MASSIVE CLAWS
The therizinosaurs represent one of the weirdest lineages in dinosaur evolution. Therizinosaurs were theropods, belonging to the line of bipedal, meat-eating dinosaurs that included Tyrannosaurus. But therizinosaurs were plant eaters. Instead of the curved, blade-like teeth of most theropods, therizinosaurs had small, leaf-shaped teeth well-suited for cropping plants. They also developed huge, pot-bellied guts that would have processed the plant material they ate. Therizinosaurus is the largest therizinosaur, measuring 33 feet in length, and it featured a long neck, long arms, and truly enormous claws on its hands. Its claws are the largest known in the animal world, measuring an incredible three feet long. Despite their wow-factor, we're not quite sure why it had these huge claws. They may have helped it to pull down tree branches to reach leaves. It's also possible that, in addition to plants, Therizinosaurus ate insects and used its large claws to rip open termite mounds or insect nests.

But as weird as it was, Therizinosaurus wasn't the strangest dinosaur in Late Cretaceous Asia. That honor belongs to an animal that represented a huge scientific mystery for nearly 50 years.

THE STRANGEST DINOSAUR
If you were to take pieces from all the dinosaurs that ever existed, mix them up in a bag, and randomly pull out one piece at a time to construct a dinosaur, you probably wouldn't come up with something weirder than Deinocheirus. For over 50 years, Deinocheirus was an enigma that was only known from its 8-foot-long arms and hands. Then in 2013 came the announcement that two new specimens had been discovered. Finally, the entire picture of Deinocheirus was complete. And what a picture it turned out to be! Deinocheirus is an ornithomimid, the group of "ostrich dinosaurs" that includes Gallimimus and Struthiomimus, but its physiology is wildly different from any other ornithomimid found to date. First off, it's huge--36 feet long. That's tyrannosaur size! And it sports a large hump or sail on its back. Finally, unlike the short skulls of most ornithomimids, Deinocheirus had an extremely long skull, more than 3 feet in length, and it ended in a broad, spoonbill-like beak. Evolution produced a lot of weird dinosaurs, but in Deinocheirus it created arguably the weirdest of them all.

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Excerpted from The Amazing World of Dinosaurs: An Illustrated Journey Through the Mesozoic Era by James Kuether
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