Liolithax

Liolithax is an extinct genus of dolphin from the Middle Miocene (Serravallian) Temblor Formation of California.

Liolithax
Temporal range: Middle Miocene, 13–11 Ma
↓
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: †Kentriodontidae
Subfamily: †Kentriodontinae
Genus: †Liolithax
Kellogg, 1931
Type species
Liolithax kernensis
Kellogg, 1931
Other species
  • ?Liolithax pappus (Kellogg, 1955)

Taxonomy

Liolithax kernensis, described by Remington Kellogg on the basis of the periotic CAS 4370 in 1931,[1] was considered the only species of the genus until Barnes (1978) reassigned "Lophocetus" pappus to Liolithax based on similarities between the holotype periotic of L. kernensis and the periotic of L. pappus. Liolithax was grouped in Kampholophinae with Kampholophos by Barnes (1978, 1985).[2][3]

The discovery of a skull from middle Miocene deposits in Baja California, Mexico cast doubt on the congenericity of "Lophocetus" pappus with the Liolithax type species by including a petrosal more similar to L. kernensis than to the petrosals included in the skulls of pappus.[4] In a 2008 SVPCA abstract, Lawrence Barnes and colleagues noted that the Baja California skull differed from "Lophocetus" pappus in having a smaller tooth diameter, a more slender rostrum, and smaller size. They classified Liolithax in Kentriodontinae while stressing that "Lophocetus" pappus is a lophocetine in need of a new generic name.[5] The cladistic analysis of Brujadelphis by Lambert et al. (2017) recovered "Lophocetus" pappus (as Liolithax pappus) as sister to Lipotidae, but did not test the phylogenetic relationships of Liolithax kernensis relative to Lipotidae, Iniidae, or other kentriodontids.[6] It is therefore possible that "Lophocetus" pappus could be an early relative of the baiji.

References
  1. Kellogg, R. 1931. Pelagic mammals from the Temblor formation of the Kern River region, California. Proceedings of the California Academy of Sciences, Series 4, 19 , 217-397.
  2. L. G. Barnes. 1978. A review of Lophocetus and Liolithax and their relationships to the delphinoid family Kentriodontidae (Cetacea: Odontoceti). Bulletin of the Natural History Museum of Los Angeles County 28:1-35
  3. L. G. Barnes. 1985. The Late Miocene dolphin Pithanodelphis Abel, 1905 (Cetacea: Kentriodontidae) from California. Contributions in Science 367:1-27.
  4. Flores-Trujillo, J.G., Aranda-Manteca, F.J., & Barnes, L.G. 2000. Identificación del delfín fósil del Mioceno Medio, Liolithax kernensis Kellogg 1931. [The identity of the fossil Middle Miocene dolphin, Liolithax kernensis Kellogg 1931.] Programa y Resúmenes, XXV Reunión Internacional para el Estudio de los Mamíferos Marinos, Sociedad Mexicana de Mastozoología Marina, La Paz, Baja California Sur, México, 7–11 May 2000, p. 4.
  5. http://svpca.org/years/2008_dublin/abstracts.pdf
  6. Olivier Lambert, Giovanni Bianucci, Mario Urbina, Jonathan H. Geisler; A new inioid (Cetacea, Odontoceti, Delphinida) from the Miocene of Peru and the origin of modern dolphin and porpoise families. Zool J Linn Soc 2017; 179 (4): 919-946. doi: 10.1111/zoj.12479. https://academic.oup.com/zoolinnean/article/179/4/919/3076080/A-new-inioid-Cetacea-Odontoceti-Delphinida-from?guestAccessKey=3b956b95-d215-488a-8d90-1cff59554290#63703008
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