Sphenodus
| Sphenodus Temporal range:
| |
|---|---|
| |
| Skeleton of Sphenodus nitidus (SMNS 96844-7) from the Late Jurassic of Germany | |
| |
| Tooth of Sphenodus nitidus | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Family: | †Orthacodontidae |
| Genus: | †Sphenodus Agassiz, 1843 |
| Type species | |
| Lamna (Sphenodus) longidens Agassiz, 1843
| |
Sphenodus is an extinct genus of shark. It is placed as a member of the extinct family Orthacodontidae, which is either considered to be a member of the extinct order Synechodontiformes,[1] or the modern shark order Hexanchiformes.[2] 29 species have been described,[3] though some of these are likely synonyms, which span from the Early Jurassic (Sinemurian) to Paleocene (Danian).[2] Most species are only known from isolated teeth,[2] though the species Sphenodus macer and Sphenodus nitidus from the Late Jurassic of Germany are known from skeletons. These suggest that it was relatively large, with a body length of 2–3 metres (6.6–9.8 ft), with a fusiform body with a single dorsal fin placed posteriorly without a fin spine.[1] The teeth of Sphenodus consist of a single long, narrow central cusp, with much smaller lateral cusplets.[2] Species of Sphenodus are thought to have been actively swimming predators.[1]
References
[edit]- ^ a b c Villalobos-Segura, Eduardo; Stumpf, Sebastian; Türtscher, Julia; Jambura, Patrick L.; Begat, Arnaud; López-Romero, Faviel A.; Fischer, Jan; Kriwet, Jürgen (March 2023). "A Synoptic Review of the Cartilaginous Fishes (Chondrichthyes: Holocephali, Elasmobranchii) from the Upper Jurassic Konservat-Lagerstätten of Southern Germany: Taxonomy, Diversity, and Faunal Relationships". Diversity. 15 (3): 386. doi:10.3390/d15030386. ISSN 1424-2818. PMC 7614348. PMID 36950327.
- ^ a b c d CUSUMANO, Antonio; D'ARPA, Carolina; DUFFIN, Christopher J. (2021). "Taxonomic revision of the shark Sphenodus in the Jurassic collections of the "Museo Geologico G.G. Gemmellaro" (Palermo, Sicily)". Bollettino della Società Paleontologica Italiana: 169–181. doi:10.4435/BSPI.2021.10. ISSN 0375-7633.
- ^ Kanno, Shiori; Nakajima, Yasuhisa; Hikida, Yoshinori; Sato, Tamaki (2017-04-01). "Sphenodus (Chondrichthyes, Neoselachii) from the Upper Cretaceous in Nakagawa Town, Hokkaido, Japan". Paleontological Research. 21 (2): 122. doi:10.2517/2016PR009. ISSN 1342-8144. S2CID 133054888.