Falcatus

Falcatus is an extinct genus of Falcatidae which lived during the early Carboniferous Period in Bear Gulch bay and what is now Montana.

Description
It was a 25–30 cm or 10-12 inches long "cladodont-toothed stethacanthid shark" [1] The first material known from the genus were the prominent fin spines that curved anteriorly over the head of the animal. When first described in 1883 from the St. Louis Limestone, these remains were given the name Physonemus falcatus. However, in 1985, fossils of a new type of condrichthyan from Montana were described that displayed a high degree of sexual dimorphism. The same spines that were previously named P. falcatus were found on one of the morphs, identified as the male due to the presence of valvae.

In popular culture
Falcatus was featured briefly in an episode of Paleoworld called "Prehistoric Sharks". Falcatus was also shown in two Shark Week specials, one also labelled as "Prehistoric Sharks" (where both were shown in restored form by Paleoartist Ray Troll) and the other known as "Jurassic Shark" where it was labelled as a unicorn shark.