Parahelicoprion

Parahelicoprion Temporal range: Early Permian 298.9–295Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Eugeneodontida
Order:	Eugeneodontida
Family:	Agassizodontidae
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 eugeneodontid, shark-like 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, growly 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]

Paleobiology

Parahelicoprion was a nektonic carnivore that preyed upon a variety of different species, using its blade-like teeth to cut at exposed flesh like a hatchet or wedge. Many different prey species were identified at the beginning of the Permian, from sarcopterygian fish ill-equipped to deal with large predators (Menaspis and Petalodus being common prey items), xenacanthid sharks, plentiful species of ammonite and trilobite, and due to its size, other smaller eugeneodontids. Parahelicoprion is even believed to participate in cannibalism of its own species. ^[4]

References