The distribution of integumentary structures in a feathered dinosaur

Abstract

Non-avian theropod dinosaurs with preserved integumentary coverings are becoming more common; but apart from the multiple specimens of Caudipteryx, which have true feathers, animals that are reasonably complete and entirely articulated that show these structures in relation to the body have not been reported. Here we report on an enigmatic small theropod dinosaur that is covered with filamentous feather-like structures over its entire body.

Bristle-like integumentary structures at the tail of the horned dinosaur Psittacosaurus

“…3), which possibly indicates the presence of a hollow lumen inside these structures, as in the filamentous structures of some theropods (Schweitzer et al 1999). However, the "bristles" of Psittacosaurus are oriented in parallel, whereas at least some of the filaments of theropods originate from a single point and form a radiating spray (Ji et al 2001;Xu et al 2001). Furthermore, they do not show any branching, which was recently reported for the filaments of the theropod genera Beipiaosaurus and Sinornithosaurus (Xu et al 1999a(Xu et al , 2001.…”

“…Filamentous integumentary structures have been described in a number of theropod dinosaurs from the early Cretaceous of China and have been considered to be possibly homologous to avian feathers (Chen et al 1998;Xu et al 1999aXu et al , b, 2000Xu et al , 2001Ji et al 2001). Similar structures are, however, unknown in non-theropod dinosaurs concerning whose integument little is known.…”

Pre‐modern Birds: Avian Divergences in the Mesozoic

“…Feathers were, until the last few decades, known exclusively within Aves (de Beer, 1954), yet now integumentary structures hypothesized as homologous to feathers are known throughout Dinosauria (Mayr et al, 2002;Xu et al, 2004;Ji et al, 2007;Zheng et al, 2009) and pennaceous (Ji et al, 1998(Ji et al, , 2001Norell et al, 2002;Xu et al, 2009b;Hu et al, 2009). Evolutionary stages in feather development are documented in the fossil record with "proto-feathers," unbranched filamentous structures, present among a wide range of nonavian theropods (e.g.…”

Theropod Diversity and the Refinement of Avian Characteristics

“…The large predatory tyrannosauroids, the beaked and herbivorous (Kobayashi et al, 1999, Zanno & Makovicky, 2010 ornithomimosaurs, and small compsognathids are generally considered to be basal lineages within the coelurosaur radiation, whereas birds and their closest taxa form a more exclusive clade within Coelurosauria known as Maniraptora. In the past decade, discoveries of numerous coelurosaur taxa sporting protofeathers, fully formed flight feathers (Ji et al, 2001), and even specialized feathers convergent on display structures in oscines (Zhang et al, 2008) have been made in Jurassic and Cretaceous lake-bed deposits of northeastern China. Together, these discoveries indicate that possession of plumage covering most of the body with the exception of the feet and snout likely characterizes at minimum the coelurosaurian node.…”