Livyatan melvillei
Livyatan
- Pisco Formation ( Peru)
- Livyatan melvillei
Livyatan is an extinct sperm whale genus from the middle Miocene epoch, 13-12 million years ago. The only previously known species, Livyatan melvillei, was described in 2010 based on an image obtained 75% of the skull and lower jaw with teeth of an occupied front part. The fossils were found in 2008 in the Pisco Formation in the southern Peru ( 35 km southwest of Ica ).
The genus was named after the mythological sea monster Leviathan and biblical- type Livyatan melvillei after the author of the novel Moby Dick, Herman Melville named. Since the genus name Leviathan had already been introduced in 1841 (now considered a synonym for the genus Mammut Blumenbach, 1799), the genus name has been changed from the descriptors little later in the Hebrew form Livyatan.
Features
The skull has a length of three meters and is 1.9 meters wide at its widest point, the teeth in the upper and lower jaws reach a diameter from 8.1 to 12.1 centimeters and a maximum length of 36 centimeters. They are the largest teeth of a tetrapod that has ever been found. In each ramus (dental ) there are eleven deep alveoli (alveoli ), in each maxilla nine. The premaxilla is edentulous. With the exception of some individuals of the dwarf sperm whale Livyatan had so by all sperm whale relatives few teeth.
The muzzle is short and only slightly longer than the back skull. It is wide at the base and tapers to. A large concave structure on the front of the skull Livyatan could have included a filled with spermaceti organ. The cranial window is very large and very different from the smaller cranial window of the sperm whale. The total length of the whale is estimated to be 13.5 to 17.5 meters. He was thus the largest sperm whale relatives found so far.
Ecology
Because of the strong dentition, the researchers suggest that Livyatan melvillei similarly to the at the same time living large shark Carcharocles megalodon fed on larger vertebrates; among other large fish, seals and baleen whales. The Miocene formed a highlight for the diversity of the baleen whales, yet more than 25 genera are shown, and at the site of Livyatan more than 20 skeletons of a previously undescribed baleen whales of the family of Cetotheriidae were found. So Livyatan took a completely different ecological niche than the one -feeding of tiefseebewohnenden cephalopods sperm whale. With the end of the Middle Miocene climatic optimum biodiversity of the baleen whales went back and the predatory of large vertebrates sperm whale relatives died out. Their ecological role was later taken over by the killer whales of the dolphin family.
System
Livyatan melvillei is related to the recent sperm whale and dwarf sperm whale, but differs from the latter mainly by the dentate maxilla. The systematic position of Livyatan melvillei illustrated by the following cladogram:
Eudelphis †
Acrophyseter †
Zygophyseter †
Brygmophyseter †
Livyatan †
Placociphius †
Orycterocetus †
Physeterula †
Aulophyseter †
Sperm whale ( Physeter )
Aprixokogia †
Thalassocetus †
Scaphokogia †
Praekogia †
Dwarf sperm whales ( Kogia )