title: 3D Camouflage in an Ornithischian Dinosaur.
abstract: Countershading was one of the first proposed mechanisms of camouflage [1, 2]. A dark dorsum and light ventrum counteract the gradient created by illumination from above, obliterating cues to 3D shape [3-6]. Because the optimal countershading varies strongly with light environment [7-9], pigmentation patterns give clues to an animal's habitat. Indeed, comparative evidence from ungulates [9] shows that interspecific variation in countershading matches predictions: in open habitats, where direct overhead sunshine dominates, a sharp dark-light color transition high up the body is evident; in closed habitats (e.g., under forest canopy), diffuse illumination dominates and a smoother dorsoventral gradation is found. We can apply this approach to extinct animals in which the preservation of fossil melanin allows reconstruction of coloration [10-15]. Here we present a study of an exceptionally well-preserved specimen of Psittacosaurus sp. from the Chinese Jehol biota [16, 17]. This Psittacosaurus was countershaded [16] with a light underbelly and tail, whereas the chest was more pigmented. Other patterns resemble disruptive camouflage, whereas the chin and jugal bosses on the face appear dark. We projected the color patterns onto an anatomically accurate life-size model in order to assess their function experimentally. The patterns are compared to the predicted optimal countershading from the measured radiance patterns generated on an identical uniform gray model in direct versus diffuse illumination. These studies suggest that Psittacosaurus sp. inhabited a closed habitat such as a forest with a relatively dense canopy. VIDEO ABSTRACT.
authors.affiliation: School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK; School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK. Electronic address: jakob.vinther@bristol.ac.uk.
authors.forename: Jakob
authors.initials: J
authors.lastname: Vinther
authors.affiliation: Palaeocreations, 35 Hopps Road, Kingswood, Bristol BS15 9QQ, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Nicholls
authors.affiliation: School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK.
authors.forename: Stephan
authors.initials: S
authors.lastname: Lautenschlager
authors.affiliation: Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong.
authors.forename: Michael
authors.initials: M
authors.lastname: Pittman
authors.affiliation: Burke Museum of Natural History and Culture, 4331 Memorial Way Northeast, Seattle, WA 98195, USA.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Kaye
authors.affiliation: School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK.
authors.forename: Emily
authors.initials: E
authors.lastname: Rayfield
authors.affiliation: Department of Ornithology, Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, 60325 Frankfurt, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Mayr
authors.affiliation: School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK. Electronic address: i.cuthill@bristol.ac.uk.
authors.forename: Innes C
authors.initials: IC
authors.lastname: Cuthill
mesh_terms: D000818:Animals; D000067558:Biological Mimicry; D002681:China; D025061:Dinosaurs / Q000502:physiology*; D017753:Ecosystem; D005580:Fossils; D010858:Pigmentation
keywords: Jehol biota; Lagerstätte; Yixian Formation; behavioral ecology; countershading; defensive coloration; paleocolor; paleoenvironment; soft-tissue preservation; taphonomy