Bizarre Dinosaurs - Photo Gallery - National Geographic Magazine

Current Issue January 2009
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Extreme Dinosaurs

Fossil finds are revealing how evolution took some dinosaurs in bizarre directions, from domed skulls to sickle-shaped toenails.

/galleries/bcove/assets/e41b0fe4-de9c-4ba7-91f6-6c4555f4248e.jpg /galleries/bcove/assets/679f2d9d-4632-4794-8a9d-c8234b33e822.jpg AMARGASAURUS X-FACTOR: Double row of spines on neck and back WHEN: 130-125 million years ago WHERE: Argentina Like the tail fins on a 1959 Cadillac, a bizarre double row of spines extending from the vertebrae of Amargasaurus may have served little purpose other than to turn heads. Since the discovery of the sauropod was announced in 1991, paleontologists have pondered the function of the delicate bony rods, which would have offered limited defense at best against predators.]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1106366 /galleries/bcove/assets/900d202e-64fa-434e-9b7b-170b851e058b.jpg /galleries/bcove/assets/629c7222-dcb7-4fe5-a4d5-53c67ff64cc4.jpg AMARGASAURUS Spine fossil (Skull is a speculative cast). Perhaps the bony rods were covered with skin, forming sails similar to those on some living lizards. If so, Amargasaurus might have flushed blood into the sails to help cool its body. But their likely function, says Smithsonian paleontologist Hans-Dieter Sues, was to attract mates or intimidate rivals. “In evolution nothing is really bizarre. Every structure makes perfectly good sense to the organism. In the case of extinct animals the challenge is to identify what the purpose might have been.” ]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102485 /galleries/bcove/assets/03_biz-dino_CORR_gall.jpg /galleries/bcove/assets/ae938005-6991-435d-b91c-0db4176d9529.jpg CARNOTAURUS X-FACTOR: Bull horns, tiny arms WHEN: 82-67 million years ago WHERE: Argentina Consider the evolutionary hand dealt to Carnotaurus, or “meat-eating bull”: a big, bad, but seemingly underequipped predator, as if nature had set out to design a perfect killing machine but ran out of funding. Powerful jaws and long, agile legs suggest a highly mobile hunter prowling the lakeshores of what is now Patagonia. ]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1106367 /galleries/bcove/assets/77504e6a-cd42-49d4-8bce-2a5a7cc3dc6a.jpg /galleries/bcove/assets/22ca7707-a683-44de-acfb-6f618954330e.jpg CARNOTAURUS Skull fossil Its skull, constructed like a battering ram, features a stout pair of horns. Yet accompanying this formidable hardware are tiny arms (even more stunted than the famously puny arms of Tyrannosaurus rex) and surprisingly small teeth. Some scientists, like University of Chicago paleontologist Paul Sereno, envision Carnotaurus and its kin as dinosaurian hyenas—fleet of foot and short-snouted to track down and gnaw on carcasses. “Who needs arms for that?” he asks.]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102484 /galleries/bcove/assets/05_biz-dino_CORR_gall.jpg /galleries/bcove/assets/ff7f36ae-b0fe-4ec8-a98a-cfbfd9a6d8a1.jpg PARASAUROLOPHUS Skull fossil X-FACTOR: Trombone crest WHEN: 76 million years ago WHERE: North America The tubular bone sweeping back from a Parasaurolophus walkeri skull has inspired a variety of theories about its function. Weapon? Breathing tube? Hypersensitive nose? None of the above? Aided by computer modeling, scientists now think it was used to generate sounds like a trombone, though it also may have played a role in sexual display.]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102487 /galleries/bcove/assets/f51ce1e4-166d-4c6c-bded-d93755c75b0b.jpg /galleries/bcove/assets/91361fdb-8b09-41e2-9513-025520b2a03c.jpg MASIAKASAURUS X-FACTOR: Inscrutable teeth WHEN: 70-65 million years ago WHERE: Madagascar The mouth of Masiakasaurus speaks to how this German shepherd-size meat-eater survived in the river basins of northwestern Madagascar, near the end of the dinosaurs’ reign. But what is it saying?]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1106371 /galleries/bcove/assets/38e53811-3297-4ce6-a83d-d589893903ae.jpg /galleries/bcove/assets/11c62810-045e-45e9-a310-c2e0976bfd40.jpg MASIAKASAURUS Lower jaw fossil (larger than actual size) Stony Brook University paleontologist David Krause led the team that found the remains, including part of the lower jaw. Masiakasaurus has long, conical front teeth with hooked tips that curl out of its mouth—unique among theropods—while its back teeth are more typically blade-like and serrated. So how did it use such a specialized mouth? “Our best guess is the teeth up front were used to stab small prey, perhaps mammals, lizards, and/or birds,” says team member Scott Sampson of the University of Utah, “and the teeth at the rear of the jaw were then used to tear up the kill.” Despite its formidable dentition, Masiakasaurus was likely prey itself for crocs and other large carnivores, like the 20-foot-long (6 meters) theropod Majungasaurus, with which it shared territory. Against such monsters, its best defenses would have been speed and agility. ]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102491 /galleries/bcove/assets/090ca3ed-0fba-466e-9ecc-b6fd95810798.jpg /galleries/bcove/assets/8dcd51fc-9067-4557-a632-58339425d50c.jpg TUOJIANGOSAURUS X-FACTOR: Shoulder spikes WHEN: 161-155 million years ago WHERE: China With a thorny tail and rows of bony plates along its back, Tuojiangosaurus, like its better known cousin Stegosaurus, resembles a Jurassic tank. What grants this ponderous Chinese herbivore admission to the ranks of the truly bizarre, however, is the long, tapering spike thrusting out from each shoulder. ]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1106373 /galleries/bcove/assets/dd8834e2-fb31-4ac3-93ab-d6714b4fae4b.jpg /galleries/bcove/assets/f86538e4-4ba4-4028-b679-9b647d531573.jpg TUOJIANGOSAURUS Shoulder spike fossil “The shoulder spikes would have helped protect its vulnerable flanks, which would have been right at the level of an attacking allosaur,” says University of Maryland paleontologist Thomas Holtz. As for the plates on its back, their purpose is a matter of much debate, says Susannah Maidment, a paleontologist at Cambridge University. Early armored dinosaurs were covered with small scutes to protect against a predator’s bite, a trait passed on more or less unchanged to some of their descendants. But in others such as Tuojiangosaurus, the scutes gave way to plates along the backbone, which perhaps made the animal look bigger, but offered little protection. A large theropod, says Maidment, would have been able to chomp through them “like potato chips.”]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102488 /galleries/bcove/assets/11_biz-dino_CORR_gall.jpg /galleries/bcove/assets/7abedb57-3a1b-4956-988d-273c07f0b80f.jpg DEINOCHEIRUS X-FACTOR: Enormous arms, giant claws WHEN: 70 million years ago WHERE: Mongolia Anatomically, Deinocheirus's forearms and hands seem most similar to those of ornithomimids, a group of fleet-footed dinosaurs that resembled ostriches and used their arms for grasping prey. Yet when scientists try to estimate Deinocheirus's size based on a general ratio of arms-to-body size in this group, the calculations project a massive animal 40 feet (12 meters) long, putting it among the largest known theropods, such as Carcharodontosaurus. Or perhaps it’s a smaller dinosaur with outlandishly long arms (pictured above). “The body is a mystery,” says Thomas Holtz. “It might not be an ornithomimid at all. But then what is it?”]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1106368 /galleries/bcove/assets/10_biz-dino_CORR_gall.jpg /galleries/bcove/assets/7d81d939-2034-457a-8ef5-6795897e342c.jpg DEINOCHEIRUS Arm fossils Whose arms are these? The question has puzzled paleontologists for nearly four decades. Unearthed in Mongolia near an assortment of predatory dinosaur remains, the reconstructed limbs each measure eight feet (2.4 meters) long, tipped with ten-inch (26 centimeters) claws. But few other parts of the original find have ever been recovered. Paleontologists dubbed the creature Deinocheirus (“terrible hand”) and tried to match the bones with those of known species.]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102490 /galleries/bcove/assets/eb4cfe69-69c6-4068-85d8-2990a4182ce8.jpg /galleries/bcove/assets/8f4a3d40-dde0-4a2b-a7a7-85ae229b5fa1.jpg DRACOREX X-FACTOR: Spiky head and snout WHEN: 67-65 million years ago WHERE: North America Bristling with spikes and pointed knobs, the skull of a Dracorex looks like something forged in medieval legend. Yet the creature it belonged to probably resembled a flower-eating wild pig more than the fire-breathing “dragon king” its name implies. Found by amateur fossil hunters in the South Dakota part of the Hell Creek formation, Dracorex has been assigned by paleontologists Robert Bakker and Robert Sullivan to the plant-eating pachycephalosaur family. Many species in this group had thick domes atop their skulls, which, like a bighorn sheep’s horns, may have allowed them to use their heads as battering rams. Could Dracorex, with its relatively flat skull, also have been a headbanger? Why not? asks Bakker. He points to the giant forest hog of Africa, which uses a similarly flat skull and long muzzle to defend against predators and ram its rivals in violent clashes over mates. Endowed with flesh and skin, Dracorex stares out from this month's magazine cover.]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102483 /galleries/bcove/assets/17d8b5d9-a80c-41a7-9a7f-b2d4ef056c5d.jpg /galleries/bcove/assets/ab28f222-9939-47b1-894e-c71dc82645a9.jpg EPIDENDROSAURUS X-FACTOR: Tiny body, elongated finger WHEN: 160 million years ago WHERE: China At the diminutive end of the extreme dinosaur spectrum perches tiny Epidendrosaurus, a sparrow-size theropod with grossly oversize hands. Described in 2002 by paleontologists at the Chinese Academy of Sciences, it is the smallest known dinosaur, excluding birds, though scientists remain unsure whether the bones and impressions (next image), discovered in siltstone in Inner Mongolia, are those of an adult or a juvenile. ]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1106370 /galleries/bcove/assets/14_biz-dino_CORR_gall.jpg /galleries/bcove/assets/337a1562-d10b-4c87-9691-a12.jpg Epidendrosaurus might have had birdlike plumage. “But until we find more specimens, we can’t say.” ]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102489 /galleries/bcove/assets/15_biz-dino_CORR_gall.jpg /galleries/bcove/assets/15_biz dino_CORR_60.jpg STYRACOSAURUS X-FACTOR: Massive horned frill WHEN: 75 million years ago WHERE: North America Like an armor-laden knight, Styracosaurus would have cut an imposing figure on the forested river plains in what is now Alberta, Canada. Multiple individuals of these rhino-size herbivores have been identified in the same bone beds, suggesting they traveled in herds. Horned dinosaurs are a well-understood group, says Hans-Dieter Sues, and since Styracosaurus lived near the end of this lineage, we can trace the evolutionary paths that led to it. “Its ancestors began with a little bump over their nose and then developed a little bit of a frill at the back of the skull,” says Sues, “but Styracosaurus takes these traits to the top.” ]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1106372 /galleries/bcove/assets/1744f3ed-52d8-4fe5-a16a-5ad30980039d.jpg /galleries/bcove/assets/5b596d9f-4b37-41fe-bc4e-f81821584411.jpg STYRACOSAURUS Skull fossil The bump on the nose in ancestral species evolved into an enormous spike that would have given Styracosaurus a potent weapon to fight off predators and fend off rivals. Meanwhile, the skull frill enlarged and added a profusion of horns, which probably let other styracosaurs identify it from a distance. Some scientists have suggested blood pumped into the skin covering the frill could have caused it to change color, possibly to attract mates or to scare enemies. “These extreme traits just didn’t suddenly appear,” says Sues. “There were compelling reasons why they were selected and pushed down the evolutionary line.”]]> http://pictopia.com/perl/ptp/natgeo?photo_name=1102486