Guanling Biota： A Marker of Triassic Biotic Recovery from the end-Permian Extinction in the Ancient Guizhou Sea

Afteraslowrecoveryfromtheend-PermianextinctionduringtheEarlyTriassicandrapidradiationintheMiddleTriassic,evolutionoforganismsreachedanewpeakphaseintheLateTriassic.TheGuanlingBiotafromtheWayaoMember(conodontParagondolellapolygnathiformisZone),FalangFormation,Xinpu,GuanlingCounty,GuizhouProvince,southwesternChinacorrespondstothispeakthatmarksthefullrecoveryfromtheend-Permianextinctionofmarineecosystems.Thebiotaisofhighdiversity,containingwellpreservedandcompletelyarticulatedskeletonsofvertebratescomprisingmarinereptiles,fishes,andinvertebratesincludingcrinoids,ammonites,bivalves,andotherfossils,andisoneofthebestexamplesofmarineecosystemrecordsinlifehistory.Thefossilmarinereptilesandcrinoidsaremostsignificantinthisbiota,especiallythemarinereptiles,whichprovideanimportantlinkbetweentheTriassicPacificandTethys,andbetweenTriassicbasalformsandtheJurassic-Cretaceousmarinetoppredators.Themostremarkablefossilsarethelargecompletelyarticulatedichthyosaurskeletonsuptoandmorethan10m,andthefirstrecordedthalattosaursandplacodontsinChina.Followingourreview,ofthe17namedreptiliantaxatheeightlistedhereareconsideredtobevalid:threeichthyosaurs(QianichthyosauruszhouiLi,1999;GuizhouichthyosaurustangaeCaoandLuoinYinetal.,2000,GuanlingsaurusliangaeYininYinetal.,2000),threethalattosaurs(AnshunsaurushuangguoshuensisLiu,1999,XinpusaurussuniYininYinetal.,2000,XinpusauruskohiJiangetal.,2004),andtwoplacodonts(SinocyamodusxinpuensisLi,2000,PsephochelyspolyosteodermaLiandRieppel,2002).MixosaurusguanlingensisCaoinYinetal.,2000mightbeajuniorsynonymofQianichthyosauruszhouiLi,1999,andCymbospondylusasiaticusLiandYou,2002andPanjiangsaurusepicharisChenandCheng,2003mightbejuniorsynonymsofGuizhouichthyosaurustangaeCaoandLuoinYinetal.,2000.Itneedstore-describethehol