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HolidayBuyer's Guide

You wish these weird animals were still alive

Mammoths might've produced 400 pounds of poop a day!

Armadillos were 'the size of a Volkswagen Beetle'!

Whales had legs! And looked like rat-dogs!

Unicorns were totally real, man!

Triceratops 'danced like birds'

Crocodiles were 'almost the size of a bus'!

This ancient bug had its own Baby Bjorn!

The Tully monster was no monster

Global warming made horses teeny-tiny!

Prehistoric dogs were pampered, except when they were dinner

The biggest bear was disturbingly big

Size totally mattered for the dimetrodon!

Blinged-out dinos ruled!

Girl dinosaurs were indistinguishable from boy dinosaurs!

Oh, ancient Earth, your animal kingdom was wonderfully weird.

Take the kangaroo. More than 30,000 years ago, a forerunner of our modern-day hippity-hopping mammal probably didn't hop at all, researchers say; it was just too bulky. Instead, the quarter-ton "short-faced giant kangaroo" loped around on two legs.

Here are 13 other cool facts about prehistoric animals, both great and shrunken.

Caption by / Photo by Brian Regal/Brown University

Since the Ice Age favorites were roughly the size of today's African elephants, the logic follows that mammoths were the equals of elephants in the eating and waste-elimination departments.

Caption by / Photo by Shutterstock/Digital Storm

Today, the giant armadillo tops out at about 5 feet long and 70 pounds. Four million years ago, the glyptodent, a presumed forerunner of the armored mammal, was as big as a compact car.

Caption by / Photo by Carl Buell

You'd have to look closely, very closely, at the skeleton of a 50-million-year-old Pakicetus to understand why it's called the "first whale." The furry, four-legged, land-lubber sported "an ear bone with a feature unique to whales," per the American Museum of Natural History.

Caption by / Photo by Nobu Tamura/Wikipedia

A recent fossil find shows that the one-horned Elasmotherium sibiricum, a rhino known as the Siberian unicorn, was among us as recently as 29,000 years ago. Previously, scientists thought the beast had gone extinct 350,000 years ago.

Caption by / Photo by Stanton F. Fink/Wikipedia

Since theropod dinosaurs, like the triceratops and Tyrannosaurus rex, are presumed ancestors of the modern-day bird, they "more than likely" shared the latter's affinity for mating dances, paleontologist Jack Horner told National Geographic.

Caption by / Photo by David Roland/Shutterstock

A recently uncovered 30-foot-long, 6,000-pound Machimosaurus rex "definitely was at the top of the food chain" of ancient Tunisia, scientists say. It especially liked to snack on turtles.

Caption by / Photo by Davide Bonadonna/Facebook

Some 430 million years ago, the Aquilonifer spinosus "carried its young in capsules tethered to the parent's body like tiny, swirling kites," per a research summary from Yale University.

Scientists nicknamed the arthropod "The Kite Runner."

Caption by / Photo by Derek Briggs, Derek Siveter, David Siveter, Mark Sutton, David Legg/Yale University

For decades, scientists could not figure out what the Tully monster was exactly. A worm? A fish? An arm with teeth on the end? Finally, researchers cracked the case: The Tully "monster" was a 300-million-year-old vertebrate...and forerunner of the lamprey.

Caption by / Photo by Sean McMahon/Yale University

Actually, scientists say all sorts of mammals got smaller during two heat-up periods 53 to 55 million years ago. The hyracotherium, an early horse, saw its dog-size frame shrink by 19 percent and then another 30 percent.

Caption by / Photo by Danielle Byerly/University of Florida

A dog graveyard in Siberia, possibly 8,000 years old at the time of its discovery, showed that back in the day, humans ate pooches, ritually killed pooches...and occasionally kept them as treasured little fuzzy-wuzzies.

Caption by / Photo by Jellis Vaes/Shutterstock

Eleven feet tall. Some 3,500 pounds. No, you wouldn't have wanted to run into the plus-size Arctotherium angustidens, or short-faced bear, on an Argentinian hiking trail 2 million years ago. (Wired assures us the bear wasn't "hypercarnivorous," but still...)

Caption by / Photo by Blaine Schubert, Leopoldo Soibelzon/Journal of Paleontolgy

This reptile of 250 million years ago sported a fan-like sail on its back. According to About.com's Bob Strauss, the larger the sail, the "more attractive" the male dimetrodon was to the female.

Caption by / Photo by David Roland/Shutterstock

Dinosaurs that sported bony crests or other ornamentation on their massive heads, such as the Allosaurus, got bigger faster than their plainer counterparts. "Something about their world clearly favored bling and big bods," North Carolina State University scientist Terry Gates says.

Caption by / Photo by Anton_Ivanov/Shutterstock

Now, we don't think the dinosaurs had trouble sorting themselves out. But human scientists have really struggled with gender-typing. That's why the recent find of a fossilized pregnant Tyrannosaurus rex has been hailed as a big deal.

Caption by / Photo by Mark Hallett/North Carolina State University
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