Exceptions to the temperature-size rule: No Lilliput effect in end-Permian ostracods (Crustacea) from Aras Valley (NW Iran)

The body size of marine ectotherms is often negatively correlated with ambient water temperature, as seen in many clades during the hyperthermal crisis of the end-Permian mass extinction (c. 252 Mya). However, in the case of ostracods, size changes during ancient hyperthermal events are rarely quantified. In this study, we evaluate the body size changes of ostracods in the Aras Valley section (NW Iran) in response to the drastic warming during the end-Permian mass extinction at three taxonomic levels (class, order, species). On the assemblage level, the warming triggers a complete species turnover in the Aras Valley section, with larger, newly emerging species dominating the immediate post-extinction assemblage for a short time. Individual ostracod species and instars do not show dwarfing or a change in body size as an adaptation to the temperature stress during the end-Permian crisis. This may indicate that ostracods might be exceptions to the temperature-size rule (TSR), using an adap..., , R/R Studio, any PDF reader, Microsoft Excel or an open-source alternative.海洋外温动物的体型通常与环境水温呈负相关关系，这一点在二叠纪末大灭绝（约2.52亿年前）的超热危机期间的多个演化支中均有体现。然而，针对介形类（ostracods），古超热事件期间的体型变化鲜有量化研究。本研究以伊朗西北部阿拉斯河谷剖面的介形类为对象，在纲、目、物种三个分类学层级上，评估其响应二叠纪末大灭绝期间剧烈升温的体型变化情况。在组合群层面，升温事件引发了阿拉斯河谷剖面的物种完全更替，体型更大的新兴物种在灭绝后初期的组合群中短暂占据主导地位。单个介形类物种及其龄期并未表现出体型小型化或体型变化以适应二叠纪末危机期间的温度胁迫。这或许表明介形类可能是体型-温度规则（temperature-size rule, TSR）的例外类群，采用了一种适应性…… 可使用R/R Studio、任意PDF阅读器、Microsoft Excel或其开源替代工具。