Amniotes through major biological crises: faunal turnover among parareptiles and the end-Permian mass extinction

摘要

The Parareptilia are a small but ecologicallyudand morphologically diverse clade of Permian and Triassicudcrown amniotes generally considered to be phylogeneticallyudmore proximal to eureptiles (diapsids and their kin) thanudto synapsids (mammals and their kin). A recent supertreeudprovides impetus for an analysis of parareptile diversityudthrough time and for examining the influence of the end-udPermian mass extinction on the clade’s origination andudextinction rates. Phylogeny-corrected measures of diversityudhave a significant impact on both rates and the distributionudof origination and extinction intensities. Time calibrationudgenerally results in a closer correspondence betweenudorigination and extinction rate values than in the case ofudno time correction. Near the end-Permian event, extinctionudlevels are not significantly higher than origination levels,udparticularly when time calibration is introduced. Finally,udregardless of time calibration and ⁄ or phylogenetic correction,udthe distribution of rates does not differ significantlyudfrom unimodal. The curves of rate values are discussed inudthe light of the numbers and distributions of both rangeudextensions and ghost lineages. The disjoint time distributionsudof major parareptile clades (e.g. procolophonoids andudnycteroleterids-pareiasaurs) are mostly responsible for theudoccurrence of long-range extensions throughout the Permian.udAvailable data are not consistent with a model of suddenuddecline at the end-Permian but rather suggest a rapidudalternation of originations and extinctions in a numberudof parareptile groups, both before and after the Permian ⁄udTriassic boundary.