page_title: Atlanticopristis
section_title: Description
hierarchical_section_title: Atlanticopristis / Description
caption_attribution_description: English: Onchopristis numidus from Kem Kem, Morocco; Tegana Formation (Cenomanian, Cretaceous).
context_page_description: Atlanticopristis is an extinct genus of sclerorhynchid that lived during the Middle Cretaceous of what is now the Northeast Region of Brazil, between 100.5 and 93.9 million years ago. Fourteen fossil teeth from Atlanticopristis were found in the Alcântara Formation, and referred to the closely related Onchopristis in 2007; a redescription in 2008 by Portuguese paleontologists Manuel Medeiros and Agostinha Pereira assigned it to a new genus containing one species, Atlanticopristis equatorialis.
  Like all sawfish, it would have had a long snout armed with modified fish scales shaped into "teeth", but Atlanticopristis's teeth had barbs on both sides. Atlanticopristis inhabited fresh to brackish water estuaries near large conifer forests, and lived in the same time and place as many species of bony fish, cartilaginous fish, and lobe finned fish, as well as some crocodilians, and several dinosaurs. Many of the taxa present in the Alcântara Formation are also known from the Middle Cretaceous Kem Kem Beds in Morocco, due to the past connection of South America and Africa into the supercontinent Gondwana.
context_section_description: The teeth on the rostrum (snout) of Atlanticopristis have a varied number of barbs at the front and rear margins. They are also laterally compressed, with both sides displaying thin enamel ridges extending outward from the base of the tooth, forming a fan shape. Some of the teeth also have grooves running down their length on both sides. The peduncle (or base) of the tooth is enlarged, and covered in irregular ridges, the bottom is typically concave, having a sub-rectangular or ellipsoid shape.
  The specimens range in size from 11.5 mm (0.45 inches) to 18.8 mm (0.74 inches). The holotype (CPHNAMA-VT 1174) is 15 mm (0.59 inches) in length, including the peduncle; which itself is 6.3 mm (0.24 inches) wide, and 3 mm (0.11 inches) long. It has a thickness of 3 mm (0.11 inches). The barb number on all specimens ranges from two to four barbs at the front margin and four to five at the rear, some specimens like CPHNAMA-VT 1085 having vestigial bumps that could be considered additional barbs.
  Sawfish evolved long snouts armed with rows of teeth on both sides, although these spines do not represent true teeth, but highly modified fish scales, or dermal denticles. This adaptation could be related to their feeding habits, such as sifting through sand/mud to search for food or to slash at prey. Like extant sawsharks, these spines were attached to the rostrum of sclerorhynchids like Atlanticopristis using ligaments, compared to modern sawfish which have their teeth attached via alveoli (tooth sockets). The longitudinal ribbing, or ridges, of enameloid that can be seen on sclerorhynchid teeth would have aided in the attachment of these ligaments.
caption: Onchopristis numidus tooth, displaying the same enamel ribbing found in Atlanticopristis
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