Abstract
In the present study, the historical development of Parareptilia as a phylogenetically valid clade is summarized, and for the first time a modern phylogenetic definition of both Parareptilia as well as Eureptilia is presented, which will facilitate the study of problems of early amniote classification. Furthermore, a preliminary study of the rates of diversification in parareptiles is performed on the basis of topological information on species diversity. While acknowledging that the bias of the fossil record also needs to be considered for a more definitive statement on parareptile diversification, our results show that a significant increase in diversification rate could be recorded only among Triassic procolophonoids, making it difficult to interpret evolutionary novelties such as herbivory or impedance-matching hearing as being key innovations that might have driven diversification. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200800011" target="_blank">10.1002/mmng.200800011</a>
Highlights
The origin and radiation of amniotes in the Late Paleozoic represents the first colonization of land by fully terrestrial vertebrates, and as such can be regarded as one of the key events in tetrapod evolution
It is widely agreed that early amniotes can be subdivided into three major clades, Synapsida Osborn, 1903, which includes mammals, Eureptilia Olson, 1947, which includes diapsid reptiles, and Parareptilia Olson, 1947, which together with Eureptilia forms the clade Reptilia Laurenti, 1768 (Reisz 1997)
There is a lack of fossils from Early Permian sites, and there has yet to be a parareptile found in the Carboniferous
Summary
The origin and radiation of amniotes in the Late Paleozoic represents the first colonization of land by fully terrestrial vertebrates, and as such can be regarded as one of the key events in tetrapod evolution. Members of the group were scattered throughout Tetrapoda It is acknowledged, that Parareptilia is a strongly supported clade, supported in the most recent analyses by six unequivocal autapomorphies: the absence of a lacrimal-narial contact, the absence of a caniniform region, a shortened postorbital region, a single median embayment of the posterior margin of the skull roof, the absence of a supraglenoid foramen, and the absence of a subtemporal process of the jugal (see Mçller & Tsuji 2007). Outside of these unequivocal autapomorphies, the clade is distinguished by a number of other characters, including a solid prefrontal-palatine contact, a dorsally expanded quadratojugal, a large foramen on the maxilla just below the naris (anterior maxillary foramen), and a jaw articulation at the level of or slightly posterior to the occiput (Laurin & Reisz 1995; deBraga & Rieppel 1997)
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