| Strophodus Temporal range: | |
|---|---|
 | |
| Jaw fragment of Strophodus atlasensis | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Order: | † Hybodontiformes |
| Family: | † Acrodontidae |
| Genus: | † Strophodus Agassiz, 1838 |
| Species | |
Strophodus is an extinct genus of durophagous hybodont known from the Triassic to Cretaceous. It was formerly confused with Asteracanthus.
It has long been confused with Asteracanthus due to the fin spines of the latter being found associated with the teeth of Strophodus. However, both genera can now be reliably be distinguished base on the morphology of both the fin spines and teeth. [1] [2]
Species of Strophodus had heavily rounded, durophagous crushing teeth, contrasting strongly with those of Asteracanthus, which are much more similar to those of Hybodus . Species of Strophodus have been estimated to reach up to 3 metres (9.8 ft) in length, making them some of the largest hybodonts. [3] Like Asteracanthus, but unlike other hybodonts, the fin spines of Strophodus are covered in tubercles rather than being ribbed. [2]
Strophodus has been intepreted as a bottom-dwelling animal that fed on hard-shelled invertebrates, though isotopic evidence has suggested that it may have been pelagic. It may also have been euryhaline. [3]
Species of Strophodus: [4]
Indeterminate remains of Strophodus possibly extend into the Albian stage of the Early Cretaceous. Claimed records of the genus from the Late Cretaceous are doubtful. [4]
Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks, rays, skates, and sawfish. Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil.
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