Anchiornis huxleyi represents a significant discovery in understanding the early evolution of birds. This small, feathered dinosaur lived approximately 160 million years ago in what is now China’s Liaoning Province. Its well-preserved fossils provide unique insights into the appearance and characteristics of early paravian dinosaurs, advancing scientific understanding of the features that bridge the evolutionary gap between dinosaurs and modern birds.
Discovery and Physical Description
The first Anchiornis huxleyi specimen was discovered in China’s Tiaojishan Formation, with hundreds more found in the same region. Its name, “Anchiornis,” means “near bird” in Greek, and “huxleyi” honors Thomas Henry Huxley, an early proponent of the evolutionary link between birds and dinosaurs. This small dinosaur was roughly the size of a modern crow, measuring about 34 centimeters (13 inches) long and weighing around 110 grams (3.9 ounces).
A notable feature of Anchiornis was its extensive feather covering, including long, well-developed feathers on its arms, legs, and tail, giving it a “four-winged” appearance. These feathers were pennaceous, meaning they had a central shaft and vanes, but were symmetrical and “fluffier” than the tightly-zipped, aerodynamic feathers of modern birds. The forelimbs were proportionally long, about 80% the length of the hind limbs. The presence of feathers on the feet and toes further distinguished its plumage.
Reconstructing a Dinosaur in Color
Scientists determined the life coloration of Anchiornis huxleyi, making it one of the first non-avian dinosaurs to have its color scheme reconstructed. This relied on analyzing microscopic melanosomes, pigment-containing organelles preserved within fossilized feathers. By comparing the shape and arrangement of these fossilized melanosomes to those in modern birds, researchers inferred the original colors.
The analysis revealed a striking appearance for Anchiornis. Its body was generally gray, but its wings and legs featured black-spangled tips on white feathers, creating a patterned look. A reddish-brown, mohawk-like crest adorned its head, complemented by facial speckles. This mapping of colors across individual feathers provided a glimpse into the plumage of a Mesozoic dinosaur, suggesting color patterns might have played a role in communication or mate attraction, similar to modern birds.
A Key to Bird Origins
Anchiornis huxleyi is important in the evolutionary lineage of paravian dinosaurs, a group closely related to birds. Its existence during the Late Jurassic period, potentially older than Archaeopteryx, helps address gaps in the fossil record concerning bird origins. The preservation of its feathers provides evidence for the widespread presence of feathered integument among early theropods.
The anatomy of Anchiornis, particularly its four wings and feather structure, offers insights into the evolution of flight. While its long hind legs suggest a running adaptation, the feathers on its feet would have hindered such movement, indicating a more complex locomotor strategy. Scientists debate whether Anchiornis was primarily a glider or if its feather arrangement allowed for limited powered flight, or perhaps supported other behaviors like leaping or pouncing. Regardless, Anchiornis remains a compelling piece of the puzzle, illustrating the diverse evolutionary experimentation in wing-assisted locomotion leading up to modern avian flight.