Trigonotodus

Trigonotodus
Temporal range: Late Eocene-Middle Miocene
35–13.7 Ma
Lateral tooth of Trigonotodus alteri
Scientific classification Edit this 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 (nomen nudum)
  • †T. alteri
    (Kozlov, 2001)
  • †T. grandis?
    Leriche, 1942
  • †T. palatasi?
    Kent & Ward, 2018

Trigonotodus is an extinct genus of sharks, most likely belonging to the family Alopiidae. This genus includes three extinct species, which span from the Late Eocene to the Middle Miocene. It was originally placed in the family Otodontidae, but subsequently found to have affinities with thresher sharks. This genus is sometimes considered part of the genus Alopias. It is currently only known from isolated teeth. Recent studies proposed a relation ship with Cretoxyrhinidae because of the similarity with Squalicorax and Cretoxyrhina in the case of T. grandis and T. palatasi, but the proposal was questioned and it was proposed that Trigonotodus be placed in incertae sedis.

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. 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.
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
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)

Others species such as Alopias grandis and A. palatasi are now also placed in this genus.

References

  1. 1 2 3 4 5 Jim Bourdon (2006). "Thresher sharks — Lower Eocene - Recent". elasmo.com. Retrieved 2020-02-04.
  2. ↑ Kohno, N., Tanaka, T. (2025). "Paleozoic, Mesozoic and Cenozoic Chondrichthyes from the Japanese Islands" (PDF). National Museum of Nature and Science Monographs (56): 1–184.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ↑ Bampi, H., Granzotti, D.S. (2026). "Taxonomic and morphometric revision of Alopiidae (Lamniformes) shark family: a qualitative holistic approach based on dental characters". Historical Biology. doi:10.1080/08912963.2026.2651906.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ↑ 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.
  5. 1 2 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.
  6. ↑ "Trigonotodus tusbairicus". Shark-References.com. Retrieved 2020-02-04.
  7. ↑ 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.
  8. ↑ Ward, D. J.; Kent, B. W. (2015). "A new giant species of thresher shark from the Miocene of the United States". Natural History Museum. doi:10.13140/RG.2.1.1723.0969. {{cite journal}}: Cite journal requires |journal= (help)