Distributed under Creative Commons Cc-by 4.0 a New Hynobiid-like Salamander (amphibia, Urodela) from Inner Mongolia, China, Provides a Rare Case Study of Developmental Features in an Early Cretaceous Fossil Urodele
Distributed under Creative Commons Cc-by 4.0 a New Hynobiid-like Salamander (amphibia, Urodela) from Inner Mongolia, China, Provides a Rare Case Study of Developmental Features in an Early Cretaceous Fossil Urodele
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Jia Jia-Jia;K. Gao
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作者：
Jia Jia-Jia;K. Gao
本文记述了一种新的蜥蜴化石--青海新蜥蜴Nuominepeton Aquilonaris(Gen.)ET sp.Nov.)，根据内蒙古早白垩世光华组中国的标本命名和描述。这一新发现记录了中国地区早白垩世火蜥蜴的远北产状，将该群中生代化石记录的地理分布从热河地区(北纬40-45度)延伸到北纬49度附近。这种新蜥蜴的特征是：眼眶呈半圆形；肩峰喙突板明显扩张，具有凸出的腹缘和后缘；腕部和踝部的两个中央骨化；第一个指骨的长度约为第二个指骨长度的一半。新的火蜥蜴似乎与小蜥蜴有密切的亲缘关系，尽管这种推断的关系有待我们正在进行的对隐鳃类关系的形态和分子组合分析的研究证实。通过幼体标本和幼体标本与幼体标本和变态后幼体标本的比较，可以了解该化石物种颅骨和颅后骨骼的发育模式，特别是在变态过程中腭骨和腭翼前部的吸收以及下颌的冠状突的吸收，以及手部和后部中足部的变态后成骨。因此，这项研究为研究中生代火蜥蜴的发育特征提供了一个罕见的案例。
A new fossil salamander, Nuominerpeton aquilonaris (gen. et sp. nov.), is named and described based on specimens from the Lower Cretaceous Guanghua Formation of Inner Mongolia, China. The new discovery documents a far northern occurrence of Early Cretaceous salamanders in China, extending the geographic distribution for the Mesozoic fossil record of the group from the Jehol area (40th–45th parallel north) to near the 49th parallel north. The new salamander is characterized by having the orbitosphenoid semicircular in shape; coracoid plate of the scapulocoracoid greatly expanded with a convex ventral and posterior border; ossification of two centralia in carpus and tarsus; and first digit being about half the length of the second digit in both manus and pes. The new salamander appears to be closely related to hynobiids, although this inferred relationship awaits confirmation by research in progress by us on a morphological and molecular combined analysis of cryptobranchoid relationships. Comparison of adult with larval and postmetamorphic juvenile specimens provides insights into developmental patterns of cranial and postcranial skeletons in this fossil species, especially resorption of the palatine and anterior portions of the palatopterygoid in the palate and the coronoid in the mandible during metamorphosis, and postmeta-morphic ossification of the mesopodium in both manus and pes. Thus, this study provides a rare case study of developmental features in a Mesozoic salamander.