State Key Laboratory of Biogeology and Environmental Geology, and School of Earth Sciences, China University of Geosciences, Wuhan, China.
PeerJ. 2022 May 16;10:e13447. doi: 10.7717/peerj.13447. eCollection 2022.
Although malformations are found in both extant organisms and the fossil record, they are more rarely reported in the fossil record than in living organisms, and the environmental factors causing the malformations are much more difficult to identify for the fossil record. Two athyrid brachiopod taxa from the Upper Devonian Hongguleleng Formation in western Junggar (Xinjiang, NW China) show distinctive shell malformation. Of 198 and 405 specimens, 18 and 39 individuals were malformed, respectively; an abnormality ratio of nearly 10%. Considering the preservation status and buried environment of the abnormal specimens, and analysis of trace elements and rare earth elements from whole-rock and brachiopod shells, we conclude that the appearance of malformed athyrids is likely related to epi/endoparasites, or less likely the slightly higher content of heavy metal in the sea.
虽然畸形在现生物种和化石记录中都有发现，但在化石记录中比在现生物种中更为罕见，而且化石记录中导致畸形的环境因素更难识别。来自中国新疆西部上泥盆统红沟勒楞组的两种石燕贝类标本显示出明显的壳畸形。在 198 个和 405 个标本中，分别有 18 个和 39 个个体畸形，畸形率接近 10%。考虑到异常标本的保存状态和埋藏环境，以及对全岩和腕足动物壳微量元素和稀土元素的分析，我们得出结论，畸形石燕贝类的出现可能与外寄生/内寄生有关，或者不太可能与海水中重金属含量略高有关。
