Thrinacodus is a thrinacodontid phoebodontiform cartilaginous fish from the Late Devonian-Mississippian of the United States of America, Russia, Morocco, Poland, France, Iran, Ireland, Armenia, and the United Kingdom. It was named in 1875 by Orestes Hawley St. John and Amos Henry Worthen. It was one of the many bizzare sharks that swam around in the waters of the Carboniferous period, as well as one of the more widespread.
Physiology[]
Thrinacodus more resembled an eel than the typical shark. It was a cartilaginous fish with a long, slender body, rounded pectoral fins that bore a trailing edge, a lack of any dorsal fins, a long, vaguely tadpole-like caudal fin, and a small head with a long snout. Its body would have been covered in scaly skin.
Diet[]
Thrinacodus was a predator, preying on smaller fish and crustaceans. Its teeth were small but each bore three prongs, and were used for getting a hold of struggling prey.
Ecology[]
Thrinacodus' long, serpentine body suggests that it was not a very active swimmer, often lurking between the vaguely tree-like sponges in its habitat and only swimming for short periods of time. Combined with how long its snout was as well as the fact that its gill arches were spaced widely apart and placed behind its head, it likely would have lunged towards prey with its mouth open in order to generate a vacuum that sucked them into its jaws, with its enlarged jaw bones providing ample muscle attachment for a quick and powerful bite; since its snout was so thin, it would have likely have been able to snag food with a sideways swipe of its head without experiencing drag, similarly to gars. Stomach contents from two specimens of Thrinacodus gracia (once considered to be its own genus, "Thrinacoselache" [1]) reveal that it was mainly a piscivore that fed on smaller cartilaginous fish like Falcatus, with another specimen having chitin plates likely attributable to shrimp. Due to the lack of any features that would indicate sensory organs on its snout, it is unlikely that Thrinacodus would have used those to detect prey, using its eyesight or sense of smell to do so instead.[2]
References[]
- Ginter, M., & Turner, S. (2010). THE MIDDLE PALEOZOIC SELACHIAN GENUS THRINACODUS. In Source: Journal of Vertebrate Paleontology (Vol. 30, Issue 6).
- Grogan, E. D., & Lund, R. (2008). A basal elasmobranch, Thrinacoselache gracia n. gen & sp., (Thrinacodontidae, new family) from the Bear Gulch Limestone, Serpukhovian of Montana, USA. Journal of Vertebrate Paleontology, 28(4), 970–988. https://doi.org/10.1671/0272-4634-28.4.970