Tuesday, 17 January 2012

Feathers on your Tyrannosaurs

Life restoration of Dilong paradoxus
Ever since Archaeopteryx was discovered 150 years ago there has been speculation about the connection between dinosaurs and birds, this relationship has now become so well established that birds are considered to be a subset of dinosaurs.
During the 1990s this was further cemented by the find of many unusually well-preserved dinosaur fossils in the Chinese province of Liaoning that showed them to have feathers. The feathered dinosaurs found were small Theropods, and among them was an early member of the Tyrannosauridea.

The Emperor Dragon
The distant cousin of Tyrannosaurus rex found in china was Dilong (Di for emperor and long for dragon, a suffix often used for Chinese dinosaurs) an early member of the Tyrannosaurids. It was also quite small, with the adult size estimated to about 2 meters.
The feathers found on the Dilong fossil were different from the feathers found in modern birds and are better described as protofeathers, Wikipedia notes that "they could not have enabled flight". Which may seem superfluous as this animal had no wings, but it reinforces the notion that feathers were not originally developed for flight,
Most likely the protofeathers formed an insulating coat, similar to fur in mammals. 

Was T-Rex a big chicken?
It has often been suggested, generally firmly tongue-in-cheek, that Tyrannosaurus rex was akin to a big chicken (or turkey, depending on the season) because it is closely related to modern birds. 
So did T. rex have feathers as well? That question doesn't have a definite answer yet. 
Only a few skin imprints of Tyrannosaurs are known, and they all show scales. But they are only partial imprints. Tyrannosaurus may have had both scales and feathers, just like modern birds still have scales on their legs.
One hypothesis, derived from the fact that all feathered dinosaurs found so far are small Theropods, is that may not have needed feathers to keep warm. According to that hypothesis large Theropods like T. rex would not have had feathers, or only in their juvenile form when they were much smaller.

[image from Wikipedia]

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