Rapator

Rapator is a genus of carnosaurian dinosaurs from the Griman Creek Formation of New South Wales, Australia, dating to the Aptian age of the early Cretaceous period, 105 million years ago.[1] It contains only the type species, Rapator ornitholestoides, which was originally named by Friedrich von Huene in 1932.

Description
The holotype and only known specimen, BMNH R3718, consists of a single left hand bone, discovered around 1905 near Wollaston, on the Lightning Ridge.[3] The fossil has been opalised.[3] The bone has a length of seven centimetres.[2] This manual element shows a prominent dorsomedial process, a feature shared with the much smaller Ornitholestes which occasioned the specific name.[3] The process with Ornitholestes is much less distinctive though.[3] On its upper end there is only one cotyle, from which von Huene deduced it must have been a metacarpal.[2] However, several coelurosaurian groups lack a second cotyle on the first phalanx also. If Rapator had a build like Australovenator, it would have attained a considerable size: a body length of 9 metres (30 ft) has been estimated.

Classification
The type specimen of Rapator was originally described as a metacarpal I, a bone from the upper part of a theropod's hand.[2] It was later noted that the bone is similar to a finger bone, the first phalanx of the first finger, of an alvarezsaur[4] or of a primitive coelurosaurian similar to 'Nqwebasaurus.[5] With the discovery of Australovenator, which had a similar metacarpal, Rapator'' was recognized as a probable megaraptoran. In fact, Australovenator and Rapator differ only in some small details of the bone and may be synonyms, though Agnolin and colleagues in 2010 considered Rapator a dubious genus (nomen dubium) due to its fragmentary nature.[6] However, White et al. found differences between the hand bone of Rapator and the equivalent bone of Australovenator, supporting the distinction between the two. They also noted that the two genera come from formations separated chronologically by about 10 million years, making them unlikely to be synonymous.[1]

Rapator has been synonymised with Walgettosuchus, a theropod found in the same formation.[7] As the latter is only known from a caudal vertebra, the identity cannot be proven.