Achillobator

Achillobator ( ; meaning "Achilles hero") is a genus of large dromaeosaurid theropod dinosaur that lived during the Late Cretaceous period about 96 million to 89 million years ago in what is now the Bayan Shireh Formation of Mongolia. The genus is currently monotypic, only including the type species A. giganticus. The first remains were found in 1989 during a Mongolian-Russian field expedition and later described in 1999. Remains at the type locality of Achillobator may represent additional specimens. It represents the first and largest dromaeosaurid known from the Bayan Shireh Formation.

It was a large, heavily-built, ground-dwelling, bipedal carnivore that would have been an active feathered predator hunting with the enlarged sickle claw on each second toe. Measuring around long and weighing between , Achillobator is considered to be one of the largest dromaeosaurs, along with Austroraptor and Utahraptor. Achillobator was a deep-bodied and relatively short-armed dromaeosaurid with stocky and robust legs. Some of the most notable features consisted in the robustly built skeleton—an unusual trait in dromaeosaur dinosaurs, which were generally lightly built animals—such as the deep maxilla and femur, along with the primitive pelvis, having a vertically oriented pubis that differs from most other dromaeosaurids.