| Scincosauridae Temporal range: Late Carboniferous | |
|---|---|
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| Life restoration of Scincosaurus crassus | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Sarcopterygii |
| Clade: | Tetrapodomorpha |
| Order: | † Nectridea |
| Family: | † Scincosauridae Jaeckel, 1909 |
The Scincosauridae are an extinct family of nectridean tetrapodomorphs. It includes the genera Scincosaurus and Sauravus . [1] Unlike most other nectrideans, scincosaurids are thought to have been terrestrial.
Lepospondyli is a diverse taxon of early tetrapods. With the exception of one late-surviving lepospondyl from the Late Permian of Morocco, lepospondyls lived from the Early Carboniferous (Mississippian) to the Early Permian and were geographically restricted to what is now Europe and North America. Five major groups of lepospondyls are known: Adelospondyli; Aïstopoda; Lysorophia; Microsauria; and Nectridea. Lepospondyls have a diverse range of body forms and include species with newt-like, eel- or snake-like, and lizard-like forms. Various species were aquatic, semiaquatic, or terrestrial. None were large, and they are assumed to have lived in specialized ecological niches not taken by the more numerous temnospondyl amphibians that coexisted with them in the Paleozoic. Lepospondyli was named in 1888 by Karl Alfred von Zittel, who coined the name to include some tetrapods from the Paleozoic that shared some specific characteristics in the notochord and teeth. Lepospondyls have sometimes been considered to be either related or ancestral to modern amphibians or to Amniota. It has been suggested that the grouping is polyphyletic, with aïstopods being primitive stem-tetrapods, while recumbirostran microsaurs are primitive reptiles.
Adelospondyli is an order of elongated, presumably aquatic, Carboniferous amphibians. They have a robust skull roofed with solid bone, and orbits located towards the front of the skull. The limbs were almost certainly absent, although some historical sources reported them to be present. Despite the likely absence of limbs, adelospondyls retained a large part of the bony shoulder girdle. Adelospondyls have been assigned to a variety of groups in the past. They have traditionally been seen as members of the subclass Lepospondyli, related to other unusual early tetrapods such as "microsaurs", "nectrideans", and aïstopods. Analyses such as Ruta & Coates (2007) have offered an alternate classification scheme, arguing that adelospondyls were actually far removed from other lepospondyls, instead being stem-tetrapod stegocephalians closely related to the family Colosteidae.
Nectridea is the name of an extinct order of lepospondyl tetrapods from the Carboniferous and Permian periods, including animals such as Diplocaulus. In appearance, they would have resembled modern newts or aquatic salamanders, although they are not close relatives of modern amphibians. They were characterized by long, flattened tails to aid in swimming, as well as numerous features of the vertebrae.
Ptyonius is an extinct genus of nectridean tetrapodomorphs within the family Urocordylidae.
Arizonerpeton is an extinct genus of nectridean tetrapodomorphs. It contains a single species, Arizonerpeton wellsi. It lived in what is now the Swisshelm Mountains of modern-day Arizona, United States. This locality belongs to the Black Prince Limestone Formation, which is dated to the middle Pennsylvanian sub-period of the Carboniferous period.
Batrachiderpeton is an extinct genus of nectridean lepospondyl within the family Diplocaulidae; it was a basal member of the family. The type species is B. reticulatum and was found in a coal field in Northumberland, England at a locality that also yields the remains of Anthracosaurus russelli. A second species is also known: B. lineatum.
Ctenerpeton is an extinct genus of nectridean tetrapodomorphs within the family Urocordylidae.
Crossotelos is an extinct genus of nectridean tetrapodomorphs within the family Urocordylidae. It contains a single species, Crossotelos annulatus.
Diceratosaurus is an extinct genus of nectridean lepospondyl within the family Keraterpetontidae. Fossils of Diceratosaurus were first described by Edward Drinker Cope in 1874. The species D. brevirostris is well known from Jefferson County, Ohio, with approximately 50 specimens having been collected from the Ohio Diamond Coal Mine. The mine was situated in the village of Linton, which became obscure soon after operations were completed and the mine closed in 1921.
Lepterpeton is an extinct genus of nectridean tetrapodomorphs within the family Urocordylidae.
Montcellia is an extinct genus of nectridean tetrapodomorphs within the family Urocordylidae that lived in the late Carboniferous period in the modern France.
Rhynchonkos is an extinct genus of rhynchonkid microsaur. Originally known as Goniorhynchus, it was renamed in 1981 because the name had already been given to another genus; the family, likewise, was originally named Goniorhynchidae but renamed in 1988. The type and only known species is R. stovalli, found from the Early Permian Fairmont Shale in Cleveland County, Oklahoma. Rhynchonkos shares many similarities with Eocaecilia, an early caecilian from the Early Jurassic of Arizona. Similarities between Rhynchonkos and Eocaecilia have been taken as evidence that caecilians are descendants of microsaurs. However, such a relationship is no longer widely accepted.
Utaherpeton is an extinct genus of lepospondyl amphibian from the Carboniferous of Utah. It is one of the oldest and possibly one of the most basal ("primitive") known lepospondyls. The genus is monotypic, including only the type species Utaherpeton franklini. Utaherpeton was named in 1991 from the Manning Canyon Shale Formation, which dates to the Mississippian-Pennsylvanian boundary. It was originally classified within Microsauria, a group of superficially lizard- and salamander-like lepospondyls that is now no longer considered to be a valid clade or evolutionary grouping, but rather an evolutionary grade consisting of the most basal lepospondyls. Utaherpeton has been proposed as both the most basal lepospondyl and the oldest "microsaur", although more derived lepospondyls are known from earlier in the Carboniferous. However, its position within Lepospondyli remains uncertain due to the incomplete preservation of the only known specimen. The inclusion of Utaherpeton in various phylogenetic analyses has resulted in multiple phylogenies that are very different from one another, making it a significant taxon in terms of understanding the interrelationships of lepospondyls.
Urocordylus is an extinct genus of nectridean tetrapodomorphs. It is the type genus of the family Urocordylidae. Fossils have been found from Ireland that date back to the Westphalian stage of the late Carboniferous. It had total length of about 19.5 in (500 mm), but the skull was only about 1.3 in (33 mm) long.
Scincosaurus is an extinct genus of nectridean tetrapodomorphs within the family Scincosauridae.
Sauropleura is an extinct genus of nectridean tetrapodomorphs within the family Urocordylidae. Fossils are known from the United States and Europe. The following species are included:
Sauravus is an extinct genus of nectridean tetrapodomorphs within the family Scincosauridae.
Holospondyli is a proposed clade of lepospondyls from the Early Carboniferous to the Late Permian that includes the aistopods, the paraphyletic nectrideans, and possibly also Adelospondyli. However, aistopods have since been recovered as stem-tetrapods more primitive than temnospondyls or other groups of lepospondyls.
The Urocordylidae are an extinct family of nectridean lepospondyl amphibians. Urocordylids lived during the Late Carboniferous and Early Permian in what is now Europe and North America and are characterized by their very long, paddle-like tails. In life, they were probably newt-like and aquatic.
Sauropleurinae is an extinct subfamily of nectridean tetrapodomorphs. Along with the subfamily Urocordylinae, Sauropleurinae is part of the family Urocordylidae. Like other urocordylids, sauropleurines have long, flattened tails and superficially resemble aquatic newts. They differ from urocordylines in having narrow, pointed skulls. Sauropleurinae includes the genera Sauropleura, Crossotelos, Lepterpeton, and Montcellia, which lived during the Late Carboniferous and Early Permian in what is now North America and Europe.
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