17 February 2010

When feathered dinosaurs ruled the Earth


Beipiaosaurus inexpectus

One of the first feathered dinosaurs ever uncovered, Beipiaosaurus was unearthed in 1997 by Xu Xing and colleagues near the city of Beipaio in Liaoning province, China. This “unexpected” find gave support to the theory that feathers were widespread in dinosaurs and that dinosaurs were the ancestors of modern birds.

(Image: Zhao Chuang and Xing Lida)

Sinornithosaurus millenii

When Xu Xing described Sinornithosaurus millenii, or “millennial Chinese bird lizard”, in 1999, it represented the fifth known genus of feathered dinosaur; the others had also been uncovered in China. A pending anatomical study of the dinosaur’s jaw, which includes grooved, fang-like teeth, suggests Sinornithosaurus may be the first known venomous dinosaur. The roughly metre-long creature lived 125 million years ago and may have fed on small birds that coexisted with dinosaurs at the time.

(Image: National Geographical Society)

Microraptor gui

The first description of Microraptor gui, published in 2003, forever changed palaeontologists' understanding of the dinosaur-to-bird transition. M. gui had long feathers attached to its legs and forelimbs, making it the first known four-winged dinosaur.

A century ago palaeontologist William Beebe predicted that there would be a phase in evolution involving a four-winged “tetrapteryx”, but at the time there was no fossil evidence to support his theory.

Since Xu Xing’s initial description of M. gui, more than 1000 four-winged dinosaur specimens have been unearthed in China.

M. gui lived 120 million years ago and is one of the smallest known dinosaurs, measuring just 42 to 83 centimetres long and weighing only about 1 kilogram. It is unlikely that the microraptor could truly fly; it probably glided down from trees instead.

(Image: Portia Sloan)


Mei long

Mei long or “soundly sleeping dragon” provided a rare glimpse into the behaviour of bird-like dinosaurs when Xu Xing and colleagues uncovered this well-preserved goose-sized fossil in Liaoning province in 2003. Mei long was resting with its head nestled under one of its forelimbs, like a modern bird with its head under its wing. It was probably buried alive under volcanic ash 125 million years ago.

(Image: Mick Ellison)


Pedopenna or "feather foot" had hind wings similar to Microraptor gui but its feathers were less stiff and worse adapted to flight.

Xu and colleagues suggest early ancestors of the bird-like dinosaur may have used their hind wings for gliding but later lost the ability to glide, though they retained their long feathers for display. The fossil was uncovered in Inner Mongolia and described by Xu in 2005.

(Image: Zhang Zongda and Xing Lida)


Guanlong or "crowned dragon" is the earliest known ancestor of the tyrant lizard king, Tyrannosaurus rex, and gets its name for the prominent nasal crest that was probably used for sexual display.

This feathered beast lived 160 million years ago in what is now the Gobi desert of Xinjiang province.

Guanlong’s existence roughly 10 million years before Archaeopteryx, the first known bird, provides evidence that feathers may have developed in dinosaurs before birds.

(Image: Zhang Zongda and Xing Lida)


Gigantoraptor stood twice as tall as a human, weighed about 1.5 tonnes and had a turtle-like beak. The giant bird-like dinosaur was discovered in Inner Mongolia in 2005 by Xu Xing and colleagues and is the largest feathered dinosaur ever found.

Gigantoraptor’s huge size came as a surprise, as it is a member of the oviraptorosaurs, a group of flightless, feathered dinosaurs closely related to birds that typically weighed less than 40 kilograms.

(Image: Zhao Chuang and Xing Lida)


Tianyulong was a small dinosaur about the size of a house cat with a row of long, hollow filaments, or proto-feathers, that ran down its back. Before it was discovered, feathers and proto-feathers like those found on Tianyulong had been found only on theropods, a group of two-legged dinosaurs, and birds.

Tianyulong, however, comes from a different lineage, the Ornithischia, that includes horned and armoured dinosaurs. The find suggests feathers may date back to the very earliest dinosaurs, before they split into different lineages.

(Image: Zhao Chuang and Xing Lida)

Anchiornis huxleyi

Anchiornis or “near bird” was a four-winged, feathered dinosaur that lived 10 to 15 million years before Archaeopteryx. Anchiornis's discovery lends further support to the theory that birds evolved from dinosaurs.

The bird-like dinosaur measured just 34 centimetres from head to tail, and, according to a recently released study, its wings were black-and-white striped with a reddish-brown crown in a pattern like that of modern woodpeckers.

Journal reference: Science, DOI: 10.1126/science.1186290

(Image: Zhao Chuang and Xing Lida)

Haplocheirus sollers

Described by Xu Xing and colleagues last month, Haplocheirus lived 160 million years ago in what is now Xinjiang province. The find further supports the development of bird-like dinosaurs prior to the emergence of birds and pushes back the date of the first known Alvarezsaurs, a group of bird-like dinosaurs with a large claw on one forelimb, by 63 million years.

Journal reference: Science, DOI: 10.1126/science.1182143

(Image: Portia Sloan)