Original Scientific Articles

Evolution: Education and Outreach

, Volume 2, Issue 2, pp 272-288

Open Access This content is freely available online to anyone, anywhere at any time.

From Land to Water: the Origin of Whales, Dolphins, and Porpoises

  • J. G. M. ThewissenAffiliated withDepartment of Anatomy and Neurobiology, Northeastern Ohio Universities College of Medicine Email author 
  • , Lisa Noelle CooperAffiliated withDepartment of Anatomy and Neurobiology, Northeastern Ohio Universities College of MedicineSchool of Biomedical Sciences, Kent State University
  • , John C. GeorgeAffiliated withDepartment of Wildlife Management, North Slope Borough
  • , Sunil BajpaiAffiliated withDepartment of Earth Sciences, Indian Institute of Technology

Abstract

Cetaceans (whales, dolphins, and porpoises) are an order of mammals that originated about 50 million years ago in the Eocene epoch. Even though all modern cetaceans are obligate aquatic mammals, early cetaceans were amphibious, and their ancestors were terrestrial artiodactyls, similar to small deer. The transition from land to water is documented by a series of intermediate fossils, many of which are known from India and Pakistan. We review raoellid artiodactyls, as well as the earliest families of cetaceans: pakicetids, ambulocetids, remingtonocetids, protocetids, and basilosaurids. We focus on the evolution of cetacean organ systems, as these document the transition from land to water in detail.

Keywords

Dolphins Whales Porpoises Evolution Cetacea Mammals