Squatinactis
Squatinactis is a genus of extinct elasmobranch Chondrichthyes known from the Carboniferous aged Bear gulch limestone in Montana.[1] This fish was discovered in 1974 by Richard Lund.[1] The type specimen, named CMNH 46133, consists of a brain case, poorly preserved jaws and gills, a pectoral fin, and a partial vertebral axis.[1] This creatures most startling feature were its broad pectoral fins which resembled those of Stingrays and Angel sharks (Squatina).[1] The holotype specimen has about 15 teeth in its jaw.[1] This creature is named after the angel shark.[1] Teeth found in Derbyshire, England have been tentatively identified as those belonging to S. caudispinatus.[2]
| Squatinactis Temporal range: | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Order: | †Squatinactiformes Zangerl, 1981 |
| Family: | †Squatinactidae Cappetta et al., 1993 |
| Genus: | †Squatinactis Lund and Zangerl, 1974 |
| Species: | †S. caudispinatus |
| Binomial name | |
| †Squatinactis caudispinatus Lund and Zangerl, 1974 | |
Classification
Because of the bizarre nature of Squatinactis, it is somewhat difficult to classify. In the original study conducted in 1974, Lund noted that the teeth of this fish are Cladodont is design.[1] This doesn't really help however, as the term ´´Cladodont´´ is used to describe most paleozoic Chondrichthyeans based on their teeth and not phylogeny (including Cladoselache, Ctenacanthus, and Dracopristis). This fish is currently classed within the Elasmobranchii, more specially in its own grouping, the Squatinactiformes.[3]
| Phylogenetic position of D.hoffmanorum, which also shows the position of S. caudispinatus. after Hodnett & Grogan 2021. |
| Elasmobranchii |
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References
- Lund, Richard (1988-09-23). "New information on Squatinactis caudispinatus (Chondrichthyes, Cladodontida) from the Chesterian Bear Gulch Limestone of Montana". Journal of Vertebrate Paleontology. 8 (3): 340–342. doi:10.1080/02724634.1988.10011718. ISSN 0272-4634.
- Ginter, Michal (2015). "Late Viséan pelagic chondrichthyans from northern Europe" (PDF). bioone.
- Ginter, M. (2012-08-17). Chondrichthyes, Paleozoic Elasmobranchii: Teeth. In H.P. Schultze (ed.), Handbook of Paleoichthyology 3D. pp. 1–168.