Dinosaurs and their ancestors are the stuff paleontologists and kids dream about. And with good reason, these reptiles, birds, and mammals are utterly fascinating.
Seeing an animal that roamed the Earth so long ago connects us to the past, unlike anything else. Their strange beauty has made them one of our culture’s most popular and enduring symbols. They have captured imaginations from the beginning of time.
Their legacy lives on in nature and our history. They were so successful that, even though dinosaurs themselves have been extinct for millions of years, we still have very close relatives today.
Meet the Dinosaur Cousins: Birds
Birds are a group of animals descended from dinosaurs and share many features with them. It means that you are looking at a descendant of the dinosaurs whenever you see a bird. Scientists classify birds as avian dinosaurs. They have the same dinosaurian anatomy and share common ancestors with other types of dinosaurs.
In 1868, Thomas Huxley noticed some similarities between Archaeopteryx and Compsognathus (a small carnivorous dinosaur). He suggested they were somehow related to each other and represented a step in the evolution of birds from dinosaurs.
Birds are living dinosaurs because they evolved from a group of theropod dinosaurs. It included small, predatory species. Like their modern descendants, Saurischian dinosaurs dominated the Mesozoic relatives (lizard-hipped). Many of them had three-toed limbs and clawed hands.
Although ornithischian (bird-hipped) dinosaurs were diverse, only two groups made it through the end-Cretaceous mass extinction event that wiped out almost all their kin and most other life on Earth.
Ornithischians survived because of evolutionary adaptations like spiked beaks, aided by behavioral shifts such as pack hunting. They may have been more omnivorous than other dinosaurs.
The other group to make it through the end-Cretaceous mass extinction was pterosaurs or flying reptiles. Pterosaurs evolved from terrestrial predators at least 220 million years ago during the Triassic period.
There are an estimated 10,000 species of birds alive today. Scientists estimate that there were more than 100 times more species alive at the time of the dinosaurs. Researchers don’tt know why so few bird species survived the Cretaceous extinction event while other groups of animals recovered quickly after this event.
Alligators and crocodiles: The answer lies in their teeth
Alligators and crocodiles are part of a group called archosaurs (or “ruling lizards”). It includes birds, pterosaurs (flying reptiles), and crocodilians. This group is closely related to dinosaurs due to major similarities in their anatomy. They have a bird-like body plan with four limbs and long tails.
While alligators and crocodiles are more closely related to birds than other reptiles, they are still considered reptiles. Their closest living relatives are snakes, lizards, turtles, and tortoises. If you were to look at an alligator’s skeleton under a microscope, it would be easy to mistake it for that of a snake. Characteristics of crocodiles and alligators include:
- scales – not feathers or fur
- both have four limbs (two legs and two arms);
- eyes – both sides of their heads,
- both have elongated tails used for swimming and balancing (although alligators’ tails are larger than those of most snakes)
- they are egg layers (rather than livebearers)
- they have very powerful jaws and sharp teeth
These traits make it easy to see how they share an evolutionary history with dinosaurs.
Crocodiles are mostly found in Africa and Australia, while alligators live in North America. Crocodiles are bigger than alligators. Some species grow up to 20 feet (6 meters) long – but they have shorter snouts and more slender bodies than their cousins.
The relationship between dinosaurs, alligators, and crocodiles is a complex one. On the one hand, alligators and crocodiles are the living descendants of dinosaurs. On the other hand, they don’t look anything like them. How can we be sure that these two groups share a common ancestor? The answer lies in their teeth.
Alligators and crocodiles have similar teeth to those of their dinosaur ancestors. Their teeth are also similar in function. Alligators and crocodiles have teeth designed to bite prey with their mouths closed and hold on tightly while eating it whole. This feature is very different from most modern-day mammals.
They tend to chew their food before swallowing it (even then, they don’t eat anything whole). The way that alligators and crocodiles eat is very much like how dinosaurs did. Scientists can use this information to tell us where dinosaurs came from.
The Secret Dinosaurs Left Behind: Sea Turtles and Tortoises
These creatures have survived on Earth for millions of years—and they might even be living descendants of dinosaurs. Sea turtles and tortoises are reptiles, which means they are cold-blooded and have scales instead of fur. They also have a shell covering their bodies, just like many ancient dinosaurs did.
Sea turtles live in saltwater oceans worldwide and grow about two feet long. Tortoises live mostly on land but can also live in freshwater lakes or rivers. Both types of animals get their water from plants, not drinking it directly from streams or ponds as many other animals do. Both also lay eggs that hatch into baby sea turtles or tortoises after several months of incubation—just like their ancient cousins.
Turtles and tortoises are mostly known for their ability to live for long periods. They don’t need to eat every day, and they can go without water for several days. They can also survive in extremely hot or cold environments—and they can even hibernate during the winter months.
These animals share many characteristics with the dinosaurs that roamed Earth millions of years ago. They have thick shells that protect them from predators. Unlike most reptiles, their body temperature remains high regardless of whether they’re active.
This feature allows them to regulate their body temperature while staying warm enough to survive harsh winters or hot summers. It’s easy to see why these ancient beasts might have evolved from dinosaurs.
Family Tree of Snakes and Lizards
Snake ancestors have been around for about 100 million years, and today’s snakes are the same as their ancestors from that time. Snakes are directly descended from an ancient group of reptiles called synapsids. They first appeared on Earth in the Permian Period.
On the other hand, Lizards evolved from amphibians that lived in the Carboniferous Period. They survived through that period and into the Mesozoic Era (when dinosaurs were around). When dinosaurs went extinct at the end of this era, lizards could thrive. They were small enough to hide from predators such as birds and mammals.
Snakes and lizards are overall found on every continent except Antarctica. Snakes live on land, while lizards live in water or on land.
Although they look very different, snakes and lizards share a common ancestor with dinosaurs. Their bodies are fully covered with scales, and they have four legs, a long tail, and sharp claws on their feet.
There are many differences between snakes and lizards too. Most snakes have long forked tongues that can sense smells. They have no eyelids and can only see when their eyes are open, so they tend to look like they’re always blinking. Lizards have eyelids and can see even when their eyes are mostly closed—and some kinds of lizards can change colors.
Both reptiles lay eggs that hatch into babies called hatchlings or younglings (depending on whether they’re snakes or lizards). Baby reptiles grow very quickly during their first few years of life. Some species of lizard can grow up to 10 inches (25 centimeters) in just one year.
All birds are dinosaurs, and there’s a good reason for that. Birds are descendants of theropods. It is the same group of dinosaurs that includes the T. rex, Velociraptor, and other famous meat-eaters.
Theropods have a lot in common with modern chickens. They have feathers, beaks instead of teeth, and are warm-blooded. But theropod ancestors began evolving into birds more than 100 million years ago. Many of their similarities have been mostly lost over time.
Some chicken characteristics have evolved since then—chickens have no teeth. All birds lay eggs instead of giving birth to live young. It’s still possible for us to see similarities between chickens’ eggshells today and those from ancient times when dinosaurs were still roaming the Earth.
Chickens are the descendants of dinosaurs. Chickens are the closest living relatives to dinosaurs, and they share some of their features. Chickens have scales on their legs and feet, similar to dinosaurs. Chickens also have a three-fingered hand, similar to a dinosaur’s hand. These features show that chickens are well related to dinosaurs.
The ostrich is a living dinosaur descendent, but it’s not just their legs that make them so dinosaur-like—it’s also their brains, eyesight, and large size.
They are the only birds left in the world capable of running long distances at high speeds. Their bodies are well-adapted for this feat: they have strong leg muscles and short toes with two or three toes on each foot (instead of four). Their long necks help them balance while running wildly with their heads held high in the air.
Ostriches also have very good eyesight—they can see things as far away as two miles. Without corrective lenses, humans can only see things up to three hundred feet away. And did you know that ostriches have binocular vision? It means that their eyeballs can focus on different things at once so they can see more clearly than humans do.
Ostriches also have a way of lifting their heads that’s very similar to how some dinosaurs used their necks (like the Brachiosaurus) when they were alive millions of years ago.
By learning more about dinosaurs, you might gain a great appreciation for their place in the history of our world. The various types of dinosaurs that lived millions of years ago aren’t just a curiosity. Instead, they hold a prestigious place in our evolutionary development.
So be sure to learn as much about these fascinating creatures as possible. You never know what you’ll discover and how it may positively impact your life.
Dinosaurs might not be walking among us anymore, but many other amazing creatures are waiting for us to discover them. We can maybe even learn something new along the way.