Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing, 100044, China.
College of Earth Science, University of Chinese Academy of Sciences, Beijing, 100049, China.
Nat Ecol Evol. 2017 Oct;1(10):1470-1476. doi: 10.1038/s41559-017-0293-5. Epub 2017 Sep 4.
The fossils assigned to the tetrapod stem group document the evolution of terrestrial vertebrates from lobe-finned fishes. During the past 18 years the phylogenetic structure of this stem group has remained remarkably stable, even when accommodating new discoveries such as the earliest known stem tetrapod Tungsenia and the elpistostegid (fish-tetrapod intermediate) Tiktaalik. Here we present a large lobe-finned fish from the Late Devonian period of China that disrupts this stability. It combines characteristics of rhizodont fishes (supposedly a basal branch in the stem group, distant from tetrapods) with derived elpistostegid-like and tetrapod-like characters. This mélange of characters may reflect either detailed convergence between rhizodonts and elpistostegids plus tetrapods, under a phylogenetic scenario deduced from Bayesian inference analysis, or a previously unrecognized close relationship between these groups, as supported by maximum parsimony analysis. In either case, the overall result reveals a substantial increase in homoplasy in the tetrapod stem group. It also suggests that ecological diversity and biogeographical provinciality in the tetrapod stem group have been underestimated.
归入四足动物干群的化石记录了从肉鳍鱼类到陆地脊椎动物的演化。在过去的 18 年中，这个干群的系统发育结构一直非常稳定，即使在适应新发现（如最早的已知干群四足动物中华螈和鱼石螈（鱼类-四足动物的中间类型））时也是如此。在这里，我们展示了一个来自中国晚泥盆世的大型肉鳍鱼类，它打破了这种稳定性。它结合了根齿鱼类的特征（被认为是干群的一个基部分支，与四足动物相距较远），以及衍生的鱼石螈类和四足动物类特征。这种特征的混合可能反映了根齿鱼类和鱼石螈类加上四足动物之间的详细趋同，这是根据贝叶斯推断分析推导出的系统发育情景，或者是这些群体之间以前未被认识到的密切关系，这得到了最大简约分析的支持。在这两种情况下，总体结果都表明四足动物干群中的同余性显著增加。这也表明，四足动物干群的生态多样性和生物地理局限性被低估了。
Zotero 插件