Shark Spines and Fish Jaws Turn Out to be Pterosaur Mandibles

Over the last few months, Everything Dinosaur has reported upon the research into the Pterosauria conducted by scientists from the University of Portsmouth and the University of Leicester in collaboration with academics from several other institutions.  We really do seem to be having a “Golden Age” of pterosaur research with lots of exciting discoveries about flying reptile behaviour and lifestyles as well as a number of new species being named and described.

Pterosaur Research Has Not Been Standing Still

Pterosaur research has not been standing still.  There have been lots of new and exciting discoveries made recently.

Picture Credit: Everything Dinosaur

Recently, we have reported upon a suite of new Late Cretaceous flying reptiles from Morocco*, research that re-examined some of the evidence associated with integumentary coverings when it comes to flying reptiles**, a new tapejarid from the Wessex Formation (Wightia declivirostris) and last month, team members looked into the tactile qualities of sensitive pterosaur jaws: The Sensitive Beaks of Pterosaurs.

*For our article reporting upon the discovery of several new pterosaurs from the Late Cretaceous of Morocco: Pterosaurs, Pterosaurs the “Golden Age” of Pterosaur Research.

*A fourth new pterosaur from Morocco is announced: Afrotapejara zouhrii.

**For the Everything Dinosaur article looking at integumentary coverings in the Pterosauria: Naked Pterosaurs!  No Protofeathers on Pterosaurs.

Researchers from the University of Portsmouth in collaboration with colleagues from the University of Leicester and the London Natural History Museum have published a new paper this week.  Writing in the “Proceedings of the Geologists’ Association”, they report upon the discovery of a new species of toothless pterosaur after the re-examination of vertebrate fossil collections at the Sedgwick Museum (Cambridge) and the Booth Museum (Brighton).

It was Portsmouth University PhD student, Roy Smith, already a published author, as the links we have posted above testify, who found evidence for the new species when searching through material in the collections that had been misidentified either as shark spines or the jaws from prehistoric fish.

Explaining How to Identify the Edentulous (Toothless) Beak of a Pterosaur

PhD student Roy Smith explaining what the edentulous beaks of pterosaurs look like.

Picture Credit: Portsmouth University

Late Cretaceous Pterosaurs

The fossil material studied comes from the Cretaceous Cambridge Greensand Member of the West Melbury Marly Chalk Formation.  The fossils had been collected in Cambridgeshire during the latter part of the 19th century, when very little was known about the Pterosauria.  As these sediments represent a marine environment, this does explain to some extent how the toothless beaks of flying reptiles could be confused with shark spines and fish jaws.  Thanks to the efforts of the researchers, a number of of new specimens of edentulous pterosaur jaw fragments have been identified.  These are now recognised as pterosaurian jaw tips and referred to Ornithostoma sedgwicki, which was first named and described by the British palaeontologist Harry Seeley.

It had been thought that O. sedgwicki was a member of the Pteranodontia, perhaps the most famous of all the types of flying reptile known as the genus Pteranodon is part of this group.

A Prehistoric Scene Featuring Pteranodon

Dramatic scene from the Western Interior Seaway painted by Burian.  Images such as this helped to popularise the Pteranodon genus.

Picture Credit: Zdeněk Burian

Time to Re-classify Ornithostoma sedgwicki

The research team which includes Professor David Martill (Portsmouth University), Dr David Unwin (University of Leicester), Dr Lorna Steel (London Natural History Museum) as well as PhD student Roy Smith, conclude that as tiny pits along the side of the jaw bone have been identified in these fragmentary fossils, it might be time to revise the taxonomy of O. sedgwicki.

If these pits and minute holes indicate the presence of neural foramina (nerves passing through the jaw to make contact with the beak’s surface to help the animal sense its environment), then as neural foramina are not known in the Pteranodontia, Ornithostoma could have been placed in the wrong part of the flying reptile family tree.

The scientists assign O. sedgwicki to the Azhdarchoidea group instead.  Whatever the classification of Ornithostoma, its fossils still probably represent the first evidence of toothless pterosaurs to have ever been discovered.

Student Roy Smith, summarising what the team found as they re-examined the material from the 19th century stated:

“Two of the specimens discovered can be identified as a pterosaur called Ornithostoma, but one additional specimen is clearly distinct and represents a new species – it is a palaeontological mystery.”

Unfortunately, like most of the pterosaur fossils associated with the Cambridge Greensand of England, this fossil is too fragmentary to permit a new genus to be erected.

The scientific paper: “Edentulous pterosaurs from the Cambridge Greensand (Cretaceous) of eastern England with a review of Ornithostoma Seeley, 1871” by Roy E. Smith, David M. Martill, David M. Unwin and Lorna Steel published in the Proceedings of the Geologists’ Association.

Mapping the Genome of Homotherium latidens

The diverse and geographically widespread machairodonts, a subfamily of the cat family (Felidae), have fascinated palaeontologists for a very long time and there is still a great deal of research directed towards these sabre-toothed predators.  Recently, Everything Dinosaur published an article that looked at how those enlarged canines might have been used by different types of sabre-toothed creature known from the fossil record: Sabre-toothed Predators Evolved Different Hunting Styles.  However, a team of international scientists led by researchers from the University of Copenhagen (Denmark), have taken a more holistic view when it comes to these long-fanged mammals.  They have mapped the entire nuclear genome of the machairodont Homotherium latidens and their research suggests that this tiger-sized carnivore was a highly social, pursuit predator.

A Pack of Homotherium Pursue a Prehistoric Horse

A pack of Homotherium latidens chasing a prehistoric horse.  What an amazing example of paleoart – our congratulations to the artist.

Picture Credit: Velizar Simeonovski/University of Copenhagen

Writing in the academic journal “Current Biology”, the scientists were able to extract DNA from a H. latidens specimen found in thawing Pleistocene permafrost near Dawson City in the Yukon Territory (Canada).  A variety of modern genomic sequencing strategies were applied to reveal a map of the entire genome of the fossil.  The data was then compared to living felids such as the domestic cat as well as lions and tigers.  The DNA study reveals what genes were highly selected upon and important in evolution of the species.

Commenting on the significance of this research, Michael Westbury, a co-author of the paper based at the University of Copenhagen stated:

“Their genetic makeup hints towards scimitar-toothed cats being highly skilled hunters.  They likely had very good daytime vision and displayed complex social behaviours.  They had genetic adaptations for strong bones and cardiovascular and respiratory systems, meaning they were well suited for endurance running.  Based on this, we think they hunted in a pack until their prey reached exhaustion with an endurance-based hunting-style during the day light hours.”

This type of hunting behaviour is sometimes seen in lions today, although they are mainly ambush predators and they also hunt at night.  Perhaps the most relevant modern analogue to the hunting behaviour proposed for Homotherium latidens is that of the gray wolf (Canis lupus), which is primarily a diurnal, pursuit predator of large prey.

The genome analysis also revealed that this scimitar-toothed cat was genetically very diverse when compared to extant cat species.

Doctor Westbury, a postdoctoral researcher in the GLOBE Institute at the University of Copenhagen also stated:

“We know that genetic diversity correlates to how many of a given species that exists.  Based on this, our best guess is that there were a lot of these big cats around.  This also makes perfect sense given that their fossils have been found on every single continent except Australia and Antarctica.”

To read a related article about the discovery of a treasure trove of prehistoric mammal fossils including machairodonts that have been found in Venezuela: Oil Companies Assist with Huge Fossil Discovery.

The Genome of the Extinct Machairodont Homotherium latidens has been Mapped

Researchers have mapped the genome of the prehistoric cat Homotherium latidens.  The analysis suggests that these cats were highly social and adapted to a long pursuit, endurance form of hunting.

Picture Credit: University of Copenhagen/Current Biology

Homotherium Distantly Related to Extant Felids

The study demonstrated that the Homotherium genus is only very distantly related to all modern cats.  This type of cat diverged from the Felidae lineage around 22.5 million years ago (early Miocene Epoch) and this conclusion supports the hypothesis that the Machairodontinae are a distinct subfamily within the Felidae.

The Demise of Homotherium

The fossil record demonstrates that Homotherium and related genera were extremely successful.  These cats were both geographically and temporally widely dispersed.  It remains a mystery as to why these carnivores were unable to survive to the present day.  The authors of the paper speculate that some of the adaptations/specialisations that led to Homotherium’s success could also have played a pivotal role in its demise and eventual extinction.

Toward the end of the Late Pleistocene, a decrease in large prey availability may have caused more direct competition with other cat species that were likely more effective at capturing the remaining smaller prey species.  The specific adaptations Homotherium had acquired would have suddenly become less advantageous, leading to an irreversible decline that ultimately resulted in extinction.

Fellow co-author Ross Barnett, (GLOBE Institute at the University of Copenhagen), explained:

“This was an extremely successful family of cats.  They were present on five continents and roamed the earth for millions of years before going extinct.  The current geological period is the first time in 40 million years that earth has lacked sabre-tooth predators.  We just missed them.”

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

The scientific paper: “Genomic Adaptations and Evolutionary History of the Extinct Scimitar-Toothed Cat, Homotherium latidens” by Ross Barnett, Michael V. Westbury, Marcela Sandoval-Velasco, Filipe Garrett Vieira, Sungwon Jeon, Grant Zazula, Michael D. Martin, Simon Y. W. Ho, Niklas Mather, Shyam Gopalakrishnan, Jazmín Ramos-Madrigal, Marc de Manuel, M. Lisandra Zepeda-Mendoza, Agostinho Antunes, Aldo Carmona Baez, Binia De Cahsan, Greger Larson, Stephen J. O’Brien, Eduardo Eizirik, Warren E. Johnson, Klaus-Peter Koepfli, Andreas Wilting, Jörns Fickel, Love Dalén, Eline D. Lorenzen, Tomas Marques-Bonet, Anders J. Hansen, Guojie Zhang, Jong Bhak, Nobuyuki Yamaguchi and M. Thomas P. Gilbert published in the journal Current Biology.

Gavialimimus almaghribensis – Specialised Piscivore from Morocco

An international team of researchers including scientists from the University of Alberta, the University of Cincinnati (USA) and Flinders University (Adelaide, Australia), have identified a new species of marine reptile from fossil remains found in Upper Cretaceous rocks from Morocco.  The animal, a new species of mosasaur has been named Gavialimimus almaghribensis, its long, narrow snout and interlocking teeth suggest that it specialised in hunting fast-swimming, bony fish.

These adaptations suggest that this carnivore, distantly related to modern snakes and lizards, occupied a specific niche in the Moroccan marine ecosystem.  Around a dozen different species of mosasaur are known from the Upper Cretaceous of Morocco, many with different shaped jaws and teeth.  This suggests that these reptiles diversified rapidly during the Late Cretaceous and adapted to differing roles in the ecosystem to avoid direct competition with each other.  The researchers writing in the “Journal of Systematic Palaeontology” suggest that these are examples of niche partitioning in the ancient environment.

A Life Reconstruction of the Newly Described Gavialimimus almaghribensis

A life reconstruction of the newly described Moroccan mosasaur Gavialimimus almaghribensis which is thought to have been a specialised piscivore (fish-eater).

Picture Credit: Tatsuya Shinmura

Corresponding author for the scientific paper, Catherine Strong (University of Alberta), stated:

“Its long snout reflects that this mosasaur was likely adapted to a specific form of predation, or niche partitioning, within this larger ecosystem.  For some species, these adaptations can be very prominent, such as the extremely long snout and the interlocking teeth in Gavialimimus, which we hypothesised as helping it to catch rapidly moving prey.”

Resembling a Gavial (Gavial Mimic)

The genus name means “Gavial mimic”, a reference to the similarity between the jaws and dentition of this mosasaur to that of the extant long-snouted gavial (gharial).  Whilst the trivial or species name is derived from the Romanised version of the Arabic term for Morocco (al-Maghrib) paired with the Latin suffix “ensis”, thus denoting the country of origin of the holotype.

The Skull of a Gharial (Gavial)

The skull of a gharial (gavial) from the Grant Museum of Zoology (London).  The long snout and teeth superficially resemble the jaws and teeth of the newly described mosasaur Gavialimimus almaghribensis.

Picture Credit: Everything Dinosaur

From the Oulad Abdoun Basin

The fossils, including a metre-long skull come from the upper Maastrichtian deposits of the Oulad Abdoun Basin of northern Morocco.  The phosphate mines in this region are a rich source of mosasaur fossils and occasionally a dinosaur or two: The Last Dinosaur from Africa.

These sediments have revealed new species of pterosaur too: Pterosaurs More Diverse at the End of the Cretaceous than Previously Thought.

The Fossilised Skull of the Newly Described Gavialimimus almaghribensis

The fossilised skull of the newly described mosasaur G. almaghribensis.

Picture Credit: Catherine Strong (University of Alberta)

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

The scientific paper: “A new species of longirostrine plioplatecarpine mosasaur (Squamata: Mosasauridae) from the Late Cretaceous of Morocco, with a re-evaluation of the problematic taxon ‘Platecarpus’ ptychodon” by Catherine R. C. Strong, Michael W. Caldwell, Takuya Konishi and Alessandro Palci published in the Journal of Systematic Palaeontology.