Achillobator

Fossils of Achillobator (a small dromaeosaurid related to Velociraptor) were first discovered during a Mongolian and Russian field expedition, and collected by Burkhant in 1989, but the specimen was not described and named until 1999, by Mongolian paleontologist Altangerel Perle, and American paleontologists Mark Norell and Jim Clark, although the description was not complete and was actually published without the knowledge of the latter two paleontologists. The fossils of the type specimen of Achillobator, FR.MNUFR 15, were found associated but mostly disarticulated, and include a left maxilla with teeth, two cervical vertebrae, two dorsal vertebrae, rib fragments, seven caudal vertebrae, a scapula and coracoid, a pelvis with a right ilium, pubis and ischium, a radius, an incomplete manus, a left femur and tibia, and an incomplete pes. Smith at al. (2012) noted that this genus represents the second largest of the known dromaeosaurid taxa with a tibial length of 490 mm. Its femur, which is 3% longer than the tibia, a rare trait in Dromaeosaurs, measures 505 mm in length. Estimates suggest that Achillobator weighed 350 kg (771.6 lb) at most. The teeth are serrated and recurved, and the posterior serrations are slightly larger than the anterior serrations.

The genus name Achillobator means 'Achilles hero' and is derived from Achilles, a famous ancient Greek warrior who fought in the Trojan War, and the Mongolian word baatar, anciently bagatur, which means 'hero'. The generic name refers to the large Achilles tendon that connects to the sickle claw on the foot, which was the major combat weapon of dromaeosaurids. The specific name giganticus, is derived from Greek word gigantas (γίγαντας) meaning 'giant', which is in reference to Achillobator's size, which exceeds that of most other dromaeosaurids.