Oksoko avarsan: New Bird-Like Dinosaur Unearthed in Mongolia

Thursday, October 8, 2020

Three individuals of Oksoko avarsan. Image credit: Michael W. Skrepnick.

Paleontologists in Mongolia have found the fossilized skeletal remains from a new genus and species of two-fingered oviraptorosaur that walked the Earth during the Cretaceous period.

The newly-discovered dinosaur lived approximately 68 million years ago (Maastrichtian stage of the Late Cretaceous period).

The feathered, omnivorous creature was a type of oviraptorosaur, a diverse group of theropod dinosaurs known from an excellent fossil record spanning much of the Cretaceous of Asia and North America.

Dubbed Oksoko avarsan, the ancient animal was about 2 m (6.6 feet) long and had a large, toothless beak.

It had one less finger on each forearm than its close relatives, suggesting an adaptability which enabled the animals to spread during the Late Cretaceous.

Holotype block with skeletons of Oksoko avarsan in ventral view; colors distinguish different individuals; the holotype individual is in blue. Image credit: Funston et al, doi: 10.1098/rsos.201184.

Multiple associated skeletons of Oksoko avarsan were collected from the Nemegt Formation in the Gobi Desert.

Oksoko avarsan represents the sixth genus of oviraptorid and ninth genus of oviraptorosaur from the Nemegt Formation, adding to previous evidence for a remarkable diversity of oviraptorosaurs in the Maastrichtian of Asia,” said University of Edinburgh paleontologist Gregory Funston and colleagues.

“The remarkably well-preserved fossils provided the first evidence of digit loss in the three-fingered family of dinosaurs known as oviraptors.”

“The discovery that oviraptorosaurs could evolve forelimb adaptations suggests the group could alter their diets and lifestyles, and enabled them to diversify and multiply.”

Skeletal anatomy of Oksoko avarsan: (a) skeletal reconstruction; (b, c) skull in left lateral view; (d) anterior cervical vertebra in left lateral view; (e) articulated sacrum and ilium in ventral view, anterior is to the left; (f) mid-caudal vertebra in left lateral view; (g) pygostyle vertebrae in left lateral view; (h) right scapulocoracoid in lateral view; (i) furcula in anterior view; (j) right and left sternal plates in anterior view; (k) articulated pelvis in right lateral view; (l) right femur in posterior view; (m) proximal metatarsus and distal tarsals in proximal view; (n) tibia, fibula and pes in ventral view. Image credit: Funston et al, doi: 10.1098/rsos.201184.

The researchers also discovered that Oksoko avarsan — like many other dinosaur species — were social as juveniles. The fossillized remains of four young dinosaurs were preserved resting together.

Oksoko avarsan is interesting because the skeletons are very complete and the way they were preserved resting together shows that juveniles roamed together in groups,” Dr. Funston said.

“But more importantly, its two-fingered hand prompted us to look at the way the hand and forelimb changed throughout the evolution of oviraptors — which hadn’t been studied before.”

“This revealed some unexpected trends that are a key piece in the puzzle of why oviraptors were so diverse before the extinction that killed the dinosaurs.”

The discovery is reported in a paper in the journal Royal Society Open Science.


Gregory F. Funston et al. 2020. A new two-fingered dinosaur sheds light on the radiation of Oviraptorosauria. Royal Society Open Science 7 (10); doi: 10.1098/rsos.201184

Source: www.sci-news.com/