The Science Behind Determining The Colors Of Dinosaurs

An illustration of what the Caihong Juji, paravian theropod dinosaurs with iridescent feathers, may have looked like.

From 1841, when the term “Dinosauria” (terrible lizard) was coined, until the late twentieth century, dinosaurs were imagined as sluggish, swamp-bound reptiles with dull and leathery skin. Mid-twentieth century museum murals and textbooks fueled the misconception of dinosaurs, depicting them as massive, scaly creatures with muted palates. The 1996 discovery of Sinosauropteryx was groundbreaking. It was the first feathered theropod discovered to not be a direct relative of birds. This discovery was the catalyst for more research towards debunking long-held beliefs about the animals. Today, major revolutions in paleontology concern color. Through advances in microscopy, geochemistry, and molecular analysis, scientists have developed methods to determine the pigmentation of animals that haven’t inhabited the Earth for 66 million years. 

Specialized cells called melanocytes are responsible for producing pigment (melanin) in animals. Eumelanin presents black and brown, while pheomelanin appears yellow or red, though both are often seen simultaneously in vertebrates. Once synthesized, melanin is stored in melanosomes, which determine skin tone depending on their arrangement within keratinocytes. For decades, scientists assumed that soft tissue structures such as skin and feathers decay too rapidly to preserve microscopic biological information. Fossils couldn’t reveal color, or could they? 

The late 2000s and early 2010s were periods of major scientific breakthroughs. Using scanning electron microscopy, researchers from Yale University examining fossils noticed miniscule, elongated and spherical structures embedded within fossilized feathers. These structures were originally thought to be carbon traces from bacteria. However, further chemical analysis provided more insight into the discovery. In 2008, scientist Jacob Vinther and his colleagues revealed that the dark bands of the feathers contained pigment-harboring structures similar to what we see in modern feathers. Ornithologist Richard Prum predicted that if melanosomes could fossilize, then color itself might be recoverable. 

In 2010, scientists reconstructed the color pattern of the chicken-sized dinosaur Anchiornis huxleyi. Using scanning electron microscopy, the researchers catalogued several fossilized melanosomes across different regions of the animal’s plumage. Then, they compared their shapes to melanosomes in birds today, which corelate to specific pigments. Eumelanin is typically elongated, whereas pheomelanin is known to be spherical. By pinpointing where each melanosome type occurred in the feathers, scientists were able to generate a model of how Anchiornismost likely looked. The paravian dinosaur had predominately black and white tipped wings, a gray body, and a reddish crest on its head.  

Similar techniques were applied to Sinosauropteryx, revealing a banded, raccoon-like tail pattern of alternating light and dark discoloration. This study was published in 2010 by Vinther and his team, demonstrating that simple filamentous protofeathers preserved enough information to reach conclusions previous scientists could only dream of. All of these discoveries regarding the color of dinosaur feathers fundamentally altered how dinosaurs are depicted in both scientific and public illustrations. 

An image of pollen grains taken on a scanning electron microscope, showing its signature characteristics and level of depth.

Scanning electron microscopy (SEM) is an advanced tool that allows scientists to visualize structures at nanometer scales, but determining dinosaur color requires more evidence than just melanosome shape. Researchers have begun to deploy a combination of imaging and chemical techniques to solidify their theories. To support paleontologists’ argument that the present melanosomes belonged to the dinosaur and not the microbes that colonized its carcass, Johan Lindgren pioneered Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). This technique works by detecting degraded melanin and measuring the time it takes secondary ions from the fossil to travel to a detector after being hit by primary ions. Different organic compounds, such as eumelanin or pheomelanin, have distinct molecular weights, and the arrival time signifies what chemicals are present. 

Despite these advances in technology, finding the exact color of dinosaurs remains complex. Melanosomes showcase melanin-based hues (blacks, browns, grays, and reds). Here, the issue lies in the fact that many modern animals display vibrant blues and greens that are not produced by pigment. Instead, these striking hues come from structural coloration and diet. Microscopic arrangements of keratin and air pockets that refract light are the largest contributors to structural coloration. While some bird feathers are iridescent structures and can be preserved, it is difficult to accurately reconstruct the color of pigment-relying dinosaurs.  

Scientists are not researching the colors of past animals just to debunk outdated depictions. Color offers insight into behavior and ecology. In modern animals, pigmentation aids in camouflage, thermoregulation, mate selection, and species recognition. Countershading patterns, where there is darker pigmentation on the back and lighter pigmentation on the underside, help scientists infer what habitats animals lived in. The orca is a well-known example of countershading: its body is black on top to blend into the waters above, while its white underside matches the sunlit water, making the animal invisible to prey below. Dinosaur species had the same camouflage mechanisms. Psittacosaurus, an early relative of the Triceratops, has fossils that display clear countershading, and from those fossils, paleontologists have concluded that the dinosaur most likely inhabited forests with maximal light. According to Jacob Vinther, melanosomes darkened the top of its body, counter-illuminating its shadows and making Psittacosaurus appear flat. 

Although scientists have research to support their theories, their claims cannot be regarded as absolute. Fossilization is a constructive process in the regard that although it preserves hard structures, it often destroys, at the same time, soft tissues and organic material. Heat, pressure, and chemical alteration over millions of years modify molecules and melanin residues may degrade. As a result, scientists’ reconstructions only represent the most probable interpretation, rather than a concrete record of the specimen’s appearance. Overall, the study of dinosaur coloration has advanced remarkably, and ongoing research will continue to deepen our understanding of the eras that came before ours.