Teen Pregnancy Considered Normal

January 15th, 2008

A recent report out of Berkely confirms that dinosaurs had high rates of teen pregnancies. Dinosaurs descended from reptiles and evolved into today’s birds, but their growth and sexual maturation were more like that of mammals - complete with teen pregnancy, according to a new study by University of California, Berkeley, scientists.

The conclusion, reported the week of Jan. 14 in the online early edition of the journal Proceedings of the National Academy of Sciences, comes from an analysis of the only three dinosaur fossils that have been definitively identified as female. Thin slices of these dinosaurs’ fossil bones all show an internal structure similar to tissue found in living female birds - a layer of calcium-rich bone tissue called medullary bone that is deposited in the marrow cavity just before egg-laying as a resource for making eggshells.

Tenontosaurus lived in North America during the Early Cretaceous period, 125 to 105 million years ago, and was an ancestor of the duck-billed dinosaurs. A common plant eater, it is known for its long tail that made the dinosaur up to 27 feet long when walking on four legs. Because fossils of these one- to two-ton beasts are common in Oklahoma, Werning was able to obtain many fossil bone slices from the Oklahoma Museum of Natural History. Both a femur (thigh bone) and a tibia (shin bone) from the same fossilized Tenontosaurus showed medullary bone, while growth rings in its bones indicated the pregnant dinosaur was eight years old. As the father of a pre-teen girl this article caught my eye.

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