title: A mummified duck-billed dinosaur with a soft-tissue cock's comb.
abstract: Among living vertebrates, soft tissues are responsible for labile appendages (combs, wattles, proboscides) that are critical for activities ranging from locomotion to sexual display [1]. However, soft tissues rarely fossilize, and such soft-tissue appendages are unknown for many extinct taxa, including dinosaurs. Here we report a remarkable "mummified" specimen of the hadrosaurid dinosaur Edmontosaurus regalis from the latest Cretaceous Wapiti Formation, Alberta, Canada, that preserves a three-dimensional cranial crest (or "comb") composed entirely of soft tissue. Previously, crest function has centered on the hypertrophied nasal passages of lambeosaurine hadrosaurids, which acted as resonance chambers during vocalization [2-4]. The fleshy comb in Edmontosaurus necessitates an alternative explanation most likely related to either social signaling or sexual selection [5-7]. This discovery provides the first view of bizarre, soft-tissue signaling structures in a dinosaur and provides additional evidence for social behavior. Crest evolution within Hadrosaurinae apparently culminated in the secondary loss of the bony crest at the terminal Cretaceous; however, the new specimen indicates that cranial ornamentation was in fact not lost but substituted in Edmontosaurus by a fleshy display structure. It also implies that visual display played a key role in the evolution of hadrosaurine crests and raises the possibility of similar soft-tissue structures among other dinosaurs.
authors: Department of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia. Electronic address: pbell@une.edu.au.
authors: Phil R
authors: PR
authors: Bell
authors: Dipartimento di Scienze Biologiche, Geologiche e Ambientali and Museo Geologico Giovanni Capellini, Alma Mater Studiorum, Università di Bologna, 40126 Bologna, Italy.
authors: Federico
authors: F
authors: Fanti
authors: Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
authors: Philip J
authors: PJ
authors: Currie
authors: Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.
authors: Victoria M
authors: VM
authors: Arbour
mesh_terms: D000818:Animals; D025061:Dinosaurs / Q000033:anatomy & histology* / Q000235:genetics; D005580:Fossils; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology; D014057:Tomography, X-Ray Computed