A mummified duck-billed dinosaur with a soft-tissue cock's comb

Area of Science:

• Paleontology
• Vertebrate Paleontology
• Mesozoic Era

Background:

• Soft-tissue appendages are crucial for vertebrate functions like locomotion and sexual display but rarely fossilize.
• Cranial crests in extinct dinosaurs are typically studied based on bony structures, with function often linked to vocalization in some groups.

Purpose of the Study:

• To report the discovery of a soft-tissue cranial crest in a hadrosaurid dinosaur, Edmontosaurus regalis.
• To propose alternative functions for dinosaur cranial structures beyond vocalization, focusing on social signaling and sexual selection.

Main Methods:

• Analysis of a unique "mummified" specimen of Edmontosaurus regalis from the latest Cretaceous Wapiti Formation.
• Comparative anatomical study of cranial ornamentation in hadrosaurids.

Main Results:

• Discovery of a three-dimensional, soft-tissue cranial crest (comb) in Edmontosaurus regalis, a structure previously unknown in dinosaurs.
• The fleshy nature of the crest suggests functions related to social signaling or sexual selection, contrasting with the vocalization hypothesis for other hadrosaurids.
• Evidence indicates that cranial ornamentation in Hadrosaurinae was not lost but substituted with soft-tissue structures in Edmontosaurus.

Conclusions:

• This finding provides the first direct evidence of soft-tissue signaling structures in dinosaurs.
• Visual display likely played a significant role in the evolution of hadrosaurine crests.
• The discovery raises the possibility of similar soft-tissue cranial structures in other extinct dinosaur taxa.