Onchopristis
| Onchopristis Temporal range:
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|---|---|
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| Tooth of O. numidus from the Tegana Formation, of the Kem Kem Beds | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Order: | Rajiformes |
| Suborder: | †Sclerorhynchoidei |
| Genus: | †Onchopristis Stromer, 1917[1] |
| Type species | |
| †Gigantichthys numidus Haug, 1905
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| Species | |
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| Synonyms[2] | |
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Onchopristis is a genus of extinct giant sclerorhynchoid (a sawfish-like chondrichthyan) from the Lower Cretaceous to Upper Cretaceous of North America, North Africa, Brazil, and New Zealand. It had an elongated snout lined laterally with barbed "teeth", or denticles.[2][3]
Taxonomy
Despite formerly being classified within a family of extinct sawfish-like rays known as Sclerorhynchidae,[4] phylogenetic analyses indicate that Ischyrhiza, Schizorhiza, and Onchopristis form a distinct clade that groups closer with the extant family Rajidae, which contains the true skates, possibly rendering the suborder Sclerorhynchoidei paraphyletic.[5]
Description
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The rostrum, or snout, was around 1–2 metres (3.3–6.6 feet) long,[6] lined with barbed "teeth" or denticles. In the type species, O. numidus, each tooth had one barb, but in O. dunklei there were two to five barbs on each tooth, and two to three in O. d. praecursor.[2] This sclerorynchid was about 5–6 metres (16.4–19.7 feet) long.[6]
Paleobiology
As with the modern sawfish, Onchopristis' eyes were on top of its head, to spot predators rather than prey, and its mouth and gills were under its body. The rostrum most likely would have had electroreceptors to detect food in the water below them like most modern sharks and some rays. Onchopristis may have raked through the riverbed to find and then eat prey.[7]
Predators
It is thought that some species of Onchopristis may have migrated up rivers to breed. At the height of the breeding season, piscivores like Spinosaurus aegyptiacus may have preyed upon the them.[8]
References
- ^ Stromer, E. (1917). "Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens: Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman)". Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften, Math.-naturwiss. Abt., N.F. 28 (8): 1–28.
{{cite journal}}:|chapter=ignored (help) - ^ a b c Keyes, I.W. (1977). "Records of the northern hemisphere Cretaceous Sawfish genus Onchopristis (order batoidea) from New Zealand". New Zealand Journal of Geology and Geophysics. 20 (2): 263–272. doi:10.1080/00288306.1977.10420706.
- ^ Medeiros, Manuel Alfredo; Lindoso, Rafael Matos; Mendes, Ighor Dienes; Carvalho, Ismar de Souza (2014-08-01). "The Cretaceous (Cenomanian) continental record of the Laje do Coringa flagstone (Alcântara Formation), northeastern South America". Journal of South American Earth Sciences. 53: 50–58. Bibcode:2014JSAES..53...50M. doi:10.1016/j.jsames.2014.04.002. ISSN 0895-9811.
- ^ "Fossilworks: Sclerorhynchidae". fossilworks.org. Retrieved 2020-10-17.
- ^ Villalobos‐Segura, Eduardo; Underwood, Charlie J.; Ward, David J. "The first skeletal record of the enigmatic Cretaceous sawfish genus Ptychotrygon (Chondrichthyes, Batoidea) from the Turonian of Morocco". Papers in Palaeontology. n/a (n/a). doi:10.1002/spp2.1287. ISSN 2056-2802.
- ^ a b This huge ancient sawfish had harpoons on its face
- ^ Scott, C. (2012). Planet Dinosaur: The Next Generation of Killer Giants. Firefly Books. pp. 72–73. ISBN 978-1-77085-049-1.
- ^ www.bbc.co.uk https://www.bbc.co.uk/programmes/p00kgk6n. Retrieved 2020-08-15.
{{cite web}}: Missing or empty|title=(help)
- Dutheil, D.B., Brito, P.M., 2009. Articulated cranium of Onchopristis numidus (Sclerorhynchidae, Elasmobranchii) from the Kem Kem Beds, Morocco. In: Jalil, N.-E. (Ed.), 1st International Congress on North African Vertebrate Palaeontology, Program & Abstracts, Marrakech, 25–27 May 2009, p. 66.
- Haug, E. Paléontologie. Documents Scientifiques de la mission saharienne (mission Foureau-Lamy). Publications de la Société de Géographie, p. 751-832
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