Trigonotodus

Trigonotodus Temporal range: early Eocene-late Oligocene 35–23 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Lateral tooth of Trigonotodus alteri
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	Lamniformes
Family:	Alopiidae
Genus:	Trigonotodus Kozlov, 1999
Type species
Trigonotodus tusbairicus Kozlov, 1999
Species
Trigonotodus aktulgaicus (Kozlov, 1999) Trigonotodus tusbairicus Kozlov, 1999 Trigonotodus alteri Kozlov, 2001

Trigonotodus is an extinct genus of sharks, most likely belonging to the family Alopiidae. This genus includes three extinct species, which span from the early Eocene to the late Oligocene. It was originally placed in the family Otodontidae, but subsequently found to have affinities with Thresher sharks.^[1] This genus is sometimes considered part of the genus Alopias.^[1] It is currently only known from isolated teeth.

Species

Species within this genera include:

Species	Notes	Images	Ref.
Trigonotodus aktulgaicus	Known primarily from the early Eocene of Kazakhstan. It is extremely similar to T. tushbairicus, and if not synonymous is likely its ancestor. It is also sometimes spelled T. aktulagaicus. Some scientists regard it as a Nomen nudum, early eocene species being called Trigonotodus cf. T. tushbairicus.		[2][3][1]
Trigonotodus tushbairicus	Known primarily from the middle Eocene of Kazakhstan. It is similar to other early threshers such as A. hermani and A. latidens in terms of size and robustness but has lateral cusplets. It is the type species of Trigonotodus.	Trigonotodus tushbairicus from the Middle Eocene of Kazakhstan	[4][1][3]
Trigonotodus alteri	Known primarily from the late Oligocene of South Carolina (Ashley Marl and Chandler Bridge Formations). It is commonly known as the Cusped Giant Thresher. May have one or two lateral cusplets. It is much larger than the other two.	Trigonotodus alteri lateral tooth (Oligocene, Chandler Bridge FM, SC)	[1][5]

References

1. Jim Bourdon (2006). "Thresher sharks — Lower Eocene - Recent". elasmo.com. Retrieved 2020-02-04.
2. Malyshkina, T.P.; Ward, D.J. (2016-06-24). "The Turanian Basin in the Eocene: the new data on the fossil sharks and rays from the Kyzylkum Desert (Uzbekistan)". Proceedings of the Zoological Institute RAS. 320 (1): 50–65. doi:10.31610/trudyzin/2016.320.1.50. ISSN 0206-0477.
3. Zhelezko VI, Kozlov VA (1999). "Elasmobranhii i biostratigraphia paleogena Zauralia i Srednei Asii" [Elasmobranchii and Palaeogene biostratigraphy of Transural and Central Asia]. Materialy Po Stratigrafii I Paleontologii Urala [Materials on Stratigraphy and Paleontology of the Urals]. 3. Ekaterinburg: UrO RAN: 324.
4. "Trigonotodus tusbairicus". Shark-References.com. Retrieved 2020-02-04.
5. Kozlov VA (2001). "Novyj vid akuly roda Trigonotodus KOZLOV, 1999 iz oligotsenovykh otlozhenij severnoj ameriki" [A new shark species of the genus Trigonotodus Kozlov, 1999, from Oligocene sediments of Northern America]. Materialy Po Stratigrafii I Paleontologii Urala [Materials on Stratigraphy and Paleontology of the Urals]. 6: 89–91.