Whales, dolphins, and porpoises are collectively known as Cetaceans. The Cetaceans are fully marine mammals that have completely lost the ability to come onto land, of which the fossil record has shown this transition in its entirety. The oldest Cetacean fossils known come from a small creature in Pakistan called Pakicetus, which date to the Eocene epoch, approximately 50-48 million years ago. Pakicetus and its kin superficially resembled wolves, though spent most of their time in and around fresh water environments. In time, more forms would evolve, such as the fully marine Cetaceans called the Basilosaurids of the late Eocene, approximately 41-35 million years ago. Basilosaurids would be a hallmark in Cetacean evolution, as the original hoofed hindlimbs of their ancestors were now small, vestigial flippers. Cetaceans of today have completely lost their hind limbs, which have been reduced to rudimentary dwarfed femurs that exist within the body, but are not attached to the skeleton. Within 15 million years, Cetaceans had completely evolved from being small and terrestrial, into ocean-going giants. Today, there exists two varieties of Cetaceans, the Odontids (toothed whales including sperm whales, dolphins, and porpoises), and the Mysticetids (filter-feeding baleen whales). Baleen whales possess plates of stiff, hair-like keratin in the upper jaw, with which they use to filter feed zooplankton, while toothed whales actively hunt fish, squid, seals, or other whales, depending on the species. Toothed whales do most of their hunting by means of echolocation, in which they emit sounds that bounce off of the whale's surroundings, which then return to the whale, and then is interpreted by the whale as being prey or non-prey items. Cetaceans also use sounds to communicate amongst each other, including clicks, moans, whistles, and "songs." From their inconspicuous dog-like ancestors of prehistory, Cetaceans would become the dominant mammals of the oceans, even evolving into the largest animal of modern times, the 100 ft. blue whale.
-Size: 4&3/8"L x 2&1/2"W x 3&1/2"H -Species: species undetermined -Notes: A good example of a prehistoric whale vertebra. Personally excavated by the Darwin and Wallace team. -Age: Miocene Epoch, 23-5 million years ago -Location: Interbedded sediments of Peace River, Florida