Parahelicoprion

Parahelicoprion Temporal range: Early Permian 298.9–295 Ma PreЄ Є O S D C P T J K Pg N ↓
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Eugeneodontida
Order:	Eugeneodontida
Family:	Helicoprionidae
Genus:	Parahelicoprion Karpinsky, 1924
Type species
Helicoprion clerci Karpinsky, 1916
Species
P. clerci (Karpinsky, 1916) P. mariosuarezi Merino-Rodo & Janvier, 1986

Parahelicoprion is an extinct genus of shark-like eugeneodontid holocephalid from the Permian of the Ural Mountains and South America.^[1] Its name is a derivation of Helicoprion, from the Ancient Greek words "Nearly coiled saw", another holocephalid that shares similar traits to it, including the helical whorl of teeth. One of the primary qualities that separate Parahelicoprion from the aforementioned Helicoprion is the shape, thickness and angle of the tooth whorl. This whorl sharks teeth protrude outwards not like a tightly coiled saw but instead a curved arrangement of cutting blades indicating it relied less on crushing slow-moving invertebrates and catching squid and other small mollusk prey, but inflicting traumatic damage against more durable, faster prey.^[2] Their teeth grew at a much slower pace than that of other whorl-tooth sharks, resulting in a depreciated spiral, growing only half of the teeth a Helicoprion would grow in its life time. The tooth spiral also was able to indicate the age of the eugeneodontidans in question. ^[3]

Description

Parahelocoprion is estimated to have grown to lengths of around 12 meters or so. It was once thought that Parahelicoprion was the largest of its family, but in 2013, a tooth whorl of a yet to be named species of Helicoprion was described and indicated that the genus Helicoprion could grow to lengths of more than 12 meters. Although Parahelicoprion is about as long, the fossils indicate an animal that was overall more slender than Helicoprion, which means an animal that was less heavy.^[4]

It was once believed that Parahelicoprion reached lengths of up to 30 meters in length, but this was based on eel proportions instead of the classic, shark-like look of eugeneodonts. The figure was later discarded.^[5]

Paleobiology

Parahelicoprion is thought to have been a nektonic carnivore that probably preyed upon a variety of different species, using its blade-like teeth to cut at exposed flesh like a hatchet or wedge.^[6]

References