Science

There’s been an ongoing dispute over what was the world’s largest carnivorous dinosaur.

Calculating a dinosaur’s weight is not an exact science, and some research has suggested that estimates of extinct animals’ mass have been vastly overestimated: when applied to living animals like elephants, these methods (basing weight off of specimen length, bone length/density, etc.) have proved inaccurate.

Conversely, the weight of dinosaurs such as T. Rex, who was recently found to have grown far more quickly during its teenage years, may have been underestimated.

So rest assured, as new specimens are discovered and new models developed, the debate will continue. The following list is based on mass estimates taken from Dinoanimals.com.

10. TARBOSAURUS — This six-ton cousin of the North American Tyrannosaurus Rex was first discovered in China’s Gobi Desert. The largest specimen found in a 70-million-year-old rock foundation in Mongolia measured 40 feet in length. The Apex predator differentiates from T. Rex due to its smaller arms and skull shape, though there’s still some controversy over whether or not Tarbosaurus was its own dinosaur or a Tyrannosaurus Rex.

9. ACROCANTHOSAURUS– This “high-spined lizard” (English translation) weighed up to seven tons and prowled North America 105-155 million years ago. Measuring 36 feet in length, the first remains of Acrocanthosaurus were discovered in 1940 in Oklahoma, with other fossils and tracks subsequently found in Texas, Utah, and Arizona. While it’s unclear what purpose the high-spine “sail” of the “Acro” may have served, some theories believe it may have been a defensive mechanism to appear larger or to regulate body temperature. The dinosaur also had very small feet for a creature its size, perhaps due to the dry climate it walked in.

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8. OXALAIA QUILOMBENSIS –– The largest Spinosaur (more on them later) to be found in South America, this dinosaur spent part of its time in the water, munching on fish with its huge, crocodile-like jaws. Not much is known about Oxalaia quilombensis, as all researchers currently have are skull fragments dating back 95 million years ago. From these two fragments, the dinosaur is calculated to have weighed up to almost eight tons.

7. DEINOCHEIRUS — For decades, all researchers had of this Omnivorous giant theropod was a pair of eight-foot-long limbs bearing eight-inch claws. The arms were discovered in the Gobi Desert back in 1965, inspiring scientists to dub the creature it came from Deinocheirus mirificus (Greek translation: “Terrible Hands”). Fast forward to 2014 when two complete specimens are assembled with newly discovered (and recovered, as bones that had been poached resurfaced) parts- finally giving us more insight into the ostrich-like ornithomimosaur, which at 33 feet long, 16 feet high, and up to over nine tons was no slouch in the size department. With its long bill, sharp teeth and claws, Deinocheirus fed on plants, fish, and more than likely any other small creature that crossed its path. It also had a thick, spiny sail-like backbone, giving it an even more unique look. Deinocheirus prowled Asia from 100.5 million years ago to right about the time the comet that wiped out the dinosaurs hit what is now Mexico.

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6. BAHARIASAURUS — First described by famed paleontologist Ernst Stromer in 1934, Bahariasaurus was a four to nine-and-a-half ton theropod (ancestrally carnivorous dinosaurs with hollow bones and three-toed legs and arms) that prowled the jungles of Africa 95 million years ago. Similar in its general look to the T. Rex, Bahariasaurus could measure up to 16 feet high and 40 feet long, with little spines that cropped up on its head and back. The only bones of the dinosaur (originally found in Egypt) were kept in a Munich museum that was unfortunately destroyed by Allied bombs during World War II. New Baharariasaurus remains have yet to be found.

5. TYRANNOSAURUS REX — In 1991, researchers in Canada discovered the bones of the largest T. Rex ever. Dubbed “Scotty,” the specimen is calculated to have weighed nearly 10 tons and measured 42 feet in length. Scotty lived 66 million years ago on Canada’s then-subtropical coast and bore a broken rib, infected jaw, and a bite from another T. Rex on its tail. Perhaps the most famous dinosaur of all time, T. Rex’s place on this list has often been disputed by researchers, with some believing the dinosaur to be the largest of all time.

4. GIGANOTOSAURUS — According to LiveScience, Giganotosaurus was once thought to be the largest meat-eater of all back when it was first discovered in the mid-’90s, though larger specimens of other dinosaurs have since been found. Weighing in at over 14 tons, the first specimen found in Southern Argentina measured 41 feet from head to tail, with its skull over five feet long. A study from 2001 done with a model suggested that Giganotosaurus couldn’t chase its prey over 31.3 mph or else it would lose its balance, so as long as you’re in your car and not in a school zone when you meet one, you should be fine.

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3) CARCHARODONTOSAURUS SAHARICUS (15 tons) and 2) CARCHARODONTOSAURUS IGUIDENSIS (over 15 tons) — First described by Ernst Stromer in 1931, this 45 foot-long theropod prowled what is now North Africa between 145 and 72 million years ago. Its teeth were serrated to slice into flesh just like the Great White Sharks of today, inspiring scientists to name its family Carcharodontosauridae (translation: shark-toothed lizard). Researchers calculate that Carcharodontosaurus saharicus weighed up to 15 tons, putting it at number three on this list. Like the bones of Bahariasaurus and the first Spinosaurus, the Carcharodontosaurus specimen described by Stromer was destroyed in the Allied forces’ 1944 bombing of Munich, though the remains of the even larger Carcharodontosaurus iguidensis (later described by Dr. Steve Brusatte) were found in 1997.

1) SPINOSAURUS–The largest dinosaur on this list and the only one to have spent more than half its time in the water, Spinosaurus measured 50 feet in length and is believed to have weighed up to a massive 22 tons— roughly equal to the anchor of a cruise ship. First described by paleontologist extraordinaire Ernst Stromer in 1915, Spinosaurus (“spined lizard”) had 7-foot-long spines that grew out of its back, forming a fin. Researchers also believe Spinosaurus was the first dinosaur that could swim, spending more time in the water than on land. While prowling the North African swamps 97 million years ago, the dinosaur survived on a diet of fish that it chomped up in its long, razor-toothed snout.

So Spinosaurus was the heaviest meat-eating dinosaur of all time. Or was it? Fox News asked paleontologist Dr. Steve Brusatte from the University of Bristol in the U.K. to weigh in on the matter.

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“There’s perpetual debate over the biggest meat-eating dinosaurs, because several species seem to reach about the same size, but many of them are known from very limited fossils,” he told Fox News. “It seems like T. rex, Carcharodontosaurus, Giganotosaurus, and some other species all got to be about 40-45 feet long, so in that sense they were the same general size, but T. rex has the biggest, thickest bones, indicative of a robust, muscular body, so it probably weighed more than these other giants. So for my money, T. rex is still the biggest purely meat-eating dinosaur that we know of, and the biggest pure carnivore that we know of that’s ever lived on the land.”

But what about Spinosaurus?

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“Spinosaurus throws a bit of a wrench into this, as it was a theropod, and it was probably bigger than T. rex, although its fossils are so scrappy that we don’t have anywhere near a complete skeleton to measure,” Brusatte explained. “But even so, Spinosaurus had a taste for fish and lived at the interface of the water and the land, so it was a semiaquatic hunter-slash-fisher, whereas T. rex was a fully land-living animal. Regardless of all of the facts and figures though, there’s one thing I’m pretty sure about: if I was around in the Mesozoic and could pick a single dinosaur to avoid at all costs, I would go with T. rex, [as] it was the biggest, baddest, smartest giant predatory dinosaur that ever lived.”