The integument of Psittacosaurus from Liaoning Province, China: taphonomy, epidermal patterns and color of a ceratopsian dinosaur

Abstract

Preserved skin of small dinosaurs is rare. Here, a specimen of the ceratopsian dinosaur, Psittacosaurus, presents some of the best preserved epidermal scales observed to date in a relatively small dinosaur, over wide areas extending from the head to the tail. We study the preserved epidermis of SMF R 4970, the different types of scales, color, and patterns, and their respective locations in the body. We use modern application of high-power digital imaging for close-up analysis of the tubercles and fragments of preserved color. Three types of scales are preserved, large plate-like scales, smaller polygonal scales or tubercles, and round pebble-like scales. The sizes of the plate-like scales vary in different parts of the body and vanish altogether posteriorly. Light and dark cryptic patterns are created by the associations of the tubercle and plate-like scales, and there is also evidence of countershading in the proximal caudal region, the body darker dorsally and lighter ventrally. Perhaps most impressive are the distinctive pigmented impressions of scales over most of the skeletal elements. The pigmentation follows the curvature of the bones implying that when it was deposited, the skin was still pliable and able to wrap around the visible parts of the elements. The present record of color is the first in a non-theropod dinosaur and only the second record in a non-avian dinosaur. Because of its resistance to degradation and ability to produce various color tones from yellows to blacks, we suggest that melanin was the dominant chemical involved in the coloration of Psittacosaurus. The data here enable us to reconstruct the colors of Psittacosaurus as predominantly black and amber/brown, in cryptic patterns, somewhat dull, but useful to a prey animal. Indeed, skin pigment within a partially degraded bone indicates that Psittacosaurus was scavenged shortly after death. The theropod dinosaur Sinosauropteryx has recently been reported to have naturally pigmented integumental structures, which the authors interpret as proof that they are protofeathers and not support fibers of collagen. Our findings in Psittacosaurus, on the other hand, indicate a more parsimonious and less profound alternative explanation, i.e., decomposition of the skin releases pigments that readily permeate underlying structures.

Morphological and Geochemical Evidence of Eumelanin Preservation in the Feathers of the Early Cretaceous Bird, Gansus yumenensis

“…Our results are also in accordance with recent work demonstrating the use of trace metals, especially organically bound copper, within fossilized soft tissue as a biomarker for eumelanin presence within Gansus yumenensis [37]. The issue of contamination at the time of deposition by melanosomes leaching from decomposing skin has previously been raised [38], but the fact that the feathers are both isolated from any other soft tissue makes this highly unlikely. We note that there are possible transfer mechanisms even for an isolated feather, for example the feather could have been dislodged from a rotting carcass just before burial.…”

Three‐dimensional soft tissue preservation revealed in the skin of a non‐avian dinosaur

“…). Skin colouration patterns have been reconstructed in ornithischian dinosaurs (Lingham‐Soliar & Plodowski ; Vinther et al . ; Brown et al .…”

Dinosaur Integument

“…Among the people connected with the specimen's rescue and fine preparation and with providing an understanding of its lithology is Professor Gerhard Plodowski of the Institute. Because of the paucity of information on the skin of small dinosaurs the descriptions will be included here in some detail from the study by Lingham-Soliar and Plodowski (2010).…”

“…Small, light, pebble-like scales occur in a small section of skin in the region of the throat and in the ventrolateral regions of the posterior body and tail. These are assumed to have sparse pigmentation in life (Lingham-Soliar and Plodowski 2010).…”