10 Greatest Dinosaurs of All Time

From the doorknob-turning, toe-tapping velociraptors in "Jurassic Park" to the menacing Sharptooth and stubborn Cera in the "The Land Before Time," never before has a species inspired such imagination as the dinosaur. But there's much more to these creatures than what you'll find in the movies.
Originating some 230 million years ago, during the Mid- to Late-Triassic period, dinosaurs started out as small meat-eating creatures, eventually evolving into thousands of different species ranging from tiny carnivores the size of your lap dog to towering plant-eaters weighing more than 80 tons. Although other prehistoric stars such as pterodactyls and ichthyosaurs are often lumped in with the dinosaurs; dinosaurs, or "fearfully great lizards" in Greek, are defined as strictly-terrestrial reptiles, thus excluding groups like the soaring pterosaurs and amphibious plesiosaurs. They're also differentiated by a set of unique features, such as a jaw muscle extending to the roof of their skull, that are common only to dinosaurs.
These features were apparently pretty impressive too, because they enabled this most captivating of prehistoric creatures to dominate land for more than 160 million years. While researchers learn more about the mysterious beasts every day and are constantly uncovering new and interesting specimens, here we highlight 10 of the biggest, baddest and most interesting dinosaurs yet discovered. First up is a dino that doesn't look especially impressive, but just wait until you hear him sing.

While another velociraptor got all the Hollywood screen time, Deinonychus was every bit as fearsome as Spielberg's T-Rex. It was fast, intelligent and fierce despite its size.Image Credit: Getty Images

10. Parasaurolophus

Some dinosaurs impress us with their size, some with their speed and others with their ferocity. This one does it with its nasal cavity.
Parasaurolophus wasn't especially big, not necessarily a speed demon and lacked anything in the sharp teeth, long claws, and spiky tail departments. But when you have an auditory cortex capable of picking up on advancing predators from miles away and communicating the impending danger to the rest of your herd, none of those things really matter.
A plant-eating member of the hadrosaur family, also known as the duck-billed dinosaurs, Parasaurolophus' main feature was its curved head crest. This crest, which also may have been used for mate attraction or for identification, housed the animal's nasal cavity. Far from an ordinary nasal cavity, though, this schnoz was comprised of a looping tube stretching 8 feet (2.4 meters) long.
When Parasaurolophus pushed sound through this trombone like cavity, the result was a low frequency call deeper than that of a foghorn. This so-called "infrasound" was capable of traveling over extremely long distances and warned others in the group of approaching danger. Coupled with the dinosaur's super-strength hearing capable of detecting predators from far off in the distance, these unique calls were all Parasaurolophus needed to stage a powerhouse defense [source: Discovery Channel].
The next dinosaur on the list subdued not with its song, but with its sting.

The advanced auditory system parasaurolophus got from its curved headcrest let it hear danger miles before it arrived.Image Credit: Getty Images

9. Sinornithosaurus

Sinornithosaurus, whose name means "Chinese bird lizard," was a small, turkey-sized member of the raptor family. This dinosaur's claim to fame came in late 2009 when researchers discovered the feathered carnivore may have been venomous. While other dinosaurs have shown signs of being able to inject venom, the Sinornithosaurus findings are the most conclusive to date [source: Viegas].
Similar to other venomous animals like snakes, Sinornithosaurus appears to have had long fang-like teeth with a thin groove running from the root to the tip, indicating a venom pathway. The researchers also found what looks like a groove extending along the animal's jaw to a small hollow chamber that could have housed the venom gland, as well as small pits at the tops of the teeth for delivering the venom. The back teeth of Sinornithosaurus were shorter and broader for chewing.
It's likely the raptor used its fangs to inject venom into prey such as birds, pterosaurs, lizards and mammals and then devoured them once they were rendered helpless -- not unlike the bite-and-hold method today's cobras use [source: Discovery Channel.
Venom notwithstanding, Sinornithosaurus may have had a hard time getting through to this next dinosaur, a veritable walking tank.

8. Ankylosaurus

Stretching 35 feet long (10.7 meters) and weighing between three and four tons, Ankylosaurus met few rivals when it roamed the Earth during the Late Cretaceous period [source: Wilson]. With a back and sides covered with steel-like plates, horns behind its eyes, eyelids made of bone and bone plates attached to the outside of its skull and jaws, this plant-eating dinosaur was almost entirely covered in armor. As if the seemingly impenetrable shield weren't enough, Ankylosaurus was also equipped with a massive tail capable of delivering blows with 43,000 pounds of force [source: Discovery Channel].
Thanks to a muscular top half and fused vertebrae on the bottom, the tail could be swung like a whip 45 degrees in either direction at speeds up to 48 mph (77 kph). To top it all off, at the end of this swinging mace was a 100-pound (45 kilograms) bony mass that could have shattered the leg bones of rivals without looking any worse for the wear [source: Discovery Channel.
The only thing not imposing about this dinosaur was its small, beak-like mouth, with teeth designed for chewing plants.
The next dinosaur was neither threatening nor massive. In fact, if you'd been walking around when it was alive, chances are you wouldn't have even seen it.

7. Oryctodromeus Cubicularis

How does a dinosaur weighing barely 70 pounds (32 kilograms) survive in a landscape dominated by towering beasts 10 times its size? In the case of Oryctodromeus cubicularis, a small plant-eating dinosaur that lived during the early Cretaceous period, it disappears.
By digging small burrows and hiding out underground, this dinosaur managed not only to escape predators, but probably harsh weather as well. Based on remains found in both Australia and Montana, Oryctodromeus, whose name means "digging runner of the lair," was a well-designed digging machine. The dinosaur had a snout that could have been used as a shovel, strong shoulder muscles and sturdy hip bones for bracing against the ground. If all else failed, Oryctodromeus also had long hind legs for running [source: Boswell].
The burrow in which the remains were found was just barely as long as the dinosaur itself, ensuring that desperate predators couldn't come in after it. While Oryctodromeus was 7 feet long (2 meters) -- not too shabby for a dinosaur -- more than half of that was tail, making the digger's body roughly the size of a coyote's. [source: Hecht].
The fact that the bones were discovered in a burrow alongside two of the dinosaur's young also indicates this member of the hadrosaur family also practiced extended parental care, providing some of the best evidence yet that dinosaurs did so.
Whether or not the next dinosaur was a good parent remains to be seen. If the way it treated its prey is any indication, it's highly doubtful.

6. Spinosaurus

Tyrannosaurus Rex often steals the show as the most fearsome predator in dinosaur movies, but it's the Spinosaurus that holds the record as the world's largest carnivorous beast. Weighing in at a full 9.9 tons, Spinosaurus, which means "spine lizard" in Greek, got its name from the distinctive sail on its back composed of long spines covered in skin. This imposing sail, which may have served as a built in thermostat, mate magnet or simply for intimidation, rose a full 6 feet (2 meters) tall when Spinosaurus arched its back [source: Viegas].
Another distinctive characteristic of this dominant Cretaceous Period predator was its 6 foot (2 meter) long head -- the longest of the meat eaters -- and narrow snout full of knife-like teeth. While most other carnivorous dinosaurs possessed curved teeth, the teeth of Spinosaurus were straight, probably to spear slippery prey like fish [source: Viegas]. Based on similarities between this prehistoric dinosaur and today's crocodiles, scientists also think Spinosaurus likely grabbed its prey and proceeded to thrash its head back and forth to kill it [source: Discovery Channel.
If Spinosaurus thought it could thrash this next dinosaur around, though, it had another thing coming.

If you're looking for the largest carnivore in history, Spinosaurus is your dino. All 9.9 tons of him. Note the distinctive "sail" rising up along its back.Image Credit: AP Photo

5. Sauroposeidon

While predators such as Spinosaurus are often viewed as having the toughest job, finding, eating and digesting enough plant matter to fuel a 60-ton body is no simple task. At 60 feet (18 meters) tall and 100 feet (30 meters) long, Sauroposeidon, a member of the plant-eating sauropod family, was the tallest land animal to ever exist [source: Discovery Channel]. Its neck alone was 35 feet (11 m) long, with neck bones the size of fourth graders [source: BBC].
Sauroposeidon's hefty girth meant it had to consume up to a ton of vegetable matter daily, practically a never-ending job. To accomplish this feat, the dinosaur bore 52 chisel-like teeth that it used to strip plants of their leaves, in one fell swoop. It didn't even bother with chewing; it gulped the tasty vegetation straight down to a 1-ton stomach the size of a swimming pool. Then it let its super-strength stomach acid -- capable of dissolving iron -- do all the work [source: Discovery Channel]. Gizzard stones, rocks the dinosaurs swallowed to help them digest the fiber, further helped the process.
It's a good thing this dinosaur had so much help in the digestion department, because with a lifespan of 100 years, one of the longest of the dinosaur kingdom, that chewing would have gotten old pretty fast [source:Discovery Channel].
Sauroposeidon would have towered over our next dinosaur, but never underestimate a small opponent.

4. Deinonychus

While his cousin Velociraptor won the lead role in Jurassic Park, Deinonychus was every bit as fearsome and wily as that doorknob-turning film star. You don't get tagged with a name meaning "terrible claw" for no reason.
A bird-like dinosaur measuring approximately 5 feet tall (1.5 meters), 10 feet long (3 meters) and 200 pounds (91 kilograms), Deinonychus more than made up for its small size with its speed, intelligence and an impressive arsenal of weaponry [source: Discovery Channel].
Both its hands and feet were equipped with razor sharp claws, including a long curved claw 5 inches (13 centimeters) long on the second toe of each hind foot [source: Col]. This claw, which Deinonychus held erect while walking, was likely used to grasp onto prey with a death grip while it proceeded to use its 60-plus serrated teeth to tear the unfortunate victim to shreds [source: NewScientist]. Deinonychus may also have used its strong tail to balance on one foot while it kicked out at foes karate style with its killer claw.
And while the strong legs of Deininonychus likely enabled it to pounce on and take down prey easily on its own, it also probably joined with others to tackle prey several times its size. Already among the deadliest hunters of the late Cretaceous by themselves, these packs of Deinonychus were a force to be reckoned with.
One dinosaur, though, may have been up to the challenge they presented.

3. Triceratops

If any dinosaur could stand up to the wrath of dinosaurs like Deinonychus, it was this guy. The largest and heaviest of the horned dinosaurs, Triceratops was one of the most dangerous animals to have evolved on land [source: Discovery Channel]. This is one dinosaur that played both offense and defense equally well.
Characterized by a short nose horn and two longer horns up to 3 feet (1 meter) long over the eyes, Triceratops's offensive weapons were made of keratin, an antler-like material that could have easily gored even the most formidable foes. On the defensive end, Triceratops wore a 6.5 foot (2 meter) wide neck frill that was six times thicker than a human skull [source: Discovery Channel]. Besides being a nearly impenetrable form of protection, this several-layers-thick shield may also have been used to regulate body temperature or attract mates.
Triceratops wasn't lacking when it came to size, either. This rhinoceros on steroids was half as tall as T-Rex but weighed the same, making for a hefty package 26 feet long (8 meters), 10 feet tall (3 meters) and weighing 6 tons [source: Discovery Channel]. The positioning of the dinosaur's legs was yet another bonus. With straight back legs and splayed front legs, its center of gravity was directed toward the head, an ideal design for a strong frontal attack.
With such a well-stocked toolbox, it's no wonder Triceratops was the most common dinosaur during its time period. In the Late Cretaceous, Triceratops outnumbered T-Rex 10 to 1 [source: Discovery Channel].
Speaking of Tyrannosaurus, find out the many reasons why he graces our list next.

Triceratops roamed the earth protected by a thick neck frill and long nose horns.Image Credit: AP Photo

2. Tyrannosaurus Rex

Easily the world's most famous dinosaur, Tyrannosaurus Rex was the dominant predator for 25 million years. With finely tuned senses, a bite force 16 times as strong as an alligator's and seven tons of pure muscle, this is one dinosaur that definitely lives up to its name, which translates as "tyrant lizard king." [source: Discovery Channel].
One of Tyrannosaurus's most imposing features was its head. The size of a grown man, its head was 2/3 muscle and along with its neck, weighed a full 1,000 pounds (454 kilograms) [source: Discovery Channel]. This bone cruncher's jaws, stocked with more than 50 teeth up to a foot long, were strong enough to crush a car [source: BBC]
The brain inside that looming skull wasn't too shabby, either. The cerebrum of Tyrannosaurus was one of the largest relative to body size of any animal in the prehistoric era, making it well suited to analyzing the wealth of information the dinosaur's eyes and nose sent its way. Thanks to the placement of its eyes 16 inches (41 centimeters) apart, Tyrannosaurus had excellent binocular vision capable of seeing fine detail for up to four miles (6.4 kilometers). The large olfactory bulbs in T-Rex's brain suggest its nose was just as powerful. By some estimates its sniffing power was equal to that of 1,000 bloodhounds [source: Discovery Channel].
Contrary to what you may have seen in the movies, though, the one thing T Rex wasn't is fast. Based on the ratio of the dinosaur's thigh bone to his shin, T Rex was likely just a fast walker or a jogger [source: Discovery Channel]. But with such highly refined senses, steel-crushing jaws and dagger-like teeth, who needs speed?
The next dinosaur on the list may not have. After all, it practically had wings.

Visitors to Chicago's Field Museum look at "Sue," the world's most complete T-Rex skeleton. The museum also has the skull, which it must display separately. The skull weighs 600 pounds and would collapse the entire skeleton.Image Credit: Getty Images

1. Archaeopteryx

It's a bird! It's a dinosaur! It's ... Archaeopteryx!
A transitional link between birds and reptiles, this particular animal has perhaps stirred up more controversy than any other. So much so, in fact, that there's no real consensus on how to categorize it.
Although its remains, first discovered in 1861, had feathers similar to those of modern birds, they also bore a striking resemblance to those of small meat-eating dinosaurs. As a result, Archaeopteryx has been placed in a sort of categorical no-man's land: It's both primitive bird and feathered dinosaur.
On the bird side, the crow-sized Archaeopteryx with a 2-foot (.6-meter) wingspan had feathers, wings, a furcula (or wishbone) and smaller fingers. On the dinosaur side, it had teeth, a flat breastbone, a bony tail and claws. It's uncertain whether this curious creature used its feathers for flight, temperature regulation or a little bit of both, but if they did fly, the flat breastbone indicates they probably didn't do it for long periods [source: Natural History, UCMP].
Regardless of its flying skills, the status of Archaeopteryx as the first known bird set the stage for our current understanding of how birds evolved. Don't look now, but Tyrannosaurs Rex's cousin is at your bird feeder!
For more on dinosaurs, birds and everything in between, explore the links on the next page.

Archaeopteryx, seen in this display, is both primitive bird and feathered dinosaur. The jury's still out on how to categorize it.