The colonization of deserts by tetrapods occurred for the first time in the late Paleozoic. In spite of amniotes being the most abundant and diverse taxon in such environments, fossil tracks indicate that anamniotes also inhabited late Paleozoic deserts. In this paper, the presence of the tetrapod-footprint ichnotaxa Ichniotherium sphaerodactylum and cf. Ichniotherium is documented in the eolian Coconino Sandstone (early Permian), based on 16 trackways found at several localities in Arizona, USA. Because there is a strong association between Ichniotherium and different species of diadectomorphs, we also discuss some aspects of the ichnotaxonomy of this ichnogenus. Diadectomorpha is considered the sister taxon of Amniota and, as a consequence, the tracks described in this paper represent the oldest evidence of occupation of deserts by non-amniote tetrapods. The presence of Ichniotherium in this environmental context also sheds light on the paleobiology of Diadectomorpha and, as a result, the emergence of features typically related to Amniota. The ichnofauna of the Coconino Sandstone has been used as a model for the Chelichnus ichnofacies, which supposedly indicates a low-diversity desert fauna. On the other hand, the tracks described here demonstrate that diadectomorphs were also important faunal components of such deserts and suggests that the significance of this ichnofacies should be reconsidered.

中文翻译：

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关于大峡谷可可尼诺砂岩（西奥利亚人）中冰ch的存在以及非羊膜四足动物对沙漠的占领

在古生代晚期，四足动物首次在沙漠中定居。尽管在这种环境中羊膜虫是最丰富多样的分类单元，但化石踪迹表明羊膜藻也居住在晚古生代沙漠中。在本文中，存在的四足足迹的鱼鳞白斑病的Ichniotherium sphaerodactylum和比照。在美国亚利桑那州的多个地方发现的16条走道中，风成岩的Coconino砂岩（早二叠世）中记载了冰ch。因为水ch之间有很强的联系以及不同种类的十二齿动物，我们还讨论了该鱼鳞属的鱼鳞分类的某些方面。Diadectomorpha被认为是Amniota的姊妹分类群，因此，本文中描述的轨迹代表了非羊膜四足动物占领沙漠的最古老证据。在这种环境中水ch的存在也揭示了双十二线虫的古生物学，因此也揭示了通常与羊水有关的特征。Coconino砂岩的鱼类动物已经被用作Chelichnus的模型鱼类相，据推测是低多样性的沙漠动物群。另一方面，这里描述的迹线表明，十二变体也是此类沙漠的重要动物区系，并建议应重新考虑这种鱼类相的重要性。