Ambulocetus

Taxobox
name = "Ambulocetus"
fossil_range = Early Eocene

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image_width = 270px
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Cetacea
subordo = Archaeoceti
familia = Ambulocetidae
subfamilia = Ambulocetinae
genus = "Ambulocetus"
species = "A. natans"
binomial = "Ambulocetus natans"
binomial_authority = Thewissen et al., 1996

"Ambulocetus" ("walking whale") was an early cetacean that could walk as well as swim. It lived during early Eocene some 50-49 million years ago. It is a transitional fossil that shows how whales evolved from land-living mammals. Having the appearance of a 3 metre long mammalian crocodile, it was clearly amphibious, as its back legs are better adapted for swimming than for walking on land, and it probably swam by undulating its back vertically, as otters and whales do. It has been speculated that Ambulocetids hunted like crocodiles, lurking in the shallows to snatch unsuspecting prey. Chemical analysis of its teeth shows that it was able to move between salt and fresh water.

"Ambulocetus" did not have external ears. To detect prey on land, they may have lowered their heads to the ground and felt for vibrations.Scientists consider "Ambulocetus" to be an early whale because it shares underwater adaptations with them: it had an adaptation in the nose that enabled it to swallow underwater, and its periotic bones had a structure like those of whales, enabling it to hear well underwater. In addition, its teeth are similar to those of cetaceans.

The "Ambulocetus" fossils were found in Pakistan by anthropologist Johannes Thewissen. When the animal was alive, Pakistan was a coastal region bordering the ancient Tethys Sea.

See also

* Evolution of cetaceans

References

*

External links

* [http://www.bbc.co.uk/nature/wildfacts/factfiles/432.shtml BBC Online]
* [http://www.neoucom.edu/DEPTS/ANAT/Thewissen/whale_origins/whales/Ambulocet.html Ambulocetidae: The First Costal Whales] by J. G. M. Thewissen.