| Lepidotes | |
|---|---|
 | |
| Fossil specimen ofL. gigas | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Clade: | Ginglymodi |
| Order: | Lepisosteiformes |
| Family: | †Lepidotidae |
| Genus: | †Lepidotes Agassiz, 1832[1] |
| Type species | |
| †Lepidotes gigas Agassiz, 1832 | |
| Species[3] | |
| Synonyms[4] | |
Genus synonymy Species synonymy
| |
Lepidotes (fromGreek:λεπιδωτόςlepidōtós, 'covered with scales') (previously known asLepidotus)[5] is an extinct genus ofMesozoicray-finned fish. It has long been considered awastebasket taxon, characterised by "general features, such as thick rhomboid scales and, for most of the species, by semi-tritorial or stronglytritorial dentition".[clarify][6] with dozens of species assigned to it.[4] Fossils attributed toLepidotes have been found in Jurassic and Cretaceous rocks worldwide.[7][8][9][10] It has been argued thatLepidotes should be restricted to species closely related to the type speciesL. gigas, which are only known from the Early Jurassic of Western and Central Europe, with most other species being not closely related, with other species transferred to new genera such asScheenstia.[7]Lepidotes belongs toGinglymodi, a clade of fish whose only living representatives are thegars (Lepisosteidae). The type speciesL. gigas and close relatives are thought to be members of the familyLepidotidae, part of the orderLepisosteiformes within Ginglymodi, with other species occupying various other positions within Ginglymodi.[7]
Inhabiting both freshwater lakes and shallow seas,Lepidotes was typically about 30 centimetres (12 in) long. The body was covered with thick, enamelledscales.[11]
Lepidotes was one of the earliest fish in which the upper jawbones were no longer attached to thejugal bone. This allowed the jaws to be stretched into a 'tube' so that the fish could suck in prey from a greater distance than in previous species.[11] This system is still seen in some modern fish, such ascarp.
Lepidotes scales are ovular in shape, and are 18.5 millimetres (0.73 in) long and 3 millimetres (0.12 in) thick at the thickest point.[12] The scales are smooth and shiny on the external surface, with only a few small depressions scattered toward the centre that are shaped like punctures.[12]
Stomach contents ofLepidotes from the Early Jurassic of Germany have found remains of crustaceancuticles, and it is suggested that they fed on relatively soft-bodied prey, which was grasped with the slender marginal teeth, before being crushed by the rounded palatal teeth.[13]
Many characteristics were identified by Woodward in 1895, and they are listed below:[4]
Currently valid species after.[7]
Thetype species of the genus, it is known from the Early Jurassic (Toarcian) of Germany.[7]
L. elvensis was described byDucrotay de Blainville in 1818. It is known from an almost complete specimen housed in theParis Museum of Natural History. The specimen measures up to 75 centimetres (2.46 ft) long. The specimen is from theUpper Lias, inBavaria. The specimens P. 7406, P. 7407, P. 7408, P. 2014, P. 2054, P. 3529a, P. 3529b, 18992, 18993/94 19662, 32421, and 32422 have all been assigned to this species. The external bones of this species are smooth, but some have sparsely-placed coarse tuberculations (protuberances). Thefrontal bone is more than twice the length of theparietal in the specimens. It also has a comparatively narrow marginalsymphysis (articulation).[4] Other specimens are known from France.[7]
This species was named by Agassiz in 1837 and is known from some incomplete remains. It has been classified as closely related toL. elvensis. It is more elongate thanL. elvensis, being four times as long as tall. It also has more sharply angulated sutures between its parietals, and the parietals are also proportionally longer. It is known from the specimens P. 1127, P. 7409, P. 2012, P. 2012a, P. 3527, P. 3528, P. 3528a, P. 5213, P. 5228, P. 6394, P. 7410, and 35556, all from the Upper Lias ofYorkshire, England[4]
Known from the Early Jurassic of (Toarcian) Germany.[7]
"Lepidotes" latifrons from the Middle-Late Jurassic of England has been reassigned to the genusIsanichthys.[14] Many other European species from the Late Jurassic-Early Cretaceous have been reassigned toScheenstia.[7]
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