What's the Largest Land Animal That Ever Existed on Earth?

To determine the largest animal ever (stipulating that it was the largest land animal), we have to venture back to the age of the largest dinosaurs — specifically the preposterously proportioned titanosaur clade of giant sauropods, which lived over 66 million years ago.

But which among these long-necked, long-tailed quadrupeds was truly the largest?

As you might expect, it's here we confront the inherent incompleteness of the fossil record. Just because a scale-busting sauropod existed, it doesn't mean it managed to die in just the right circumstances to wind up fossilized, much less discovered by a paleontologist and cast opposite Chris Pratt in a Hollywood blockbuster.

Although we have fossil evidence of a gigantic dinosaur, we don't necessarily have enough to accurately calculate body mass or height. In many cases, some potential contenders exist only as a few bones today, complicating the story.

1. Amphicoelias fragillimus

Amphicoelias fragillimus might have stretched an astonishing 190 feet (58 meters) from nose to tail, but the single incomplete fossil specimen emerged in the tumultuous world of late-19th-century bone-hunters and has been lost for decades. All we have now are sketches.

2. Artgentinosaurus

Proponents of Argentinosaurus have championed this estimated 77-ton (78,235-kilogram) sauropod as the largest dinosaur, but it all depends on a mere half-dozen fossilized vertebrae.

3. Dreadnoughtus schrani

In 2014, Drexel University paleontologists made a discovery that makes one of the strongest cases for the largest land animal of all time. A 70-percent-complete fossilized skeleton of the sauropod has been assembled, which estimates suggest would have been 85 feet (26 meters) and 65 tons (59 metric tonnes). Fittingly named after a type of early-20th-century battleship, Dreadnoughtus schrani would have boasted a body the size of a house and mass equal to an entire elephant herd.

As noted, the fossil record gives us a few species of well-documented titans and a slew of closely related contenders with varying levels of fossil completeness.

For instance, the ambitiously named Ultrasaurus emerged from a 1979 fossil dig in South Korea, but later proved to be chimeric — that is, mistakenly assembled from disparate fossil specimens.

While the land animals of the distant past put all modern species to shame, size-wise, its a different story for sea creatures. Indeed, the blue whale is the largest animal that has ever existed, and, luckily for us, it still exists today (although it is endangered).

An adult blue whale can reach 75 feet (23 meters) to 100 feet (30.5 meters) from head to tail, and can weigh as much as 150 tons (136 metric tonnes). Female blue whales are actually larger than males, and the largest specimen ever recorded was 98 feet (29.9 meters) in length and weighed 219.4 tons (199 metric tonnes).

It's pretty cool that you can see the blue whale sculpture hanging in the Museum of Natural History in New York and know that such majestic creatures share the planet with us.

You might've heard whispers that a large, prehistoric sea creature rivaled the blue whale for sheer size, and there's some truth to that idea. It's been suggested that one or more shastasaurus ichthyosaur (an extinct group of sea dinosaurs) was as big or bigger, but as of now, this is unconfirmed — and according to many scientists, unlikely.

When it comes to largest animals that are also mammals, a handful of contenders arise from the eons of yore. Back in the Oligocene epoch, the Paraceratherium was a long-necked, hornless rhino that weighed as much as three of the current record holder — that would be the African elephant (Loxodonta spp).

This massive animal boasted a formidable 16- to 18-foot (5- to 5.4-meter) shoulder height already challenging the full 20-foot (6-meter) stature of the tallest giraffe.