How Do We Know Dinosaurs Had Scales?

The discovery and study of dinosaur fossils has long been a fascination for modern humankind. Although ancient civilizations are likely to have come across some colossal fossils, the first documented discovery of what we now know to be a dinosaur bone occurred in 1677. However, it was only in the 1800s that scientists began to really examine and define fossils as dinosaurs. It was with the birth of paleontology and fossil excavation that we finally started piecing together how these mighty beasts looked and lived all those millennia ago.

We know dinosaurs had scales as there have been several fossils found that still had their skin intact and preserved. Paleontologists have been able to closely study these samples as well as excavated skin impressions to determine the type of scaly skin of various dinosaurs.

But not all dinosaurs had the same external covering. In the mid-1990s, a number of feathered fossils were found in China and subsequently, more have been unearthed in other regions. This has led to a great debate amongst dinosaur enthusiasts as to whether these legendary animals, who once roamed the earth, were scary or fluffy.

How Do Scientists Know Dinosaurs Had Scales?

When we think of unearthing dinosaurs, we usually imagine massive bones being uncovered beneath the ground. While finding the skeletons of dinosaurs is a significant aspect of paleontology, smaller finds have an almost greater impact on our understanding of the appearance of dinosaurs and their habits. Some of these finds that give us great insight into dinosaurs include preserved gut content, eggs, nests, skin and soft tissue, impressions, footprints and even feces.

The first piece of fossilized dinosaur skin was found in Bexhill on the south coast of the UK. In total, there have now been 77 specimens discovered with some skin or skin impression intact. Some of these pieces of skin have been so well preserved it is evident, even to the untrained eye, that the skin is of a scaly nature.

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A large part of reconstructing dinosaurs is done through comparative anatomy, whereby dinosaur findings are compared to living animals. In terms of dinosaurs with scaly skin, especially prevalent with horned species, was a crocodile type skin, while other scaly dinosaur skin has been described as looking more like that of a large lizard. It is even suggested that many dinosaurs were clothed in a scaly skin like that of a chicken’s foot, softer and more flexible than reptile skin.

The advancement in technology has also helped scientists reach better understandings of how dinosaurs looked, as 3D renderings give them the freedom to experiment in ways that delicate fossils do now allow.

Through numerous skin impressions and even detailed footprints, it has become widely accepted that herbivorous dinosaurs in the ceratopsian and sauropod groups were likely to be completely covered in scales.

A few of the dinosaurs that we know through fossils had scales at least covering part of their bodies are:

Triceratops
Haestasaurs
Tyrannosaurus Rex
Edmontosaurus
Saurolophus

Through the clues that the fossils leave behind, we can know for certain that some dinosaurs had scaly skin.

Do All Dinosaurs Have Scales?

For many decades dinosaurs were solely associated with reptiles, and therefore the idea of what they looked like, including scaly skin, was based on the reptile anatomy. Although the first dinosaur with feathers, the Archaeopteryx, was already found in the 1860s, scientists viewed the find as an evolutionary link between dinosaurs and birds and not as a bird-like dinosaur which it is described as today.

In the 1960s, John Ostrom of Yale University in studying the Deinonychus came to the conclusion it was a warm-blooded, bird-like animal and advocated for the idea that birds are dinosaurs. However, it was only in the 1990s, with the discovery of the feathered dino fossils in Sihetun, China, that the idea of birds being dinosaurs really began to be solidified.

The discovery of the China feathery flock sent the paleontology world into disarray, many questioning whether all dinosaurs had feathers. Not so long ago, the fraternity became largely convinced of this.

Over the last 30 years, many new discoveries of the evidence of feathers have been made. These discoveries are specifically prevalent within the carnivorous theropods, many of whom are proven to have had feathers or plumage. Even Velociraptors, which Jurassic Park had us believing were terrifying, intelligent reptiles, are actually genetically linked to the common pigeon. Proof of feather features on Velociraptors comes in the form of marks on the forearm bone, which relate to the quill knobs where the flight feather of pigeons attach.

*Some evidence suggests that many dinosaurs had feathers rather than scales*

Did The Tyrannosaurus Rex Have Scales Or Feathers?

Even the mighty T-rex has been brought into the mix, with people questioning whether this predatory giant was covered in fluffy feathers. A close relative of the Tyrannosaurus Rex, the Yutyrannus, a large dinosaur growing in the region of 30 feet, was found to have feathers, and so the speculation about the T-rex began.

However, proof of scaly skin impressions have been found on T-rex fossils while proof of feathers have not, so we do know with certainty that at least part of their bodies were covered in scales. However, the absence of feather evidence does not prove without a doubt that the T-rex was definitely featherless. Feathers are notoriously difficult to preserve, and the conditions need to be exact for this to occur. One could therefore argue that of the T-rex fossils found, none were ever in a condition conducive to preserving feathers.

Much of paleontology is a science of educated conjecture. Without any witnesses and documentation of the time, scientists can only use the clues left behind by fossils to create a complete picture of how these creatures once appeared. There are often gaps that need to be filled in by looking at modern-day animals and also in understanding the environments dinosaurs inhabited.

Although it cannot be determined with absolute certainty at this stage, it is unlikely that the T-rex had any feathers. Looking at large animals that populate the planet today, such as rhinos and elephants, we see that they have evolved to reduce the amount of hair that covers their body. This is because big, bulky animals in warm climates simply don’t require thick coverings to stay warm.

It has been determined that the T-rex lived in hot, dry, arid areas and added to this, they were hunters reaching estimated speeds of 45 miles an hour. The Yutyrannus, on the other hand, lived in cool, dark forests. Just as the Asian elephant that lives in forests has more hair than the African elephant out on the savannah, so too is it likely that these Jurassic cousins had different clothing evolved to suit their habitat.

With the environment of the T-rex, feathers are likely to have been a hindrance. When you take the habitat and lifestyle into consideration, along with the scale imprints found, the educated guess would be that the T-rex was a scaly kind of guy.

Do All Dinosaurs Have Feathers?

With the influx of feathered dinosaurs unearthed, along with discoveries of traces of feathers in dinosaurs that were once believed to be scaled, the idea of all dinosaurs being feathered began to emerge.

In a recent study, Professor Paul Barrett, a dinosaur researcher at the Natural History Museum, analyzed the evolution of feathers. In this study, they looked at all the discovered specimens of dinosaur skin and mapped them into an evolutionary tree to see how they relate.

Most of the dinosaur fossils found with clear feather evidence have been those of the meat-eating theropods. Still, a few feather discoveries have been from completely separate groups leading to the feathered dinosaur debate.

By tracing the skin samples’ evolutionary tree, Professor Barrett’s team could find no evidence that the first dinosaurs had feathers. Although feathers played a big role for theropods, the conclusion they reached was that for most dinosaurs, they did not. So feel free to feather up the meat-eaters, but for the most part, the herbivorous dinos probably had scales.

Conclusion

We know that both scales and feathers are prevalent in the story of dinosaurs from the fossil remains found with skin and feather samples preserved. While we now know with certainty that all birds are living dinosaurs, not all dinosaurs were birds.

Paleontology is a science of continued learning, and we discern more with each new fossil excavated and with the advancements in technology. It’s not yet possible to know with absolute certainty exactly what each dinosaur looked like, but we are getting closer. What the fossils do tell us without question is that some dinosaurs definitely had scales, and some definitely had feathers; the rest is still unwritten.