Data from: Exceptional preservation and the fossil record of tetrapod integument

The fossil record of exceptionally preserved soft tissues in Konservat-Lagerstätten provides rare yet significant insight into past behaviours and ecologies. Such deposits are known to occur in bursts rather than evenly through time, but reasons for this pattern and implications for the origins of novel structures remain unclear. Previous assessments of these records focused on marine environments preserving chemically heterogeneous tissues from across animals. Here, we investigate the preservation of skin and keratinous integumentary structures in land-dwelling vertebrates (tetrapods) through time, and in distinct terrestrial and marine depositional environments. We also evaluate previously proposed biotic and abiotic controls on the distribution of 143 tetrapod Konservat-Lagerstätten from the Permian to the Pleistocene in a multivariate framework. Gap analyses taking into account sampling intensity and distribution indicate that feathers probably evolved close to their first appearance in the fossil record. By contrast, hair and archosaur filaments are weakly sampled (five times less common than feathers), and their origins may significantly pre-date earliest known occurrences in the fossil record. This work suggests that among-integument variation in preservation can bias the reconstructed first origins of integumentary novelties and has implications for predicting where, and in what depositional environments, to expect further discoveries of exquisitely preserved tetrapod integument.

特异埋藏化石库（Konservat-Lagerstätten）中保存的精美软躯体化石记录，为探究远古生物的行为模式与生态环境提供了稀缺却极具价值的视角。已知这类化石产出呈脉冲式分布而非随时间均匀出现，但该分布模式的成因，以及其对生物新奇结构起源的启示仍未明晰。此前针对这类化石记录的研究多聚焦于可保存跨类群动物化学异质性软组织的海洋环境。本研究聚焦于陆生脊椎动物（四足动物，tetrapods）的皮肤与角质表皮结构的埋藏保存情况，探讨其随时间的变化规律，以及不同陆地与海洋沉积环境下的保存差异。同时，本研究采用多变量分析框架，评估了此前提出的、控制二叠纪至更新世143处四足动物特异埋藏化石库分布的生物与非生物因素。结合采样强度与分布情况开展的空白分析显示，羽毛的演化时间极可能与其化石首次出现时间相近。与之形成对比的是，毛发与主龙类细丝的化石采样率极低（出现频率仅为羽毛的1/5），它们的起源时间可能远早于目前已知的化石首次出现记录。本研究表明，不同表皮结构的埋藏保存差异可能会对表皮新奇结构的首次起源重建结果造成偏倚，同时也为预测何处、何种沉积环境中有望发现更多精美保存的四足动物表皮化石提供了理论依据。