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The term “dinosaur” originates from two Greek words. The first, deinos, means “terrible,” “mighty,” or “marvelous.” The second, sauros, translates to “lizard.” Fossils continually provide new insights into dinosaurs, challenging many once-accepted “facts” that are now considered either debunked or contentious. Here's a list of 10 such so-called “facts” that have evolved over time.
10. ‘Dinosaurs Left Their Eggs Behind Like Lizards’
In earlier times, it was commonly believed that dinosaurs abandoned their eggs after they hatched, much like reptiles. However, recent research reveals that many dinosaurs likely cared for their young, similar to modern-day birds. Fossilized nests and burrows provide deep insights into their behavior. These nests range from basic pits to more complex designs with mud rims, and they are found both individually and in groups. The arrangement of the nests and their eggs offers valuable clues about the dinosaurs' nurturing habits.
Numerous Maiasaura nests have been discovered in Montana, where nests, eggs, hatchlings, juveniles, and adults have been found in close proximity. This evidence suggests that these dinosaurs exhibited a high degree of parental care and were highly social. The nests were simple depressions in the ground, measuring 1.8–2.1 meters (6–7 ft) in width and about 1.1 meters ( ft) in depth. The newborns measured approximately 0.3 meters (1 ft) in length. Nests were spaced roughly 9 meters (30 ft) apart, corresponding to the size of an adult Maiasaura. In one area, over 40 nests span a 2.5-acre region.
9. ‘Dinosaurs Were Fully Covered In Scales’
It was once believed that all dinosaurs had scales, but recent discoveries have revealed that over 30 species of non-avian dinosaurs actually had feathers, supported by direct fossil evidence and features like quill knobs. Previously, feathered dinosaurs were only known to be carnivorous ancestors of birds. However, in 2013, the fossils of a new herbivorous dinosaur were found near the Olov River in Siberia. This species, Kulindadromeus zabaikalicus, showed signs of feathers, suggesting that feathers may have been widespread among all dinosaurs.
K. zabaikalicus existed around 160 million years ago and measured approximately 3 meters (10 feet) in length. Though many skeletons found were incomplete, the bipedal creature had short front limbs and longer back legs with five toes. The presence of a river in the area during its time suggests that the animal may have died near water. Its body was shielded from scavengers, allowing for the preservation of feather and scale imprints.
8. ‘Dinosaurs Were Cold-Blooded’
Many people assume that dinosaurs were cold-blooded like modern reptiles, but such a metabolism would have been insufficient for them to hunt other dinosaurs. To study their metabolic rates, scientists examined fossilized bones, using the size of thigh bones and growth ring patterns to estimate the dinosaurs' body mass and growth rates. Their findings revealed that dinosaurs had metabolic rates that were neither fully cold-blooded nor warm-blooded.
Dinosaurs were unlike any animals we know today, not resembling mammals, birds, reptiles, or fish. Their biological makeup was distinct from that of modern creatures. While dinosaurs were once thought to be slow, cumbersome, cold-blooded beings, ongoing fossil discoveries reveal many species, such as the Velociraptor, that seem much more agile. This has led many scientists to believe that dinosaurs were as active as warm-blooded mammals and birds.
However, the simple classification of animals as either cold-blooded or warm-blooded doesn't adequately describe the full range of possibilities. Some animals alive today, such as the great white shark, leatherback sea turtle, and tuna, don’t fit neatly into either category. When scientists analyze growth patterns and energy usage to trace metabolic systems, they find that dinosaurs actually occupied a middle ground.
7. ‘Pterosaurs Were Dinosaurs’
Pterosaurs are widely recognized, partly due to their appearances in films like The Land Before Time and Jurassic Park, but they were not actually dinosaurs. These Mesozoic reptiles were the first vertebrates to achieve flight and belong to a separate group entirely. While the term “dinosaur” is often used broadly to describe all prehistoric reptiles, not all of them are true dinosaurs.
Dinosaurs are part of a remarkably varied group of land-dwelling reptiles with distinctive anatomical characteristics. Pterosaurs, however, were flying reptiles and are not considered dinosaurs for this reason. One key feature that sets dinosaurs apart from other reptiles is the position of their limbs. Unlike ancient crocodiles, which had sprawling limbs, dinosaurs had limbs directly beneath their bodies, enabling them to stand upright.
6. ‘Brontosaurus Isn’t Real’
The Brontosaurus was first identified in the 1870s, but by 1903, paleontologists concluded that the fossils actually belonged to an Apatosaurus. However, in the 1970s, another fossil of a Brontosaurus was discovered in the western United States and named Brontosaurus excelsus, meaning the “noble thunder lizard.” Eventually, scientists determined that B. excelsus was so similar to the Apatosaurus that it was reclassified as Apatosaurus excelsus.
A recent study conducted by Oxford University has reinstated Brontosaurus as a valid genus. This was achieved by using advanced computer software to analyze differences between various species and genera of diplodocid dinosaurs. In reality, the distinctions between Brontosaurus and Apatosaurus are as significant as those found between any two separate genera.
5. ‘Dinosaurs Are All Extinct’
Are dinosaurs truly extinct? Not exactly. While groups like sauropods and many others are long gone, one of the major dinosaur families, the theropods, survived the mass extinction event at the end of the Cretaceous period. One of the 40 subgroups of theropods eventually evolved into the birds we see today.
It’s widely believed that all dinosaurs vanished around 65 million years ago, but that’s not entirely accurate. In fact, thousands of dinosaur species are still alive today. According to modern evolutionary classification, there’s no scientific reason to exclude birds from being considered a specialized form of dinosaur.
Biologists categorize dinosaurs into two primary groups: the Saurischia (“lizard-hipped”) and the Ornithischia (“bird-hipped”). The lizard-hipped dinosaurs are further split into the Sauropodomorpha, which includes long-necked species, and the Theropoda, a group that, despite the name, also encompasses modern birds and bipedal dinosaurs like Tyrannosaurus rex.
4. ‘Velociraptors Were Large Dinosaurs’
Thanks to Jurassic Park, most people are familiar with Velociraptors—intelligent, scaly dinosaurs that loom over terrified children. But what if those creatures weren’t actually Velociraptors? In paleontology, as in other fields, names are constantly evolving. Some dinosaurs are given different names by various scientists, while others are renamed to avoid confusion. While these changes usually stay within the scientific community, there are instances when a well-known dinosaur is called by a name different from what paleontologists originally used. The Velociraptors in Jurassic Park were far from accurate, and experts caught on to the mistake quickly.
The first Velociraptor fossils were discovered in Mongolia during the 1920s. These small predators reached only about 0.5 meters (1.6 feet) in height and 1.8 meters (6 feet) in length. It is believed that they used the sickle-shaped claws on their feet to hunt and kill their prey.
When Jurassic Park was released, the film’s portrayal of the Velociraptor seemed to match one known species—Deinonychus. Deinonychus was first discovered in the 1960s. It was originally thought to be a larger version of Velociraptor, but the two genera actually differ in numerous ways. Deinonychus was nearly twice the size of its Mongolian counterpart, with larger sickle claws on each foot, long arms equipped with grasping hands, and a rigid tail to maintain balance while pursuing prey. Does that sound familiar?
3. ‘Plesiosaurs Are Dinosaurs’
The Loch Ness Monster is often identified as a Plesiosaur, but many people don’t realize that Plesiosaurs weren’t actually dinosaurs. Dinosaurs belong to a broad group of land-dwelling reptiles with specific anatomical traits. Like pterosaurs, marine reptiles like Plesiosaurs don’t fall into the dinosaur category.
Plesiosaurus had a wide body and a short tail, measuring between 2.4 to 14 meters (8–46 feet) in length. With long necks, small heads, and large flippers instead of legs, they were distinct from dinosaurs. Other plesiosauroids had shorter necks and larger heads. The flippers helped them rotate quickly in the water, though they were likely not fast swimmers. Their extended necks allowed them to snatch prey from just beneath the surface. Many depictions show Plesiosaurs with their heads above water, but this wasn’t feasible. They couldn’t bend their necks that way, and even if they could, gravity would have tipped them over.
2. ‘T-Rex Had Useless Arms’
Many people believe that the arms of Tyrannosaurus rex were small and ineffective, but this might not be true. Each arm was heavily muscled, capable of lifting up to 199 kilograms (439 pounds). The main evidence supporting this comes from stress fractures found in the furcula (wishbone-like bones) of numerous Tyrannosaurus rex fossils. These bones are part of the forelimbs, and the fractures likely resulted from intense struggles with prey or other T. rex individuals.
It’s possible that Tyrannosaurus rex used its powerful jaws to clamp down on the throat of its prey to suffocate it, while using its arms to hold the prey still. Alternatively, T. rex may have employed its forelimbs to push off the ground when standing or to hold onto a mate during reproduction. However, these activities wouldn’t have caused the fractures observed in the fossils, suggesting that the arms were indeed used for hunting.
1. ‘T-Rex Had Poor Vision’
We all recall the iconic line, 'Don’t move! It can’t see us if we don’t move!' from Jurassic Park. However, Tyrannosaurus rex didn’t suffer from poor eyesight as commonly believed. The first clue that T. rex had sharp vision comes from its forward-facing eyes and narrow skull, which provided exceptional depth perception. In addition, each of its eyes was roughly the size of a softball.
Research revealed that T. rex had a binocular field of vision extending 55 degrees, which is wider than a hawk's, supporting earlier assumptions. Furthermore, similar to other theropods, T. rex’s visual range was comparable to that of modern raptors. Additional studies have shown that Tyrannosaurus rex had 13 times the visual clarity of a human, with some experiments even suggesting it could distinguish objects as far as 6 kilometers (3.7 miles) away.
