A lungfish survivor of the end-Devonian extinction and an Early Carboniferous dipnoan radiation
A lungfish survivor of the end-Devonian extinction and an Early Carboniferous dipnoan radiation
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DOI：
10.1080/14772019.2019.1572234
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发表时间：
2019-08-07
影响因子：
2.6
通讯作者：
Hill, Henrietta
中科院分区：
文献类型：
--
作者：
Challands, Tom J.;Smithson, Timothy R.;Hill, Henrietta
直到最近，法门纪（上泥盆纪）的Hangenberg事件的直接后果被认为已经摧毁了包括肺鱼在内的肉爬行动物群，只有两个分类群，Occludus romeri和Sagenodus spp.，在Tournaisian时代（早石炭世，早石炭世）的岩石中明确记录。最近在苏格兰南部和英格兰北部发现的许多形态多样的肺鱼齿板表明，石炭纪早期至少存在10个dipnoan分类群。在这些分类群中，只有两个，Xylognathus和Ballgadus，保留了头骨和颅后骨骼的元素，这些元素尚未被描述。在这里，我们提出了一个新属和新种肺鱼的头骨的描述，Limanichthys fraseri gen. et sp. nov.，它来自苏格兰南部伯恩茅斯巴拉干组最早期的Tournaisian。这个新标本代表了最早确定的图尔奈斯人肺鱼头骨材料，因此提供了宝贵的见解，了解这一群体的反应——实际上，整个石龙目——在最近的泥盆纪汉根堡事件之后。系统发育分析表明，Limanichthys fraseri属于泥盆纪“phaneropleurid-fleurantiid”肺鱼等级，石炭纪肺鱼代表了起源于泥盆纪中晚期的肺鱼形态，以及来自石炭纪独特辐射的肺鱼形态。
Until recently the immediate aftermath of the Hangenberg event of the Famennian Stage (Upper Devonian) was considered to have decimated sarcopterygian groups, including lungfish, with only two taxa, Occludus romeri and Sagenodus spp., being unequivocally recorded from rocks of Tournaisian age (Mississippian, Early Carboniferous). Recent discoveries of numerous morphologically diverse lungfish tooth plates from southern Scotland and northern England indicate that at least 10 dipnoan taxa existed during the earliest Carboniferous. Of these taxa, only two, Xylognathus and Ballgadus, preserve cranial and postcranial skeletal elements, which have yet to be described. Here we present a description of the skull of a new genus and species of lungfish, Limanichthys fraseri gen. et sp. nov., which hails from the very earliest Tournaisian in the Ballagan Formation of Burnmouth, southern Scotland. The new specimen represents the earliest definitive Tournaisian lungfish skull material, thus providing an invaluable insight into the response of this group - and, indeed, Sarcopterygii as a whole - immediately following the latest Devonian Hangenberg event. Phylogenetic analysis places Limanichthys fraseri within the Devonian 'phaneropleurid-fleurantiid' grade of lungfish and shows that the Carboniferous lungfish represent forms that have their origins deep in the Middle and Late Devonian as well as those from a unique Carboniferous radiation.