two empty alveoli, four cervical vertebrae, three dorsal vertebrae and eight caudal vertebrae, a nearly complete pelvic girdle compromising both pubes, right ilium and right ischium, both femora and left tibia, left metatarsals III and IV, manual and pedal phalanges with some unguals, right scapulocoracoid, an isolated radius, two ribs, and caudal chevrons. It was collected and prepared by the assistant paleontologist, Namsarai Batulseen, and stored as MNUFR-15. Ten years later, the specimen was formally described in 1999 and became the holotype for the new genus and species Achillobator giganticus. It was identified as a dromaeosaurid taxon. The description was performed by Mongolian paleontologist Altangerel Perle and North American paleontologists Mark A. Norell and James M. Clark. In terms of etymology, the generic name, Achillobator, is derived from the Latin word "Achillis" (genitive singular of Achilles) in reference to the large Achilles tendon that supported the second pedal ungual (known as "sickle claw") of most dromaeosaurids, and the old Mongolian word "баатар" (baatar, meaning hero). However, the description was published in a very preliminary format, being not complete at all, having issues with preserved elements and numerous typographical errors. Due to a misinterpretation, the pedal ungual II (or sickle claw) was claimed to be preserved and to articulate with the pedal phalanx II, bit this was corrected by Senter in 2007 and this ungual actually represents a manual one. Turner and colleagues in 2012 during their large revision of the Dromaeosauridae stated that the describing paper of Achillobator was likely published without the knowledge of the two latter paleontologists as indicated by a draft left in Mongolia in 1997. In 1993 on August 13, a large dromaeosaur claw was found at the Burkhant locality, which is the type locality of Achillobator, by a Japanese-Mongolian joint paleontological expedition. Later in 2010, paleontologist Mahito Watabe and colleagues reported that additional postcranial elements remains were found, all of them belonging to a large-sized dromaeosaurid. In 2007 Mongolian paleontologist Rinchen Barsbold and team reported new dinosaur fossil findings at the Shine Us Khuduk locality of the Bayan Shireh Formation. Among elements, an isolated pedal phalange II-2 (second phalanx of the second digit of the foot) shares similar traits to that of Achillobator and "Troodon". The remains were discovered during excavations of the Mongolian Academy of Sciences in 2005 and 2006. Chimera hypothesis The pelvic girdle of Achillobator features plesiomorphic (primitive) saurischian characteristics compared to