Physogaleus

Physogaleus Temporal range: Upper Thanetian-Tortonian 56–9.5  Ma PreꞒ Ꞓ O S D C P T J K Pg N [1] Possible Pliocene records [2]
Tooth of Physogaleus contortus from the Temblor Formation
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Division:	Selachii
Order:	Carcharhiniformes
Genus:	† Physogaleus Cappetta, 1980
Type species
†Physogaleus secundus (Winkler, 1876)
Species
Physogaleus americanusCase, 1994 Physogaleus contortus(Gibbes, 1849) Physogaleus hemmooriensisReinecke & Hoedemakers, 2006 Physogaleus huberensis(Case, 1981) Physogaleus latecuspidatusMuller, 1999 Physogaleus latus(Storms, 1894) Physogaleus maltzani(Winkler, 1875) Physogaleus onkensisBoulemia & Adnet, 2023 [3] Physogaleus rosehillensisCase & Borodin, 2000 Physogaleus secundus(Winkler, 1876) Physogaleus tertius(Winkler, 1876)

Physogaleus is an extinct genus of small requiem shark ^[4] that lived from the Late Paleocene ^[3] to Miocene epochs. ^{[5] [6]}

Description

Physogaleus is only known from fossil teeth and isolated vertebra. The teeth are similar to those of the modern Tiger shark, but are smaller, with a more central cusp that projects further from the base of the tooth. The species of Physogaleus were originally described as belonging to the same genus as the modern Tiger shark, Galeocerdo . Recognition of numerous differences in dental anatomy of each of these species compared to other species of Galeocerdo lead researchers to establish the genus Physogaleus to include taxa that were more morphologically similar to one another than they were to Galeocerdo. ^[7]

Physogaleus teeth reach a maximum size that is smaller than true tiger sharks, and they lack the heavy serrations typical of Galeocerdo. They are also more slender and the central cusp can be somewhat twisted toward the crown. This indicates individuals of Physogaleus probably had a diet of bony fish, similar to the living sand-tiger shark. ^[6]

References

1. Perez, Victor J.; Pimiento, Catalina; Hendy, Austin; González-Barba, Gerardo; Hubbell, Gordon; MacFadden, Bruce J. (May 2017). "Late Miocene chondrichthyans from Lago Bayano, Panama: Functional diversity, environment and biogeography". Journal of Paleontology. 91 (3): 512–547. Bibcode:2017JPal...91..512P. doi:10.1017/jpa.2017.5. ISSN   0022-3360.
2. César, Laurito (2018). Los selaceos fósiles de Ia localidad de Alto Guayacan ( y otros ictiolitos asociados).
3. S. Boulemia, S. Adnet (2023). "A new Palaeogene elasmobranch fauna (Tebessa region, eastern Algeria) and the importance of Algerian-Tunisian phosphates for the North African fossil record". Annales de Paléontologie. 109 (3). Bibcode:2023AnPal.10902632B. doi: 10.1016/j.annpal.2023.102632 . S2CID   264571594.
4. D. J. Cicimurri, J. L. Knight, J. A. Ebersole (March 2022). "Early Oligocene (Rupelian) fishes (Chondrichthyes, Osteichthyes) from the Ashley Formation (Cooper Group) of South Carolina, USA". PaleoBios. 39 (1): 1–38. doi: 10.5070/P939056976 .
5. Reinecke, Thomas; Hoedemakers, Kristiaan (2006). "Physogaleus hemmooriensis (Carcharhinidae, Elasmobranchii) A New Shark Species from the Early to Middle Miocene of the North Sea Basin". PalaeoVertebrata. 34 (1–2): 1–25.
6. "Tiger Shark Facts and Information". Fossilguy.
7. Hernandez, C. 2015. Paleobiology of the Mio-Pliocene sharks, with emphasis on the extinct apex predator Carcharocles megalodon. University of Florida. Unpublished Ph.D. Dissertation