Lissodus is an extinct genus of chondrichthyan fish in the large order of Hybodontiformes, which is often assigned to sharks. Like many prehistoric chondrichthyans, it is known primarily from dental fossils. This genus was firstly described by Brough in 1935, and numerous specimens were assigned to Lissodus since that year. Fossils have been reported from strata ranging from the Tournaisian (Carboniferous)[1][2] to the Maastrichtian (Cretaceous),[3] which represents a huge temporal range about 358.9 to 66 Ma (million years ago).
The type species, Lissodus africanus, was described from the Upper Triassic of Free State, South Africa, and originally assigned to the genus Hybodus by Broom in 1909. A slightly older, Middle Triassic materials, probably belonging to this species, were also reported from Poland.[4] Thus, even excluding other and indeterminate species, Lissodus was probably cosmopolitan.
Description[]
As a hybodontiform, Lissodus had pointed but wide teeth, which made it possible to evenly distribute the load when biting and chew relatively hard covers, possibly carapaces and some shells. Some teeth belonging to this genus are very small, no more than 1.5 mm in width at the lower edge.[2] Depending on the species, adult individuals did not exceed 15-50 cm in length.[5] Like all hybodontiforms, it was likely slower than modern sharks.
Paleoecology[]
Fossils of Lissodus have been reported from both marine and freshwater sediments. During Late Triassic, L. africanus lived alongside pholidophoriform (Pholidophorus), palaeonisciform (Helichthys, Dicellopyge), dipnoan (Ceratodus kannemeyeri) and coelacanthiform (Coelacanthus africanus) fish that it could hunt. Its main target was most likely small fry.
Lissodus duffini (a probable synonym of Pristrisodus tikiensis[6]) was found in the Carnian fluvial strata of Tiki Formation, India, alongside with various cartilaginous and bony fish as well as amphibians, sauropsids and synapsids. Predators of the ecosystem include Metoposaurus, a temnospondyl, Parasuchus, a phytosaur, and Rewaconodon, a cynodont.[7]
References[]
- ↑ A. Ivanov (1999). "Late Devonian - Early Permian chondrichthyans of the Russian Arctic". Acta Palaeontologica Polonica 49 (3): pp. 267-285.
- ↑ 2.0 2.1 Brett Roelofs; Milo Barham; Arthur J. Mory; Kate Trinajstics (2016). "Late Devonian and Early Carboniferous chondrichthyans from the Fairfield Group, Canning Basin, Western Australia". Palaeontologia Electronica. 19 (1): pp. 1–28. DOI:10.26879/583
- ↑ G. R. Case; H. Cappetta (1997). "A new Selachian Fauna from the Late Maastrichtian of Texas (Upper Cretaceous/Navarroan; Kemp Formation)". Münchner Geowissenschaftliche Abhandlungen (A) (34): pp. 131-189.
- ↑ J. Liszkowski (1993). "Die Selachierfauna des Muschelkalks in Polen: Zusammensetzung, Stratigraphie und Paläoökologie". Muschelkalk, Schöntaler Symposium 1991. Sonderbände der Gesellschaft für Naturkunde in Württemberg 2: pp. 177-185.
- ↑ J. Fischer "Brief synopsis of the hybodont form taxon Lissodus Brough, 1935, with remarks on the environment and associated fauna". Freiberger Forschungshefte Serie C, 528 (2008), pp. 1-23.
- ↑ "Pristrisodus tikiensis (Prasad, Singh, Parmar, Goswami, & Sudan, 2008)". https://shark-references.com/species/view/Pristrisodus-tikiensis.
- ↑ J. Kumar; K. M. Sharma (2019). "Micro and mega-vertebrate fossils from the Late Triassic Tiki Formation, South Rewa Gondwana Basin, India: palaeoenvironmental and palaeobiogeographic implications". Journal of the Palaeontological Society of India 64 (2): pp. 151-168.