Megaraptor

Megaraptor Temporal range: Late Cretaceous,91–88 Ma PreЄ Є O S D C P T J K Pg N ↓
Claw cast with a ruler for scale
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Clade:	†Megaraptora
Genus:	†Megaraptor Novas, 1998
Species:	†M. namunhuaiquii
Binomial name
Megaraptor namunhuaiquii Novas, 1998

Megaraptor ("giant thief") is a genus of large theropod dinosaur that lived in the Turonian to Coniacian ages of the Late Cretaceous. Its fossils have been discovered in the Patagonian region of Argentina. Initially thought to have been a giant dromaeosaur-like coelurosaur, it was classified as a neovenatorid allosauroid in previous phylogenies, but a more recent phylogeny has placed it as a basal tyrannosauroid coelurosaur. The discovery and phylogeny of Gualicho suggests that Megaraptor is either an allosauroid or basal coelurosaur.

Megaraptor was initially described as a giant dromaeosaur, known primarily from a single claw (about 30 cm long) that resembled the sickle-shaped foot claw of dromaeosaurids. The discovery of a complete front limb, however, showed that this giant claw actually came from the first finger of the hand. In 2010, Gregory S. Paul estimated its length at eight metres, its weight at one tonne. The hands were unusually elongated, bearing sickle-shaped claws even more recurved than those of spinosaurids.

The hand is quite distinct from other basal tetanurans, so it was not initially clear whether Megaraptor was an allosaurid, a carcharodontosaurid, a spinosauroid, or something else entirely. Subsequent studies, as well as the identification of close relatives with similar large claws on the forelimbs (see below), helped identify Megaraptor as a highly advanced and lightly built allosauroid, and a member of the family Neovenatoridae. More recent studies have proposed that Megaraptor and its kin are actually tyrannosauroids or spinosauroids as opposed to allosauroids. A juvenile specimen described in 2014 has provided more evidence towards Megaraptor being a primitive tyrannosauroid. The discovery of Gualicho indicates that Megaraptor may not be a tyrannosauroid, but either an allosauroid or basal coelurosaur.