The Regional and Temporal Diversity of Mongolian Dromaeosaurids

By | May 1st, 2021|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Earlier this year (January 2021), a new species of dromaeosaurid dinosaur was named and described from a partial skeleton excavated from deposits associated with the Barun Goyot Formation at Khulsan (Ömnögovi Province, Mongolia). The dinosaur, which was closely related to Velociraptor was named Shri devi. This little, fleet-footed carnivore was named after a female deity from Tibetan/Mongolian Buddhism.

Shri devi fossil material.
Pelvis and right hind limb of Shri devi IGM 100/980 after initial preparation whilst still in burlap jacket. Lateral view (top image) and ventral view (bottom view). Note scale bar = 5 cm.

Plotting the Regional Diversity of Dromaeosaurids

Although dromaeosaurid fossils are relatively rare, there have been several new dromaeosaur species described from this region of Asia in the last two decades. Shri devi is the first unequivocal dromaeosaurid taxon from the Late Cretaceous Barun Goyot Formation. Dating of the strata associated with these fossil finds has been problematical, but generally it is thought that the Djadochta Formation is the oldest, with the Barun Goyot Formation lying above it and the Nemegt Formation deemed the youngest formation of these three fossil bearing deposits.

Fossil Material Found in 1991

The Shri devi material consisting of a partially articulated skeleton including preserved right hind limb, elements from the left leg, the pelvis along with cervical, dorsal and caudal vertebrae from a single individual was discovered in 1991 by a joint expedition between the Mongolian Academy of Sciences and the American Museum of Natural History.

A scale drawing of Shri devi
Shri devi scale drawing. Although the skull is not known, it is thought that this dinosaur was closely related to Velociraptor and about the same size.

Dromaeosaurids although specious were rare within these palaeoenvironments, as many species are known from just one or two specimens. The discovery of S. devi has helped palaeontologists to map the regional and temporal differences of dromaeosaurs from this part of Late Cretaceous Asia.

Different dromaeosaurids of Mongolia and Inner Mongolia
Map showing the geographical and temporal distribution of Late Cretaceous dromaeosaurids from Mongolia and Inner Mongolia. The different dromaeosaurid biota of the Barun Goyot Formation and the Tugrugin Member/Bayn Dzak Member of the Djadochta Formation.

When formally described (Turner et al), it was noted that the second toe, the one that possessed the enlarged sickle-like claw, was proportionately larger than that seen in similar sized dromaeosaurs such as Velociraptor mongoliensis. Shri devi could have had a slightly bigger second toe claw than Velociraptor.

Hind foot of Shri devi
The foot of IGM 100/980 still in its burlap jacket (prior to final preparation). The large sickle claw on the second toe can be seen. Although approximately the same size as the closely related Velociraptor mongoliensis, the second toe claw of Shri devi seems to have been slightly larger. Note scale bar 2 cm.