Onchopristis

In 1905, the French paleontologist Émile Haug named Gigantichthys numidus based fragmentary rostral denticles from the Continental intercalaire of Algeria, and named Platyspondylus foureaui based on vertebrae from the same formation. Articulated specimens have confirmed that the rostral denticles and vertebrae belong to the same species.{{cite book |last1=Dutheil |first1=D.B. |url=http://www.terre-a-terre.fr/DOCUMENTS/Dutheil%20_2009-NAVEP1_Onchopristis.pdf |title=1st International Congress on North African Vertebrate Palaeontology. Program & Abstracts |last2=Brito |first2=P.M. |date=2009 |editor-last=Jalil |editor-first=N.E. |location=Marrakesh |pages=58 |chapter=Articulated cranium of Onchopristis numidus (Sclerorhynchidae, Elasmobranchii) from the Kem Kem bed, Morocco |archive-url=https://web.archive.org/web/20140413143322/http://www.terre-a-terre.fr/DOCUMENTS/Dutheil%20_2009-NAVEP1_Onchopristis.pdf |archive-date=2014-04-13}} In 1917, Ernst Stromer assigned "G". numidus to a new genus Onchopristis, derived from the Ancient Greek ónkos (ὄγκος, 'barb') and prístis (πρίστις, 'saw' or 'sawfish'). Although the spelling "Onchopristis numidus" is commonly used for the type species, Greenfield (2021) suggested that this is grammatically incorrect and emended it to O. numida.{{cite journal |last1=Greenfield |first1=T. |date=2021 |title= Corrections to the nomenclature of sawskates (Rajiformes, Sclerorhynchoidei) |journal=Bionomina |volume=22 |issue=1 |pages=39–41 |doi=10.11646/bionomina.22.1.3|s2cid=239067365 }}

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, a close relative of Onchopristis, indicates that "Peyeria" were actually dermal denticles from O. numida.{{cite journal |last1=Sternes |first1=P.C. |last2=Shimada |first2=K. |date=2019 |title= Paleobiology of the Late Cretaceous sclerorhynchid sawfish, Ischyrhiza mira (Elasmobranchii: Rajiformes), from North America based on new anatomical data |journal=Historical Biology |volume=31 |issue=10 |pages=1323–1340 |doi=10.1080/08912963.2018.1452205|s2cid=90291295 }}{{Cite book |last=Chapetta |first=H |title=Handbook of Paleoichthyology |date=2012 |editor-last=Schultze |editor-first=H. P. |edition=3rd |chapter=Chondrichthyes: Mesozoic and Cenozoic Elasmobranchii. Chondrichthyes II}} In 2003, two incomplete rostral denticles, measuring {{cvt|8.15|mm|in}} and {{cvt|12.65|mm|in}} respectively, were referred to as Onchopristis cf. O. numida from the Alcântara Formation of Brazil, but were unfigured.{{cite book|author1=Pereira, A.A.|author2=Medeiros, M.A.|year=2003|chapter=Novas ocorrências de peixes no Eocenomaniano do Maranhão|title=Congresso Brasileiro de Paleontologia|volume=18|publisher=Boletim de Resumos, UNB Brasília|pages=221-222|url=https://sbpbrasil.org/anais-e-resumos/}}

A second valid species from the Woodbine Formation of Texas, Onchopristis dunklei, was named by Charles McNulty, Jr. and Bob Slaughter in 1962. O. dunklei is also known from the Cenomanian of Spain and France, and from the Albian of Tunisia based on incomplete material. In 1971, John Thurmond named the subspecies O. dunklei praecursor, but it is probably not distinct from O. dunklei.{{cite journal |last1=Case |first1=G.R. |date=1987 |title=Borodinopristis schwimmeri, a new ganopristine sawfish from the upper Blufftown Formation (Campanian) of the Upper Cretaceous of Georgia |journal=Bulletin of the New Jersey Academy of Sciences |volume=32 |issue=1 |pages=25–33 |url=https://www.researchgate.net/publication/334544559}}

Fourteen rostral denticles formerly identified as Onchopristis sp. from the Alcântara Formation of Brazil have been redescribed as their own genus and species, Atlanticopristis equatorialis.{{cite journal|last1=Pereira|first1= A. A.|last2=Medeiros|first2= M. A.|year=2008|title=A new sclerorhynchiform (Elasmobranchii) from the middle Cretaceous of Brazil|journal=Revista Brasileira de Paleontologia|volume=11|issue=3|pages=207–212|doi=10.4072/rbp.2008.3.07|doi-access=free}} Rostral denticles from New Zealand formerly referred to "O. d. praecursor" have also been reassigned to their own genus and species, Australopristis wiffeni.{{cite journal|last=Keyes |first=I.W. |year=1977 |title=Records of the northern hemisphere Cretaceous sawfish genus Onchopristis (order Batoidea) from New Zealand |journal=New Zealand Journal of Geology and Geophysics |volume=20 |issue=2 |pages=263–272 |doi=10.1080/00288306.1977.10420706|bibcode=1977NZJGG..20..263K |doi-access=free}}{{cite journal |last1=Martill |first1=D.M. |last2=Ibrahim |first2=N. |year=2012 |title=Aberrant rostral teeth of the sawfish Onchopristis numidus from the Kem Kem beds (?early Late Cretaceous) of Morocco and a reappraisal of Onchopristis in New Zealand |journal=Journal of African Earth Sciences |volume=64 |pages=71–76 |doi=10.1016/j.jafrearsci.2011.11.009 |bibcode=2012JAfES..64...71M }} An uncritical summary of 70 vertebrate taxa found in the Aguja Formation reports the presence of O. dunklei based on two fragmentary specimens, though the authors acknowledge the skepticism regarding the Campanian-Maastrichtian occurrence of this genus.{{cite journal |last1=Rowe |first1=T. |last2=Cifelli |first2=R.L. |last3=Lehman |first3=T.M. |last4=Weil |first4=A. |date=1992 |title=The Campanian Terlingua local fauna, with a summary of other vertebrates from the Aguja Formation, Trans-Pecos Texas |journal=Journal of Vertebrate Paleontology |volume=12 |issue=4 |pages=472–493 |doi=10.1080/02724634.1992.10011475|bibcode=1992JVPal..12..472R }} Subsequent studies have identified these specimens as Columbusia deblieuxi.{{cite book|author1=Kirkland, J.I.|author2=Eaton, J.G.|author3=Brinkman, D.B.|year=2013|chapter=Elasmobranchs from Upper Cretaceous freshwater facies in southern Utah|editor1=Titus, A.L.|editor2=Loewen, M.A.|title=At the Top of the Grand Staircase, the Late Cretaceous of Southern Utah|publisher=Indiana University Press|location=Bloomington|pages=153–194|isbn=978-0253008831}}{{cite journal|author1=Schubert, J.A.|author2=Wick, S.L.|author3=Lehman, T.M.|year=2017|title=An Upper Cretaceous (middle Campanian) marine chondrichthyan and osteichthyan fauna from the Rattlesnake Mountain sandstone member of the Aguja Formation in West Texas|journal=Cretaceous Research|volume=69|pages=6–33|doi=10.1016/j.cretres.2016.08.008|bibcode=2017CrRes..69....6S |s2cid=133098369 }}

In 2019, the isolated rostral denticles found in the possible late Maastrichtian-Paleocene strata from Mali were attributed to O. numida,{{Cite journal |last1=O'Leary |first1=Maureen A. |last2=Bouaré |first2=Mohamed L. |last3=Claeson |first3=Kerin M. |last4=Heilbronn |first4=Kelly |last5=Hill |first5=Robert V. |last6=McCartney |first6=Jacob A. |last7=Sessa |first7=Jocelyn A. |last8=Sissoko |first8=Famory |last9=Tapanila |first9=Leif |last10=Wheeler |first10=E. A. |last11=Roberts |first11=Eric (Eric M. ) |date=2019-06-28 |title=Stratigraphy and paleobiology of the Upper Cretaceous-Lower Paleogene sediments from the Trans-Saharan Seaway in Mali. |journal=Bulletin of the American Museum of Natural History |volume=2019 |issue= 436) |page=1 |doi=10.1206/0003-0090.436.1.1 |hdl=2246/6950 |s2cid=198398386 |url=http://digitallibrary.amnh.org/handle/2246/6950 |language=en-US|url-access=subscription }} but these specimens more likely represent cutlassfish fangs. In 2024, four fragmentary rostral denticles and an exceptionally large, {{convert|1.46|m|ft}} long rostrum of sclerorhynchoids from the Maastrichtian-aged Dakhla Formation of Egypt were referred to as Onchopristis sp.{{Cite journal|last1=Capasso |first1=L. |last2=Abdel Aziz |first2=S. |last3=Tantawy |first3=A. A. |last4=Mousa |first4=M. K. |last5=Wahba |first5=D. G. A. |last6=Abu El-Kheir |first6=G. A. |year=2024 |title=The first described Onchopristis Stromer, 1917, (Elasmobranchii: †Onchopristidae) from the Marine Maastrichtian of Dakhla Formation, Western Desert, Egypt |journal=Journal of African Earth Sciences |volume=220 |at=105415 |doi=10.1016/j.jafrearsci.2024.105415 }} However, Greenfield (2025) argued that neither of the referred material from the Dakhla Formation can be assigned to Onchopristis, and he reidentified the rostrum as an indeterminate sclerorhynchoid and the unassociated rostral denticles as Sclerorhynchus cf. leptodon.{{cite journal|author=Greenfield, T.|year=2025|title=No evidence for a giant, late-surviving Onchopristis: Comment on Capasso et al. (2024)|journal=Journal of African Earth Sciences|volume=223|at=105541|doi=10.1016/j.jafrearsci.2025.105541}} The authors of the original study stood by their original conclusion, stating that any taxonomic determination of the material without direct examination is unacceptable.{{Cite journal|last1=Capasso |first1=L. |last2=Abdel Aziz |first2=S. |last3=Tantawy |first3=A. A. |last4=Mousa |first4=M. K. |last5=Wahba |first5=D. G. A. |last6=Abu El-Kheir |first6=G. A. |year=2025 |title=Comments on the Greenfield (2025) |journal=Journal of African Earth Sciences |volume=228 |at=105642 |doi=10.1016/j.jafrearsci.2025.105642 }}

Specimens of O. numida, IPUW 353500 and IGR 2818, suggest a length estimate of {{cvt|2.94|-|4.25|m|ft}} and {{cvt|2.21|-|3.15|m|ft}}, respectively; such individuals would have weighed {{cvt|70|-|150|kg|lb}}. Isolated rostral denticles are the most common fossils of Onchopristis, but rostra, chondrocrania, jaws, oral teeth, vertebrae, and dermal denticles have also been found.

File:Stomatosuchus_skull_Stromer_1925jpg.jpg on Onchopristis and Stomatosuchus. No. 5 is a rostrum, or saw, from the former.]]

Like other sclerorhynchoids, Onchopristis had 'saw', a long rostrum with large denticles, similar to those of sawfishes and sawsharks. This feature was the result of convergent evolution, and its repeated evolution among chondrichthyans has been dubbed 'pristification'. The saw, like in those taxa and in other sclerorhynchoids, was cartilaginous and compressed dorsoventrally (from top-to-bottom).{{cite journal |last1=Greenfield |first1=T. |year=2024 |title=Pristification: Defining the convergent evolution of saws in sharks and rays (Chondrichthyes, Neoselachii) |url=http://paleorxiv.org/rtw9u/download |journal=Mesozoic |volume=1 |issue=2 |pages=121–124 |doi=10.11646/MESOZOIC.1.2.3}} It was somewhat triangular in shape, widest at the base, narrowing towards the tip. Internally, it consisted of a layer of small, prismatic cartilage blocks, covered in a fibrous cartilage layer. This layer has been compared to wood cortex, and bears well-mineralised ridges. The rostral denticles at the very front of the saw were very small,{{Cite journal |last=Stromer |first=E |date=1925 |title=Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 7. Stomatosuchus inermis Stromer, ein schwach bezahnter Krokodilier und 8. Ein Skelettrest des Pristiden Onchopristis numidus Haug sp. |journal=Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung |volume=30 |issue=6 |pages=1–22}} Those on the sides of the saw were larger with the biggest measuring {{Convert|7|cm|in|abbr=on}}, and more irregular, with different morphologies observed based on where along the saw the denticles originated from. Based on the variation in denticle size, it is likely that Onchopristis constantly shed and replaced them. Unlike other sclerorhynchoids, Onchopristis denticles possessed small, rearward-projecting projections, called barbs, which vary in number depending on the species: O. numida had one barb per denticle, while O. dunklei had up to three.

The base of the saw transitioned smoothly into the neurocranium (the base of the cranium). The neurocranium was rectangular in shape and box-like. Near the rostral base was an oval-shaped precerebral fenestra. The antorbital cartilage, that behind the eye, was triangular, with a narrow distal (far) edge which pointed posteriorly (rearward). The orbital cavity, or eye socket, is large. Lymphatic foramina were present on the posterior part of the forebrain. Onchopristis' hyomandibula, the structure from which the jaw was suspended, was triangular. Its proximal (near) end articulated with the neurocranium, while the distal end sat between the palatoquadrate and Meckel's cartilage. The jaw cartilages are poorly known, with only those structures being visible when viewed ventrally (from the bottom). Known oral teeth all display well-developed cutting edges, extending continuously between the cusp and lateral cusplets. The cusp of each tooth bends lingually (inwards).File: Onchopristis numida.png

Onchopristis' vertebral centra, as in other chondrichthyans, consist of two structures: the corpus calcareum and the intermedialia. The former is well mineralised and there is some indication that minerals were cyclically deposited, though it is not clear whether this deposition was seasonal as in other chondrichthyans. No additional postcranial remains are known, although based on other sclerorhynchoids, it can be assumed that the ratio between the length of the rostrum and the total length of the body was around 1:3.27. Like some other sclerorhynchoids, notably Ischyrhiza, Onchopristis had large dermal denticles, also known as dermal thorns. In Ischyrhiza, they resembled those of slow-moving, benthic batoids, though their arrangement cannot be fully ascertained. If, as suggested, the "Peyeria" denticles do belong to Onchopristis,{{Cite book |last=Chapetta |first=H |title=Handbook of Paleoichthyology |date=2012 |editor-last=Schultze |editor-first=H. P. |edition=3rd |chapter=Chondrichthyes: Mesozoic and Cenozoic Elasmobranchii. Chondrichthyes II}} it is possible that dermal thorns were widespread throughout sclerorhynchoids.

Specimens of Onchopristis have been associated with the jaws of Spinosaurus in North Africa, indicating that Spinosaurus would have preyed upon Onchopristis based on direct evidence of piscivory. An isolated fish vertebra, tentatively referred to Onchopristis, has been associated with the tooth alveolus of a possible specimen of Spinosaurus (MSNM V 4047).{{cite journal |last=dal Sasso |first=C. |author2=Maganuco, S. |author3=Buffetaut, E. |author4= Mendez, M.A. |year=2005 |title=New information on the skull of the enigmatic theropod Spinosaurus, with remarks on its sizes and affinities |journal=Journal of Vertebrate Paleontology |volume=25 |issue=4 |pages=888–896|doi=10.1671/0272-4634(2005)025[0888:NIOTSO]2.0.CO;2 |s2cid=85702490 }} Similarly, the dentary fragment of Spinosaurus aegyptiacus (MPDM 31) is associated with the rostral denticle of Onchopristis.{{cite journal|last1=Ibrahim |first1=N. |last2=Sereno |first2=P.C. |last3=Varrachio |first3=D.J. |last4=Martill |first4=D.M. |last5=Unwin |first5=D.M. |last6=Baidder |first6=L. |last7=Larsson |first7=H.C.E. |last8=Zouhri |first8=S. |last9=Kaoukaya |first9=U. |title=Geology and paleontology of the Upper Cretaceous Kem Kem Group of eastern Morocco|journal=ZooKeys|year=2020|issue=928|pages=1–216|doi=10.3897/zookeys.928.47517 |pmid=32362741 |pmc=7188693 |bibcode=2020ZooK..928....1I |doi-access=free }} Additionally, the teeth of Spinosaurus and rostral denticles of Onchopristis form a bone bed at one locality in the Kem Kem beds of Morocco (Errachidia Province).{{cite journal |last1=Beevor |first1=Thomas |last2=Quigley |first2=Aaron |last3=Smith |first3=Roy E. |last4=Smyth |first4=Robert S.H. |last5=Ibrahim |first5=Nizar |last6=Zouhri |first6=Samir |last7=Martill |first7=David M. |title=Taphonomic evidence supports an aquatic lifestyle for Spinosaurus |journal=Cretaceous Research |date=January 2021 |volume=117 |pages=104627 |doi=10.1016/j.cretres.2020.104627 |bibcode=2021CrRes.11704627B |s2cid=224888268 |url=https://researchportal.port.ac.uk/portal/en/publications/taphonomic-evidence-supports-an-aquatic-lifestyle-for-spinosaurus(e7fb2358-2ac6-4b6c-9697-225a525e8366).html }}

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{{Taxonbar|from=Q7092026}}

Category:Cretaceous fish of Africa

Category:Cretaceous fish of Europe

Category:Cretaceous fish of North America

Category:Prehistoric cartilaginous fish genera

Category:Cretaceous cartilaginous fish

Category:Sclerorhynchoidei

Category:Taxa named by Ernst Stromer

Category:Fossil taxa described in 1917