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From top to bottom (A) a skull of an Anapsid, (B) a Synapsid (stem-mammal) skull, and (C) a Diapsid skull. [a] Temporal fenestrae are openings in the temporal region of the skull of some amniotes, behind the orbit (eye socket). These openings have historically been used to track the evolution and affinities of reptiles.
Compared to many other ostracoderms, such as the Heterostraci and Osteostraci, anaspids did not possess a bony shield or armor, hence their name.The anaspid head and body are instead covered in an array of small, weakly mineralized scales, with a row of massive scutes running down the back, and, at least confirmed among the birkeniids, the body was covered in rows of tile-like scales made of ...
This placement within the diapsids suggests that the turtle lineage lost diapsid skull characteristics, since turtles possess an anapsid skull. This would make Parareptilia a totally extinct group with skull features that resemble those of turtles through convergent evolution .
An anapsid is an amniote whose skull lacks one or more skull openings (fenestra, or fossae) near the temples. [1] Traditionally, the Anapsida are considered the most primitive subclass of amniotes, the ancestral stock from which Synapsida and Diapsida evolved, making anapsids paraphyletic.
Scutosaurus ("shield lizard") is an extinct genus of pareiasaur parareptiles.Its genus name refers to large plates of armor scattered across its body. It was a large anapsid reptile that, unlike most reptiles, held its legs underneath its body to support its great weight. [2]
Euryapsids are usually considered entirely extinct, although turtles might be part of the sauropterygian clade [1] while other authors disagree. [2] Euryapsida may also be a synonym of Sauropterygia sensu lato. [3] The ichthyosaurian skull is sometimes described as having a metapsid (or parapsid) condition instead of a truly euryapsid one.
The clade consisting of Eunotosaurus and turtles was called Pan-Testudines (defined as all animals more closely related to turtles than to any other living group). More derived pan-testudines, such as the earliest turtle Odontochelys, have a plastron. [24] The following cladogram shows the phylogenetic position of the Eunotosaurus, from Ruta et ...
"Labyrinthodontia" (Greek, 'maze-toothed') is an informal grouping of extinct predatory amphibians which were major components of ecosystems in the late Paleozoic and early Mesozoic eras (about 390 to 150 million years ago).