Ambulocetidae
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| Ambulocetus natans | |
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Ambulocetidae
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Ambulocetidae is a family of early cetaceans from Pakistan that still were able to walk on land. The genus Ambulocetus, after which the family is named, is by far the most complete and well-known ambulocetid genus due to the excavation of an 80% complete specimen of Ambulocetus natans.[2] The other two genera in the family, Gandakasia and Himalayacetus, are known only from teeth and mandibular fragments.[3]
Description
The most basal of amphibious marine cetaceans, ambulocetids lived in shallow near-shore environments such as estuaries and bays, but were still dependent on freshwater during some stage of their life. Some of the characteristics related to sound transmission found in the lower jaws of modern whales that were absent in pakecetids are present in ambulocetids. They probably swam by paddling their large feet, which is not a very efficient mode of locomotion, suggesting they ambushed rather than chased prey. Ambulocetids had a narrow head with eyes facing laterally, giving them an appearance similar of theropod dinosaurs [4]
Ambulocetus and Gandakasia primarily ate terrestrial prey, while a combination of low oxygene isotope and high carbon isotope values suggests that Himalayacetus consumed freshwater but ate marine prey, thus that it foraged in a marine environment but returned on land to drink.[3]
Phylogeny
Ambulocetid fossils have been found in Pakistan along the former coastline of Cimmeria. The sedimentary facies in which these fossils were found indicates that ambulocetids inhabited a shallow, swampy near-shore marine environment.[5] They may have occupied a similar ecological niche to crocodilians.
The family is believed to have diverged from the more terrestrial Pakicetidae. The families Protocetidae and possibly Remingtonocetidae, are believed to have arisen from a common ancestor with ambulocetids.[6] Together with Basilosauridae, the five families are classified under the suborder Archaeoceti.[7]
See also
Notes
- ↑ Berta, Sumich & Kovacs 2006, p. 58
- ↑ Madar, Thewissen & Hussain 2002
- ↑ 3.0 3.1 Uhen 2010, pp. 201–3
- ↑ Thewissen & Williams 2002, pp. 78–80
- ↑ Heyning & Lento 2002, p. 54
- ↑ Thewissen 1998, p. 43
- ↑ Rose 2006, p. 273
References
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