''Physogaleus'' is an extinct genus of small

requiem shark Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes. They are migratory, live-bearing sharks of warm seas (sometimes of brackish or fresh water) and include such species as the bull shark, lemon shark, blac ...

that lived from the Late

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

Description

''Physogaleus'' is only known from fossil teeth and isolated vertebra. The teeth are similar to those of the modern

Tiger shark The tiger shark (''Galeocerdo cuvier'') is a species of ground shark, and the only extant member of the genus '' Galeocerdo'' and family Galeocerdonidae. It is a large apex predator, with females capable of attaining a length of over . Popula ...

, 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

, ''

Galeocerdo ''Galeocerdo'' is a genus of ground shark. Only a single species, ''G. cuvier'', the tiger shark, is extant. The earliest fossils date back to the early Eocene epoch, (Ypresian), around 56–47.8 Million years ago. While historically considered a ...

''. 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''.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 Unpublished Ph.D. Dissertation ''Physogaleus'' teeth reach a maximum size that is smaller than true tiger sharks, and they lack the heavy serrations typical of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.

References

Eocene sharks Prehistoric fish of Africa Cenozoic fish of North America Oligocene sharks Fossil taxa described in 1876 Paleocene sharks Miocene sharks {{Paleo-shark-stub