The 10 Ugliest Dinosaurs

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These 10 Dinosaurs Could Crack a Mesozoic Mirror

pegomastax
Pegomastax, one of the ugliest dinosaurs of the Mesozoic Era (Tyler Keillor).

As a whole, dinosaurs weren't the most attractive creatures ever to walk the earth--so it's no small thing to say that some theropods, sauropods and ornithopods were uglier than others. Not only were these dinosaurs afflicted by buck teeth, flabby thighs, and unsightly head growths, but it's not as if they had any recourse to spa vacations or plastic surgery. On the following slides, you'll discover the 10 dinosaurs most in need of a complete Mesozoic makeover. (Need to rest your eyes? Visit our list of the 10 cutest dinosaurs.)

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Balaur

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Balaur (Emily Willoughby).

With their slender, taut-sinewed legs and petite trunks, raptors were the ballerinas of the dinosaur family. That certainly wasn't the case for Balaur, the low center of gravity and well-muscled thighs of which made it the Cretaceous version of an excessively trained Olympic gymnast--think Nadia Comaneci on steroids. Why was Balaur such an ugly duckling, raptor-wise? You can blame this dinosaur's island habitat; animals isolated from the mainstream of evolution tend to develop some very strange physiques.

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Brontomerus

brontomerus
Brontomerus (Getty Images).

What Balaur (previous slide) was to raptors, Brontomerus was to the family of giant, quadrupedal, plant-eating dinosaurs known as sauropods: a squat, inoffensive, stocky-legged, five-ton runt. (The name Brontomerus, by the way, is Greek for "thunder thighs".) Why did Brontomerus have such an unusual physique? Paleontologists speculate that this sauropod lived in exceptionally hilly terrain, and evolved its well-muscled legs in order to climb steep gradients.

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Hippodraco

hippodraco
Hippodraco (Lukas Panzarin).

Its name conjures up some weird medieval chimera: Hippodraco, the "horse dragon." But you'll be disappointed to learn that this evocatively named dinosaur looked nothing like a horse, and certainly nothing like a dragon. Sporting the classic body plan of its more famous contemporary Iguanodon, only to a more exaggerated degree, Hippodraco had a small, unattractive head, a bloated trunk, and a run-of-the-mill tail. Not for nothing are ornithopods often compared to wildebeest, the "box lunches of the Serengeti."

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Isisaurus

isisaurus
Isisaurus (Dmitri Bogdanov).

Isisaurus--aka the Indian Statistical Institute Lizard--is one of the few titanosaurs ever to be discovered on the subcontinent, and it's an odd duck indeed. To judge by this plant-eater's exceptionally long neck, huge, well-muscled front legs and stunted hint legs, it must have looked like a giant, hairless, tiny-brained hyena. And if you're a faithful viewer of PBS nature documentaries, you already know that hyenas aren't exactly the Ashton Kutchers of the animal kingdom.

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Jeyawati

jeyawati
Jeyawati (Lukas Panzarin).

Yet another ornithopod of middle Cretaceous North America, Jeyawati was cursed not only by its membership in this uncommonly homely family of dinosaurs, but by the unwelcome addition of a wrinkly gullet and two distinctly unattractive ridges around its beady little eyes. This dinosaur's name, Zuni Indian for "grinding mouth," refers to the numerous teeth it used to chew tough vegetables; the only thing worse than watching this ornithopod from afar must have been watching it eat up close.

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Masiakasaurus

masiaksaurus
Masiaksaurus (Lukas Panzarin).

Sadly, orthodontists were scarce on the ground during the late Cretaceous period. No dinosaur was more in need of a good set of braces than Masiakasaurus, the front teeth of which angled out prominently from the end of its snout (and were probably used to snag fish from the rivers of Madagascar). Depending on your taste in rock stars, your assessment of this dinosaur's looks may or may not be affected by the fact that its species name (Masiakasaurus knopflerii) pays tribute to Dire Straits guitarist Mark Knopfler.

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Nigersaurus

nigersaurus
Nigersaurus (Australian Museum).

If the next Land Before Time sequel is in need a dopey-looking dinosaur, Nigersaurus fits the Cretaceous bill perfectly. This sauropod was oddly proportioned to begin with (witness its shorter-than-usual neck), but what really set it apart was its vacuum-cleaner-like snout, packed with hundreds of teeth arranged in dozens of separate columns. The dental apparatus of Nigersaurus was very similar to that of its distant ornithopod cousins--and if you've already read this far, you know that ornithopods weren't exactly the Angelina Jolies of the Mesozoic Era.

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Pegomastax

pegomastax
Pegomastax (Tyler Keillor).

Its name, riddled with plosives like "p," "g" and "x", is a harbinger in itself. Announced to the world in 2012, Pegomastax may have been the ugliest ornithopod that ever lived (and judging by the other genera on this list, including Hippodraco, Jeyawati and Tianyulong, that's quite a distinction). Not only was the weirdly beaked Pegomastax ("thick jaw") equipped with two prominent fangs, but its entire body was covered with bristles; mercifully, this hideous dinosaur only measured about two feet from head to tail.

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Suzhousaurus

suzhousaurus
Suzhousaurus (Wikimedia Commons).

As a group, therizinosaurs were endearingly gangly, their long beaks, pot bellies, and oversized hands making them seem as harmless as Big Bird. Suzhousaurus was the exception that proved the rule: this therizinosaur may have looked more like a vulture than an oversized canary, with an ominously bald neck and head and a thickly muscled (rather than cutely feathered) torso. Of course, Suzhousaurus' appeal depends on which paleo-artist happens to be depicting it; for all we know this dinosaur was as cuddly as Yogi Bear!

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Tianyulong

tianyulong
Tianyulong (Nobu Tamura).

What is it with ornithopods, anyway? The fourth such plant-eating dinosaur on this list, Tianyulong was a) certainly the smallest and b) arguably the ugliest. Tianyulong seems to have been covered with sharp, bristly proto-feathers, making it only the second identified non-theropod dinosaur (along with the previously listed Pegomastax) to be so adorned. Picture a feathered cat, or a furry parrot, and you can understand why Tianyulong and its ilk won't be starring in any Jurassic Park sequels anytime soon.