Modern American Alligator

Story

The Florida Museum of Natural History has one of the largest collections of amphibians and reptiles of any museum in the United States. And this includes a large collection of their skeletons as well. Being in the heart of alligator country, this collection includes a large number of skeletal specimens of American Alligators. The large size of this collection makes this a valuable resource for research.

We’ve been able to study variation in the structure of alligator skulls and the changes in skulls that occur as alligators grow. What we have learned from these studies has helped us better understand the differences we see in American Alligators and in their fossil ancestors.

Bones can tell stories. The long bones in the arms and legs of alligators can be used to determine the age of the specimen at death. If you cut a thin section through the middle of the femur, that long bone in the upper part of the hind leg, it’s possible to see rings in the bone development under a microscope. Each ring represents the growth that occurred during the warm, wet summer and each is distinct from the next because of reduced growth in the fall months followed by the winter dormant season. So, you can count these rings to estimate the age of the alligator, just as you can count the rings in the trunk of a tree.

This information learned from alligator bones has been used by biologists to estimate the age of individual dinosaurs, like T. rex, at the time of their deaths and to understand that dinosaurs became so big by growing very quickly for many years.

Kent Vliet
Coordinator of Laboratories, Biology Department
Alligator and Crocodile Biologist
University of Florida