Cretaceous amniote integuments recorded through a taphonomic process unique to resins

Sergio Álvarez-Parra,Enrique Peñalver,Mónica M Solórzano-Kraemer,Luis Alcalá,Xavier Delclòs

doi:10.1038/s41598-020-76830-8

Abstract

Fossil records of vertebrate integuments are relatively common in both rocks, as compressions, and amber, as inclusions. The integument remains, mainly the Mesozoic ones, are of great interest due to the panoply of palaeobiological information they can provide. We describe two Spanish Cretaceous amber pieces that are of taphonomic importance, one bearing avian dinosaur feather remains and the other, mammalian hair. The preserved feather remains originated from an avian dinosaur resting in contact with a stalactite-shaped resin emission for the time it took for the fresh resin to harden. The second piece shows three hair strands recorded on a surface of desiccation, with the characteristic scale pattern exceptionally well preserved and the strands aligned together, which can be considered the record of a tuft. These assemblages were recorded through a rare biostratinomic process we call “pull off vestiture” that is different from the typical resin entrapment and embedding of organisms and biological remains, and unique to resins. The peculiarity of this process is supported by actualistic observations using sticky traps in Madagascar. Lastly, we reinterpret some exceptional records from the literature in the light of that process, thus bringing new insight to the taphonomic and palaeoecological understanding of the circumstances of their origins.

Highlights

Fossil records of vertebrate integuments are relatively common in both rocks, as compressions, and amber, as inclusions
Dinosaur feathers and mammalian hair are keratin integumentary structures which constitute the different forms of vertebrate v estiture[8]
A partial mammalian skeleton which could correspond to a solenodontid was reported from the Miocene amber of the Dominican Republic[17], but this is a unique finding since mammals are usually represented in amber by hairs, as in, for example, two records of abundant solenodontid-like hair found in Dominican a mber[18]

Summary

Introduction

Fossil records of vertebrate integuments are relatively common in both rocks, as compressions, and amber, as inclusions. We describe two Spanish Cretaceous amber pieces that are of taphonomic importance, one bearing avian dinosaur feather remains and the other, mammalian hair. The second piece shows three hair strands recorded on a surface of desiccation, with the characteristic scale pattern exceptionally well preserved and the strands aligned together, which can be considered the record of a tuft. These assemblages were recorded through a rare biostratinomic process we call “pull off vestiture” that is different from the typical resin entrapment and embedding of organisms and biological remains, and unique to resins. Actualistic methods as sticky traps have been previously used to evaluate the accuracy of the record of forest arthropods in resin and amber[3,37], but this kind of traps records vertebrate vestitures and can provide an example of how resin traps these remains

Methods

Results

Conclusion