distantly related to Carnotaurus, roamed Australia in the Early Cretaceous.

A Life Reconstruction of the Australian Elaphrosaurine

A life reconstruction of the first elaphrosaur from Australia.

Picture Credit: Ruairdh Duncan (Swinburne University of Technology, Victoria)

From the Lower Cretaceous of Australia

Volunteer Jessica Parker discovered a 5-centimetre-long bone whilst helping out at the annual Dinosaur Dreaming excavation near Cape Otway, Victoria (2015).  The sediments at the site, known as Eric the Red West, date from the late Albian faunal stage of the Lower Cretaceous and are part of the Eumeralla Formation.  At first, the bone identified as a cervical vertebra (neck bone), was thought to have come from a pterosaur.

Intriguingly for Swinburne University palaeontologist Dr Stephen Poropat and PhD student Adele Pentland, once the fossil specimen had been prepared it became clear that this was not a bone from the middle portion of the neck of a flying reptile.

Dr Poropat explained:

“Pterosaur neck vertebrae are very distinctive.  In all known pterosaurs, the body of the vertebra has a socket at the head end, and a ball or condyle at the body end.  This vertebra had sockets at both ends, so it could not have been from a pterosaur.”

The Cervical Vertebra – Evidence of Australia’s First Elaphrosaur

The five-centimetre-long bone identified as a middle cervical from an elaphrosaur.

Picture Credit: Dr Stephen Poropat

Geologically Much Younger Than Most Elaphrosaurines

The taxonomic affinity of the subfamily Elaphrosaurinae within the Theropoda remains controversial.  A number of authors have placed this little-known group, characterised by their small, light, graceful bodies, tiny heads, long necks and reduced forelimbs within the Noasauridae family, which means that they are distantly related to abelisaurids such as Ekrixinatosaurus, Majungasaurus and Carnotaurus.

Most elaphrosaurs are known from the Late Jurassic, but this new elaphrosaur from Australia, lived some forty million years later. Only Huinculsaurus (H. montesi), from the Cenomanian/Turonian (early Late Cretaceous), of Argentina is geologically younger, than the Australian fossil remains.

The Fossil Find Location, Typical Elaphrosaurine Body Plan and Placing the Fossil Find in a Chronological Context

A silhouette of the elaphrosaur with a map showing fossil location and a timeline showing elaphrosaurine chronology.  The newly described elaphrosaurine from Victoria is geologically the second youngest member of this group known.

Picture Credit: Poropat et al (Gondwana Research)

A Dinosaur of the Polar Region

The discovery of this single, fossilised neckbone adds support to the idea that the elaphrosaurines were geographically and temporally much more widespread than previously thought.  The similarity of these dinosaurs to the much better-known ornithomimosaur theropods (bird mimics), could help to explain why few other Cretaceous elaphrosaur specimens have come to light. Fossil material may have been found but misidentified as representing ornithomimids.

As the Cape Otway location would have been situated much further south during the Early Cretaceous (110-107 million years ago), at around a latitude of 76 degrees south, this implies that elaphrosaurines were capable of tolerating near-polar palaeoenvironments.

Recently, Everything Dinosaur wrote a post about the discovery of noasaurid from an opal mine close to Lightning Ridge (New South Wales).  Noasaurids and elaphrosaurines were related, most scientists classifying them as different branches within the Abelisauroidea.  Coincidentally, the New South Wales noasaurid was identified from a single cervical vertebra too.  Both it and the Cape Otway elaphrosaurine dinosaur have not been assigned to any genus, but both fossils are likely to represent new species.

To read Everything Dinosaur’s article about the recently discovered noasaurid from New South Wales: Noasaurids from Australia.

The scientific paper: “First elaphrosaurine theropod dinosaur (Ceratosauria: Noasauridae) from Australia — A cervical vertebra from the Early Cretaceous of Victoria” by Stephen F. Poropat, Adele H. Pentland, Ruairidh J. Duncan, Joseph J. Bevitt, Patricia Vickers-Rich and Thomas H. Rich published in Gondwana Research.

Stellasaurus ancellae – Missing Link from the Two Medicine Formation of Montana

A new species of horned dinosaur has been described based on fossil material from the famous Two Medicine Formation of north-western Montana.  The new species named Stellasaurus ancellae is a possible missing link in the evolutionary transition of Centrosaurinae dinosaurs from Styracosaurus to one of the last of the horned dinosaurs known to science – Pachyrhinosaurus.  Stellasaurus means “star lizard”, reflecting the ornate star-shaped head crest and in honour of British rock/pop star David Bowie, famous for his flamboyant appearance and his hit single “Starman” which was released on April 28th 1972, almost 48 years to the day that the Stellasaurus scientific paper was published in Royal Society Open Science.

United by a Flamboyant Appearance David Jones AKA David Bowie and “Star Lizard” AKA Stellasaurus

David Bowie (left) and Stellasaurus ancellae (right).

Picture Credit: Getty Images and Andrey Atuchin

Stellasaurus ancellae

Just like the career of David Bowie, Stellasaurus has had to wait a while before becoming famous.  The fossil material now assigned to Stellasaurus was discovered in 1986, near the town of Cut Bank in Montana, close to the USA/Canadian border.  The discovery was made by Carrie Ancell.  It remained catalogued but not studied in the Museum of the Rockies (Montana), vertebrate fossil collection.  The contribution of Carrie Ancell, now a senior preparator at the Museum of the Rockies, has been recognised as the species name honours her.  Carrie Ancell has played a significant role in developing our understanding of northern Laramidian centrosaurines.  She discovered and prepared MOR 492, the holotype specimen of Stellasaurus ancellae, as well as the holotype of Achelousaurus horneri, and co-discovered the holotype of Einiosaurus procurvicornis.

Views of the Holotype Fossil Material of Stellasaurus ancellae

Left lateral parietal bar of Stellasaurus ancellae holotype MOR 492 in dorsal and ventral views.   The line drawing has been reproduced from a PLOS One article (Evans and Ryan).  Note scale bar on left equals 10 cm.

Picture Credit: Wilson et al/Royal Society Open Science

Reviewing the Centrosaurinae Fossil Material from the Two Medicine Formation

A review of cranial material, specifically the ornamentation associated with the neck frill (parietal processes), previously assigned to the centrosaurine Rubeosaurus ovatus resulted in the identification of this new taxon.  However, this assessment could mark the demise of R. ovatus as the researchers, which include John Wilson of Montana State University, conclude that only what was the holotype fossil, a partial parietal specimen number USNM 11869, can be attributed Rubeosaurus.  This could spell the end for Rubeosaurus.  When USNM 11869 was first described it was assigned to a new species of Styracosaurus (S. ovatus).  Thus, this new paper proposes that the genus Rubeosaurus is now no longer valid and that Styracosaurus ovatus is the sister taxon to Styracosaurus albertensis and Stellasaurus marks a missing link in centrosaurine evolution between Styracosaurus and Einiosaurus procurvicornis.

A Stratigraphical and Temporal Assessment of Late Cretaceous Centrosaurines Based on Two Medicine Formation Fossil Material *

Stratigraphic and temporal relationship between Two Medicine Formation centrosaurine taxa. * Pachyrhinosaurus lakustai fossil material is not from the Two Medicine Formation but from the younger unit 4 sediments of the Wapiti Formation of Canada.

Picture Credit: Wilson et al/Royal Society Open Science

A Missing Link Amongst the Centrosaurinae

The researchers postulate that Stellasaurus represents a missing link in the centrosaurine family tree.  The fossils of Stellasaurus are believed to be around 75 million years old.  From a stratigraphical perspective, they are younger than Styracosaurus albertensis fossils, but older than fossils assigned to Einiosaurus.  That flamboyant head shield with its various lumps and bumps could reflect a transitional stage between the headshield morphology of Styracosaurus and that of Einiosaurus.  It is suggested that Stellasaurus was preceded by Styracosaurus and that Styracosaurus evolved into Stellasaurus.  In addition, Einiosaurus evolved from Stellasaurus.

A Transitional Process – One Horned Dinosaur Leading Directly to Another Species of Horned Dinosaur

Anagenesis within centrosaurine dinosaurs.  Stellasaurus evolved from Styracosaurus and Einiosaurus evolved from Stellasaurus.

Picture Credit: Everything Dinosaur/Andrey Atuchin

Anagenesis in the Centrosaurinae

Commenting upon the importance of this new research, lead author John Wilson stated:

“The ornamental horns and spiky frills on the skulls of these animals are what changed the most through evolution.  The new species has skull ornamentation which is intermediate.  This gives us evidence these species are members of a single, evolving lineage – this type of evolution is called anagenesis.”

The Phylogeny of the Centrosaurinae from Statistical Analysis Undertaken by the Research Team

Phylogeny of the Centrosaurinae clade of the Ceratopsidae based on Bayesian statistical analysis mapped against a temporal range.  Styracosaurus ovatus (formerly Rubeosaurus ovatus), is placed as the sister taxon to Styracosaurus albertensis, whilst Stellasaurus is mapped between S. albertensis and Einiosaurus procurvicornis.

Picture Credit: Wilson et al/Royal Society Open Science

The scientific paper: “A new, transitional centrosaurine ceratopsid from the Upper Cretaceous Two Medicine Formation of Montana and the evolution of the ‘Styracosaurus-line’ dinosaurs” by John P. Wilson, Michael J. Ryan and David C. Evans published in Royal Society Open Science.