The 20 Largest Prehistoric Animals in History

Argentinosaurus is one of the heaviest land animals ever recorded, measuring about 30 to 35 meters long and weighing between 70 and 80 metric tons. It lived 94 to 97 million years ago in the floodplains of South America. Previous estimates of 110 metric tons have been revised downward based on biomechanical studies.

At first glance, its length seems normal for a whale, measuring nearly 17 to 20 meters. What is surprising is its weight. Revised estimates place it between 66 and 77 short metric tons, due to the extreme density of its bones. Living 39 million years ago, it fed in shallow waters.

Based on nearly 70% of the skeleton, scientists were able to estimate with certainty that the body measured up to 37 meters and weighed between 55 and 85 metric tons. These dinosaurs roamed the floodplains of Patagonia about 101 million years ago. The discovery of several individuals together suggests that herds moved across open terrain.

Its migration from South America likely explains its arrival in the river valleys of what is now Texas and New Mexico about 70 million years ago. As an adult, it measured nearly 26 meters in length and weighed between 30 and 35 metric tons. Some fragmentary remains suggest that certain individuals rivaled the largest titanosaurs ever known.

The fossils show a giant that was still growing. Measuring about 26 meters long and weighing between 42 and 54 metric tons, this dinosaur lived 84 million years ago in humid forests. Bone histology reveals that it gained nearly one metric ton per year during adolescence. Adults could reach 54 metric tons.

Only a few bones of Puertasaurus Reuili have survived, but they are enormous. The vertebrae alone suggest a length of nearly 30 meters and a weight of between 50 and 80 short metric tons. This broad-bodied titanosaur roamed the coastal plains about 70 million years ago.

Foot bones the size of a bathtub speak volumes. Its weight is estimated at between 44 and 66 short metric tons, with a length of about 25 to 30 meters. The open forests of Argentina were home to this animal 86 million years ago. The structure of its limbs effectively distributed its weight, making it one of the heaviest titanosaurs identified to date.

Long before whales came to dominate the oceans, this marine reptile reigned supreme. Measuring about 21 meters and weighing perhaps 88 metric tons, it roamed the ocean depths about 220 million years ago. Complete skeletons allow for a precise estimate of its size. Appearing shortly after the Permian extinction, it marked the first major leap toward marine gigantism.

Based on the size of their teeth, their length is estimated to have been between 15 and 18 meters, and their weight between 55 and 77 metric tons. This shark ruled the world’s oceans between 23 and 3.6 million years ago. Hydrodynamic constraints have refined the initial estimates. Its extinction permanently reshaped marine food webs.

Leedsichthys problematicus was between 10 and 16 meters long and weighed between 30 and 45 metric tons. It was a Jurassic-era fish that swam in shallow seas about 165 million years ago. Its lightweight skeleton allowed it to feed on plankton on a massive scale. The reconstruction of its fins finally put an end to decades of disagreement over its actual size.

Early paleontologists believed it was a reptile. It measured between 15 and 18 meters and weighed between 11 and 17 metric tons. This whale swam in the warm seas near North America and Egypt. Its serpentine body allowed it to hunt by lying in wait, and its revised weight estimates take into account its vestigial limbs, which were once mistaken for legs. Its age? 40 million years.

This predator is characterized by its massive teeth—some of which reach 35 cm in length—and its body, which is approximately 13 to 18 meters long and weighs about 55 metric tons. Off the coast of Peru, whaling reached its peak about 9 to 10 million years ago. The scale of the skull supports consistent estimates. Competition with the Megalodon likely shaped oceanic dominance during the Miocene.

This prehistoric animal stood about 4.2 to 4.5 meters at the withers and weighed between 14 and 21 metric tons. These elephants dominated Asia between 2 million and 24,000 years ago. The Indian specimens were the largest. Some recent discoveries suggest slightly smaller average sizes, but few land mammals have surpassed them.

Standing nearly 5 meters tall, this hornless rhinoceros grazed on the treetops of the Asian steppes approximately 34 to 23 million years ago. Its weight is now estimated to be between 17 and 22 metric tons, correcting previous exaggerations. Its long neck allowed it to fulfill the role of a giraffe.

River systems shaped this 99-million-year-old predator, which grew to 14 to 15 meters in length. Weighing about 7.3 metric tons, it hunted fish in North Africa. New tail fossils have allowed scientists to revise its estimated weight upward and confirm its semi-aquatic lifestyle. Its lifestyle set it apart from terrestrial theropods.

This mammoth stood about 4.5 meters tall and weighed between 15 and 17 metric tons. It lived on the Eurasian steppes between 800,000 and 200,000 years ago. The size of its tusks and bones confirms its size. Genetic evidence links it directly to woolly mammoths, including during periods of interbreeding that occurred during the climate changes of the Ice Age.

Weighing between 13 and 15 metric tons and standing about 4 meters tall, this proboscidean lived in Europe and Africa between 10 million and 1 million years ago. Fossils of its skull and limbs allow for an accurate estimate of its size. Its feeding strategy and skeletal structure were adapted for foraging for roots.

The size of this massive creature varied depending on its age. Adults reached lengths of 12 to 13 meters and weighed between 7 and 9 metric tons, roaming the plains of Argentina. Brain scans suggest coordinated hunting behavior, likely targeting sauropods. Early estimates exaggerated its size, but mature individuals were still nearly as large as the Tyrannosaurus. It lived about 98 million years ago.

Few dinosaurs have such precise measurements. Well-preserved fossils show that adults reached lengths of 12 to 13 meters and weighed between 7 and 9.8 metric tons. The “Scotty” specimen weighed about 9.7 metric tons. The ecosystems of the late Cretaceous period, about 68 million years ago, supported rapid growth, with juveniles doubling their body mass each year.

In South America, it thrived between 2 million and 8,000 years ago. This giant sloth was about 6 meters long and weighed between 3.7 and 4 metric tons. Its advantage lay in its ability to graze while standing, which broadened its dietary options, and in its 30-centimeter claws, which it used for digging and self-defense.