STL Science Center

STL Science Center

02 May 2012

Describing Tiny Dinosaurs

Admit it, you want one.
While Compsognathus roamed Europe a cousin in Sinosauropteryx was bouncing around in China. There were a number of anatomical differences, however, and additionally, a lot of strange things were found in the Sinosauropteryx fossils that have thus far been unearthed. In the list of anatomical differences the first thing that stands out is that the skull of Sinosauropteryx is about 15% longer than the femur whereas in Compsognathus the femur and the skull are about the same length. Secondly, the arms of Sinosauropteryx are shorter compared to their legs than the arms of Compys (sliding into "Jurassic Park" shortening of words, hope no one minds!). As we stated before, Sinosauropteryx had extremely long tails. In fact, the tail consisted of 64 caudal vertebrae, an enormous amount of vertebrae for such a small animal. They also had enormous hands which were about half as long as their feet and almost as long as their entire arms. Large first and second digits ended in large claws and were constructed of irregularly thick bones for fingers. Its teeth were even strange with the front teeth acting more as incisors while the further back in the mouth one goes we start to find teeth that are serrated as we expect in most theropods. This dinosaur was already a conundrum before the feather debate came about and erupted and certainly before traces of what are thought to be soft organs and last meals were found.

John Ruben described a pigmented smear within the rib cage of a Sinosauropteryx as the remnants of its liver and went on to describe the liver as existing in a crocodilian form which would have been used to help the animal breathe as a "hepatic piston." Another study determined that the flattened nature of the skeleton means this pigment could be any organ that had been squashed along with the skeleton and therefore identification was not possible. Additionally, pigmentation thought to represent the eye was found in the ocular cavity of the animal. Finding a dinosaur eye would be fantastic and I do not even know what it would mean for science right now. Additionally, there have been reported instances, though not highly publicly available, of the fossils being found with eggs in the body prior to laying and also with lizards in the stomach. Why these are not well known quite yet I cannot fully comprehend, but if the little flashes of information that I have seen about them is all true, these would be an amazing boon for the knowledge of this one genus at least. Part of the reason for this secretive nature may lie in the Chinese government, who, if they are hiding some fossil evidence, is acting like a bunch of hoodlums in depriving paleontologists the ability to study and disseminate information about the skeletons. I am not about to take on the Chinese today though!

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