Newly detected data from Haestasaurus and review of sauropod skin morphology suggests Early Jurassic origin of skin papillae

Michael Pittman,Phil R. Bell,Nathan J. Enriquez,Paul Upchurch,Thomas G. Kaye

doi:10.1038/s42003-022-03062-z

Michael Pittman, Phil R. Bell + Show 3 more

Open Access

https://doi.org/10.1038/s42003-022-03062-z

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Abstract

Discovered in 1852, the scaly skin belonging to Haestasaurus becklesii was the first to be described in any non-avian dinosaur. Accordingly, it has played a crucial role in the reconstruction of sauropod integument and dinosaurs more broadly. Here, we reassess this historic specimen using Laser-Stimulated Fluorescence (LSF), revealing extensive, previously unknown regions of skin that augment prior interpretations of its integumentary morphology and taphonomy. Under white light, polygonal–subrounded, convex scales are visible on one side of the block (‘side A’), but LSF reveals extensive smaller and more flattened scales, which are diagenetically fragmented, on the reverse block surface (‘side B’). Contrary to the prior interpretation that the visible scales are the epidermal undersides, the presence of convex, intrascale papilliform textures on side A suggests that the external skin surface is exposed. We define intrascale papillae and provide a review of sauropod skin morphology, which clarifies that intrascale papillae are unique to and widespread across stem Neosauropoda, and likely have an evolutionary origin in the Early Jurassic. Intrascale papillae may ultimately have been integral to the evolution of gigantism in this charismatic clade.

Highlights

Discovered in 1852, the scaly skin belonging to Haestasaurus becklesii was the first to be described in any non-avian dinosaur
Skin and scales preserved on NHMUK R1868 have previously been described on one surface of the block[2,4,6]
Intrascale papillae are defined here as a series of small, convex protuberances that occur across the surface of a single scale and tightly abut one another, forming papilliform textures

Summary

Introduction

Discovered in 1852, the scaly skin belonging to Haestasaurus becklesii was the first to be described in any non-avian dinosaur. It has played a crucial role in the reconstruction of sauropod integument and dinosaurs more broadly We reassess this historic specimen using Laser-Stimulated Fluorescence (LSF), revealing extensive, previously unknown regions of skin that augment prior interpretations of its integumentary morphology and taphonomy. The purpose of the current paper is to reassess the morphology, preservation and taphonomy of the skin of Haestasaurus becklesii NHMUK R1868 using LSF methods These have revealed additional, previously unknown regions of skin, highlighting the varied preservation styles that are present within this specimen. This approach yields additional data on the morphology of papillae within some scales, which are comparable to those seen in other sauropods. A review of sauropod skin morphology further addresses the distribution and importance of integumentary papillae

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