Biology:Parapontoporia
Parapontoporia is an extinct genus of lipotoid dolphin that lived during the Late Miocene to the Pliocene epochs. This genus can be found attributed across the North American coast of the Pacific Ocean. Fossils have been found in Tulare Formation of California and the Almejas Formation of Mexico.[1][2]
Taxonomy
Parapontoporia is a member of the family Lipotidae meaning that it is closely related and likely a sister taxon to the baiji (Chinese river dolphin). Within this genus there are three species; P. pacifica (type species), P. sternbergi and P. wilsoni.[2][3]
Distribution
Parapontoporia is widely distributed across the Pacific coast of North America being found in numerous marine formations. This area includes California, Baja California and possibly Japan.[3]
They first appeared during the late and middle Miocene epoch with this genus during the Neogene becoming one of the most abundantly found genus of odontocetes from the eastern North Pacific. It went extinct during the Pliocene.[1][3]
Description
It was a diminutive genus.
The morphology of the cochlea of Parapontoporia is similar to other species of toothed whales and similar between the three species. All species have approximately two turns with relatively wide inter-turn distances (0.752 to 1.26 mm) similar to the Irrawaddy dolphin and the melon-headed whale. It has a thin canaliculi cochleae and relatively thin, short canals leading to the fenestrae cochleae. The cochlear hook, starting at the fenestra cochleae, is short and wide resembling that of delphinids. This hook leads to the scala tympani which has a wide base but narrows as it reaches the apex of the cochlea.[1]
Ecology
This genus was probably inhabiting primarily shallow marine environments.[4] However fossil material of Parapontoporia have been found in the upper Tulare Formation, central California which has a mix of terrestrial vertebrate fossils suggesting that this formation is predominately freshwater. This suggests that it did not excessively inhabit a single habitat and may have been tolerant of both salt, fresh and brackish water conditions.[3][1]
Parapontoporia was likely to have been able to echolocate and hear within narrow-band high frequencies (NBHF) with some species of this genus being NBHF specialist. It is hypothesized that this may have evolved in Parapontoporia to navigate transitional habitats such are rivers.[1]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Barnes, L.G. (July 1984). "Fossil odontocetes (Mammalia: Cetacea) from the Almejas Formation, Isla Cedros, Mexico". PaleoBios 42: 1–46. http://docubase.berkeley.edu/cgi-bin/pl_dochome?query_src=pl_search&format=pdf&collection=PaleoBios_Archive_Public&id=57&show_doc=yes.
- ↑ 2.0 2.1 The Paleobiology Database
- ↑ 3.0 3.1 3.2 3.3 Boessenecker, Robert W.; Poust, Ashley W. (2015). "Freshwater occurrence of the extinct dolphin Parapontoporia (Cetacea: Lipotidae) from the upper Pliocene nonmarine Tulare Formation of California". Palaeontology 58 (3): 489–496. doi:10.1111/pala.12153. Bibcode: 2015Palgy..58..489B.
- ↑ Borce, A. (2018). Cranial anatomy and systematics of the extinct river dolphin Parapontoporia and reconstruction of ancestral habitat of odontocete cetaceans. Masters Thesis. San Diego State University.
Template:Odontoceti Wikidata ☰ Q618357 entry
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