Produced by the Population Genetics and Evolution class, Furman University

The Jurassic: Anchiornis
Anchiornis huxleyi was a chicken-sized theropod that lived 155 mya, predating Archaeopteryx by 5-10 my. It is believed to be a transitional species that bridged the gap between non-avian and avian dinosaurs. Phylogenetic analysis suggests that Anchiornis belongs to the family Troodontidae. This conclusion is supported by the fact that this theropod features hallmark troodontid traits such as long, slender transverse processes on the dorsal vertebrae and anterior-most caudal vertebrae. However, it is worth noting that Anchiornis shares several prominent traits with Avialae and Dromaeosauridae. For example, its forelimbs are much closer in length to those of basal avialans and dromaeosaurids than to troodontids. This finding suggests that Anchiornis has a complex history of morphological evolution tracing back to the earliest paravians (Dongyu 2009). Anchiornis recently made headlines when it became the first dinosaur to have its full-body color pattern deduced. A team of researchers headed by Li Quanguo used scanning electron microscopy to analyze pigment samples from fossil feathers from a single specimen and then compared these samples to pigments found in modern birds (Sloan 2010). Their analysis revealed that Anchiornis sported a crown of reddish and grayish feathers, a face painted with reddish and black spots, a dark gray body, and white limbs with black tips. According to several paleontologists, this plumage was likely used to attract mates or communicate visually (Zimmer 2010). This study has significant implications for the evolution of feathers and flight because it showed that elongated feathers with complex color patters appeared in the fossil record in dinosaurs long before the evolution of flight in birds (Sloan 2010).

Page by Robert Mazgaj
Anchiornis huxleyi. Photo Credit: National Geographic

Hu D., Hou L., Zhang L.& Xu X. 2009. A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus. Nature 461: 640-643.

Sloan C. 2010. True-color dinosaur revealed: first full-body rendering. National Geographic. Accessed April 2, 2010.

Zimmer C. 2010. Evidence builds on color of dinosaurs. The New York Times, 4 Feb, 2010. Accessed April 2, 2010.