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What are the “Big Five”? Many people have wondered about that question for years. Early explorers saw fossils and bones but had no idea what they were or how they got there. We now know that they were part of one of the most famous groups of animals that ever lived, Dinosaurs.
Hunters in Africa coined the term big five to describe the five most dangerous game animals there. In recent years the term “big five” refers to the most challenging dinosaurs for paleontologists.
Although paleontologists discovered many types of dinosaurs, there are five major groups of interest: Herbivores, carnivores, raptors, pterosaurs (flying dinosaurs), and ichthyosaurs (fish lizards).
Biggest Herbivore: Argentinosaurus
Argentinosaurus was an enormous herbivore that ever lived, bigger than any of the dinosaurs or mammals that came after it. Fossils found in Argentina were the most studied and looked at by paleontologists, hence the name (or ending). They grew to a length of 20 to 33 meters, or 73 to 108 feet. Their maximum weight is controversial because they are massive, but estimates range from 30 to 100 metric tons.
“Huge” does not even begin to describe Argentinosaurus. While it may not have been the longest dinosaur, Argentinosaurus has earned its place as the largest. This herbivore was longer than a basketball court and weighed more than ten elephants.
It may not be a coincidence that Argentinosaurus lived in South America while Brachiosaurus lived in Africa. These two were the most giant known herbivores when they lived. The shape of their bones indicates they walked very slowly along on all fours, with a barely erect spine. The size of an animal’s body determines many things about its lifestyle.
The evidence we have of Argentinosaurus is minimal. As a result, we don’t know much about how it lived. Scientists who study dinosaurs can glean information from fossils – the imprints of ancient creatures in rock. However, scientists only know seven Argentinosaurus vertebrae – the flat bones that protect an animal’s spinal cord and make up its backbone.
Paleontologists (scientists who study dinosaurs) estimate that Argentinosaurus lived around 100 million years ago during the Cretaceous Period. They were herbivores, probably eating ferns like those found growing in Argentina today. Scientists think a group of Giganotosaurus’ may have worked together to kill an Argentinosaurus. These small mammal populations would also have fed on it if left alone.
Biggest Carnivore: Tyrannosaurus Rex
Paleontologists found fossils of T.Rex in Western North America and Asia, but its range might have extended farther. Tyrannosaurus Rex was not the biggest dinosaur—that title belongs to sauropods, such as Argentinosaurus. Tyrannosaurus Rex was a giant, ferocious, meat-eating dinosaur that lived millions of years ago.
Tyrannosaurus Rex had a skull almost five feet long and had around 60 teeth. Each of the teeth was more than twelve inches long, and its strong bite allowed it to crush bones and muscle tissue. The largest Tyrannosaurus Rex specimen ever found was 42 feet in length and weighed upwards of 19 tons. The brain cavity gave space for an organ thought to be an olfactory bulb that used to smell as large as a grapefruit.
Tyrannosaurus Rex, referred to as T.Rex or T-Rex in popular media, was one of the largest carnivorous dinosaurs ever. Tyrannosaurus rex was a theropod dinosaur. It was a bipedal carnivore with a massive skull balanced by a long, heavy tail and stout legs.
It had two fingers on each hand, but scientists think it used them to grasp rather than use them as weapons. The second toe of each foot had a large claw, which the T.Rex used to rip prey apart or slash other dinosaurs during fights over territory. It walked on its two hind feet with its head held high. Its long tail and small arms helped it balance as it charged into a herd of prey.
T. Rex had a quick-burst speed of up to 15-20 mph but was likely incapable of sustained running at top speed. It had a bite force at the back of its jaws measuring 8,000 pounds per square inch (55,000 kPa) – enough to shatter bones. Scientists think T. Rex’s strong sense of smell helped it hunt its prey.
Besides its powerful legs, the neck and tail provided strength and balance when running. With so many adaptations for hunting, it is no wonder that the Tyrannosaurus Rex was one of the most formidable predators ever to walk the Earth.
Biggest Raptor: Velociraptor
Scientists found the first Velociraptor fossil in the Gobi Desert in Mongolia. Velociraptor was the biggest of the dinosaurs known as raptors and were carnivores, meaning they ate meat. They were bipedal dinosaurs, standing and walking on two legs.
Velociraptors lived alongside other carnivores such as Tyrannosaurus Rex and Tarbosaurus. Velociraptor was a pack hunter, and when it attacked, it did so in groups. Raptors were fearsome and intelligent dinosaurs that lived during the Cretaceous period, which encompassed about 145 million to 65.5 million years ago.
The Velociraptor is the type of dinosaur you might be picturing when you imagine a raptor. Velociraptor means “swift robber” in Latin. This carnivorous dinosaur was between 2 to 3 feet high and 6 to 8 feet long. Velociraptors had a big sickle-shaped claw on each foot. It was great for hunting prey and defending themselves from other predators.
Fossils of the Velociraptor show that it had feathers, which might also shed some light on why it’s usually portrayed with feathers. Discoveries in northern China have shown that some members of the dromaeosaurid family had quill knobs on their arms and legs. It was like birds today with flight feathers anchored by quill knobs.
What was Velociraptor eating? Not only did it have super sharp claws, but also it had razor-sharp teeth that were perfect for ripping through flesh.
These dinosaurs were fast runners, making them even more deadly on the hunt. Still, paleontologists estimate it could run about 40 kilometers an hour (25 miles per hour). It’s hard to believe that something terrifyingly fierce only weighed around 30 pounds. Velociraptor was a fierce raptor that lived around the same time as T. Rex.
Biggest Pterosaur (Flying Dinosaur): Quetzalcoatlus
Quetzalcoatlus, which means “feathered serpent” in Aztec, was one of the largest pterosaurs ever. Quetzalcoatlus lived during the Late Cretaceous Period about 70 million years ago in North America. Paleontologists found the first specimens of Quetzalcoatlus in Texas. Douglas A. Lawson named them in 1975. They found these fossils north of the Rio Grande River in Big Bend National Park.
It lived during the Late Cretaceous period and was one of the last dinosaurs to walk the Earth. Most paleontologists believe that this enormous pterosaur was a scavenger.
The Pterosaur, Quetzalcoatlus, measured approximately 30 feet. It was the largest flying dinosaur ever discovered. It was so heavy that it could not take off from the ground but rather from a cliff. Quetzalcoatlus is a pterosaur, which means winged lizard.
Quetzalcoatlus had an immense wingspan and could fly long distances at high speed. It is one of the largest flying animals, with a wingspan of up to 33 feet (about 10 meters). It flew over the heads of dinosaurs such as Tyrannosaurus rex and Triceratops. Its wing bones were hollow, with thin walls a quarter-inch thick.
Because it was so big, scientists thought that a Quetzalcoatlus could fly great distances at high speeds and that it could also soar for long periods without flapping its wings. Scientists believe they could soar for hours on rising air currents called thermals.
Its legs were so long that scientists thought it could not walk on all fours. Instead, it shuffled around like an emu and ran on two legs. This pterosaur also had a large skull with a beak-like shape, used for catching fish near the water.
Physically, the Quetzalcoatlus was the largest animal with a vertebral column to ever fly. These dinosaurs had long, thin necks and a crest on their heads like parrots, which may have served as an anchor for strong neck muscles.
Some paleontologists theorize that Quetzalcoatlus may have been able to hunt for land animals and fish from the water’s surface. Because of its great size, it would have been capable of snatching small dinosaurs off the ground if it swooped down while flapping its wings. They prefer to fish when they are feeding on the water. 
Biggest Ichthyosaur (Fish Lizard): Shastasaurus
Shastasaurus Sikanniensis, the largest of all Ichthyosaurs (Greek for “fish lizard”), was once the biggest marine reptile ever. Measuring around 50 feet in length and weighing about 10 tons, this monster would have been the largest Ichthyosaur in its period. The complete fossil of Shastasaurus was first discovered in British Columbia in 1965.
What caused this Ichthyosaur’s extinction is unknown. Scientists believe they all vanished around 90 million years ago during the Late Cretaceous Period. Although they look like dolphins and whales, Ichthyosaurs are more related to lizards and dinosaurs like crocodiles and lizards.
The major difference between them is that Ichthyosaurs evolved for a life at sea, whereas land lizards live on land and never adapted to an aquatic lifestyle. Scientists believe that Shastasaurus ate fish and squid using its sharp teeth to grab them and tear them apart. They swam by moving their tails from side to side and steering with their fins.
Its body shape is like that of dorado fish, which have long tails and small heads with large eyes in proportion to the head size. The animal had horny beaks with sharp cutting edges on its upper jaw. The flippers had five fingers. Small teeth were also present on the lower jaw.
The genus Shastasaurus is part of the ichthyosaur family within the order Ichthyosauria. It is a small marine reptile with a body length of approximately 9 meters and a weight of 4 tons. The species varies in color from dark grey to black. 
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Final Thoughts
These are the five most popular creatures from our prehistoric past. They’ve remained popular for a good reason, as each offers something different to discover and enjoy. From giant plant-eaters like Argentinosaurus to small fleet-footed hunters like Velociraptor, they’re worth learning more about.
With so many resources available on the subject, there’s no shortage of places to start if you want to learn more about them. They will never disappoint and only inspire everyone who reads about them, shares stories about them, discuss their history and becomes fascinated with their existence. We hope you’ve enjoyed this small guide to the Big Five and that it’s inspired you to
