Beluga Whale - Evolution

Evolution

Mitochondrial DNA studies have shown modern cetaceans last shared a common ancestor between 30 and 34 million years ago. The Monodontidae family separated relatively early from the other odontoceti; it split from the Delphinoidea family between 11 and 15 million years ago, and from the Phocoenidae, its closest relatives in evolutionary terms, more recently still.

The beluga's earliest known ancestor is the prehistoric Denebola brachycephala from the late Miocene period (9-10 million years ago). A single fossil from the Baja California peninsula indicates the family once inhabited warmer waters. The fossil record also indicates, in comparatively recent times, the beluga's range varied with that of the polar ice packs expanding during ice ages and contracting when the ice retreated. Counter-evidence to this theory comes from the finding in 1849 of fossilised beluga bones in Vermont in the United States, some 240 km (150 mi) from the Atlantic Ocean. The bones were discovered during construction of the first railroad between Rutland and Burlington in Vermont, workers unearthed the bones of a mysterious animal in the town of Charlotte. Buried nearly 10 ft (3.0 m) below the surface in a thick blue clay, these bones were unlike those of any animal previously discovered in Vermont. Experts identified the bones as those of a beluga. Because Charlotte is over 150 mi (240 km) from the nearest ocean, early naturalists were at a loss to explain the presence of the bones of a marine mammal buried beneath the fields of rural Vermont. However, the remains were found to be preserved in the sediments of the Champlain Sea, an extension of the Atlantic Ocean within the continent resulting from the rise in sea level at the end of the ice ages some 12,000 years ago. Today, the Charlotte whale aids in the study of the geology and the history of the Champlain Basin, and this fossil is now the official Vermont State Fossil (making Vermont the only state whose official fossil is that of a still extant animal).