Squalicorax, informally known as the crow shark, is an anacoracid mackerel shark from the Late Cretaceous of the entire world. It was officially named in 1987 by Henri Cappetta. It was one of the most widespread marine sharks during the Cretaceous, as well as one of the most successful.
Squalicorax resembled a typical mackerel shark, with 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.
Squalicorax was a predator, preying on fish, cephalopods, turtles, diving birds, small plesiosaurs, pterosaurs, and small mosasaurs. Its teeth pointed sideways, and were equipped with massive, sharp serrations, allowing it to bite through any organic substance; in one species, Squalicorax pristodontus, the jaws were proportionally large, allowing for a prey based on slightly larger animals than usual.
Squalicorax is known to have scavenged on carcasses it could find, as many marine tetrapods have been found with toothmarks from this shark, and even a dead hadrosaur presumably swept out to sea had a tooth embedded in its foot. However, as is the case with many carnivores today, such scavenging likely did not define the shark's way of acquiring food; its teeth were similar in shape and size to the extant tiger shark, and so, much like the large requiem shark, it could have also been an extremely competent predator, feeding mainly on fish, but also willingly preying on other animals within its size range, using its sharp teeth to slice through flesh, bone, and keratin alike. In places where large mosasaurs were absent, it was even the apex predator, and was able to effectively compete with (and even sometimes prey on) the smaller mosasaurs it lived with. Due to the shape of its scales, it can be assumed that it was an active and fast-swimming shark, not unlike the modern white sharks that inhabit oceans today.
In popular culture
Squalicorax was featured in the 3rd episode of the 2003 documentary Chased by Sea Monsters, where it preys a flock of Hesperornis alongside a shoal of Xiphactinus and a Halisaurus. It appeared again in another documentary, Sea Monsters: A Prehistoric Adventure, where it attacks the protagonist Dolichorhynchops before being eaten by a Tylosaurus; despite the unsuccessful attack, the shark still managed to get a tooth embedded in one of the plesiosaur's flippers.