Friday, 26 March 2010

Megaraptor; a dinosaur that has changed more in the last decade than Allosaurus has in the last century!

Above; Megaraptor's huge 30 cm claw in the hands of its discoverer Fernando E Novas!
Megaraptor is perhaps the coolest of dinosaurs and even though it has changed identities so many times the sight of a 30cm claw still sends shivers down my spine! However it is the mystery surrounding this beast that fascinates me most!

Above; Megaraptor as, well..... a Raptor.

First discovered and described by Fernando E Novas from the late Cretaceous of Argentina Megaraptor boomed into the media as the largest Dromaeosaur (Raptor) dinosaur ever found and was calculated to be a staggering 8 meters in length.

Above; Megaraptor as a Spinosaur.

Subsequently the Dromaeosaur status of Megaraptor looked bleak as it was soon found that the huge raptorial killing claw was on the hand, not the foot as in true Raptors (ironically later on in 2009 a true giant Raptor Australovenator was discovered from the same area as Megaraptor). Scientists noted similarities with Spinosaurids and indeed some reconstructions show Megaraptor as a Spinosaur. The similarities include the powerful arm and huge claw, but here the similarity ends.

Above; Australian Megaraptor arm.
At around the same time Megaraptor like arm bones with the complimentary claw were found in Australia, showing that these dinosaurs were very widespread in the southern continents.

Above; Australovenator fills in all the gaps.

Finally a discovery from Australia described in 2009 cleared up the mess. Australovenator was a smallish Carnosaur similar to Charcharadontosaurids, but was certainly unique. And guess what was on the tip of its thumb; a huge scythe like claw. We now know that Australovenator was a relative of Megaraptor and thanks to its complete remains many other mystery therapods have been reclassified in a new family; Neovenatoridae. This group includes Neovenator from Europe, Megaraptor from Australia and South America, Australovenator from Australia and Fukuiraptor from Japan. In fact this family spanned the entire Cretaceous period, thats a full 80 million years and is just under half the time the dinosaurs had been around for in total.

Above; Fukuiraptor was the earliest Neovenatorid from the early Cretaceous (top), Neovenator (upper middle), Orkoraptor the latest Neovenatorid from the late Cretaceous (lower middle) and Megaraptor with its Carnosaur makeover (bottom).

Yet another mysterious carnivore has been placed firmly into the dinosaur family tree thanks to new discoveries. Hopefully the mystery surrounding such enigmas as Valdoraptor and Beckelspinax will be resolved in later years.

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