Rapator

*Rapator ornitholestoides*

***Rapator*** is a species of Megaraptoran theropod dinosaur from the Griman Creek Formation of New South Wales, Australia, dating to the Albian age of the early Cretaceous period, 105 million years ago. It contains only the type species: Rapator ornitholestoides, which was originally named by Friedrich von Huene in 1932.

## Discovery

The holotype and only known specimen, **BMNH R3718**, consists of a single left hand bone, discovered around 1905 near Wollaston, on the Lightning Ridge. The fossil has been opalised. The meaning of the generic name is problematic. Von Huene gave no etymology. "Rapator" does not exist in Classical Latin and occurs only very rarely in Mediaeval Latin with the meaning "violator".

One possible explanation is that von Huene, having been influenced by Latin *raptare*, "to plunder", mistakenly thought such a word actually existed with the meaning of "plunderer". It has also been considered a simple misspelling of, or confusion with, raptor, "seizer" or "thief". The specific name means "resembling Ornitholestes". Remains of a megaraptorid, referred to by the public media as "Lightning Claw," discovered in opal fields southwest of Lightning Ridge, Australia, may well represent more material of *Rapator*.

## Description

The bone has a length of seven centimetres. This manual element shows a prominent dorsomedial process, a feature shared with the much smaller Ornitholestes which occasioned the specific name. The process with Ornitholestes is much less distinctive though.

On its upper end there is only one cotyle, from which von Huene deduced it must have been a metacarpal. 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 nine 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. It was later noted that the bone is similar to a finger bone, the first phalanx of the first finger, of an alvarezsaur or of a primitive coelurosaurian similar to *Nqwebasaurus*. 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. 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.

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

## JPInstitute.com Description

Rapator was a large meat-eater from Australia - maybe. To date, only one hand bone has been found, but it is enough for scientists to determine the basic type of dinosaur from which the bone came. This is a good example of how a little clue can provide a lot of information. Rapator was probably about as large as Allosaurus, but it isn't known if they were related.

Australia is not known for its dinosaur discoveries, so Rapator represents a rare and interesting bit of prehistory. It has been suggested that Rapator was a large ornitholestid, a carnosaur, or even a very large bird-like dinosaur. Some have envisioned this creature as feathered and belonging to the alvarezsauria.

## Links

http://web.archive.org/web/20040214171552fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_rapto.html