Alligator thomsoniAlligator thomsoni is an extinct species of alligator that existed during the Early Miocene period. Their range was principally in what is now known as Nebraska, United States.ClassificationAlligator thomsoni is a member of the subfamily Alligatorinae, within the larger family Alligatoridae. It is closely related to the living American alligator, as shown in the cladogram below:MeasurementsThe average measurement for the skull of a A. thomsoni is 363.0 x 223.0 in millimeters. Based on the length, the estimated body mass 67.8 kg.