The 10 Most Important Dinosaurs You've Never Heard Of

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These Obscure Dinosaurs Are Every Bit as Important as T. Rex

Psittacosaurus, the distant ancestor of Triceratops. Wikimedia Commons

More often than you might think, the dinosaurs the public happens to latch onto--Apatosaurus, Velociraptor, Tyrannosaurus Rex, etc.--are less important to paleontologists than they are to journalists, fiction writers and movie producers. Here's a slideshow of 10 dinosaurs you've probably never heard of, but which have made substantial contributions to our knowledge of prehistoric life during the Mesozoic Era.

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Camarasaurus (Nobu Tamura).

Diplodocus and Apatosaurus (the dinosaur formerly known as Brontosaurus) get all the press, but the most common sauropod of late Jurassic North America was Camarasaurus. This long-necked plant-eater "only" weighed about 20 tons, compared to 50 tons or more for its more famous contemporaries, but it made up for its lack of heft by its pronounced social inclinations, roaming the plains of the American west 150 million years ago in vast herds (which have yielded an abundant number of fossils).

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Coelophysis (Nobu Tamura).

Perhaps because it's so difficult to spell (not to mention pronounce: SEE-low-FIE-sis), Coelophysis has been unjustly neglected by the popular media. The bones of this teenager-sized, late Triassic theropod have been dug up by the thousands in New Mexico, particularly at the famous Ghost Ranch quarry. Coelophysis was almost certainly a direct descendant of the very first dinosaurs, which evolved in South America about 15 million years before this big-eyed meat-eater appeared on the scene.

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The tail club of Euoplocephalus. Wikimedia Commons

Ankylosaurus is by far the most popular armored dinosaur, and one that has bestowed its name on its entire sluggish family--the ankylosaurs. As far as paleontologists are concerned, though, the most important ankylosaur was the hard-to-pronounce Euoplocephalus (YOU-oh-plo-SEFF-ah-luss), a low-slung, heavily armored plant eater that looked like the Cretaceous equivalent of the Batmobile. To date, over 40 near-complete Euoplocephalus fossils have been discovered in the American west, shedding valuable light on the behavior of these formidable dinosaurs.

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Hypacrosaurus, "almost the highest lizard". Sergey Krasovskiy

The name Hypacrosaurus means "almost the highest lizard," and that pretty much sums up this duck-billed dinosaur's fate: it has almost, but not quite, purchased a hold on the popular imagination. What makes Hypacrosaurus important is that the preserved nesting grounds of this dinosaur--complete with eggs, hatchlings and juveniles--have been explored in detail, giving paleontologists a valuable glimpse into dinosaur family life during the late Cretaceous period. (A close runner-up in this category is Maiasaura, another duckbill that has left abundant evidence of its social behavior.)

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The skull of Massospondylus. Massospondylus

Massospondylus (Greek for "large vertebrae") was the prototypical prosauropod: a breed of relatively petite plant-eating dinosaurs that were distantly ancestral to the huge sauropods and titanosaurs of the later Mesozoic Era (discussed in slide #2). The discovery of preserved Massospondylus nesting grounds in southern Africa has taught us a lot about this dinosaur's behavior: for instance, it's now believed that prosauropods were bipedal, occasionally omnivorous, and much more nimble than paleontologists had previously speculated.

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Psittacosaurus. Wikimedia Commons

Although Psittacosaurus wasn't the earliest ceratopsian--the family of horned, frilled dinosaurs typified by Triceratops--it's one of the best known among paleontologists, comprising about a dozen separate species dating to the early-to-middle Cretaceous period (about 120 to 100 million years ago). Compared its huge (and hugely popular) descendants, Psittacosaurus was a relatively tiny dinosaur, ranging in size from 50 to 200 pounds, and some species may have subsisted entirely on nuts; analysis of its fossils has shed valuable light on ceratopsian evolution.

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Saltasaurus (Alain Beneteau).

Discovered in the Salta region of Argentina a few decades ago, Saltasaurus presented a true enigma: a smallish, long-necked sauropod whose skin was covered by tough, bony armor (in fact, this dinosaur was at first mistaken for a specimen of Ankylosaurus!) Even more baffling, Saltasaurus lived during the late Cretaceous period, whereas the sauropods peaked in population almost 100 million years earlier, during the late Jurassic. So what were paleontologists dealing with? One of the first identified titanosaurs, a family of dinosaurs that had spread to every continent by the end of the Mesozoic Era.

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Shantungosaurus. Zhucheng Museum

Shantungosaurus is a true oddity: a late Cretaceous hadrosaur, or duck-billed dinosaur, that weighed as much as a medium-sized sauropod. Not only did Shantungosaurus tip the scales at 15 tons, but it was probably capable of running on two legs when pursued by predators, which would make it the largest bipedal terrestrial animal in the history of the planet. Shantungosaurus was also equipped with about 1,500 tiny teeth, with which it shredded copious amounts of vegetation. Despite all of its credentials, don't expect much of a reaction when you name-check Shantungosaurus to your poker buddies.

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Sinosauropteryx (Emily Willoughby).

Quick poll: how many of you have heard of Archaeopteryx, and how many of you have heard of Sinosauropteryx? You can put down your hands: Archaeopteryx may be famous as the first feathered proto-bird, but Sinosauropteryx, which lived about 20 million years later, was the genus that made feathered dinosaurs a household phrase around the world. The discovery of this toddler-sized theropod in China's Liaoning fossil beds caused a worldwide sensation, but Sinosauropteryx has since been eclipsed by even better-preserved tufted dinosaurs.

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Therizinosaurus. Wikimedia Commons

Considering how weird this dinosaur was--long, stringy feathers, two-foot-long claws, a prominent pot belly and an even more prominent beak--you'd think Therizinosaurus would be as familiar to schoolkids as Stegosaurus. Sadly, fame has eluded the "reaping lizard," which is also notable for being one of the few theropod dinosaurs to pursue an entirely herbivorous diet. One day, perhaps, a show called "Theodore the Therizinosaurus" will rectify this huge injustice in the historical record.