Around 65 million years ago, a giant asteroid collided with Earth and set in motion a chain of events that led to the extinction of dinosaurs. Before this cataclysmic event, dinosaurs had roamed and ruled the world for around 165 million years.
These impressive creatures, all coming in different shapes and sizes, only left behind fossils as evidence of their existence. And since we started discovering the first dinosaur fossils, we've been trying to reconstruct their appearance. You've probably seen drawings of a T-Rex in books or a GCI version in movies, but how accurate is that depiction? Would you still consider the mighty T-Rex to be a formidable beast after learning it may have had feathers like a chicken?
In science, you can't really "know" anything - instead, scientists conduct experiments to arrive at the most likely conclusion (the one supported by the most evidence). With this in mind, paleontologists have to make educated guesses about the appearance of dinosaurs from fossils. Fossils are preserved remains or impressions formed when the biological material (in this case, bone) is slowly replaced with minerals over time. In other words, the bone becomes a rock.
So what can we learn from rocky impressions of dinosaur bones?
Sharp and pointed teeth tell us the dinosaur was most likely a carnivore. Carnivores have long, sharp, and defined teeth for killing their prey and tearing the meat. By contrast, a herbivore has wider and flatter teeth designed to grind plant matter and aid digestion. Omnivores, which eat both plant matter and meat, have a combination of sharp front teeth and flat molars. However, only a few of the known dinosaurs were omnivores, with one being Velociraptor.
The shape of the skeleton and individual bones can also tell us how and where the muscle is attached to the frame. Scientists can then compare these bone grooves to those of modern animals to determine how the dinosaur may have carried muscle and even moved.
In rare cases, we find fossils where not only the bones are intact but also some tissue. For example, in 1999, paleontologist Tyler Lyson found an Edmontosaurus with fossilized tissue. The mummified dinosaur had preserved skin, ligaments, and tendons, telling us an enormous amount about how these creatures moved.
Yes, some of them did, and more of them than you might think. For example, Velociraptor was much fuzzier than Jurassic Park would have you believe.
Scientists have long known that modern birds evolved from dinosaurs, and as such, there was likely a transition where younger dinosaurs (those alive just before the extinction event) had feathers. However, we now have evidence that the first feathered dinosaurs date back 180 million years, perhaps even longer.
But why did it take so long to discover many species of dinosaurs had feathers? It all comes down to how complete the fossils we found were. We didn't see the first dinosaur fossils with feather-like structures until the 1990s, and it took many more discoveries to assert that feathers were not rare confidently.
Finding impressions of scales and feathers in dinosaur fossils was already remarkable - far less than 1% of fossils have these features intact. But when it comes to color, scientists have to rely almost entirely on guesswork. Why? Because color is very rarely preserved, and even when it is, scientists can't be sure it isn't simply a by-product of the fossilization process. This is why dinosaurs are usually depicted with earth tones like green, grey, and brown. However, some dinosaur species may have been much more colorful. Like surviving reptilian relatives today, dinosaurs may have used color to attract mates or warn predators.