Physogaleus

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

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 americanus Case, 1994 Physogaleus contortus (Gibbes, 1849) Physogaleus hemmooriensis Reinecke & Hoedemakers, 2006 Physogaleus huberensis (Case, 1981) Physogaleus latecuspidatus Muller, 1999 Physogaleus latus (Storms, 1894) Physogaleus maltzani (Winkler, 1875) Physogaleus onkensis Boulemia & Adnet, 2023[3] Physogaleus rosehillensis Case & Borodin, 2000 Physogaleus secundus (Winkler, 1876) Physogaleus tertius (Winkler, 1876)

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]