Fossil cetaceans

The fossils in this picture comprise the skull, pelvic bones, a few vertebrae, and hind limb bones of two organisms that have been presented as a part of an evolutionary sequence leading from terrestrial mammals to whales. Number 1 in the foreground is Rhodocetus, number 2 in the background is Basilosaurus. The specimens, on display at the Chicago Field Museum of Natural History, are meant to convey to the observer the concept of progressive adaptation to a fully aquatic behavior. However, inferences about the relation of past life forms should be introduced with awareness of the fragmentary nature of the fossil record.

Cetaceans mammals evolutionary series