Whale Fossils For Sale
MIOCENE to PLEISTOCENE PERIOD: 23.3 million - 10,000 years ago
Whales, dolphins and porpoises make up the group of air-breathing marine mammals called CETACEANS. Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. This group is comprised of three sub-groups - the extinct ARCHAEOCETI, and two living types, the ODONTOCETI (toothed whales) and MYSTICETI (baleen whales). All have a body structure that is highly adapted for their marine environment. These features include paddle-like forelimbs, lack of external hind limbs, large tail for propulsion underwater, dorsally located nostrils for breathing just above the surface of the water, specialized ears for underwater hearing and a streamlined body profile for efficient hydrodynamic locomotion. Odontocetes are more prevalent and varied than Mysticetes. All of the smaller current living whales (porpoises, orcas, narwhals, pilots, etc.) and a few of the larger ones (Sperm Whale) are toothed (Odontocetes). Mysticetes include the largest animal that ever lived on the earth, the Blue Whale. Whales split into two separate parvorders around 34 mya – the baleen whales (Mysticetes) and the toothed whales (Odontocetes).
Whales are creatures of the open ocean; they feed, mate, give birth, suckle and raise their young at sea. Whales range in size from the 2.6 metres (8.5 ft) and 135 kilograms (298 lb) dwarf sperm whale to the 29.9 metres (98 ft) and 190 metric tons (210 short tons) blue whale, which is the largest creature that has ever lived. The sperm whale is the largest toothed predator on earth.
Odontocetes, such as the sperm whale, possess teeth with cementum cells overlying dentine cells. Unlike human teeth, which are composed mostly of enamel on the portion of the tooth outside of the gum, whale teeth have cementum outside the gum. Only in larger whales, where the cementum is worn away on the tip of the tooth, does enamel show. Mysticetes have large whalebone, as opposed to teeth, made of keratin. Mysticetes have two blowholes, whereas Odontocetes contain only one.
All cetaceans are carnivorous with a main diet consisting of fish, invertebrates and other marine mammals. Many cetacean fossils are found in sediments alongside fossil shark teeth and other marine vertebrates but whale fossils are much less common compared to other marine vertebrate fossils of the same period and region and whale fossils are often found in fragments or show evidence of predation by prehistoric sharks, no doubt, cetaceans most feared enemy in their prehistoric past.