Saturday, 27 March 2010

The mystery of the horned Oviraptor, yet another Theropod that has changed dramatically

Above; a currently up to date image of Oviraptor.

Oviraptor means egg thief. Quite a demeaning name for such a noble looking beast. This animal was tall and parrot like, probably coated in feathers like its relatives and was was an intelligent beast with long and nimble hands that allowed it to manipulate food with dexterity. It is seen as a swift and fast eagle eyed predator that used its crushing beak to crunch the bones of small critters such as monitor lizards and Multituberculates that attempted to steal its eggs.
Above; the hideous, scabby egg theif Oviraptor with horrrible green scaly skin and a demon like horn plunders an undefended nest!

The name originates from the fact that an Oviraptor skeleton has been found near a clutch of eggs, possibly those of Protoceratops. Immediately the palaeontologists concluded that this animal was attempting to steal these eggs for food, but. Later on in the 1990's a skeleton of Oviraptor's close relative Citipati was found fossilised in a brooding position over the same type of egg. Rather than being an egg thief Oviraptor was an egg protector.

Above; two completely opposite views of Oviraptor: Top; a horned Oviraptor runs away with an egg, followed by a furious mother. Bottom; a chrested Oviraptor broods its chicks and gaurds its nest full of eggs.

Anyway back to the mystery of the horned Oviraptor. Right up to the 1990's text books show Oviraptor and on occasion its close relatives with a horn on its nose and a strangely long face despite discoveries that its relatives had tall faces with a plate like crest sticking out of the skull above the eyes. Nowadays all Oviraptor reconstructions portray it as a crested animal rather than with a horn and this made me wonder; "why do some books show Oviraptor with a crest and others horned?". Clearly there was something going on and I needed to find out why there were such inconsistencies in Oviraptor reconstructions.
Above; AMNH 6517.

When you look at the type specimen of Oviraptor (AMNH 6517) the answer is clear. On an expedition lead by Roy Chapman Andrews in 1924 a crushed skull was discovered 4 inches from an alleged "Protoceratops" nest. The skull is clearly damaged and fragmentary, no wonder the light hollow crest was not present. As one of the most delicate skull features it would have been the first to erode. Even so a small portion of the crest was present above the tip of the snout, enough to convince Henry Farefield Osborn (the original describer of Oviraptor) that this "horn" was a distinctive feature.

Above; yet another horny Oviraptor!

As AMNH 6517 was the type specimen of Oviraptor most reconstructions of that time conformed to this single skull despite the fact that subsequent discoveries disproved the horn's existence and for a century the familiar yet inaccurate horned Oviraptor can be found prowling the pages of dinosaur books to this very day.

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