Finding out which dinosaurs were the largest in history isn’t as straightforward as one might think. There are very few complete skeletons of these reptiles found, but giant fossils are often found. There is often only one massive skeleton to identify giant dinosaurs such as Argentinosaurus, while smaller dinosaurs typically fossilize all at once. 🦴
There is convincing evidence that Argentinosaurus grew to a significant size, despite paleontologists’ claims to the contrary. In 1986, remains of this giant titanosaur were discovered in Argentina, where it was named after the country. It measured about 120 feet (36.5 meters) long and weighed about 100 tons. 🦕
An Argentinosaurus vertebra is over 4 feet (1 meter) thick. It is also believed that Futalognkosaurus, Bruhathkayosaurus and Amphicoelias can claim the title as “largest dinosaur.” However, an anonymous dinosaur measuring about 130 feet (40 meters) long has recently been discovered in Argentina.
The Argentinosaurus in video
2. The Spinosaurus was the largest carnivorous dinosaur
The Spinosaurus (with its huge crocodilian snout and a veil of skin peeking from its back) may have been slightly heavier than the Tyrannosaurus Rex in this category, and weighed up to 10 tons.
Aside from being large, Spinosaurus was also very agile: recent evidence indicates it was the first dinosaur to swim. Experts are of the opinion that South America’s Giganotosaurus may have matched, and sometimes even outclassed, its North African cousin as the largest meat-eater. 🥩
3. The Utahraptor is the world's largest raptor
The Velociraptor has received all the attention since its starring role in Jurassic World, but this chicken-sized carnivore was anemic compared to Utahraptor, which weighed 1500 pounds (680 kilograms) and stood 20 feet (6 meters) high. In contrast to the general evolutionary rule that smaller progenitors evolve into larger offspring, Utahraptor lived tens of millions of years before its more well-known relative (and smaller).
A terrifying feature of Utahraptor is that its gigantic, curved hind claws were nearly a foot (30 centimeters) long, and were capable of slashing and disemboweling its prey, including Iguanodon.
4. The Tyrannosaurus Rex, the largest Tyrannosaurus
The former world leader in carnivorous dinosaurs, the Tyrannosaurus Rex has now been surpassed in the rankings by the Spinosaurus (from the African continent where many dinosaur footprints have been found) and the Giganotosaurus (from the South American continent).
The largest tyrannosaur in the world still exists in North America, a category that also includes T.-Rex-sized predators such as Tarbosaurus and Albertosaurus. There is evidence that Tyrannosaurus rex females outnumbered males by about half a ton, a classic example of sexual selection among theropods. It is estimated that the largest tyrannosaur found weighed eight tons. 🦖
5. The Dinosaur with the largest horns and ruffs: the Titanoceratops
6. The Magnapaulia: the largest dinosaur with duck-bills
On this list, Argentinosaurus represents the titanosaurs, which were typically the largest dinosaurs during the Mesozoic era. Magnapaulia, a 50 feet (15 meters long), 25-ton titanosaur from North America, was among many other hadrosaurs that became titanosaurs.
As a result of its enormous size, “Big Paul” (named after Paul G. Hagaa, Jr, the chairman of the board of the Natural History Museum of Los Angeles) may have been able to run from its predators by running on its hind legs.
7. The Gigantoraptor: The largest dinosaur bird
You might expect Gigantoraptor to be the largest raptor on this list, an honor currently awarded to Utahraptor. Despite the fact that this Central Asian bird was twice the size of its North American relative, it was not a raptor, but rather a milder species of theropod called an oviraptorosaur (named after its genus, Oviraptor).
The one thing we don’t know about Gigantoraptor is whether it was herivorous or carnivorous; let’s hope it preferred plants for its Late Cretaceous contemporaries. Two tons were the weight of the largest dinosaur of its kind.
8. The Deinocheirus, the largest bird that mimics dinosaurs
The “terrible hand,” Deinocheirus, was correctly identified by paleontologists after a long period of time. It was discovered in Mongolia in 1970 that this feathered theropod had enormous forelimbs. Dinosaurs like Deinocheirus were not formally classified as ornithomimids until 2014 (after additional fossils were discovered). 🐦
Its massive, clawed legs looked like a pair of Cretaceous scythes and it was at least three to four times larger than North American ornithomimids like Gallimimus and Ornithomimus.
9. The Riojasaurus is the largest prosauropod
Before giant sauropods like Apatosaurus and Diplodocus ruled the earth, there were prosauropods, small herbivores that were distantly related to these Late Jurassic Behemoths. In the late Triassic period more than 200 million years ago, Riojasaurus from South America was the largest prosauropod ever identified, measuring 30 feet (9 meters) long and weighing 10 tons.
In contrast to its massive descendants, the prosauropod Riojasaurus has a relatively short neck and tail.
10. The Quetzalcoatlus was the largest pterosaur ever discovered
A pterosaur’s wingspan, not its weight, determines its size: 34 feet (10.5 meters). Quetzalcoatlus weighed about 225 kilograms, but its massive wings probably allowed it to glide over long distances.
Paleontologists speculate that Quetzalcoatlus was not capable of flight and stalked its prey on two legs, similar to a land-based theropod. A long-extinct Aztec god, Quetzalcoatl was a feathered serpent, was the fitting name for this giant winged reptile.
11. The Sarcosuchus is the world's largest dinosaur crocodile
A 40 feet (12 meters) long crocodile weighing up to 15 tons, the Sarcosuchus was twice as long and ten times as heavy as any crocodile alive today. 🐊
However, Sarcosuchus lived a typical crocodile lifestyle despite its enormous size. Taking advantage of the African rivers of the Middle Cretaceous to hunt dinosaurs that got too close. Sarcosuchus may sometimes have mixed with Spinosaurus, another member of this list.
12. The Titanoboa was the largest dinosaur snake
Titanoboa was to contemporary snakes what Sarcosuchus was to contemporary crocodiles. 60 to 70 million years ago, in its lush habitat, this huge ancestor terrorized small birds, mammals, and reptiles. 🐍
Early Paleocene South America was home to Titanoboa, a 50 feet (15 meters) long, nearly a ton predator. Only about five million years after dinosaurs became extinct, it was home to an impressive number of giant reptiles (including Carbonemys, one-ton prehistoric turtles).
13. The Archelon was the largest dinosaur turtle.
To put the Archelon in perspective, the largest chelonian living today is the leatherback turtle specimen, which can measure up to five feet from tail to head and weighs about 1000 pounds (450 kilograms). Archelon, a Late Cretaceous dinosaur, measured about 10 feet long and weighed about two tons. 🐢
The weight was not only four times that of a leatherback turtle, but also eight times that of a Galapagos tortoise, or twice that of a VW Beetle! A giant turtle fossil was found in Wyoming and South Dakota, which were submerged under the Western Interior Sea 75 million years ago.
14. The Shastasaurus, the largest ichthyosaur
During the Triassic and Jurassic periods, Ichthyosaurs dominated the oceans as large dolphin-like marine reptiles. It was thought that Shonisaurus was the largest ichthyosaur until the discovery of an oversized Shonisaurus specimen (75 tons) led to the creation of the new genus Shastasaurus (from Mount Shasta in California).
In spite of its size, Shastasaurus survived not with comparable fish and marine reptiles, but with soft-bodied cephalopods and other small marine creatures (akin to the plankton-filtering blue whales that currently populate the world’s oceans). 🐋
15. The Kronosaurus, the largest Pliosaurus
Cronos, the mythical Greek god who ate his own children, inspired the name Kronosaurus. It was a fearsome pliosaur, a family of marine reptiles with squat torsos, thick heads protruding from short necks, and long, ungainly fins that ruled the mid-Cretaceous seas, eating almost anything (fish, sharks, other marine reptiles). 🦈
Liopleurodon was once thought to be bigger than Kronosaurus, but it now appears to have been about the same size as this marine reptile. The Kronosaurus weighed seven tons.
16. The Elasmosaurus was the largest Plesiosaurus
When it comes to plesiosaurs, a group of marine reptiles with slender trunks, long necks, and streamlined fins, Elasmosaurus emerges as the most imposing. Kronosaurus was the largest identified pliosaur of the Cretaceous period.
It measured about 45 feet (13.7 meters) from head to tail and weighed two to three tons. Fish and squid were its primary prey, not marine reptiles of comparable size. During the Bone Wars between Edward Drinker Cope and Othniel C. Marsh in the 19th century, Elasmosaurus played a prominent role. 🦴
17. The Mosasaurus is the largest member of the Mosasauridae
The ichthyosaurs, pliosaurs and plesiosaurs were either extinct or close to extinction at the end of the Cretaceous, 65 million years ago. Marine reptiles called Mosasauridae dominated the world’s oceans, eating everything from fish to lobster.
Mosasaurus was the biggest and fiercest of all Mosasauridae, measuring 50 feet (15 meters) long and 15 tons in weight. There were only slightly less enormous sharks that could compete with Mosasaurus and its ilk. The cartilaginous killers ascended the underwater food chain once marine reptiles died out due to K/T extinction.
18. Among the Archosaurians, Smok was the largest
During the Early to Middle Triassic period, archosaurs were dominant land reptiles. They evolved not only into dinosaurs, but also into pterosaurs and crocodiles. Smok, a dinosaur-like predator that of nearly a ton, was the exception that proved the rule: most archosaurs weighed only 50 pounds.
Paleontologists are unable to explain Smok’s existence in late Triassic Europe because it was so large and so obvious that it was not a dinosaur. Additional fossil evidence will be needed to confirm Smok’s existence. 👨🔬
19. The Moschops is the largest therapsid
255 million years ago, Moschops roamed the plains of southern Africa in herds, and it could be considered the “cow” of the late Permian. 2000 pounds was the maximum weight of the largest dinosaurs in this genus.
Therapsids are the first mammals, having evolved from reptiles tens of millions of years later. Here’s a little quiz to share with your friends: Moschops starred in a children’s show in 1983 where the main character shared a cave with Diplodocus and Allosaurus (somewhat inappropriately). 🦕
20. The Cotylorhynchus is the largest Pelycosaurus
The Dimetrodon, a Permian four-legged, small-brained reptile often mistaken for a dinosaur, is the most famous pelycosaur of all time. The 500 pounds Dimetrodon, however, is nothing compared to Cotylorhynchus, One of the lesser-known pelycosaurs that could weight up to two tons (but lacked the distinctive dorsal sail that makes the Dimetrodon famous).
The Dimetrodon, the Cotylorhynchus, and all their cousins pelycosaurs went extinct 250 million years ago; the only remaining distant reptiles are the sea turtles and land turtles. 🐢