STL Science Center

STL Science Center

21 January 2013

Dinosaurs Out of Motion

It is always somewhat sad when there is not any kind of video related to the dinosaur for the week. I even like seeing simple interviews with the people that described or discovered the skeleton; even when they are not very long or exceptionally informative. We shall trudge ever onward with only a few small tribute videos though and discuss something else today. The skeleton of Tyrannotitan is very unique in a number of ways that make it looks as though it fits into a number of differentin at this time  families. First there is the small tyrannosaur like arm and scapula that is built much like that of a tyrannosaur. The acromion process, a spur of bone where a number of muscles attach to the shoulder, is roughly perpendicular to the rest of the bone, a trait found more in tyrannosaurids than in the family in which Tyrannotitan is placed (Caracharodontosaurs). Much of the limbs and other bones found are in possession of characters which placed Tyrannotitan in the family it was placed in; however, there are many more differences that pull Tyrannotitan into its own classification away from Giganotosaurs, Carcharodontosaurs, and the Tyrannosaurs they are similar to in many aspects. The teeth are unique, the orbitals are unique (I want to save these for Wednesday) and there are other strange attributes to the skeleton in the vertebrae. The caudal vertebrae possess tall neural spines (in known caudal vertebrae) which would have made the tail rather deep at the base and potentially, as a result of the expanded space, quite muscular. Additionally, in the vertebral column, the sacral and caudal vertebrae lack pneumaticities, or small holes for air, or air sacs, in the centra of these vertebrae; Carcharodontosaurus and other members of the family possess vertebrae with pneumaticities in them in these parts of the body (tail and hips). Why these holes/sacs are absent from Tyrannotitan is not certain at this time given the lack of skeletal material attributed to the dinosaur, but perhaps in time that will change for the better.

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