Sarcoprion (from the Ancient Greek, "flesh saw") is an extinctgenus of eugeneodontholocephalan from the Permian of Greenland. Similar to other helicoprionids such as Agassizodus and Helicoprion,[1] it possessed tooth whorls on the symphysis of the jaw as well as flattened, pavement-type teeth. It is distinguished from other members of its family by the presence of sharp, symphyseal teeth on both the upper and lower jaws. The tooth whorl on the lower jaw bore sharp, compact tooth crowns, while a row of backward facing, triangular teeth was present on the roof of the mouth.[2] The preserved material does not show evidence of a distinct upper jaw, implying it may have been fused to the cranium, reduced, or lost entirely.[2][3] The type and only species in the genus is S. edax.[2]
The first four Sarcoprion fossils were first discovered during the 1930s by paleontologistEigil Nielsen,[2] and originated inside concretions from the Foldvik Creek Formation of East Greenland.[4][5] These specimens were described by Nielsen in 1952, and the most complete of them was designated as the holotype (name-bearing specimen on which the species is based). Part of the holotype specimen was collected in 1932, and other fragments were collected later in 1937.[2][6] Nielsen suspected that a larger portion of this specimen was originally preserved, but that it had most likely become broken apart and lost due to erosion.[2] A block of matrix containing the remainder of this specimen's skull has since been identified.[7]
The genus name is derived from the Greek roots sarcos, meaning "flesh", and prion, meaning "saw".[6] The species name, edax, means "gluttonous".[9]
Description
Reconstruction based on the partial skull described by Nielsen (1952)
Sarcoprion had a thin, pointed snout, with two opposing rows of large teeth along the midline of its upper and lower jaws. The rostrum was greatly elongated compared to its relatives with comparable known skull material. The most complete known Sarcoprion specimen consists of a skull and lower jaws which are nearly 90 centimeters (3.0ft) long,[2][7] and the total length of the animal was estimated to be up to 6 meters (20ft) by paleontologist John A. Long.[9]
Nielsen suggested that, based on his reconstruction of the genus' skull and lower jaw, Sarcoprion was likely incapable of closing its mouth. Rows of flattened teeth were present along the lateral surfaces of the mouth in addition to the midline tooth whorls, and Nielsen thought these were likely armor for the snout rather than useful for feeding.[2]
Classification
Reconstructed jaw and dentition of Sarcoprion (top right) alongside a whorl of the related Helicoprion bessonowi (left)
Sarcoprion is a member of the order Eugeneodontiformes and the family Helicoprionidae.[10][11] Earlier research by paleontologist Svend Erik Bendix-Almgreen suggested that the genus may be unrelated to other fish now called eugeneodonts, and instead be part of a group containing only Erikodus and Fadenia.[12] This is no longer supported.[1]
Paleobiology and paleoecology
In life, Sarcoprion was a pelagic predator that likely hunted large prey.[9] The preserved tooth whorls of S. edax show signs of wear, both as a result of contact with prey and from contact with one another. Nielsen, as well as later authors such as Oleg Lebedev and Wayne Itano, have hypothesized that the animal used its whorls like a pair of scissors to cut prey during feeding.[2][11][13] In a 2009 paper, Lebedev proposed that features of Sarcoprion's teeth and snout suggest a diet of fish and squid, based on comparisons with living toothed whales such as sperm whales.[10] John Long has speculated that Sarcoprion had a generalist diet that included other cartilaginous fish as well as hard-shelled cephalopods.[9]
123456789Nielsen, Egil (30 August 1952). "On new or little known Edestidae from the Permian and Triassic of East Greenland". Palaeozoologica Groenlandica. 6 (144): 5–55.
12Ewing, Susan (2017). Resurrecting the shark: a scientific obsession and the mavericks who solved the mystery of a 270-million-year-old fossil (1sted.). New York: Pegasus Books. p.139. ISBN978-1-68177-343-8. OCLC951925606.
1234Long, John A. (2024). The secret history of sharks: the rise of the ocean's most fearsome predators (1sted.). New York: Ballantine Books. p.182. ISBN978-0-593-59807-8.
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