A new semionotiform (Actinopterygii, Neopterygii) from Upper Jurassic Lower Cretaceous deposits of north-east Thailand, with comments on the relationships of semionotiforms
A new semionotiform (Actinopterygii, Neopterygii) from Upper Jurassic Lower Cretaceous deposits of north-east Thailand, with comments on the relationships of semionotiforms
复制标题
DOI：
10.1111/j.1475-4983.2006.00539.x
复制
发表时间：
2006-03-01
期刊：
影响因子：
2.6
通讯作者：
Suteethorn, V
中科院分区：
文献类型：
--
作者：
Cavin, L;Suteethorn, V
本文报道了一种半尖形鱼类新种--沼泽异鳞鱼Isanichthys palustris gen.et sp. nov.，描述于泰国东北部晚侏罗世-早白垩世Phu Kradung组。I. palustris是已知的从一个单一的，几乎完整的标本发现丰富的Lepidotes标本在Phu Nam Jun地点。I.沼生鱼具有类似半嵴椎的特征，例如面颊骨化的图案，以及类似鳞虫的特征，例如身体形状和与臀鳍相对的背鳍。I. palustris只具有目前用来定义Semionotidae的一些特征。分支分析，包括各种semionotide和gar类群，连同Amia calva和Leptolepis coryphaenoides，表明Semionotiformes（Lepisosteidae和'Semionotidae'）形成一个单系分支，但'Semionotidae'类群形成一个未解决的多分支。Semionotiformes，Halecomorphi和Teleostei之间的关系尚未解决。当限制到最知名的类群，但是，分析显示单系的Semionotidae狭义（Semionotus + Lepidotes）和姐妹组之间的关系halecomorphs和硬骨鱼。最后两个结果被认为是进一步研究的首选假设。I.沼泽兽是唯一已知的食肉的，可能是食鱼的“半雄虫”。它说明了晚侏罗世-早白垩世期间半紫罗兰形的巨大多样性和生态适应性。我们质疑的系统发育关系的“古老的鱼类”建立在分子为基础的树木，因为我们怀疑，使用很少最近的类群代表以前不同的血统是一个不可避免的，但重要的，在建设这样的树的偏见。
A new semionotiform fish, Isanichthys palustris gen. et sp. nov., is described from the Late Jurassic - Early Cretaceous Phu Kradung Formation, north-east Thailand. I. palustris is known from a single, nearly complete specimen found alongside abundant Lepidotes specimens at the Phu Nam Jun locality. I. palustris shows a mixture of semionotid-like characters, such as the pattern of cheek ossifications, and lepisosteid-like characters, such as the body shape and a dorsal fin opposed by an anal fin. I. palustris possesses only some of the characters currently used to define the Semionotidae. Cladistic analyses including various semionotid and gar taxa, together with Amia calva and Leptolepis coryphaenoides, suggest that the Semionotiformes (Lepisosteidae and 'Semionotidae') form a monophyletic clade, but the 'Semionotidae' taxa form an unresolved polytomy. The relationships between Semionotiformes, Halecomorphi and Teleostei are unresolved. When restricted to the best-known taxa, however, the analysis shows the monophyly of the Semionotidae sensu stricto (Semionotus + Lepidotes) and a sister-group relationship between halecomorphs and teleosts. These last two results are regarded as the preferred hypothesis for further studies. I. palustris is the only known example of a predaceous, probably piscivorous, 'semionotid'. It illustrates the great diversity and ecological adaptation of the semionotiforms during the Late Jurassic - Early Cretaceous. We question the phylogenetic relationships of 'ancient fishes' founded on molecular-based trees because we suspect that the use of very few Recent taxa as representatives of previously diverse lineages is an inevitable, but important, bias in the construction of such trees.