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
Subclass:	Elasmobranchii
Division:	Selachii
Order:	Lamniformes
Family:	Alopiidae
Genus:	†Trigonotodus; Kozlov, 1999
Type species
	†Trigonotodus tusbairicus; (Kozlov, 1999)
Other species
	†T. aktulgaicus?; (Kozlov, 1999) (possible nomen nudum); †T. alteri; (Kozlov, 2001);

Phylum:Chordata

Class:Chondrichthyes

Subclass:Elasmobranchii

Division:Selachii

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.

[1]

Species	Notes	Images	Ref.
Trigonotodus aktulgaicus	Known primarily from the early Eocene of Kazakhstan. It is extremely similar to T. tusbairicus, 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. tusbairicus.		^[2]^[3]^[1]
Trigonotodus tusbairicus	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 tusbairicus 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]

Trigonotodus

References

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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
Subclass:	Elasmobranchii
Division:	Selachii
Order:	Lamniformes
Family:	Alopiidae
Genus:	†Trigonotodus Kozlov, 1999
Type species
†Trigonotodus tusbairicus (Kozlov, 1999)
Other species
†T. aktulgaicus? (Kozlov, 1999) (possible nomen nudum) †T. alteri (Kozlov, 2001)