First rhynchocephalian (Reptilia, Lepidosauria) from the Cretaceous–Paleogene of India
First rhynchocephalian (Reptilia, Lepidosauria) from the Cretaceous–Paleogene of India
复制标题
印度白垩纪古近纪第一个喙头类动物（爬行类、鳞龙类）
DOI：
10.1080/02724634.2022.2118059
复制
发表时间：
2022
影响因子：
1.4
通讯作者：
Wilson Mantilla, Jeffrey A.
中科院分区：
文献类型：
--
作者：
Anantharaman, S.;DeMar, David G.;Sivakumar, R.;Dassarma, Dilip Chandra;Wilson Mantilla, Gregory P.;Wilson Mantilla, Jeffrey A.
喙头类，一个曾经多样化的蜥蜴类爬行动物分支，在中生代的大部分时间里几乎遍布全球。到了晚白垩世，喙头类的多样性和地理分布范围明显减少，只有少量的深巢分类群（例如，楔齿龙亚科）发现于巴塔哥尼亚晚白垩世-古新世和新西兰中新世-新近纪。在这里，我们描述了一个rhynchocephalian从Naskal地方，在印度半岛的德干陷阱火山省内的一个intertrapetrium存款的牙齿的部分齿骨。这一发现代表了巴塔哥尼亚以外的喙头动物的第一个原始-古近纪（K-Pg）记录，并且：（i）证明了该分支在白垩纪期间的冈瓦纳分布范围比以前更广，（ii）加强了喙头动物在早白垩世之后仅限于冈瓦纳的新模式。这进一步扩展了印度的喙头动物记录，现在它跨越了中生代的大部分时间（晚三叠世到大约2000年）。K-Pg边界）。根据其区域化的端齿边缘齿系，纳斯卡尔喙头类是端齿亚目的一员。它的幼齿似乎是独一无二的（例如，冠部近中端，沿着远缘斜坡明显间断），形态与印度早-中侏罗世的Godavarosaurus lateefi最为相似。虽然纳斯卡尔内陷最有可能是在最近的马斯特里赫特时期沉积的，但需要在印度K-Pg边界上进行额外的化石采样，以确定纳斯卡尔喙头类动物是白垩纪末大灭绝的受害者还是幸存者。
Rhynchocephalia, a once diverse clade of lizard-like reptiles, had a nearly global distribution during much of the Mesozoic. By the Late Cretaceous rhynchocephalians underwent a marked reduction in their diversity and biogeographic range, with sparse records of only deeply nested taxa (e.g., Sphenodontinae) found in the Upper Cretaceous–Paleocene of Patagonia and the Miocene–Recent of New Zealand. Here we describe a partial dentary with teeth of a rhynchocephalian from the Naskal locality, an intertrappean deposit within the Deccan Traps Volcanic Province in peninsular India. This discovery represents the first Cretaceous–Paleogene (K–Pg) record of a rhynchocephalian outside of Patagonia and: (i) demonstrates the clade had a broader Gondwanan distribution during the Cretaceous than previously appreciated and (ii) reinforces the emerging pattern that Rhynchocephalia were confined to Gondwana after the Early Cretaceous. This further extends the rhynchocephalian record in India, which now spans most of the Mesozoic (Late Triassic to ca. K–Pg boundary). The Naskal rhynchocephalian is a member of Acrosphenodontia based on its regionalized, acrodont marginal dentition. Its hatchling teeth appear to be unique (e.g., crowns mesially tipped, distinct break in slope along distal margin) and most similar in morphology to those ofGodavarisaurus lateefifrom the Lower–Middle Jurassic of India. Although the Naskal intertrappean most likely was deposited during the latest Maastrichtian, additional fossil sampling across the K–Pg boundary in India is needed to determine whether the Naskal rhynchocephalian was a victim or survivor of the end-Cretaceous mass extinction.