Garudimimus (meaning "Garuda mimic") is a genus of ornithomimosaur that lived in Asia during the Late Cretaceous. The genus is known from a single specimen found in 1981 by a Soviet-Mongolian paleontological expedition in the Bayan Shireh Formation and formally described in the same year by Rinchen Barsbold; the only species is Garudimimus brevipes. Several interpretations about the anatomical traits of Garudimimus were made in posterior examinations of the specimen, but most of them were criticized during its comprehensive redescription in 2005. Extensive undescribed ornithomimosaur remains at the type locality of Garudimimus may represent additional specimens of the genus.
The only known specimen of Garudimimus was a medium-sized animal measuring nearly in length and weighing about . It was an ornithomimosaur with a mix of basal and derived features; unlike primitive ornithomimosaurs, both upper and lower jaws were toothless, a trait that is often reported in more derived ornithomimids. Garudimimus had relatively short and stocky hindlimbs, robust feet, and a reduced ilia. The foot had four toes with the first one very reduced, whereas ornithomimids were three-toed with the first toe lost. The toothless skull has very straight jaws ending in a more rounded snout tip than that of other genera. It was previously thought that this primitive ornithomimosaurian possessed a lacrimal "horn" at the top of the skull, in front of the eye socket. However, the redescription of the only specimen has shown that this structure was simply the distorted left prefrontal bone. Another early interpretation was the metatarsus reconstructed with an arctometatarsalian condition.
With the first description in 1981, Garudimimus was identified as a primitive ornithomimosaurian within its own family. However, with the description of new specimens of Deinocheirus in 2014, it was found that the latter was the sister taxon of Garudimimus, grouping within the Deinocheiridae—ornithomimosaurs not adapted for running or agile movements. But this placement has also been found to be unlikely. The pelvic girdle and hindlimbs of Garudimimus show that the musculature of the legs was not as well-developed as in the fast-running ornithomimids, therefore, indicating poor cursorial capacities. Like other members of Ornithomimosauria, Garudimimus was an omnivore/herbivore with a reduced bite force that was compensated by a horny beak.
History of discovery
In 1981, during a Soviet-Mongolian paleontological expedition to the Gobi Desert, a relatively small theropod skeleton was discovered by the team at Bayshi Tsav in the Late Cretaceous Bayan Shireh Formation, Southeastern Mongolia. The remains are catalogued as MPC-D 100/13 (Mongolian Palaeontological Center; originally GIN 100/13) and represent a rather complete and articulated skeleton. In the same year this specimen was formally and briefly described by the Mongolian paleontologist Rinchen Barsbold as the holotype of the genus and species Garudimimus brevipes. The generic name, Garudimimus, combines a reference to Garuda which are legendary winged creatures from Mongolian Buddhist mythology and Latin mimus (meaning mimic). The specific name is derived from Latin brevis (meaning short) and pes (meaning foot), referring to the short metatarsus. Barsbold identified Garudimimus as an ornithomimosaurian taxon but noted it was more primitive than ornithomimids and gave it its own family, the Garudimimidae. Barsbold described additional remains of the holotype specimen in 1983, and later in 1990 with Halszka Osmólska.
The holotype consist of the skull in its entirety, 8 cervical vertebrae (including the atlas and axis), 9 dorsal vertebrae, 6 sacral vertebrae and 4 caudal vertebrae, some ribs, both ilia, pubes, femora, tibiae, fibulae, and a virtually complete left pes of a sub-adult individual.