Many modern-day animals use camouflage, clever patterns of skin pigmentation, to hide from and evade predators in plain sight. About 120 million years ago during the early Cretaceous period, a small plant-eating dinosaur also used the same visual trick to protect itself from hungry carnivores.
The creature, a type of ancient reptile known as Psittacosaurus, or "parrot lizard," lived in what is now China. The region was not a safe neighborhood for animals as small as the Psittacosaurus.
This particular Psittacosaurus, which was only about the size of a golden retriever, was surrounded by dangerous local predators that include the likes of the T. rex-like giant Yutyrannus, which weighed at least a ton, and the smaller T. rex relative called Dilong.
Its dark back and lighter belly, which can still be seen in the remaining scales of specimens, could have helped the Psittacosaurus stay out of the claws of the hungry carnivores.
Psittacosaurus is also marked by a beaked jaw, stubby spikes on its cheeks and quills along its tail, which likely appeared like the bristles of a toothbrush.
A team of researchers created and painted a life-size model of the Psittacosaurus and photographed this at a nearby botanic garden. The images revealed that the coloring of the animal provided the best camouflage in diffuse light and not under the full sun, suggesting that it likely lived in the forest and not on a savanna.
"The patterns are compared to the predicted optimal countershading from the measured radiance patterns generated on an identical uniform gray model in direct versus diffuse illumination," paleontologist Jakob Vinther, from the University of Bristol in the United Kingdom, and colleagues reported in their study [pdf], which was published in the journal Current Biology.
"These studies suggest that Psittacosaurus sp. inhabited a closed habitat such as a forest with a relatively dense canopy."
Animals that live in forested environments are often characterized by pale stomachs and sometimes speckles on the body that mimic dappled light from the canopy. This is called countershading and it helps animals blend into the landscape by making themselves appear flat to predators. The strategy is very effective, and armed forces these days utilize this when developing man-made camouflage.
The researchers said they are now interested in exploring other types of camouflage in fossils and using the evidence they find to better understand how predators perceive their environment, as well as how they shape biodiversity and evolution.
The parrot lizard is not the only ancient creature found to use camouflage. An ancient stick insect, which was also discovered in China, was also found to use this visual strategy. The insect mimicked the leaves of an ancient plant called Membranifolia admirabilis.