''Onchopristis'' is an extinct genus of sclerorhynchoid from the Cretaceous of North Africa, Europe, and

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. Its name is derived from the Ancient Greek ''ónkos'' ( ὄγκος, 'barb') and ''prístis'' ( πρίστις, 'saw' or 'sawfish'). It contains two valid species, ''O. numida'' and ''O. dunklei''. ''Onchopristis'' first appeared in the Barremian and its latest occurrence dates to the Campanian, making it one of the oldest and longest-lived sclerorhynchoid genera.

Description

Specimens of ''O. numida'', IPUW 353500 and IGR 2818, suggest a length estimate of and , respectively; such individuals would have weighed . Like other sclerorhynchoids, it had a long rostrum with large denticles similar to

sawfishes Sawfish, also known as carpenter sharks, are a family of rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish wit ...

and

sawsharks A sawshark or saw shark is a member of a shark order (Pristiophoriformes ) bearing a unique long, saw-like rostrum (snout or bill) edged with sharp teeth, which they use to slash and disable their prey. There are eight species within the Pristio ...

. This feature was

convergently evolved Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

and its closest living relatives are actually skates. Isolated rostral denticles are the most common fossils of ''Onchopristis'', but rostra, chondrocrania, jaws, oral teeth, vertebrae, and dermal denticles have also been found.

Taxonomy

'' Gigantichthys numidus'' was named by

Émile Haug Gustave Émile Haug (19 June 1861 - 28 August 1927) was a French geologist and paleontologist known for his contribution to the geosyncline theory. Career Émile Haug was born on 19 June 1861. In 1884 he received his doctorate in natural scie ...

in 1905 for fragmentary rostral denticles from the Continental intercalaire of Algeria. Haug also named ''Platyspondylus foureaui'' for vertebrae from the same formation. Articulated specimens have confirmed that the rostral denticles and vertebrae belong to the same species. In 1917, Ernst Stromer named the new genus ''Onchopristis'' with "''G''". ''numidus'' as the type species. Although the spelling "''Onchopristis numidus''" is commonly used, it is grammatically incorrect and has been emended to ''O. numida''. Oral teeth from the Bahariya Formation of Egypt were named '' Squatina aegyptiaca'' by Stromer in 1927, and were later renamed as the separate genus ''Sechmetia'' by Christa Werner in 1989. Again, articulated specimens confirmed that these teeth belong to ''O. numida''. In 1935, Wilhelm Weiler named ''Peyeria libyca'' for what he thought were sawfish rostral denticles from the Bahariya Formation. An associated specimen of ''

Ischyrhiza mira ''Ischyrhiza'' is an extinct genus of sclerorhynchoid ray from the Late Cretaceous and Early Paleogene. It had a large, toothed rostrum closely resembling that of a modern-day sawfish. Despite formerly being classified within a family of e ...

'', a close relative of ''Onchopristis'', indicates that "''Peyeria''" are actually dermal denticles from ''O. numida''. A second valid species from the

Woodbine Formation The Woodbine Group is a geological formation in east Texas whose strata date back to the Early to Middle Cenomanian age of the Late Cretaceous. It is the producing formation of the giant East Texas Oil Field (also known as the "Black Giant") from ...

of Texas, ''Onchopristis dunklei'', was named by Charles McNulty, Jr. and Bob Slaughter in 1962. In 1971, John Thurmond named the subspecies ''O. dunklei praecursor'', but it is probably not distinct from ''O. dunklei''. Rostral denticles from New Zealand formerly referred to "''O. d. praecursor''" have been reassigned to their own genus and species, '' Australopristis wiffeni''.

References

Prehistoric cartilaginous fish genera Cretaceous cartilaginous fish Prehistoric fish of Africa Sclerorhynchoidei {{paleo-cartilaginous-fish-stub