Up until a few years ago, the general consensus about dinosaurs is that they looked like giant, scale-y and featherless lizards. However, discoveries of well-preserved feathered dinosaurs in China has led researchers to suggest that theropod dinosaurs (the carnivorous 2-legged ones such as the velociraptor and T-Rex) had feathers, and looked more like overgrown turkeys than the scaly villains of “Jurassic Park”. Since it’s now widely accepted that modern-day birds can trace their evolutionary lineage back to theropod dinosaurs, and birds have feathers, it isn’t too much of a stretch to assume that dinosaurs would too. Nonetheless, it’s a hotly-debated issue in the scientific world.
For smaller theropods, feathers make more sense, since they’d provide the insulation necessary for a smaller dinosaur. But when you scale up to the sizes of theropods such as the famous T-Rex, keeping warm isn’t as important as avoiding overheating, so feathers could be a problem. Yet at the same time, filament-like feathers were discovered on the Yutyrannus huali, a much larger dinosaur closely related to the T-Rex, so maybe overheating wasn’t an issue to them.
Keeping these factors in mind, a new study has approached the issue. They studied skin impressions from T-Rex specimens found in Montana, as well as from fossils of related dinosaurs. These have revealed that the abdomen, tail and neck regions are scaly much like the T-Rex, yet there wasn’t any evidence available for leaf-like “veins”. This led them to conclude that large tyrannosaurids were scaly, and any feathers they did have would be limited to the back region. They suggested that their scales could have evolved from the filament-like feathers seen in earlier Chinese tyrannosaurids, similar to how the scales on the legs of modern birds are derived from feathers. This loss of feathers, they suggested, was due to the evolution of a large body size. Nonetheless, there’s a long way to go before the debate of feathers vs. non-feathers is ever settled.