Using taphonomy to infer differences in soft tissues between taxa: an example using basal and derived forms of Solnhofen pterosaurs

Abstract

In fossilised vertebrates, the presence of soft tissues is the most obvious way to determine aspects of anatomy and functional morphology; however, occurrences are rare and other lines of evidence must be sought to indicate its extent and strength. For example, pterosaurs possessed a large wing membrane that enabled powered flight but other tissues are not widely preserved. A semi-quantitative analysis comparing skeletal articulation and completeness of the pterodactyloid Pterodactylus and non-pterodactyloid pterosaur Rhamphorhynchus from Solnhofen-type deposits implies there were anatomical differences between soft-tissue structure and attachments articulating skeletal joints of each. Typically, skeletons of Pterodactylus disarticulate to a greater extent than those of Rhamphorhynchus, which in turn suggests decay progressed to more advanced states in the former. However, this generalisation masks a mosaic of differences between different body parts, for example Rhamphorhynchus tends to lose the wings as complete units but retains a complete and still articulated tail in a greater number of specimens than Pterodactylus.

Evidence for the Cretaceous sharkCretoxyrhina mantellifeeding on the pterosaurPteranodonfrom the Niobrara Formation

“…Predator targeting of their relatively muscular torsos might explain why wing skeletons (which had considerably less soft-tissue, see Bennett, 2003) are the most common form of associated pterosaur fossil in the Smoky Hill Chalk Member. Articulated wings are also common in the Late Jurassic Solnhofen fauna where this may reflect decay and the loss of wings from floating pterosaur corpses (Beardmore, Lawlor & Hone, 2017), although this is not mutually exclusive with the effects of predation and scavenging. Witton (2018) noted that, to date, only the larger, more robust elements—limb bones and neck vertebrae—of larger pterosaur species are known to preserve embedded teeth and speculated that small pterosaurs and more gracile pterosaur bones were probably too easily destroyed to record evidence of carnivore bites.…”

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

“…This process was followed by the rapid coverage of the carcasses with sediment (Barthel et al, 1990). A reducing environment, low oxygen levels, a high salt content, and the scarcity of decomposers favoured the delayed degradation of the organic matter and thus the excellent preservation of the fossils (Barthel, 1964;Barthel et al, 1990;Beardmore et al, 2017;Kölbl-Ebert and Cooper, 2019). Due to the limited amount of microbial activity, the outline of the body had the chance to be imprinted on the surrounding sediment; a prerequisite for the former soft tissues to be preserved as impressions (Barthel et al, 1990).…”

“…In the genus Rhamphorhyn-chus, there are also remains of a terminally located tail vane (Frey et al, 2003). Remains of the musculature or vascular system have also been reported, albeit rarely (Tischlinger and Frey, 2002;Frey et al, 2003;Bennett, 2007;Beardmore et al, 2017). In some cases, there is even evidence for the preservation of the original organic materials of soft tissues, i.e., in the form of ungual sheaths of claws (Frey et al, 2003).…”

“…Pterosaurs were the first vertebrates in Earth's history capable of powered flight (Chatterjee and Templin, 2004;Elgin et al, 2011;Beardmore et al, 2017). They first appeared in the Late Triassic and were highly diverse, with substantial morphological disparity and taxonomic richness until the end of the Late Cretaceous (Benton and Pfretzschner, 2007;Longrich et al, 2018).…”

Peer Review #2 of "Evidence for the Cretaceous shark Cretoxyrhina mantelli feeding on the pterosaur Pteranodon from the Niobrara Formation (v0.1)"

“…Both Bennett (2001) and Hargrave (2007) have noted that Pteranodon may have been consumed destructively by large aquatic carnivores, their relatively muscular torsos being targeted, perhaps explaining why wing skeletons (which had considerably less soft-tissue, see Bennett, 2008) 2018:09:30992:1:1:NEW 26 Oct 2018) Manuscript to be reviewed Chalk Member. It should be noted however, that articulated wings are also common in the Late Jurassic Solnhofen fauna where this may reflect decay and the loss of wings from intact and floating corpses of pterosaurs (Beardmore, Lawlor & Hone, 2017), although this is not mutually exclusive with the effects of predation and scavenging. Witton (2016) noted that, to date, only the larger, more robust elements -limb bones and neck vertebrae -of larger pterosaur species are known to preserve embedded teeth, and speculated that small pterosaurs and/or more gracile pterosaur bones were probably too easily destroyed to record evidence of carnivore bites.…”