Sarcoprion

Sarcoprion Temporal range: Wuchiapingian, 259–254  Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Paratype specimen of Sarcoprion edax, from the collection of the Natural History Museum of Denmark
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	† Eugeneodontiformes
Family:	† Helicoprionidae
Genus:	† Sarcoprion Nielsen, 1952
Type species
Sarcoprion edax Nielsen, 1952

Sarcoprion (from the Ancient Greek, "flesh saw") is an extinct genus of eugeneodont holocephalan 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]

Research history and naming

The first four Sarcoprion fossils were first discovered during the 1930s by paleontologist Eigil 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]

Researcher Leif Tapanila began research on S. edax fossils at the Natural History Museum of Denmark in 2023. ^[7]

Etymology

The genus name is derived from the Greek roots sarcos, meaning "flesh", and prion, meaning "saw". ^[6] The species name, edax, means "gluttonous". ^[8]

Description

Reconstruction based on the partial skull described by Nielsen (1952)

Sarcoprion had a thin, pointed snout, with a pair of tooth whorls along the midline of its upper and lower jaws and a greatly elongated rostrum compared to its relatives for which comparable skull material is known. The most complete known specimen consists of a partial cranium and lower jaws. ^[2]

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 proposed these were likely armor for the snout rather than used for crushing prey. ^[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. ^{[9] [10]} Earlier research by paleontologist Svend Erik Bendix-Almgreen suggested it may be unrelated to other fish now called eugeneodonts, and instead formed a clade with Erikodus and Fadenia . ^[11] This is no longer supported. ^[1]

Paleobiology and paleoecology

In life, Sarcoprion was a pelagic predator that likely hunted large prey. ^[8] 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] [10] [12]} 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. ^[9] Paleontologist John A. Long has speculated that Sarcoprion had a generalist diet that included other cartilaginous fish, as well as hard-shelled cephalopods. ^[8]

References

1. Zangerl, Rainer; Schultze, Hans-Peter (1981). Chondrichthyes I: Paleozoic Elasmobranchii. Handbook of Paleoichthyology (2nd ed.). G. Fischer. ISBN   978-3-437-30337-1.
2. Nielsen, Egil (30 August 1952). "On new or little known Edestidae from the Permian and Triassic of East Greenland". Palaeozoologica Groenlandica. 6 (144): 5–55.
3. Zangerl, Rainer (1966). A new shark of the family Edestidae, Ornithoprion hertwigi, from the Pennsylvanian Mecca and Logan quarry shales of Indiana / Rainer Zangerl --. [Chicago]: Field Museum of Natural History. doi:10.5962/bhl.title.5302.
4. Ginter, Michał; Hampe, Oliver; Duffin, Christopher J. (2010). Handbook of paleoichthyology: teeth. München: F. Pfeil. p. 129. ISBN   978-3-89937-116-1.
5. Duffin, Christopher J. (2016). "Cochliodonts and chimaeroids: Arthur Smith Woodward and the holocephalians". Geological Society, London, Special Publications. 430 (1): 137–154. doi:10.1144/SP430.9. ISSN   0305-8719.
6. Ewing, Susan (2017). Resurrecting the shark: a scientific obsession and the mavericks who solved the mystery of a 270-million-year-old fossil (1st ed.). New York: Pegasus Books. p. 139. ISBN   978-1-68177-343-8. OCLC   951925606.
7. Idaho State University (September 7, 2023). "Fossil Found: Idaho No. 5 Returns to Idaho Museum of Natural History after 60+ Years". isu.edu. Archived from the original on July 11, 2025.
8. Long, John A. (2024). The secret history of sharks: the rise of the ocean's most fearsome predators (1st ed.). New York: Ballantine Books. p. 182. ISBN   978-0-593-59807-8.
9. Lebedev, O. A. (2009). "A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function". Acta Zoologica. 90 (s1): 171–182. doi:10.1111/j.1463-6395.2008.00353.x. ISSN   1463-6395.
10. Lebedev, Oleg A.; Itano, Wayne M.; Johanson, Zerina; Alekseev, Alexander S.; Smith, Moya M.; Ivanov, Aleksey V.; Novikov, Igor V. (2022). "Tooth whorl structure, growth and function in a helicoprionid chondrichthyan Karpinskiprion (nom. nov.) (Eugeneodontiformes) with a revision of the family composition". Earth and Environmental Science Transactions of The Royal Society of Edinburgh. 113 (4): 337–360. doi:10.1017/S1755691022000251. ISSN   1755-6910.
11. Bendix-Almgreen, Svend Erik (1976). "Palaeovertebrate faunas of Greenland". Geology of Greenland. doi:10.22008/GPUB/38226.
12. Itano, Wayne M. (2015). "An abraded tooth of Edestus (Chondrichthyes, Eugeneodontiformes): Evidence for a unique mode of predation". Transactions of the Kansas Academy of Science (1903-). 118 (1/2): 1–9. doi:10.2307/26434021. ISSN   0022-8443.