Physogaleus is a requiem shark from the Eocene-Miocene of the entire world. It was officially named in 1980 by Henri Cappetta. It was previously thought to be a species of tiger shark before finally being described as its own genus.
Physiology
Although no body fossils of Physogaleus have been found, it can be assumed that, as an extinct requiem shark, Physogaleus may have resembled its close relative, the tiger shark; it was a fish that would have had a torpedo-shaped body, triangular pectoral (arm) and dorsal (back) fins, a crescent-shaped caudal (tail) fin, a mid-sized head with a pointy, conical nose and large jaws, and 5 gills located near the head on each side of its body. Its body would have been covered in scaly skin.
Diet
Physogaleus was a predator, preying mainly on bony fish, but also snacking on smaller cartilaginous fish, crustaceans, and small cephalopods. Although its teeth were sharp and pointy, they did not have massive, sharp serrations; due to this, it can be assumed that it would have not preyed on hard-shelled vertebrates such as turtles, rather going for prey it could easily slice into smaller, more digestible chunks of flesh.
Ecology
So far, all we know about Physogaleus is that it would have had a diet that mainly consisted of bony fish, but also rarely included smaller sharks, rays, cephalopods, and crustaceans (similarly to the extant sand tiger shark); as well as this, similar to modern requiem sharks, it would have swam around in warmer oceans as opposed to colder ones, and it would have been a slow-moving ambush predator that could achieve sudden bursts of speed in order to catch prey.
In popular culture
In the second episode of the 2001 documentary Walking with Beasts, an unidentified shark is shown as a prey item for the giant whale Basilosaurus (which is portrayed as a seafaring animal rather than the brackish water creature it is); later, when the Basilosaurus is attempting to hunt down a troop of Apidium in the mangrove swamps, the shark kills one of the monkeys and frightens the others into fleeing, depriving the whale of its food. Many people assume that this shark is Physogaleus; this does make some sense, as Physogaleus had a global distribution and lived during the Eocene (however, it is unknown how opportunistic of a predator Physogaleus was).