Redescription of soft tissue preservation in the holotype of Scaphognathus crassirostris (Goldfuß, 1831) using reflectance transformation imaging

Abstract

The description of the holotype of the non-pterodactyloid pterosaur Scaphog-nathus crassirostris from the Upper Jurassic Solnhofen Formation by the German palaeontologist Georg August Goldfuß in 1831 was the basis for the first published scientific life reconstruction of a pterosaur. In the time since Goldfuß, the technologies used in imaging soft parts in fossils have advanced greatly, but despite its historical importance, the holotype of S. crassirostris has received relatively little attention, limit-ing comparisons to more recent pterosaurian soft part finds. In this study, reflectance transformation imaging (RTI) was used to investigate fine surface details of the S. cras-sirostris type specimen. The observations of Goldfuß concerning the existence of different preservational patterns of the hair-like integumentary structures (pycnofibres) in this specimen were confirmed. Individual pycnofibre types differ both in their position and frequency and may indicate variation in pycnofibre morphology across different body regions in the living animal. Pycnofibre types forming a ‘tuft’ or a ‘feather-like’ structure are similar to those of other pterosaur fossils from the southern German Sol-nhofen Formation and the northeastern Chinese Tiaojishan Formation. However, some types, such as ‘forked’ pycnofibre impressions, could be artefacts of taphonomic pro-cesses. This study provides further evidence for the similarity in the preservation of integumentary appendages and associated preservational patterns in pterosaurs across different localities, palaeoenvironments, stratigraphic ages, and systematic positions.