中国化石讲述兔形类起源与演化

Chinese fossils tell the story of origin and evolution of lagomorph

兔形类是现生哺乳动物重要的组成部分,然而有关兔形类的起源、分类位置及其与其他哺乳动物之间的系统发育关系等问题,曾是学界长期争议的话题。20世纪70年代以来在中国发现的有关化石为解决以上争议发挥了重要作用。经研究,安徽潜山盆地发现的安徽模鼠兔代表了兔形类祖先的“态模”,在分支系统上是与兔形目最为接近的化石类群。发现于内蒙古二连盆地的远古道森兔是兔形目中已知最早的代表,因此被誉为“世界第一兔”,也表明了兔形目的亚洲起源。依据以安徽模鼠兔为代表的基干兔形类化石,通过形态解剖学和分子生物学的综合研究表明,兔与鼠系统关系最为密切,兔形类和啮齿类为啮型动物下的姐妹群。近年来,通过综合地层学的工作,在中国内蒙古始新世和渐新世地层中发现大量的兔形类化石,这些化石为探讨兔形目研究中尚未解决的热点问题带来新的可能。

Lagomorpha is a significant component of the mammal and comprises two living families:Leporidae(rabbits and hares)and Ochotonidae.Since 1970s,our understanding of the origin,taxonomy,and phylogenetic relationships of Lagomorpha has greatly improved,largely due to the discovery of new fossils in China.Recent phylogenetic analyses indicate that Asia is likely the center of origin for Lagomorpha.Fossil evidence of stem lagomorph taxa has been found in Paleocene to lowest Eocene deposits in this region.One importantfinding is the presence of Mimotona in the early-middle Paleocene of the Qianshan Basin,Anhui,China,which is considered a primitive“morphotype”that may represent the ancestor of lagomorphs.The oldest known Lagomorpha,Dowsonolagus,has been discovered in the late early Eocene of the Erlian Basin,China.Thisfinding further supports the hypothesis of an Asian origin for Lagomorpha.The view that rodents and lagomorphs share an exclusive common ancestry is widely accepted among morphological researchers,and recent molecular studies have provided additional support for this idea.Now,the close relationship between these two groups is well-established.Recently,in Nei Mongol,China,extensive and well-preserved lagomorph fossils have been collected from Eocene and Oligocene strata through comprehensive investigations.These newly discovered fossils offer exciting opportunities to unravel long-standing mysteries surrounding the evolution and history of lagomorphs.