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Dinosaurs and Birds - The Link Between Them

Little Clint 2007 Fact Sheet

Did we return to the Little Clint site?
Yes, we went back to the Little Clint site because we suspected that more bones of the dinosaur would be in the ground. We thought this because the original discovery included four bones found in association (deposited together) on top of a distinct layer of rock. We only excavated a square meter of sandstone, and it was clear that the underlying rock layer continued into the hill. Therefore, it was reasonable to assume that there would be more bones scattered at that level.

Did we find more bones of Little Clint?
Yes! We found three new bones and more fragments of the tibia (shin bone) we collected in 2006. The new bones include (1) a rib from the thorax; (2) a radius, the thin bone of the forearm; and (3) the top end of the left femur (thigh-bone). The fragments of the tibia have been glued together with the rest of the bone.

Is the excavation finished?
No, we didn’t have enough time in 2007 to finish the excavation, so we will complete it in the summer of 2008. We expect to find several more bones because last summer’s excavation revealed that Little Clint’s bones are scattered over a wide area. This scatter leads toward a much larger dinosaur, probably a hadrosaurid (duckbilled dinosaur), several meters away. This excavation will probably be the focus our entire expedition, because we will have to remove an entire hill to get to the bone layer.

What new things have you learned about Little Clint?

1) Last fall Dr. Carr took Little Clint’s femur to the Burpee Museum of Natural History (Rockford, IL) to compare it with Jane’s (a 21-foot subadult T. rex). It turned out that Little Clint’s femur is half the size of Jane’s. Therefore, it is reasonable to expect that Little Clint was no more than 11 feet long when it died.

2) The incomplete and scattered condition of Little Clint and the duckbill indicate they were deposited together at the same time. The skeletons were probably complete before the flowing water of a river moved them, which rapidly lost velocity. The skeletons were moved some distance because none of the bones are in articulation (in life position) and many of them are damaged from transport.

What research is being done on Little Clint?
Dr. Carr will include Little Clint in an exhaustive study of growth in T. rex that he has in progress. In January 2008 he will take Little Clint’s tibia to the Museum of the Rockies (Bozeman, MT), where a piece of it will be thin sectioned by Dr. Jack Horner. The purpose of this destructive procedure is to count the growth rings in the bone. Like many dinosaurs, T. rex deposited annual layers of bone that can be counted like tree rings. For the rings to be seen, a thin slice of bone must be ground down until light can pass through it. The number of rings corresponds to the amount of time the animal was alive before it died.

How old do you expect Little Clint will be?
The size of Little Clint, and the development of its bones, indicates that it is the youngest T. rex (with skull and postcranial bones) ever found. To test this hypothesis, Little Clint will have its growth rings counted. So far the youngest T. rex, where the rings are counted, is 2.5 years old. That specimen is larger than Little Clint, so we predict that it will be less than 2.5 years old, but greater than one year old because it needed enough time to grow from about one meter (the size a T. rex hatchling might have been) to three meters.