New mammals from the Naskal intertrappean site and the age of India’s earliest eutherians
New mammals from the Naskal intertrappean site and the age of India’s earliest eutherians
复制标题
纳斯卡尔陷阱间遗址的新哺乳动物和印度最早的真兽类的时代
DOI：
10.1016/j.palaeo.2022.110857
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Dassarma, Dilip Chandra
中科院分区：
文献类型：
--
作者：
Wilson Mantilla, Gregory P.;Renne, Paul R.;Samant, Bandana;Mohabey, Dhananjay M.;Dhobale, Anup;Tholt, Andrew J.;Tobin, Thomas S.;Widdowson, Mike;Anantharaman, S.;Dassarma, Dilip Chandra
在印度发现的第一批白垩纪哺乳动物是在德干火山区（DTVP）东南边缘的纳斯卡（Naskal）地区发现的，它保存在两个玄武岩流之间。由于DTVP喷发跨越了白垩纪-古近纪界线（KPB），因此通常不知道与圈闭相关的化石遗址的年龄是白垩纪晚期（马斯特里赫特阶）还是古新世早期。在已发表的与DTVP相关的沉积物中的哺乳动物记录以及其他脊椎动物微化石中，纳斯卡尔地区占了近一半。它的年龄在印度哺乳动物进化的背景下，以及白垩纪末期大规模灭绝和随后胎盘动物进化辐射的影响中具有独特的重要性。在这里，我们描述了两个新的哺乳动物物种，Indoclemensia naskalensisgen。et sp. nov.和I.大型十一月，从Naskal和目前的证据40 Ar/39 Ar地质年代学，磁性地层学和化学地层学的上和下伏玄武岩流，以细化的Naskal地点和附近的Rangapur地点的年龄。结合孢粉地层学和脊椎动物生物地层学，这些地点可以肯定地限制在一个<100 kyr的时间跨度KPB。最可能的40 Ar/39 Ar年龄为白垩纪晚期（66.136- 66.056Ma），但不能排除最早的古近纪年龄。我们探讨这个年龄分配的影响，德干化学地层学和德干火山活动，古近纪（K/Pg）大规模灭绝，印度哺乳动物区系的演变，胎盘哺乳动物的起源时间。
The first Cretaceous mammals described from India were recovered from the Naskal locality, on the southeastern edge of the Deccan Traps Volcanic Province (DTVP), where it is preserved between two basalt flows. Because the DTVP eruptions spanned the Cretaceous-Paleogene boundary (KPB), it is often unknown whether trap-associated fossil sites are latest Cretaceous (Maastrichtian) or early Paleocene in age. The Naskal locality accounts for nearly half of published mammal records from DTVP-associated sediments as well as a host of other vertebrate microfossils. Its age takes on singular importance in the context of mammalian evolution in India and the effects of the end-Cretaceous mass extinction and subsequent evolutionary radiation of placentals. Here we describe two new mammal species,Indoclemensia naskalensisgen. et sp. nov. andI. magnussp. nov., from Naskal and present evidence from40Ar/39Ar geochronology, magnetostratigraphy, and chemostratigraphy of the over- and underlying basalt flows to refine the age of the Naskal locality and nearby Rangapur locality. In conjunction with palynostratigraphy and vertebrate biostratigraphy, these sites can be confidently restricted to a <100 kyr interval spanning the KPB. The most probable40Ar/39Ar age is latest Cretaceous (66.136–66.056 Ma), but an earliest Paleogene age cannot be ruled out. We explore the implications of this age assignment for Deccan chemostratigraphy and Deccan volcanism, Cretaceous-Paleogene (K/Pg) mass extinction, Indian mammalian faunal evolution, and the timing of the origin of placental mammals.