Soft tissue reconstructions of Saurolophus based on preserved skin impressions. Variations in scale arrangement and patterning are used here as a basis for possible colour patterns, which are particularly evident in the caudal region. (A) Saurolophus osborni showing mottled appearance of tail integument. (B) Saurolophus angustirostris showing midline feature-scales and banded pattern on the tail.
The characterization of palaeospecies typically relies on hard-tissue anatomy, such as bones or teeth that is more readily fossilized than soft parts. Among dinosaurs, skin impressions are commonly associated with partial and complete hadrosaurid skeletons, and consist of non-imbricating tubercles or scales. Skin impressions from various parts of the body of two species of the hadrosaurine Saurolophus (S. angustirostris from Mongolia and S. osborni from Canada) are described from multiple specimens. These species, recently validated on osteological grounds, can be differentiated based solely on soft-tissue anatomy, namely scale shape and pattern. This study demonstrates for the first time the applicability of soft-tissue (i.e., scale impressions) as a means to differentiate species within the Dinosauria. Differences are most spectacular in the tail, where S. angustirostris is differentiated by the presence of vertical bands of morphologically distinct scales, a grid-like arrangement of circular feature-scales, and tabular scales along the dorsal midline. Preliminary results indicate scale architecture remained consistent throughout ontogeny in S. angustirostris. These results support previous assertions that hadrosaurid scale architecture has a positive phylogenetic signal. As such, future taxonomic descriptions should include, where possible, the standardized description of skin impressions including the position and orientation of these impressions on the body.
Bell, P.R. 2012. Standardized Terminology and Potential Taxonomic Utility for Hadrosaurid Skin Impressions: A Case Study for Saurolophus from Canada and Mongolia. PLoS ONE. 7(2): e31295. DOI: journal.pone.0031295
Bell, P.R. 2011. Cranial osteology and ontogeny of Saurolophus angustirostris from the Late Cretaceous of Mongolia with comments on Saurolophus osborni from Canada. Acta Palaeontologica Polonica. 56. DOI:10.4202/app.2010.0061.
Bell, P.R.; and Evans, D.C. 2010. Revision of the status of Saurolophus (Hadrosauridae) from California, USA. Canadian Journal of Earth Sciences. 47 (11): 1417–1426. DOI: 10.1139/E10-062