Caudipteryx

Chapter • Meet the dinosaur

Overview

Caudipteryx was a small, long-legged, feathered dinosaur roughly the size of a peacock. It measured about 70 to 100 centimetres from snout to tail tip and probably weighed five to eight kilograms. The fossils from Liaoning in north-eastern China are so finely preserved that the plumage shows up as dark impressions in the rock: short downy feathers over the body, a fan of long feathers at the very end of the tail, and rows of vaned feathers up to twenty centimetres long along the short arms. Crucially, these feathers were symmetrical — equally wide on both sides of the shaft — which means they did not work as flight feathers. The skull was short and deep, with a beak-like front end retaining just four small, pointed teeth at the tip of the upper jaw. Caudipteryx was built for running. Its legs were long and slender, the foot bones tightly compressed, and its centre of mass sat well forward, much as in modern ground-dwelling birds such as ostriches and rheas. The arms, by contrast, were far too short to lift the animal off the ground, so palaeontologists interpret the feather panels on the arms and tail as display structures, balance aids during fast turns, and possibly shade or brooding cover for young. A 2019 study modelled whether flapping while running could generate useful lift; the effect turned out to be small, but such behaviour may represent an early step on the road to powered flight in related lineages. Several specimens preserve clusters of small polished stones in the stomach region — gastroliths. Plant-eating birds swallow such stones to grind tough food in a muscular gizzard, and combined with the nearly toothless jaws this strongly suggests that Caudipteryx fed mainly on plants: seeds, shoots and leaves. Some insects or other small prey cannot be ruled out, so a number of researchers prefer to call it an omnivore rather than a strict herbivore. Caudipteryx zoui was described in 1998 by Ji Qiang, Philip Currie, Mark Norell and Ji Shu-an, based on material from the Yixian Formation of Liaoning. The discovery made headlines worldwide because it was one of the first unambiguous non-avian dinosaurs with true vaned feathers. Placed among the oviraptorosaurs — the group that also includes Oviraptor — it became one of the strongest pieces of evidence that feathers evolved long before flight. A second species, Caudipteryx dongi, was named in 2000, and around a dozen well-preserved skeletons are now held in Chinese museum collections.

Chapter • Where it lived

Habitat

Caudipteryx lived roughly 125 to 120 million years ago, in the Early Cretaceous, in what is now Liaoning Province in north-eastern China. This landscape — the famous Jehol Biota — was a mosaic of conifer forest and early flowering plants around large freshwater lakes, crossed by rivers and wetlands and overlooked by active volcanoes. Repeated ashfalls buried animals and plants rapidly in fine lake-bottom mud, which is why feathers, skin outlines and gut contents survive in such extraordinary detail. Every known specimen comes from the Yixian Formation, above all from the Jianshangou and Sihetun localities.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy