Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls

Article Abstract:

Research is presented concerning the discovery of two types of early fossil cetaceans from the Eocene period which have revealed that the ancestors of modern whales were able to run efficiently on the land and were not amphibious.

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Origin of underwater hearing in whales

Article Abstract:

The fossil whale Pakicetus possesses a hearing organ which indicates the evolution of underwater hearing in modern whales. Sound traveled to the ear of the Pakicetus along its mandible and incus similar to how sound was transmitted in land mammals. The Pakicetus is an intermediate species between cetaceans and land mammals, and its fossils indicate it was amphibious and related to artiodactyls such as camels, pigs and ruminants.

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Evolution of cetacean osmoregulation

Article Abstract:

The adaption of the cetacean osmoregulatory system to seawater took place during the Eocene period and the mammals moved away from the coasts into the deep oceans. Unlike most mammals, cetaceans ingest seawater and can survive without fresh water. Early cetaceans represented by Ambulocetus, lived in marine environment but depended partially on fresh water. Evaluation of oxygen isotope composition of phosphate in teeth of cetacean fossils enables the detection of the origin of adaption to seawater.

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