Onchopristis Numidus
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''Onchopristis'' is an extinct
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of sclerorhynchoid, or sawskate, from the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
of
North Africa North Africa (sometimes Northern Africa) is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region. However, it is sometimes defined as stretching from the Atlantic shores of t ...
,
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
,
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, and potentially
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. It contains two valid species, ''O. numida'' and ''O. dunklei'', though some researchers argue that both may be considered a single taxon with variation in morphology caused by a wide geographical range. Specimens of ''Onchopristis'' have been discovered in coastal and fluvial deposits dated from the
Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a ...
to the
Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...
ages (~125-94 mya), making this genus one of the oldest known sclerorhynchoids.


Discovery and naming

In 1905, the French paleontologist
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 ...
named '' Gigantichthys numidus'' based fragmentary rostral denticles from the
Continental intercalaire The Continental intercalaire, sometimes referred to as the Continental intercalaire Formation, is a term applied to Cretaceous strata in Northern Africa. It is the largest single stratum found in Africa to date, being between thick in some places. ...
of
Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...
, 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. In 1917,
Ernst Stromer Ernst Freiherr Stromer von Reichenbach (born on 12th of June, 1871 in Nürnberg, died on 18th of December, 1952 in Erlangen) was a German paleontologist best remembered for his expedition to Egypt, during which the discovery of the first kno ...
assigned "''G''". ''numidus'' to a new genus ''Onchopristis'', derived from the
Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), 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''. Oral teeth from the
Bahariya Formation The Bahariya Formation (also transcribed as Baharija Formation) is a List of fossiliferous stratigraphic units in Egypt, fossiliferous Formation (stratigraphy), geologic formation dating back to the early Cenomanian, which outcrops within the Baha ...
of
Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...
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 (Cenomanian-Maastrichtian). It had a large, toothed rostrum closely resembling that of a modern-day sawfish. Despite formerly being classified within a family ...
'', a close relative of ''Onchopristis'', indicates that "''Peyeria''" were actually dermal denticles from ''O. numida''. In 2003, two incomplete rostral denticles, measuring and respectively, were referred to as ''Onchopristis''
cf. The abbreviation cf. (short for either Latin or , both meaning 'compare') is generally used in writing to refer the reader to other material to make a comparison with the topic being discussed. However some sources offer differing or even contr ...
''O. numida'' from the
Alcântara Formation The Alcântara Formation is a geological Formation (geology), formation in Northeast Region, Brazil, northeastern Brazil whose strata date back to the Cenomanian of the Late Cretaceous. Fossil content Dinosaurs Sauropods Theropods ...
of
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
, but were unfigured. 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") fr ...
of
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
, ''Onchopristis dunklei'', was named by Charles McNulty, Jr. and Bob Slaughter in 1962. ''O. dunklei'' is also known from the
Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...
of
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and
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, and from the
Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...
of
Tunisia Tunisia, officially the Republic of Tunisia, is a country in the Maghreb region of North Africa. It is bordered by Algeria to the west and southwest, Libya to the southeast, and the Mediterranean Sea to the north and east. Tunisia also shares m ...
based on incomplete material. In 1971, John Thurmond named the subspecies ''O. dunklei praecursor'', but it is probably not distinct from ''O. dunklei''.


Formerly assigned material

Fourteen rostral denticles formerly identified as ''Onchopristis'' sp. from the
Alcântara Formation The Alcântara Formation is a geological Formation (geology), formation in Northeast Region, Brazil, northeastern Brazil whose strata date back to the Cenomanian of the Late Cretaceous. Fossil content Dinosaurs Sauropods Theropods ...
of
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
have been redescribed as their own genus and species, '' Atlanticopristis equatorialis''. Rostral denticles from
New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
formerly referred to "''O. d. praecursor''" have also been reassigned to their own genus and species, '' Australopristis wiffeni''. An uncritical summary of 70 vertebrate taxa found in the
Aguja Formation The Aguja Formation is a geological formation in North America, exposed in Texas, United States and Chihuahua and Coahuila in Mexico, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered ...
reports the presence of ''O. dunklei'' based on two fragmentary specimens, though the authors acknowledge the skepticism regarding the
Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...
-
Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...
occurrence of this genus. Subsequent studies have identified these specimens as ''Columbusia deblieuxi''. In 2019, the isolated rostral denticles found in the possible late
Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...
-
Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...
strata from Mali were attributed to ''O. numida'', but these specimens more likely represent
cutlassfish The cutlassfishes are about 45 species of predatory ray-finned fish in the family Trichiuridae of the order Scombriformes found in seas throughout the world. Fish of this family are long, slender, and generally steely blue or silver in colour, ...
fangs. In 2024, four fragmentary rostral denticles and an exceptionally large, long rostrum of sclerorhynchoids from the
Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...
-aged
Dakhla Formation The Dakhla Formation, also called the Dakhla Shale, is a Maastrichtian-Danian geologic formation in the Western Desert, Egypt. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referr ...
of
Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...
were referred to as ''Onchopristis'' sp. However, Greenfield (2025) argued that neither of the referred material from the
Dakhla Formation The Dakhla Formation, also called the Dakhla Shale, is a Maastrichtian-Danian geologic formation in the Western Desert, Egypt. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referr ...
can be assigned to ''Onchopristis'', and he reidentified the rostrum as an indeterminate sclerorhynchoid and the unassociated rostral denticles as '' Sclerorhynchus'' cf. ''leptodon''. The authors of the original study stood by their original conclusion, stating that any taxonomic determination of the material without direct examination is unacceptable.


Description

Specimens of ''O. numida'', IPUW 353500 and IGR 2818, suggest a length estimate of and , respectively; such individuals would have weighed . Isolated
rostral Rostral may refer to: Anatomy * Rostral (anatomical term), situated toward the oral or nasal region * Rostral bone, in ceratopsian dinosaurs * Rostral organ, of certain fish * Rostral scale The rostral scale, or rostral, in snakes and other sca ...
denticles are the most common fossils of ''Onchopristis'', but rostra, chondrocrania, jaws, oral teeth, vertebrae, and dermal denticles have also been found.


Rostrum and cranium

Like other sclerorhynchoids, ''Onchopristis'' had 'saw', a long
rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...
with large denticles, similar to those of
sawfish Sawfish, also known as carpenter sharks, are a family of very large 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 lar ...
es and
sawshark 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 Pristi ...
s. This feature was the result of
convergent evolution 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 comm ...
, 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). It was somewhat triangular in shape, widest at the base, narrowing towards the tip. Internally, it consisted of a layer of small,
prismatic An optical prism is a transparent optics, optical element with flat, polished surfaces that are designed to refraction, refract light. At least one surface must be angled—elements with two parallel surfaces are ''not'' prisms. The most fami ...
cartilage Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...
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, Those on the sides of the saw were larger with the biggest measuring , 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 In human anatomy, the neurocranium, also known as the braincase, brainpan, brain-pan, or brainbox, is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the cal ...
(the base of the cranium). The neurocranium was rectangular in shape and box-like. Near the rostral base was an oval-shaped precerebral
fenestra A fenestra (fenestration; : fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biology, biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomy, ...
. The antorbital cartilage, that behind the eye, was triangular, with a narrow
distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...
(far) edge which pointed posteriorly (rearward). The
orbital cavity In anatomy, the orbit is the cavity or socket/hole of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is ...
, or eye socket, is large. Lymphatic foramina were present on the posterior part of the forebrain. ''Onchopristis'''
hyomandibula The hyomandibula, commonly referred to as hyomandibular one(, from , "upsilon-shaped" (υ), and Latin: mandibula, "jawbone"), is a set of bones that is found in the hyoid region in most fishes. It usually plays a role in suspending the jaws ...
, the structure from which the jaw was suspended, was triangular. Its
proximal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
(near) end articulated with the neurocranium, while the distal end sat between the
palatoquadrate In some fishes, the palatoquadrate is the dorsal component of the mandibular arch, the ventral one being Meckel's cartilage. The palatoquadrate forms from splanchnocranium in various chordates including placoderms and acanthodians. See also * H ...
and
Meckel's cartilage In humans, the cartilaginous bar of the mandibular arch is formed by what are known as Meckel's cartilages (right and left; also known as Meckelian cartilages), above which the incus and malleus are located. Meckel's cartilage arises from the fir ...
. The jaw cartilages are poorly known, with only those structures being visible when viewed
ventrally Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...
(from the bottom). Known oral teeth all display well-developed cutting edges, extending continuously between the
cusp A cusp is the most pointed end of a curve. It often refers to cusp (anatomy), a pointed structure on a tooth. Cusp or CUSP may also refer to: Mathematics * Cusp (singularity), a singular point of a curve * Cusp catastrophe, a branch of bifu ...
and lateral cusplets. The cusp of each tooth bends lingually (inwards).


Postcranium and dermal denticles

''Onchopristis'''
vertebral centra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...
, 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'', it is possible that dermal thorns were widespread throughout sclerorhynchoids.


Paleobiology


Predation

Specimens of ''Onchopristis'' have been associated with the jaws of ''
Spinosaurus ''Spinosaurus'' (; ) is a genus of large spinosaurid theropod dinosaurs that lived in what now is North Africa during the Cenomanian faunal stage, stage of the Late Cretaceous Period (geology), period, about 100 to 94 annum, million year ...
'' in North Africa, indicating that ''Spinosaurus'' would have preyed upon ''Onchopristis'' based on direct evidence of
piscivory A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted repti ...
. An isolated fish vertebra, tentatively referred to ''Onchopristis'', has been associated with the tooth
alveolus Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * M ...
of a possible specimen of ''Spinosaurus'' (MSNM V 4047). Similarly, the dentary fragment of ''Spinosaurus aegyptiacus'' (MPDM 31) is associated with the rostral denticle of ''Onchopristis''. Additionally, the teeth of ''Spinosaurus'' and rostral denticles of ''Onchopristis'' form a bone bed at one locality in the
Kem Kem beds The Kem Kem Group (commonly known as the Kem Kem beds) is a geological group in the Kem Kem region of eastern Morocco, whose strata date back to the Cenomanian stage of the Late Cretaceous. Its strata are subdivided into two geological formations ...
of
Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...
(
Errachidia Province Errachidia () is a Provinces of Morocco, province located in eastern central Morocco in the region of Drâa-Tafilalet, Dra-Tafilalt. Errachidia is bordered by Algeria to the southeast and by the Moroccan provinces of Figuig Province, Figig to the ...
).


Documentary appearances

''Onchopristis'' first appeared in ''
Planet Dinosaur ''Planet Dinosaur'', is a six-part documentary television series created by Nigel Paterson and Phil Dobree, produced by the BBC, and narrated by John Hurt. It first aired in the United Kingdom in 2011, with VFX studio Jellyfish Pictures as it ...
'' in 2011 and the companion book in 2012, where it was inaccurately depicted as an sawfish. It was also featured in the 2025 revival of ''
Walking with Dinosaurs ''Walking with Dinosaurs'' is a 1999 six-part nature documentary television miniseries created by Tim Haines and produced by the BBC Science Unit, the Discovery Channel and BBC Worldwide, in association with TV Asahi, ProSieben and France 3. ...
'', where it was accurately depicted as a sawskate. In both documentaries it was shown being preyed on by ''Spinosaurus'' in accordance with the fossil evidence.


References

{{Taxonbar, from=Q7092026 Cretaceous fish of Africa Cretaceous fish of Europe Cretaceous fish of North America Prehistoric cartilaginous fish genera Cretaceous cartilaginous fish Sclerorhynchoidei Taxa named by Ernst Stromer Fossil taxa described in 1917