Lepospondyli
The Micro dinosaur Pelodosotis elongatum, graphic reconstruction
- North America, Europe, North Africa
The Lepospondyli ( " cases or Hülsenwirbler " ) are an extinct group of amphibians like, primitive and morphologically very diverse land vertebrates ( Tetrapoda ). Fossil remains of Lepospondyli were found almost exclusively in North America and Europe, only the Nectridea are also known from North Africa.
Features
In contrast to the usually large and heavy built Temnospondyli the Lepospondyli are rather small, most forms were only 10 to 20 cm long, and are similar to today's tail or crawl amphibians. Her skeleton was poorly ossified. The melting layer her strong teeth were not folded like a labyrinth, their snouts short, stocky the skull. The trailing edge terminates just an ear slot is missing. The ribs were long and curved. The eponymous and most important common feature is the spindle-shaped vertebrae. This shape of the vertebral body may be an adaptation to the low height and thus, a reduction characteristic. In this case, the Lepospondyli of various primitive terrestrial vertebrates of the Devonian or Mississippian ( " Lower Carboniferous " ) could be derived and their monophyly is thus questionable.
System
In the traditional hierarchy, they are led as a subclass of amphibians, the relationships to today's amphibians are unclear. The Lepospondyli could be their sister group, but they could also be a non- monophyletic grouping of stem group representatives of amphibians. Present, however, speaks more to ensure that they are as a basal branch in the root group of Amniota. After a re-examination of family relationships of the early land vertebrates, a team of scientists concludes that Westlothiana basal is to the Lepospondyli and forms a clade with them.
Cladogram to Benton 2007 supplement by Ruta et al ..
- Land vertebrates ( Tetrapoda ) basal tetrapods
- † Temnospondyli → ( Modern amphibians)
- Untitled monophyletic untitled monophyletic † Westlothiana
- † Lepospondyli
- † " Anthracosauria "
- Batrachosauria † Seymouriamorpha
- † Diadectomorpha
- Amniota
Untertaxa
The Lepospondyli be divided according to anatomical features in six subgroups.
- Serpent amphibians ( Aistopoda )
- Nectridea
- Lysorophidae
- Adelogyrinidae
- Acherontiscidae