Skull Bones of Saurornitholestes Point to Asian Migration

By | September 11th, 2019|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

New Study Published on Saurornitholestes langstoni

Researchers based at the University of Alberta and the Royal Ontario Museum (Canada), have published a new scientific paper on the dinosaur nicknamed the “raptor of Alberta”.  The dinosaur – Saurornitholestes langstoni, was once thought to be a troodontid, but its placement within the Dromaeosauridae has been reinforced.  Furthermore, although no impressions of preserved feathers have ever been found in association with skeletal material, a tooth wear analysis conducted by the scientists suggests that a tooth in the upper jaw might have been specialised for preening feathers.

The Beautifully Preserved Saurornitholestes langstoni Specimen

The beautifully preserved and nearly complete Saurornitholestes langstoni fossil discovered in 2014.

The nearly complete Saurornitholestes langstoni fossil discovered in 2014.

Picture Credit: University of Alberta

The researchers who produced the scientific paper, two famous and very influential palaeontologists, Professor Philip Currie (University of Alberta) and Dr David Evans (Royal Ontario Museum), also suggest that their analysis of recently described skull bones supports the idea of at least two major faunal interchanges between Asia and North America during the Late Cretaceous.

Several Partial Skeletons – Hundreds of Isolated Teeth and Bones

In 1978, Saurornitholestes langstoni was formally described based on some fragmentary fossil bones found close to the small town of Patricia in southern Alberta four years before.  Since then, four additional partial skeletons ascribed to Saurornitholestes and hundreds of isolated teeth and bones have been recovered from the Upper Cretaceous sediments (Campanian faunal stage), of Alberta and Montana.  Despite these fossils, very little was known about the skull of S. langstoni, curtailing attempts to better understand the taxonomic relationship between this Canadian dromaeosaurid and other Asian forms such as Velociraptor mongoliensis and Tsaagan mangas.

A Scale Drawing of Saurornitholestes langstoni

Saurornitholestes langstoni illustration - scale drawing.

Saurornitholestes langstoni illustration (scale drawing).

Picture Credit: Everything Dinosaur

Study of the 2014 Specimen

Frustrated by the lack of truly diagnostic fossil cranial material to study, palaeontologists could do very little to better understand where within the Dromaeosauridae the “raptor of Alberta” should reside.  This all changed in 2014 with the discovery of a nearly complete fossil specimen, ironically within a thousand metres of where the holotype specimen had been found back in 1978.  Although loaned out to Japan’s National Museum of Nature and Science (Tokyo), for a special exhibition marking fifty years of “raptor research”, analysis continued on the remarkable skeleton.

Writing in the academic journal “The Anatomical Record”, the scientists confirm that Saurornitholestes was similar in size to Velociraptor, but the facial region of the skull is relatively shorter, taller and wider.  The premaxillary teeth are distinctive, and fossil teeth collected in the Dinosaur Provincial Park (southern Alberta), ascribed to the dromaeosaurid Zapsalis abradens can now be identified as the second premaxillary tooth of S. langstoni.

A Close-up View of the Skull of S. langstoni 

Saurornitholestes langstoni fossil skull.

A close-up view of the fossilised skull of the 2014 specimen.  The skull bones were preserved in articulation, helping the scientists to understand the anatomy of the skull.

Picture Credit: University of Alberta

Teeth Used for Preening Feathers

A detailed microscopic study of the tiny abrasions preserved on the teeth located in the front of the upper jaw (premaxilla), have led the researchers to speculate that these teeth could have had a role in helping to preen and clean the dinosaur’s feathery coat.

A Typical Dromaeosaurid Tooth

Dromaeosaurid tooth from Alabama.

An isolated dromaeosaurid tooth with very different denticles (anterior and posterior).  Different sized serrations might have assisted with grooming as a secondary function of the tooth.

Picture Credit: David R. Schwimmer

A Distinctive North American Clade of Dromaeosaurs

With an almost complete specimen to study and, most importantly of all, a skull, the scientists have concluded that a distinctive North American clade of Late Cretaceous dromaeosaurids can be established within the Dromaeosauridae family.  A distinctive and separate branch from the Asian part of the Dromaeosauridae that includes the likes of Velociraptor.  Professor Currie and Dr Evans were able to identify many unique anatomical traits (autapomorphies), that permitted the establishment of this clade – the Saurornitholestinae.  This new information on the skull allows a more complete evaluation of the systematic position of Saurornitholestes langstoni within the Dromaeosauridae and supports the suggestion of at least two major faunal interchanges between Asia and North America during the Cretaceous.

At Everything Dinosaur, we have seen a resurgence in interest in “raptor” figures and models.  These theropod dinosaurs continue to feature prominently in dinosaur movies and the “Beasts of the Mesozoic” range of “raptor” models including an articulated replica of Saurornitholestes langstoni have been introduced.

To view the Beasts of the Mesozoic model range available from Everything Dinosaur: Beasts of the Mesozoic Figures

The scientific paper: “Cranial Anatomy of New Specimens of Saurornitholestes langstoni (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta” by Philip J. Currie and David C. Evans published in the journal The Anatomical Record.