Exceptional preservation and the fossil record of tetrapod integument

“…Calcium and other radiodense elements may have been adsorbed by matrix components of fetal soft tissues before re-mineralization occurred, which, together with other factors responsible for outer morphology preservation, would have resulted in fetal body surface demarcation. Research on exceptional fossil preservation and its mechanisms 27,28 will gain from further investigation of these fossils.…”

“…divergence weighting, step‐matrix gap‐weighting, implied weighting – Bardin et al, 2014; Gift & Stevens, 1997; Wiens, 2001) have been shown to accurately represent the original distribution of continuous traits (Bardin et al, 2014; Raven & Maidment, 2017; Worthington, 2017). Additionally, the uneven temporal distribution of terrestrial Konservat‐Lagerstätten (Eliason et al, 2017) may differentially impact the record of amniote eggs with a thin or absent CL, and statistical approaches that consider probability of preservation could be used to put confidence bounds on estimated ancestral states (Eliason et al, 2017; Marjanović & Laurin, 2008; Marshall, 2019; Wang et al, 2016).…”

“…Although expectations for finding direct evidence of carotenoid coloration in the vertebrate fossil record remain low, a wealth of information on the integumentary structures of extinct dinosaurs has become increasingly available through the discovery and study of exceptionally preserved fossils over the past 30 years (e.g., Clarke 2013; Barrett et al., 2015; Eliason et al., 2017; McNamara et al., 2018; Benton et al., 2019; Xu 2020). We hypothesize, based on the archelosaur observations presented here, that it is unlikely for a lineage to express carotenoid‐consistent color in integumentary structures that are shed and intermittently regrown (e.g., feathers) without first expressing these colors in other tissues (e.g., skin, rhamphotheca; Fig.…”