Basilosaurus
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Basilosaurus Temporal range: Late Eocene |
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| B. cetoides, National Museum of Natural History, Washington DC | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Infraorder: | Cetacea |
| Family: | †Basilosauridae |
| Subfamily: | †Basilosaurinae |
| Genus: |
†Basilosaurus Harlan 1834 |
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Basilosaurus ("king lizard") is a genus of early whales that lived 40 to 34 million years ago in the late Eocene. The first fossil of B. cetoides was discovered in the United States and was initially believed to be some sort of reptile, hence the suffix -"saurus", but it was later found to be a marine mammal.Richard Owen wished to rename the creature Zeuglodon ("yoked tooth"), but, per taxonomic rules, the creature's first name remained permanent. Fossils of B. isis have been found in Egypt and Jordan.
The species B. cetoides is the state fossil of Mississippi and Alabama.
Measuring 15–18 m (49–59 ft),Basilosaurus cetoides is one of the largest known animals to exist from K/T Extinction Event 66 million years ago to around 15 million years ago when modern cetaceans began to reach enormous sizes.B. isis is slightly smaller than B. cetoides.
The dental formula for B. isis is 3.1.4.23.1.4.3. The upper and lower molars and second to fourth premolars are double-rooted and high-crowned.
The head of Basilosaurus did not have room for a melon like modern toothed whales, and the brain was smaller in comparison, as well. They are not believed to have had the social capabilities of modern whales.
Fahlke et al. 2011 concluded that the skull of Basilosaurus is asymmetrical like in modern toothed whales, and not, as previously assumed, symmetrical like in baleen whales and artiodactyls closely related to cetaceans. In modern toothed whales, this asymmetry is associated with high-frequency sound production and echolocation, neither of which is thought to be present in Basilosaurus. This cranial torsion probably evolved in protocetids and basilosaurids together with directional underwater hearing and the sound-receiving apparatus in the mandible (the auditory fat pad and the pan bone (thin portion of mandible).)
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