Scapanorhynchus

Scapanorhynchus; Temporal range: Aptian to Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N
	Complete fossil of Scapanorhynchus lewisii from Sahel Alma, Lebanon
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	Lamniformes
Family:	Mitsukurinidae
Genus:	†Scapanorhynchus; Woodward, 1889
Type species
	Scapanorhynchus lewisii; Davis, 1887
Species
	Scapanorhynchus lewisii (Davis, 1887) ; Scapanorhynchus texanus (Romer, 1849); Scapanorhynchus rapax (Quaas, 1902) ; Scapanorhynchus raphiodon (Agassiz, 1843);

Scapanorhynchus (from Greek: σκάφιου scaphion, 'shovel' and Greek: ῥύγχος rhynchos 'snout')^[3] is an extinct genus of goblin shark that lived during the Cretaceous period, from the Aptian to the end of the Maastrichtian.^[1]^[2] Later records, such as those from the Miocene assigned to the species S. subulatus, are highly dubious and may be misidentified sand sharks.^[2]^[4]^[5]

It was the first goblin shark to be described, with the type species (S. lewisii) being described nearly 10 years before the living goblin shark (Mitsukurina).

Description

Scapanorhynchus had an elongated, albeit flattened snout and sharp awl-shaped teeth ideal for seizing fish, or tearing chunks of flesh from its prey. Scapanorhynchus normally did not exceed total length 4.15 metres (13.6 ft), although largest teeth with height about 6 centimetres (0.20 ft) indicates upper total length of 6.7 metres (22 ft).^[6]

Their extreme similarities to the living goblin shark, Mitsukurina owstoni, lead some experts^[7]^[8] to consider reclassifying it as Scapanorhynchus owstoni. However, most shark specialists regard the goblin shark to be distinct enough from its prehistoric relatives to merit placement in its own genus.

Ecology

Unlike modern goblin sharks, which inhabit deep ocean waters and are sluggish opportunistic feeders that feed on benthic fish and invertebrates, Scapanorhynchus appears to have been a pelagic apex predator that inhabited the epipelagic zone or continental shelf.^[2] An isotopic analysis of its teeth suggests that it largely preyed on fish and occupied a high trophic level in its ecosystem. It appears to have occupied a similar trophic level to Squalicorax, another marine lamniform of the same habitat.^[9] Its active predatory lifestyle may have made it more susceptible to the ecological impacts of the Cretaceous-Paleogene extinction event, as with other sharks that had a similar lifestyle.^[2]

Species of Scapanorhynchus may have occupied different habitats, with some like S. texanus inhabiting shallow marine environments like the Western Interior Seaway, while others like S. raphiodon may have inhabited deep marine environments, although it is also known from shallower environments.^[10]^[11] Scapanorhynchus has been found in shallow water rock deposits, such as those in Hell Creek, which appear to represent at least shoreline to brackish water conditions, and possibly even freshwater environments.^[12]

References

^ ^a ^b Hamm, Shawn A.; Shimada, Kenshu (2002). "Associated Tooth Set of the Late Cretaceous Lamniform Shark, Scapanorhynchus raphiodon (Mitsukurinidae), from the Niobrara Chalk of Western Kansas". Transactions of the Kansas Academy of Science (1903-). 105 (1/2): 18–26. ISSN 0022-8443.
^ ^a ^b ^c ^d ^e Kriwet, Jürgen; Benton, Michael J. (2004-11-18). "Neoselachian (Chondrichthyes, Elasmobranchii) diversity across the Cretaceous–Tertiary boundary". Palaeogeography, Palaeoclimatology, Palaeoecology. Mesozoic-Cenozoic Bioevents. 214 (3): 181–194. doi:10.1016/j.palaeo.2004.02.049. ISSN 0031-0182.
^ Lineaweaver, Thomas H. (1973). The natural history of sharks. Garden City, N.Y. : Anchor Natural History Books. p. 220. ISBN 978-0-385-02539-3.
^ Capetta, H., Chondrichthyes II, Mesozoic and Cenozoic Elasmobranchii, vol. 3B of Handbook of Paleoichthyology, Stuttgart, New York: Gustav Fischer Verlag, 1987.
^ Glickman, L. S., and A. O. Averianov. "Evolution of the Cretaceous Lamnoid sharks of the genus Eostriatolamia." PALEONTOLOGICAL JOURNAL C/C OF PALEONTOLOGICHESKII ZHURNAL 32 (1998): 376-384. [1]
^ K., Shimada; J., Seigel (2005). "The relationship between the tooth size and total body length in the goblin shark, Mitsukurina owstoni (Lamniformes: Mitsukurinidae)" (PDF). Journal of Fossil Research. 38 (1): 49–56.
^ Mikko's Phylogeny Archive
^ Froese, Rainer, and Daniel Pauly, eds. (2010). "List of Nominal Species of Mitsukurinidae (Goblin shark)". FishBase. Retrieved 2024-01-23. {{cite web}}: |author= has generic name (help)CS1 maint: multiple names: authors list (link)
^ Comans, Chelsea M.; Smart, Sandi M.; Kast, Emma R.; Lu, YueHan; Lüdecke, Tina; Leichliter, Jennifer N.; Sigman, Daniel M.; Ikejiri, Takehito; Martínez-García, Alfredo (2024). "Enameloid-bound δ15N reveals large trophic separation among Late Cretaceous sharks in the northern Gulf of Mexico". Geobiology. 22 (1): e12585. doi:10.1111/gbi.12585. ISSN 1472-4669.
^ Retzler, Andrew; Wilson, Mark A.; Avni, Yoav (2013-03-01). "Chondrichthyans from the Menuha Formation (Late Cretaceous: Santonian–Early Campanian) of the Makhtesh Ramon region, southern Israel". Cretaceous Research. 40: 81–89. doi:10.1016/j.cretres.2012.05.009. ISSN 0195-6671.
^ Becker, Martin A.; Wellner, Robert W.; Jr, Christopher S. Mallery; Jr, John A. Chamberlain (2010). "Chondrichthyans from the Lower Ferron Sandstone Member of the Mancos Shale (Upper Cretaceous: Middle Turonian) of Emery and Carbon Counties, Utah, USA". Journal of Paleontology. 84 (2): 248–266. doi:10.1666/09-053R.1. ISSN 0022-3360.
^ "Stratigraphy and paleontology of the Cretaceous Hell Creek Formation, Stumpf site, Morton County, North Dakota". Proceedings of the North Dakota Academy of Sciences. 48. 1994.

Description

Ecology

References

Further reading