Megaraptor

Hypothetical life restoration of an adult

Megaraptor head reconstruction based on the juvenile skull

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.[2] 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 8 metres (26 ft), its weight at 1 tonne (2,200 lb).[5] The hands were unusually elongated, bearing sickle-shaped claws even more recurved than those of spinosaurids.[6]

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.[3] 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.[7] More recent studies have proposed that Megaraptor and its kin are actually tyrannosauroids[8] or spinosauroids[9] as opposed to allosauroids.[8] A juvenile specimen described in 2014 has provided more evidence towards Megaraptor being a primitive tyrannosauroid.[10] The discovery of Gualicho indicates that Megaraptor may not be a tyrannosauroid, but either an allosauroid or basal coelurosaur.[11]

When first discovered and prior to publication, the spinosaurid Baryonyx was also reported to be a dromaeosaurid, and the allosauroid Chilantaisaurus was reported to be a possible spinosaurid, both based on the large hand claws.

Claw cast with a ruler for scale

The cladogram shown below follows an analysis by Porfiri et al., 2014.[12]

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