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首页> 外文期刊>Journal of Systematic Palaeontology >Invictokoala monticola gen. et sp. nov. (Phascolarctidae, Marsupialia), a Pleistocene plesiomorphic koala holdover from Oligocene ancestors
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Invictokoala monticola gen. et sp. nov. (Phascolarctidae, Marsupialia), a Pleistocene plesiomorphic koala holdover from Oligocene ancestors

机译：Invictokoala monticola gen。等。十一月（Pashcolarctidae，Marsupialia），来自渐新世祖先的更新世多形性考拉遗留物

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Koalas (Phascolarctidae) are uncommon elements within the Australian fossil record. The earliest representatives are recorded from late Oligocene rainforest assemblages of central Australia. In contrast, the extant Koala Phascolarctos cinereus Blainville, 1816 (the only surviving member of a once diverse family) is found only in eastern Australian open woodlands. Extinction of koalas from rainforests was previously thought to have occurred after the middle Miocene. Recent systematic cave excavations at Mt. Etna, central eastern Queensland, Australia, have revealed several remarkable new middle Pleistocene vertebrate assemblages that arc dominated by rainforest-adapted taxa. Within one of the deposits, we have identified a new, but archaic, genus and species of koala. Invictokoala monticola gen. et sp. nov. shares affinities with the most plesiomorphic member of the family, Madakoala Woodburne et ai, 1987 (late Oligocene), but is distinguished by possessing higher-crowned upper molars, with a tricsupatc (rather than linear) paraconule on M2 (autapomorphic condition within koalas), closely positioned stylar cusps, and better-developed posterior cingulae. Thus, not only does /. monticola represent a 'holdover' from an Oligocene ancestor, but the Madakoala-lnvictokoala stem represents a 'ghost' lineage within the Phascolarctidae, with no representatives known between the late Oligocene and middle Pleistocene. Previously, it was thought that the post-middle Miocene loss of koalas from rainforests may have been a result of a co-evolved dependence of koalas to open eucalypt woodlands, and/or competitive exclusion with koala-like rainforest-adapted ringtail possums. However, the inferred diet of middle Pleistocene /. monticola (i.e. non-Eucalyptus) and coeval occurrence with numerous rainforest-adapted ringtail possums does not support that hypothesis. It appears more likely that koalas had always been closely associated with rainforests, at least until the late Quaternary extinction of /. monticola. Generally, the paucity of rainforest faunal assemblages, and specifically, records of fossil koalas through the late Cenozoic drastically limits our understanding of their evolution.
机译：考拉（Phascolarctidae）是澳大利亚化石记录中罕见的元素。最早的代表来自澳大利亚中部晚渐新世的雨林组合。相反，现存的考拉Phascolarctos cinereus Blainville，1816年（曾经是异族的唯一幸存者）仅在澳大利亚东部的开放林地中发现。以前认为雨林中的考拉灭绝是在中新世中期之后发生的。最近在山的系统性洞穴发掘。澳大利亚昆士兰州中部东部的埃特纳火山揭示了几种非凡的中更新世脊椎动物新组合，这些组合以适应热带雨林的分类单元为主导。在其中一个矿床中，我们确定了一种新的但古老的无尾熊属和树种。 Invictokoala monticola gen。等。十一月1987年与马达科拉多（Madakoala Woodburne et ai）（最晚渐新世）有最亲子关系，但其特征是拥有较高的上臼齿，在M2上有tricsupatc（而不是线性）副锥（树袋熊体内的亚同形条件） ，紧密定位的茎尖和较发达的后扣带。因此，不仅/。 monticola代表渐新世祖先的“遗留物”，而Madakoala-Invictokoala茎代表了古猿科中的“鬼”世袭，在渐新世晚期和中更新世之间没有代表。以前，人们认为中雨后中新世后考拉从雨林中流失的原因可能是考拉对开放桉树林地的依存度不断提高和/或与像考拉一样适应雨林的环尾负鼠竞争性排斥的结果。但是，推断饮食为中更新世/。 Monticola（即非桉树）和同时代出现的大量雨林适应性环孢负鼠并不支持该假说。至少在直到第四纪末期灭绝之前，考拉似乎一直与雨林密切相关。蒙蒂科拉。通常，雨林动物群落的稀缺性，尤其是新生代晚期的考拉化石记录，极大地限制了我们对其进化的理解。

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