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Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene 1] Representing the earliest cetacean radiation , they include the initial amphibious stages in cetacean evolution , thus are the ancestors of both modern cetacean suborders ...
The first branch contained ancestors of Cetacea; semi-aquatic protowhales such as Pakicetus in the group Archaeoceti, which developed into the exclusively aquatic ancestors of modern cetaceans. [28] One evolutionarily significant whale ancestor was the raoellid Indohyus, which was a Himalayas-dwelling, digitgrade omnivore roughly the size of a ...
The earliest known ancestor of arctic whales is Denebola brachycephala from the late Miocene around 9–10 million years ago. [55] A single fossil from Baja California indicates the family once inhabited warmer waters. [27] [56] [57] Acrophyseter skull. Ancient sperm whales differ from modern sperm whales in tooth count and the shape of the ...
Basilosaurus (meaning "king lizard") is a genus of large, predatory, prehistoric archaeocete whale from the late Eocene, approximately 41.3 to 33.9 million years ago (mya). First described in 1834, it was the first archaeocete and prehistoric whale known to science. [2] Fossils attributed to the type species B. cetoides were discovered in the ...
Ambulocetus (Latin ambulare "to walk" + cetus "whale") is a genus of early amphibious cetacean [a] from the Kuldana Formation in Pakistan, roughly 48 or 47 million years ago during the Early Eocene . It contains one species , Ambulocetus natans (Latin natans "swimming"), known solely from a near-complete skeleton.
Though the whale may have been primarily aquatic, the discovery of ankle bones lends to the idea that this fossil may have been a transition between sea-based and land-based mammals. While whales eventually returned to the sea, the anthracotheres, ancestors of the hippopotamus, are thought to have descended from an ancestor shared with the ...
About the size of a raccoon or domestic cat, this omnivorous pig-like creature shared some of the traits of whales, and showed signs of adaptations to aquatic life. Their bones were similar to the bones of modern creatures such as the hippopotamus , and helped reduce buoyancy so that they could stay underwater. [ 4 ]
They lived during the middle to the early late Eocene and are known from all continents, including Antarctica. [ 1 ] [ 2 ] They were probably the first fully aquatic cetaceans. [ 3 ] [ 4 ] The group is noted to be a paraphyletic assemblage of stem group whales [ 5 ] from which the monophyletic Neoceti are derived.