Aucasaurus garridoi

An abelisaurid, one of the short-armed, predatory theropods from the Late Cretaceous of Argentina. Known from a single, relatively complete skeleton, we know this mid-sized relative of Carnotaurus grew to around 6.5 meters (20 feet) and weighed as much as a large polar bear (~700 kg, or 1,500 pounds).

The tiny arms are so reduced they could not have been of much use for hunting, but whether they were largely vestigial or were used for display is not currently known.