01 of 66 Meet the Sauropod Dinosaurs of the Mesozoic Era Sauroposeidon. Levi Bernardo Sauropods--the long-neck, long-tailed, elephant-legged dinosaurs of the Jurassic and Cretaceous periods--were some of the largest animals ever to walk the earth. On the following slides, you'll find pictures and detailed profiles of over 60 sauropods, ranging from A (Abrosaurus) to Z (Zby).

02 of 66 Abrosaurus Abrosaurus. Eduardo Camarga Name: Abrosaurus (Greek for "delicate lizard"); pronounced AB-roe-SORE-us Habitat: Woodlands of Asia Historical Period: Middle Jurassic (165-160 million years ago) Size and Weight: About 30 feet long and five tons Diet: Plants Distinguishing Characteristics: Moderate size; short, boxy skull Abrosaurus is one of those paleontological exceptions that prove the rule: most of the sauropods and titanosaurs of the Mesozoic Era fossilized without their skulls, which were easily detached from their bodies after death, but its preserved skull is all we know about this dinosaur. Abrosaurus was fairly small for a sauropod--"only" about 30 feet from head to tail and about five tons--but that can be explained by its middle Jurassic provenance, 10 or 15 million years before the truly gigantic sauropods of the late Jurassic period like Diplodocus and Brachiosaurus. This herbivore seems to have been most closely related to the slightly later (and much better-known) North American sauropod Camarasaurus.

03 of 66 Abydosaurus Abydosaurus. Nobu Tamura Name: Abydosaurus (Greek for "Abydos lizard"); pronounced ah-BUY-doe-SORE-us Habitat: Woodlands of North America Historical Period: Middle Cretaceous (105 million years ago) Size and Weight: About 50 feet long and 10-20 tons Diet: Plants Distinguishing Characteristics: Large size; long neck and tail Paleontologists are digging up new species of sauropods all the time, but what makes Abydosaurus special is that its fossil remains include one complete and three partial skulls, all of them found in a Utah quarry. In the vast majority of cases, sauropod skeletons are unearthed without their skulls--these giant creatures' small heads were only loosely attached to their necks, and thus easily detached (and kicked away by other dinosaurs) after their deaths. Another interesting fact about Abydosaurus is that all the fossils discovered so far have been of juveniles, which measured about 25 feet from head to tail--and paleontologists have speculated that full-grown adults would have been twice as long. (By the way, the name Abydosaurus refers to the sacred Egyptian city Abydos, reputed by legend to harbor the head of the Egyptian god Osiris.)

04 of 66 Amargasaurus Amargasaurus. Nobu Tamura Amargasaurus was the exception that proved the sauropod rule: this relatively slim plant-eater had a row of sharp spines lining its neck and back, the only sauropod known to have evolved such an imposing feature. See an in-depth profile of Amargasaurus

05 of 66 Amazonsaurus Amazonsaurus. Wikimedia Commons Name: Amazonsaurus (Greek for "Amazon lizard"); pronounced AM-ah-zon-SORE-us Habitat: Woodlands of South America Historical Period: Early Cretaceous (125-100 million years ago) Size and Weight: About 40 feet long and five tons Diet: Plants Distinguishing Characteristics: Moderate size; long neck and tail Perhaps because the rain jungle isn't a very congenial place for paleontological expeditions, very few dinosaurs have been discovered in Brazil's Amazon basin. To date, one of the only known genera is Amazonsaurus, a moderately sized, early Cretaceous sauropod that seems to have been related to the North American Diplodocus, and that is represented by very limited fossil remains. Amazonsaurus--and other "diplodocoid" sauropods like it--is noteworthy in that it was one of the last "basal" sauropods, which were eventually supplanted by the titanosaurs of the middle to late Cretaceous period.

06 of 66 Amphicoelias Amphicoelias. public domain To judge by its scattered fossil remains, Amphicoelias altus was an 80-foot-long, 50-ton plant eater very similar to the more famous Diplodocus; the confusion and competition among paleontologists pertain to the second named species of this sauropod, Amphicoelias fragilis. See an in-depth profile of Amphicoelias

07 of 66 Apatosaurus Apatosaurus. Vladimir Nikolov Long known as Brontosaurus ("thunder lizard"), this late Jurassic sauropod reverted back to Apatosaurus when it was discovered that the latter name had priority (that is, it had already been used to name a similar fossil specimen). See 10 Facts About Apatosaurus

08 of 66 Aragosaurus Aragosaurus. Sergio Perez Name: Aragosaurus (Greek for "Aragon lizard"); pronounced AH-rah-go-SORE-us Habitat: Woodlands of western Europe Historical Period: Early Cretaceous (140-120 million years ago) Size and Weight: About 60 feet long and 20-25 tons Diet: Plants Distinguishing Characteristics: Short head; longer hind than front limbs Sauropods (and the lightly armored titanosaurs that succeeded them) had a global distribution during the Jurassic and Cretaceous periods, so it was no surprise when paleontologists unearthed the partial remains of Aragosaurus in northern Spain a couple of decades ago. Dating from the early Cretaceous period, Aragosaurus was one of the last of the classic, giant sauropods before the advent of the titanosaurs, measuring about 60 feet from head to tail and weighing in the neighborhood of 20 to 25 tons. Its closest relative seems to have been Camarasaurus, one of the most common sauropods of late Jurassic North America. Recently, a team of scientists reexamined the "type fossil" of Aragosaurus and came to the conclusion that this plant-muncher may have dated to earlier in the Cretaceous period than previously believed, perhaps as far back as 140 million years ago. This is important for two reasons: first, very few dinosaur fossils have been traced to this part of the early Cretaceous, and second, it's possible that Aragosaurus (or a closely related dinosaur) may have been directly ancestral to the titanosaurs that later spread all over the earth.

09 of 66 Atlasaurus Atlasaurus. Nobu Tamura Name: Atlasaurus (Greek for "Atlas lizard"); pronounced AT-lah-SORE-us Habitat: Woodlands of Africa Historical Period: Middle Jurassic (165 million years ago) Size and Weight: About 50 feet long and 10-15 tons Diet: Plants Distinguishing Characteristics: Large size; relatively long legs Atlasaurus is only indirectly named after Atlas, the Titan of Greek myth who propped up the heavens on his back: this middle Jurassic sauropod was discovered in Morocco's Atlas Mountains, which were themselves named after the same legendary figure. The unusually long legs of Atlasaurus--longer than any other known genus of sauropod--point to its unmistakable kinship with the North American and Eurasian Brachiosaurus, of which it seems to have been a southern offshoot. Unusually for a sauropod, Atlasaurus is represented by a single, near-complete fossil specimen, including a good portion of the skull.

10 of 66 Astrodon Astrodon. Eduardo Camarga Name: Astrodon (Greek for "star tooth"); pronounced AS-tro-don Habitat: Woodlands of eastern North America Historical Period: Early-Middle Cretaceous (120-110 million years ago) Size and Weight: About 50 feet long and 20 tons Diet: Plants Distinguishing Characteristics: Large size; similarity to Brachiosaurus For an official state dinosaur (it was thus honored by Maryland in 1998), Astrodon has a fairly checkered provenance. This medium-sized sauropod was a close relative of the more famous Brachiosaurus, and it may or may not have been the same animal as Pleurocoelus, the current state dinosaur of Texas (which may itself soon lose its title to a more worthy candidate, the situation in the Lone Star State being in a state of flux). The importance of Astrodon is more historical than paleontological; two of its teeth were unearthed in Maryland way back in 1859, the first well-attested dinosaur discovery in that small state.

11 of 66 Australodocus Australodocus. Eduardo Camarga Name: Australodocus (Greek for "southern beam"); pronounced AW-stra-la-DOE-kuss Habitat: Woodlands of Africa Historical Period: Late Jurassic (150 million years ago) Size and Weight: About 50 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Large size; extremely long neck and tail The name Australodocus will prompt two associations in the mind of the average dinosaur fan, one true and one mistaken. The true one: yes, this sauropod was named in reference to the North American Diplodocus, to which it was closely related. The mistaken one: the "australo" in this dinosaur's name doesn't refer to Australia; rather, it's Greek for "southern," as in southern Africa. The limited remains of Australodocus were discovered in the same Tanzanian fossil beds that have yielded a number of other late Jurassic sauropods, including Giraffatitan (which may well have been a species of Brachiosaurus) and Janenschia.

12 of 66 Barapasaurus Barapasaurus. Dmitry Bogdanov Name: Barapasaurus (Greek for "big-legged lizard"); pronounced bah-RAP-oh-SORE-us Habitat: Plains of southern Asia Historical Period: Early-middle Jurassic (190-175 million years ago) Size and Weight: About 60 feet long and 20 tons Diet: Plants Distinguishing Characteristics: Long legs and neck; short, deep head Although its skeleton has yet to be completely reconstructed, scientists are fairly confident that Barapasaurus was among the earliest of the giant sauropods--the four-footed herbivorous dinosaurs that grazed the plants and trees of the late Jurassic period. As far as paleontologists can tell, Barapasaurus had the classic sauropod shape--huge legs, thick body, long neck and tail and small head--but was otherwise relatively undifferentiated, serving as the plain-vanilla "template" for later sauropod evolution. Interestingly, Barapasaurus is one of the few dinosaurs to be discovered in modern-day India. About half a dozen fossil specimens have been unearthed so far, but to date, no one has located this sauropod's skull (though scattered tooth remnants have been identified, which helps experts reconstruct the probable shape of its head). This isn't an unusual situation, as sauropods' skulls were only loosely attached to the rest of their skeletons and were easily detached (by scavenging or erosion) after death.

13 of 66 Barosaurus Barosaurus. Royal Tyrrell Museum Could an adult Barosaurus have raised its enormously long neck to its full vertical height? This would have required both a warm-blooded metabolism and a huge, muscular heart, indicating that this sauropod probably held its neck level to the ground. See an in-depth profile of Barosaurus

14 of 66 Bellusaurus Bellusaurus. Paleozoological Museum of China Name: Bellusaurus (Greek for "beautiful lizard"); pronounced BELL-oo-SORE-us Habitat: Woodlands of Asia Historical Period: Late Jurassic (160-155 million years ago) Size and Weight: About 13 feet long and 1,000 pounds Diet: Plants Distinguishing Characteristics: Long neck and tail; short spines on back If TV networks had existed back in the late Jurassic period, Bellusaurus would have been the lead item on the six o'clock news: this sauropod is represented by no less than 17 juveniles found in a single quarry, their bones tangled together after all of them had drowned in a flash flood. Needless to say, Bellusaurus grew to larger sizes than the 1,000-pound specimens unearthed in China; some paleontologists maintain that this was the same dinosaur as the obscure Klamelisaurus, which measured about 50 feet from head to tail and weighed anywhere from 15 to 20 tons.

15 of 66 Bothriospondylus Bothriospondylus. Dmitry Bogdanov Name: Bothriospondylus (Greek for "excavated vertebra"); pronounced BOTH-ree-oh-SPON-dill-us Habitat: Woodlands of western Europe Historical Period: Late Jurassic (155-150 million years ago) Size and Weight: About 50-60 feet long and 15-25 tons Diet: Plants Distinguishing Characteristics: Large size; long neck and tail The reputation of Bothriospondylus has taken a major hit over the last century or so. "Diagnosed" in 1875 by the famous paleontologist Richard Owen, on the basis of four enormous vertebrae unearthed in an English geologic formation, Bothriospondylus was ostensibly a giant, late Jurassic sauropod along the lines of Brachiosaurus. Unfortunately, Owen named not one, but four separate species of Bothriospondylus, some of which were shortly reassigned into (now) equally defunct genera like Ornithopsis and Marmarospondylus by other experts. Bothriospondylus is now largely ignored by paleontologists, although a fifth species (which wasn't designated by Owen) has survived as Lapparentosaurus.

16 of 66 Brachiosaurus Brachiosaurus. Wikimedia Commons Like many sauropods, the giraffe-like sauropod Brachiosaurus had an enormously long neck--about 30 feet long for adults--raising the question of how it could rear up to its full height without putting fatal stress on its circulatory system. See 10 Facts About Brachiosaurus

17 of 66 Brachytrachelopan Brachytrachelopan. Wikimedia Commons Name: Brachytrachelopan (Greek for "short-necked shepherd"); pronounced BRACK-ee-track-ELL-oh-pan Habitat: Plains of South America Historical Period: Late Jurassic (150 million years ago) Size and Weight: About 30 feet long and 5-10 tons Diet: Plants Distinguishing Characteristics: Unusually short neck; long tail Brachytrachelopan is one of those rare dinosaur exceptions that prove the rule, the "rule" being that all sauropods (giant, plodding, plant-eating dinosaurs) had long necks. When it was discovered a few years ago, Brachytrachelopan shocked paleontologists with its stunted neck, about half as long as that of other sauropods of the late Jurassic period. The most convincing explanation for this unusual feature is that Brachytrachelopan subsisted on a particular type of vegetation that grew only a few feet above the ground. By the way, the story behind Brachytrachelopan's unusual and unusually long name (which means "short-necked shepherd") is that its remains were discovered by a South American shepherd out looking for his lost sheep; Pan is the half-goat, half-human god of Greek legend.

18 of 66 Brontomerus Brontomerus. Getty Images Name: Brontomerus (Greek for "thunder thighs"); pronounced BRON-toe-MARE-us Habitat: Woodlands of North America Historical Period: Early Cretaceous (110 million years ago) Size and Weight: About 40 feet long and 6 tons Diet: Plants Distinguishing Characteristics: Moderate size; unusually thick hip bones Recently discovered in Utah, in sediments dating to the early Cretaceous period, Brontomerus was an unusual dinosaur in a number of ways. First off, there's the fact that Brontomerus seems to have been a classic sauropod, rather than a lightly armored titanosaur (an offshoot of the sauropods that flourished toward the end of the Mesozoic Era.) Second, Brontomerus was modestly sized, "only" about 40 feet long from head to tail and weighing in the neighborhood of 6 tons, petite proportions compared to most sauropods. Third, and most important, the hip bones of Brontomerus were unusually thick, implying that it had heavily muscled hind legs (hence its name, Greek for "thunder thighs"). Why did Brontomerus possess such a distinctive anatomy? Well, only incomplete skeletons have been found so far, making speculation a risky business. The paleontologists who named Brontomerus guess that it lived in particularly rough, hilly terrain, and was well-adapted to trudging up steep gradients in search of food. Then, too, Brontomerus would have had to contend with middle Cretaceous theropods like Utahraptor, so perhaps it kicked out its well-muscled limbs to keep these dangerous predators at bay.

19 of 66 Camarasaurus Camarasaurus. Nobu Tamura Probably because of its herding behavior, Camarasaurus is unusually well-represented in the fossil record, and is believed to have been one of the most common sauropods of late Jurassic North America. See an in-depth profile of Camarasaurus

20 of 66 Cetiosauriscus Cetiosauriscus. Getty Images Name: Cetiosauriscus (Greek for "like Cetiosaurus"); pronounced see-tee-oh-SORE-iss-kuss Habitat: Woodlands of western Europe Historical Period: Late Jurassic (160 million years ago) Size and Weight: About 50 feet long and 15-20 tons Diet: Plants Distinguishing Characteristics: Long neck and tail; squat trunk As you might guess, there's a story behind Cetiosauriscus ("like Cetiosaurus") and Cetiosaurus itself. That story, however, is too long and boring to go into here; suffice it to say that both of these sauropods were known by one name or the other, dating back to the late 19th century, and the confusion was only cleared up in 1927. Nomenclature issues aside, Cetiosauriscus was a fairly unremarkable plant-eating dinosaur of the late Jurassic period, almost as closely related to the North American Diplodocus as it was to its European namesake.

21 of 66 Cetiosaurus Cetiosaurus. Nobu Tamura Name: Cetiosaurus (Greek for "whale lizard"); pronounced SEE-tee-oh-SORE-us Habitat: Plains of western Europe and northern Africa Historical Period: Late Jurassic (170-160 million years ago) Size and Weight: About 50 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Long neck and tail; unusually heavy vertebrae Cetiosaurus is one of those dinosaurs that was discovered ahead of its time: the first fossil specimen was unearthed in the early 19th century, before paleontologists had grasped the enormous sizes attained by the sauropods of the late Jurassic period (other examples being the more famous Brachiosaurus and Apatosaurus). At first, it was thought that this bizarre creature was a giant whale or crocodile, hence its name, "whale lizard" (which was bestowed by the famous paleontologist Richard Owen). The most unusual feature of Cetiosaurus was its backbone. Unlike later sauropods, which possessed hollow vertebrae (an adaptation that helped to reduce their crushing weight), this huge herbivore had vertebrae of solid bone, with minimal air pockets, which may account for the 10 tons or so it packed into its relatively moderate length of 50 feet. Paleontologists speculate that Cetiosaurus may have roamed the plains of western Europe and northern Africa in vast herds, rumbling along at speeds conceivably approaching 10 miles per hour.

22 of 66 Demandasaurus Demandasaurus. Nobu Tamura Name Demandasaurus (Greek for "La Demanda lizard"); pronounced deh-MAN-dah-SORE-us Habitat Woodlands of western Europe Historical Period Early Cretaceous (125 million years ago) Size and Weight About 30 feet long and five tons Diet Plants Distinguishing Characteristics Long neck and tail; quadrupedal posture It sounds like the punchline to a joke--"what kind of dinosaur won't take no for an answer?"--but Demandasaurus actually derives its name from the Sierra la Demanda formation in Spain, not its presumed antisocial behavior. Represented by limited fossil remains, consisting of parts of its head and neck, Demandasaurus has been classified as a "rebbachisaur" sauropod, meaning it was closely related not only to the obscure Rebbachisaurus but to the very well-known Diplodocus. Pending more complete fossil discoveries, though, Demandasaurus sadly remains an early Cretaceous enigma.

23 of 66 Dicraeosaurus Dicraeosaurus. Wikimedia Commons Name: Dicraeosaurus (Greek for "double-forked lizard"); pronounced DIE-cray-oh-SORE-us Habitat: Woodlands of central Africa Historical Period: Late Jurassic (150 million years ago) Size and Weight: About 40 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Moderate size; short, spiny neck Dicraeosaurus wasn't your typical sauropod of the late Jurassic period: this medium-sized ("only" 10 tons or so) plant eater had an unusually short neck and tail, and most important, a series of double-pronged bones that jutted out from the front part of its vertebral column. Clearly, Dicraeosaurus had prominent spines along its neck and upper back, or possibly even a sail, which would have helped to regulate its body temperature (the latter possibility is less likely, since numerous sauropods besides Dicraeosaurus would have evolved sails if these had been of any adaptive value). You might not be surprised to learn that Dicraeosaurus was closely related to Amargasaurus, an unusually spiny-backed sauropod from South America.

24 of 66 Diplodocus Diplodocus. Alain Beneteau The North American Diplodocus was one of the first sauropod dinosaurs to be discovered and named, after a relatively obscure quirk of its anatomy (the "double beam" structure under one of its vertebrae). See 10 Facts About Diplodocus

25 of 66 Dyslocosaurus Dyslocosaurus. Taringa.net Name: Dyslocosaurus (Greek for "hard-to-place lizard"); pronounced diss-LOW-coe-SORE-us Habitat: Woodlands of North America Historical Period: Late Jurassic (150 million years ago) Size and Weight: About 60 feet long and 10-20 tons Diet: Plants Distinguishing Characteristics: Large size; long neck and tail In paleontology, it's very, very important to record exactly where you've found a given dinosaur skeleton. Unfortunately, this rule wasn't followed by the fossil hunter who unearthed Dyslocosaurus decades ago; he merely wrote "Lance Creek" on his specimen, leaving succeeding experts unsure whether he was referring to the Lance Creek region of Wyoming or (more probably) the Lance Formation in the same state. The name Dyslocosaurus ("hard-to-place lizard") was bestowed on this presumed sauropod by frustrated paleontologists, at least one of whom--the ubiquitous Paul Sereno--thinks that Dyslocosaurus was actually assembled out of two very different dinosaurs, a titanosaur and a large theropod.

26 of 66 Eobrontosaurus Eobrontosaurus. Sergio Perez Name Eobrontosaurus (Greek for "dawn Brontosaurus"); pronounced EE-oh-BRON-toe-SORE-us Habitat Plains of North America Historical Period Late Jurassic (150 million years ago) Size and Weight About 60 feet long and 15-20 tons Diet Plants Distinguishing Characteristics Large size; long neck and tail The American paleontologist Robert Bakker has made no secret of the fact that he thinks Brontosaurus got a raw deal, when the rules of scientific precedence dictated that it be called Apatosaurus. When Bakker determined in 1998 that a species of Apatosaurus identified in 1994 (A. yahnahpin) deserved its own genus, he was quick to invent the name Eobrontosaurus ("dawn Brontosaurus"); the trouble is that most other experts disagree with his analysis, and are content for Eobrontosaurus to remain a species of Apatosaurus. Ironically, it may yet turn out that A. yahnahpin/Eobrontosaurus was actually a species of Camarasaurus, and thus another type of sauropod entirely!

27 of 66 Euhelopus Euhelopus. Dmitry Bogdanov Name: Euhelopus (Greek for "true marsh foot"); pronounced you-HEE-low-puss Habitat: Woodlands of Asia Historical Period: Late Jurassic (150 million years ago) Size and Weight: About 50 feet long and 15 tons Diet: Plants Distinguishing Characteristics: Long neck; short hind limbs Not much progress has been made regarding Euhelopus, description- and classification-wise, since this late Jurassic sauropod was unearthed in China way back in the 1920's, the first of its kind ever to be discovered so far east (though it's since been succeeded by numerous Chinese sauropod discoveries). From its single, fragmentary fossil, we do know that Euhelopus was a very long-necked sauropod, and its general appearance (especially its long front legs and short hind legs) was reminiscent of the much better-known Brachiosaurus of North America.

28 of 66 Europasaurus Europasaurus. Wikimedia Commons Europasaurus only weighed three tons (about the size of a large elephant) and measured 15 feet from head to tail. Why was it so small? We don't know for sure, but this was likely an adaptation to the limited food resources of its ecosystem. See an in-depth profile of Europasaurus

29 of 66 Ferganasaurus Ferganasaurus (WikiDino). Name: Ferganasaurus (Greek for "Fergana lizard"); pronounced fur-GAH-nah-SORE-us Habitat: Woodlands of central Asia Historical Period: Middle Jurassic (165 million years ago) Size and Weight: About 30 feet long and 3-4 tons Diet: Plants Distinguishing Characteristics: Moderate size; basal skeletal structure The otherwise obscure Ferganasaurus is notable for two reasons: first, this sauropod dates from a relatively unknown stretch of the Jurassic period, about 165 million years ago (most sauropods discovered so far lived at least 10 or 15 million years later). And second, this was the first dinosaur ever to be discovered in the USSR, albeit in a region, Kyrgyzstan, that has since separated from Russia. Given the state of Soviet paleontology back in 1966, it may not be surprising that the "type fossil" of Ferganasaurus was neglected for decades, until a second expedition in 2000 found additional specimens.

30 of 66 Giraffatitan Giraffatitan. Dmitry Bogdanov Giraffatitan--if it wasn't actually a species of Brachiosaurus--was one of the tallest sauropods ever to walk the earth, with a hugely elongated neck that would have allowed it to hold its head more than 40 feet above the ground. See an in-depth profile of Giraffatitan

31 of 66 Haplocanthosaurus Haplocanthosaurus. Wikimedia Commons Name: Haplocanthosaurus (Greek for "single-spined lizard"); pronounced HAP-low-CANTH-oh-SORE-us Habitat: Woodlands of North America Historical Period: Late Jurassic (150 million years ago) Size and Weight: About 60 feet long and 20 tons Diet: Plants Distinguishing Characteristics: Heavy trunk; long neck and tail Despite its complicated-sounding name (Greek for "single-spined lizard"), Haplocanthosaurus was a relatively uncomplicated sauropod of the late Jurassic period, closely related to (but significantly smaller than) its more famous cousin Brachiosaurus. The only adult skeleton of a Haplocanthosaurus is on permanent display at the Cleveland Museum of Natural History, where it goes by the simpler (and much more pronounceable) name "Happy." (By the way, Haplocanthosaurus was originally named Haplocanthus, the person responsible for the change being under the impression that the latter name had already been assigned to a genus of prehistoric fish.)

32 of 66 Isanosaurus Isanosaurus (Wikimedia Commons). Name: Isanosaurus (Greek for "Isan lizard"); pronounced ih-SAN-oh-SORE-us Habitat: Woodlands of southeast Asia Historical Period: Late Triassic (210 million years ago) Size and Weight: About 20 feet long and 2-3 tons Diet: Plants Distinguishing Characteristics: Moderate size; long neck and tail Not to be confused with Pisanosaurus--a roughly contemporary ornithopod from South America--Isanosaurus may well have been one of the first true sauropods, appearing in the fossil record about 210 million years ago (near the Triassic/Jurassic boundary). Frustratingly, this plant-eater is known by only a few scattered bones discovered in Thailand, which nonetheless point to a dinosaur intermediate between the most advanced prosauropods and the earliest sauropods. Further confusing matters, the "type specimen" of Isanosaurus is of a juvenile, so it's difficult to tell how big this sauropod was fully grown--and whether it rivaled the size of another ancestral sauropod of late Triassic South Africa, Antetonitrus.

33 of 66 Jobaria Jobaria. Wikimedia Commons Name: Jobaria (after Jobar, a mythical African creature); pronounced joe-BAR-ee-ah Habitat: Woodlands of northern Africa Historical Period: Early Cretaceous (135 million years ago) Size and Weight: About 60 feet long and 15-20 tons Diet: Plants Distinguishing Characteristics: Large size; unusually short tail To a lesser or greater extent, all sauropods looked pretty much like all other sauropods. What makes Jobaria such an important find is that this plant-eater was so primitive compared to others of its breed that some paleontologists wonder if it was a true sauropod at all, or better classified as a "neosauropod" or "eusauropod." Of particular interest are Jobaria's vertebrae, which were simpler than those of other sauropods, and its unusually short tail. Further complicating matters, it's unclear if this herbivore dates to the early Cretaceous period (it was assigned to this time frame based on a nearby fossil of Afrovenator), or instead lived in the late Jurassic.

34 of 66 Kaatedocus Kaatedocus. Davide Bonnadonna Name: Kaatedocus (Native American/Greek for "small beam"); pronounced COT-eh-DOE-kuss Habitat: Plains of North America Historical Period: Late Jurassic (150 million years ago) Size and Weight: About 50 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Long neck; flat muzzle studded with numerous teeth Kaatedocus has an interesting back story: the bones of this sauropod were discovered in 1934, in Wyoming, by a team from the American Museum of Natural History in New York. No sooner had Barnum Brown and his crew carted away approximately 3,000 scattered bone fragments than the owner of the ranch got dollar signs in his eyes and decided to turn it into a tourist attraction. (Nothing came of this plan, though--most likely, he was simply trying to extract an exorbitant fee from AMNH for any further excavations!) In subsequent decades, many of these bones were destroyed either by fire or natural decay, only 10 percent surviving in AMNH's vaults. Among the surviving bones were a well-preserved skull and neck originally assumed to belong to Barosaurus. In the past decade, these fragments (and others from the same dig) have been extensively reexamined, the result being the announcement of Kaatedocus in 2012. Otherwise very similar to Diplodocus, Kaatedocus was characterized by its unusually long neck (which it seems to have held upright) as well as its flat, tooth-studded muzzle and long, thin tail, which it may have cracked like a whip.

35 of 66 Kotasaurus Kotasaurus. Getty Images Name: Kotasaurus (Greek for "Kota lizard"); pronounced KOE-ta-SORE-us Habitat: Woodlands of central Asia Historical Period: Middle Jurassic (180-175 million years ago) Size and Weight: About 30 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Large size; relatively thin legs Either a very advanced prosauropod (the early line of herbivorous dinosaurs that gave rise to the giant sauropods of the later Jurassic period) or a very early sauropod, Kotasaurus has been reconstructed from the remains of 12 separate individuals, the bones of which were found tangled together in a riverbed in India. (The most likely scenario is that a herd of Kotasaurus were drowned in a flash flood, then piled up on the bank downriver.) Today, the only place to see a Kotasaurus skeleton is at the Birla Science Museum in Hyderabad, India.

36 of 66 Lapparentosaurus Lapparentosaurus. Getty Images Name: Lapparentosaurus (Greek for "De Lapparent's lizard"); pronounced LA-pah-RENT-oh-SORE-us Habitat: Woodlands of Madagascar Historical Period: Middle Jurassic (170-165 million years ago) Size and Weight: About 40 feet long and 5-10 tons Diet: Plants Distinguishing Characteristics: Long neck and tail; longer front than hind limbs Lapparentosaurus--a mid-sized sauropod of middle Jurassic Madagascar--is all that remains of the genus once known as Bothriospondylus, which was named by the famous paleontologist Richard Owen in the late 19th century (and has been the subject of ample confusion ever since). Because it's represented by only limited fossil remains, Lapparentosaurus remains a somewhat mysterious dinosaur; all we can say with any certainty is that it was closely related to Brachiosaurus. (This dinosaur, by the way, honors the same French scientist as the ornithopod Delapparentia.)

37 of 66 Leinkupal Leinkupal. Jorge Gonzalez The importance of the early Cretaceous Leinkupal is that it was a "diplodocid" sauropod (that is, a close relative of Diplodocus) that managed to elude the evolutionary trend toward titanosaurs and prosper at a time when most of its fellow sauropods had gone extinct. See an in-depth profile of Leinkupal

38 of 66 Limaysaurus Limaysaurus. Wikimedia Commons Name Limaysaurus ("Rio Limay lizard"); pronounced LIH-may-SORE-us Habitat Plains of South America Historical Period Early Cretaceous (125 million years ago) Size and Weight About 45 feet long and 7-10 tons Diet Plants Distinguishing Characteristics Moderate size; short spines along back The early Cretaceous period was when the last classic sauropods roamed the earth, gradually to be displaced by their lightly armored descendants, the titanosaurs. Once classified as a species of Rebbachisaurus, Limaysaurus was a relative runt for a sauropod (only about 45 feet long and no heavier than 10 tons), but it made up for its lack of heft with the short spines protruding from the top of its backbone, which were likely covered by a hump of skin and fat. It seems to have been closely related to another "rebbachisaur" sauropod from northern Africa, Nigersaurus.

39 of 66 Lourinhasaurus Lourinhasaurus. Dmitry Bogdanov When Lourinhasaurus first discovered in Portugal, it was classified as a species of Apatosaurus; 25 years later, a new find prompted its reassignment to Camarasaurus; and a few years later, it was relegated to the obscure Dinheirosaurus. See an in-depth profile of Lourinhasaurus

40 of 66 Lusotitan Lusotitan. Sergio Perez Name Lusotitan (Greek for "Lusitania giant"); pronounced LOO-so-tie-tan Habitat Plains of western Europe Historical Period Late Jurassic (150 million years ago) Size and Weight About 80 feet long and 50-60 tons Diet Plants Distinguishing Characteristics Long neck and tail; longer front than hind legs Yet another dinosaur discovered in Portugal's Lourinha formation (others include the similarly named Lourinhasaurus and Lourinhanosaurus), Lusotitan was initially classified as a species of Brachiosaurus. It took half a century for paleontologists to re-examine this sauropod's type fossil and assign it to its own genus (which, thankfully, doesn't have "Lourinha" in its name). It's no coincidence that Lusotitan was closely related to Brachiosaurus, as North America and western Europe were connected by a land bridge during the late Jurassic period, 150 million years ago

41 of 66 Mamenchisaurus Mamenchisaurus. Sergey Krasovskiy Mamenchisaurus had one of the longest necks of any sauropod, about 35 feet from shoulders to skull. Could this dinosaur possibly have reared up on its hind feet without giving itself a heart attack (or toppling over backward)! See an in-depth profile of Mamenchisaurus

42 of 66 Nebulasaurus Nebulasaurus. Nobu Tamura Name Nebulasaurus (Greek for "nebula lizard"); pronounced NEB-you-lah-SORE-us Habitat Plains of eastern Asia Historical Period Middle Jurassic (170 million years ago) Size and Weight Undisclosed Diet Plants Distinguishing Characteristics Long neck; possible "thagomizer" on end of tail Not many dinosaurs are named after astronomical objects, which, unfortunately, is just about the only thing that makes Nebulasaurus stand out in the dinosaur bestiary. All we know about this plant-eater, based on a single incomplete skull, is that it was a mid-sized Asian sauropod closely related to Spinophorosaurus. There's also some speculation that Nebulasaurus may have possessed a "thagomizer," or bundle of spikes, on the end of its tail, similar to that of Spinophorosaurus and another closely related Asian sauropod, Shunosaurus, which would make it one of the few sauropods to be so equipped.

43 of 66 Nigersaurus Nigersaurus. Wikimedia Commons The middle Cretaceous Nigersaurus was a rather unusual sauropod, with a relatively short neck compared to its tail and a flat, vacuum-shaped mouth packed with hundreds of teeth--which gave it a distinctly comical appearance. See an in-depth profile of Nigersaurus

44 of 66 Omeisaurus Omeisaurus. Wikimedia Commons Name: Omeisaurus (Greek for "Omei Mountain lizard"); pronounced OH-may-SORE-us Habitat: Woodlands of eastern Asia Historical Period: Late Jurassic (165-160 million years ago) Size and Weight: About 50 feet long and 5-10 tons Diet: Plants Distinguishing Characteristics: Large size; extremely long neck Pound for pound, Omeisaurus was probably the most common sauropod of late Jurassic China, at least to judge by its numerous fossil remains. Various species of this unusually long-necked plant-eater have been unearthed over the last few decades, the smallest measuring only about 30 feet long from head to tail and the largest having a neck of about the same size. This dinosaur's closest relative appears to have been the even longer-necked sauropod Mamenchisaurus, which had a whopping 19 neck vertebrae compared to the 17 of Omeisaurus.

45 of 66 Paluxysaurus Paluxysaurus (Dmitry Bogdanov). Name: Paluxysaurus (Greek for "Paluxy River lizard"); pronounced pah-LUCK-see-SORE-us Habitat: Woodlands of North America Historical Period: Early Cretaceous (110 million years ago) Size and Weight: About 50-60 feet long and 10-15 tons Diet: Plants Distinguishing Characteristics: Large size; long neck and tail You'd expect a state as big as Texas to have an equally big state dinosaur, but the situation isn't quite as cut-and-dried as that. The middle Cretaceous Paluxysaurus has been proposed by some people as a replacement for the existing Texas state dinosaur, the very similar Pleurocoelus (in fact, some fossils of Pleurocoelus have now been attributed to Paluxysaurus). The problem is, the poorly understood Pleurocoelus may have been the same dinosaur as Astrodon, the official state dinosaur of Maryland, whereas Paluxysaurus--which represents the time when the last of the sauropods were morphing into the first of the titanosaurs--has more of a down-home Texas feel. (The issue has been rendered moot; a recent analysis has concluded that Paluxysaurus was a species of Sauroposeidon!)

46 of 66 Patagosaurus Patagosaurus. Wikimedia Commons Name: Patagosaurus (Greek for "Patagonian lizard"); pronounced PAT-ah-go-SORE-us Habitat: Woodlands of South America Historical Period: Late Jurassic (165 million years ago) Size and Weight: About 50 feet long and 5-10 tons Diet: Plants Distinguishing Characteristics: Thick trunk; long neck and tail Patagosaurus is notable not for how it looked--this large herbivorous dinosaur adhered to the plain-vanilla sauropod body plan, with its massive trunk and long neck and tail--than for when it lived. Patagosaurus is one of the few South American sauropods to date to closer to the middle than to the end of the Jurassic period, living about 165 million years ago, compared to 150 million years or so for the vast majority of sauropods discovered so far. Its closest relative appears to have been the North American Cetiosaurus ("whale lizard").

47 of 66 Pleurocoelus Pleurocoelus. Dmitry Bogdanov Name: Pleurocoelus (Greek for "hollow sided"); pronounced PLOOR-oh-SEE-luss Habitat: Woodlands of North America Historical Period: Middle Cretaceous (110 million years ago) Size and Weight: About 50 feet long and 20 tons Diet: Plants Distinguishing Characteristics: Large size; similarity to Brachiosaurus Texans weren't entirely happy with the designation, in 1997, of Pleurocoelus as the official state dinosaur. This relatively obscure sauropod may or may not have been the same beast as Astrodon (the state dinosaur of Maryland), and it's not nearly as popular as the plant-eating dinosaur it most closely resembles, Brachiosaurus, which lived about 40 million years earlier. For this reason, the Texas state legislature recently booted Pleurocoelus from the state roles in favor of another middle Cretaceous Texan sauropod of dubious provenance, Paluxysaurus, which--guess what?--may also have been the same dinosaur as Astrodon! Maybe it's time for Texas to let go of this whole state dinosaur idea and consider something less controversial, like flowers.

48 of 66 Qiaowanlong Qiaowanlong. Nobu Tamura Name: Qiaowanlong (Chinese for "Qiaowan dragon"); pronounced zhow-wan-LONG Habitat: Woodlands of Asia Historical Period: Middle Cretaceous (100 million years ago) Size and Weight: About 35 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Longer front than back legs; long neck Until recently, Brachiosaurus-like sauropods were thought to be confined to North America, but that all changed in 2007 with the discovery of Qiaonwanlong, an Asian sauropod that (with its long neck and longer front than back legs) resembled a two-thirds-scale copy of its more famous cousin. To date, Qiaowanlong has been "diagnosed" based on a single incomplete skeleton; further discoveries should help ascertain its exact place on the sauropod family tree. (On the other hand, since most North American dinosaurs of the Mesozoic Era had their counterparts in Eurasia, it's not too surprising that Brachiosaurus should have an Asian relative!)

49 of 66 Qijianglong Qijianglong. Lida Xing Name Qijianglong (Chinese for "Qijiang Dragon"); pronounced SHE-zhang-LONG Habitat Woodlands of Asia Historical Period Late Jurassic (160 million years ago) Size and Weight About 40 feet long and 10 tons Diet Plants Distinguishing Characteristics Moderate size; exceptionally long neck One of the frustrating things about sauropods is that their heads easily detach from their necks in the course of the fossilization process--hence the profusion of completely headless "type specimens." Well, that's not a problem with Qijianglong, which is represented by pretty much nothing except its head and its 20-foot-long neck, discovered recently in northeast China. As you might not be surprised to learn, the late Jurassic Qijianglong was closely related to another exceptionally long-necked Chinese dinosaur, Mamenchisaurus, and it probably fed on the high branches of trees (since the vertebrae in its neck were suited for up-and-down, rather than side-to-side, movement).

50 of 66 Rapetosaurus Rapetosaurus. Wikimedia Commons Name: Rapetosaurus (Malagasy and Greek for "mischievous lizard"); pronounced rah-PETE-oh-SORE-us Habitat: Woodlands of Madagascar Historical Period: Late Cretaceous (70-65 million years ago) Size and Weight: About 50 feet long and 20-30 tons Diet: Plants Distinguishing Characteristics: Long neck and tail; small, blunt teeth Toward the end of the Cretaceous period--shortly before the dinosaurs went extinct--the only types of sauropods roaming the earth were titanosaurs, giant, lightly armored herbivores the prime example of which was Titanosaurus. In 2001, a new genus of titanosaur, Rapetosaurus, was unearthed in a dig in Madagascar, a large island off the east coast of Africa. Unusually for a sauropod (since their skulls were easily detached from their bodies after death), paleontologists found a near-complete skeleton of a Rapetosaurus juvenile with its head still attached. Seventy million years ago, when Rapetosaurus lived, Madagascar had only recently separated from continental Africa, so it's a good bet that this titanosaur evolved from African predecessors, which themselves were closely related to giant South American sauropods like Argentinosaurus. One thing we know for sure is that Rapetosaurus lived in a harsh environment, which hastened the evolution of the huge, bony osteoderms (armored plates) embedded in its skin--the largest such structures known for any genus of dinosaur, even including Ankylosaurus and Stegosaurus.

51 of 66 Rebbachisaurus Rebacchisaurus. Nobu Tamura Name: Rebbachisaurus (Greek for "Rebbach lizard"); pronounced reh-BOCK-ih-SORE-us Habitat: Woodlands of northern Africa Historical Period: Middle Cretaceous (100 million years ago) Size and Weight: About 60 feet long and 10-20 tons Diet: Plants Distinguishing Characteristics: Long, thick neck; spines along back Not the most well-known sauropod in the dinosaur bestiary, Rebbachisaurus is important for when and where it lived--northern Africa during the middle Cretaceous period. Based on the similarity of Rebbachisaurus to later South American titanosaurs, Africa and South America may still have been joined by a land bridge as recently as 100 million years ago (these continents had previously been merged together in the supercontinent Gondwana). Other than this odd geological detail, Rebbachisaurus is notable for the tall spines that jutted out from its vertebrae, which may have supported a sail or hump of skin (or simply may have been there for decorative purposes).

52 of 66 Sauroposeidon Sauroposeidon. Levi Bernardo Considering its limited fossil remains, Sauroposeidon has made an outsized impact on popular culture. Perhaps that's because this sauropod has such a cool name, which translates from the Greek as "lizard god of the sea." See an in-depth profile of Sauroposeidon

53 of 66 Seismosaurus Seismosaurus. Vladimir Nikolov Most paleontologists suspect that the unusually hefty sauropod Seismosaurus was actually a long-lived individual of Diplodocus; even still, Seismosaurus keeps popping up on many "world's biggest dinosaur" lists. See an in-depth profile of Seismosaurus

54 of 66 Shunosaurus Shunosaurus. Vladimir Nikolov Name: Shunosaurus (Greek for "Shu lizard"); pronounced SHOE-no-SORE-us Habitat: Plains of Asia Historical Period: Middle Jurassic (170 million years ago) Size and Weight: About 33 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Long neck; low-slung heads; forelimbs shorter than hind limbs; bony club on end of tail As sauropods go, Shunosaurus wasn't even close to being the biggest--that honor belongs to giants like Argentinosaurus and Diplodocus, which weighed four or five times as much. What makes the 10-ton Shunosaurus truly special is that paleontologists have unearthed not one, but several, complete skeletons of this dinosaur, making it the best-understood of all the sauropods, anatomically speaking. Otherwise similar to its fellow sauropods (especially Cetiosaurus, to which it was most closely related), Shunosaurus distinguished itself with the small club on the end of its tail, which it likely used to swat away approaching predators. There's no way to know for sure, but the reason bigger sauropods didn't have this feature is probably that the tyrannosaurs and raptors of the Jurassic and Cretaceous periods were smart enough to leave the plus-sized adults in peace.

55 of 66 Sonorasaurus Sonorasaurus. Dmitri Bogdanov Name: Sonorasaurus (Greek for "Sonora Desert lizard"); pronounced so-NOR-ah-SORE-us Habitat: Woodlands of North America Historical Period: Middle Cretaceous (100 million years ago) Size and Weight: About 50 feet long and 10-15 tons Diet: Plants Distinguishing Characteristics: Extremely long neck; long forelimbs and short hind limbs There wasn't much special about the appearance of Sonorasaurus, which adhered to the basic body plan of Brachiosaurus-like sauropods: an extremely long neck and a thick trunk supported by significantly longer front than back legs. What makes Sonorosaurus interesting is that its remains date from middle Cretaceous North America (about 100 million years ago), a relatively sparse stretch of time when it comes to sauropod fossils. By the way, the euphonious name of this dinosaur derives from Arizona's Sonora Desert, a popular tourist destination to this day.

56 of 66 Spinophorosaurus Spinophorosaurus. Wikimedia Commons Name: Spinophorosaurus (Greek for "spine-bearing lizard"); pronounced SPY-no-FOR-oh-SORE-us Habitat: Woodlands of Africa Historical Period: Middle-Late Jurassic (175-160 million years ago) Size and Weight: About 50 feet long and 10 tons Diet: Plants Distinguishing Characteristics: Large size; spikes on end of tail Most of the sauropods of the late Jurassic period didn't have much in the way of defensive armament; that was a development that awaited the titanosaurs of the later Cretaceous. A weird exception to this rule was Spinophorosaurus, which sported a Stegosaurus-like "thagomizer" (i.e., bundle of symmetrical spikes) on the end of its long tail, probably to deter the ravenous theropods of its African habitat. Aside from this odd feature, Spinophorosaurus is notable for being one of the few African sauropods yet identified, which sheds some light on the evolution and worldwide migration of these giant herbivores.

57 of 66 Supersaurus Supersaurus. Luis Rey Befitting its name, Supersaurus may have been the biggest sauropod that ever lived--not by weight (it was only about 50 tons), but because it measured about 140 feet from head to tail, almost half the length of a football field. See an in-depth profile of Supersaurus

58 of 66 Tataouinea Tataouinea. Wikimedia Commons Name Tataouinea (after the Tunisian province); pronounced tah-too-EEN-eeh-ay Habitat Plains of northern Africa Historical Period Early Cretaceous (110 million years ago) Size and Weight About 45 feet long and 10-15 tons Diet Plants Distinguishing Characteristics Long neck and tail; "pneumaticized" bones First things first: despite what you may have read on the web, Tataouinea wasn't named after Luke Skywalker's home world in Star Wars, Tatooine, but after the province in Tunisia in which this dinosaur was discovered. (On the other hand, the paleontologists responsible are reported to be Star Wars buffs, and George Lucas may have had Tataouinea in mind when he wrote the movie.) The significant thing about this early Cretaceous sauropod is that its bones were partially "pneumaticized"--that is, they contained air sacs that helped reduce their weight. Why Tataouinea (and some other sauropods and titanosaurs) had this feature, while other giant dinosaurs didn't, is a mystery that awaits some enterprising grad student.

59 of 66 Tazoudasaurus Tazoudasaurus. French Museum of Natural History Name: Tazoudasaurus (Greek for "Tazouda lizard"); pronounced tah-ZOO-dah-SORE-us Habitat: Woodlands of northern Africa Historical Period: Early Jurassic (200 million years ago) Size and Weight: About 30 feet long and 3-4 tons Diet: Plants Distinguishing Characteristics: Moderate size; prosauropod-like teeth The very first sauropods, such as Antetonitrus and Isanosaurus, evolved on earth around the Triassic/Jurassic boundary. Discovered in 2004, Tazoudasaurus dates from the far end of that boundary, the early Jurassic period, and is represented in the fossil record by the earliest intact skull of any sauropod. As you might expect, Tazoudasaurus retained some of the characteristics of its prosauropod ancestors, especially in its jaws and teeth, and at 30 feet long it was a relative runt compared to its descendants of the later Jurassic. Its closest relative appears to have been the slightly later Vulcanodon.

60 of 66 Tehuelchesaurus Tehuelchesaurus. Wikimedia Commons Name Tehuelchesaurus (after the Tehuelche people of Argentina); pronounced teh-WELL-chay-SORE-us Habitat Woodlands of South America Historical Period Middle Jurassic (165 million years ago) Size and Weight About 40 feet long and 5-10 tons Diet Plants Distinguishing Characteristics Moderate size; long neck and tail The middle Jurassic period was a relatively unproductive time, geologically speaking, for the preservation of dinosaur fossils--and Argentina's Patagonia region is best know for yielding giant titanosaurs of the late Cretaceous period, like the huge Argentinosaurus. So, wouldn't you know it, Tehuelchesaurus was a mid-sized sauropod of middle Jurassic Patagonia, sharing its territory with the roughly similar Patagosaurus and (oddly) most resembling the Asian Omeisaurus, which lived thousands of miles away. These were among the earliest true sauropods, which only evolved to truly earth-shaking sizes toward the end of the Jurassic period, 15 million years later.

61 of 66 Tornieria Tornieria (Heinrich Harder). The late Jurassic sauropod Tornieria is a case study in the convolutions of science, having been named and renamed, classified and reclassified, numerous times since its discovery in the early 20th century. See an in-depth profile of Tornieria

62 of 66 Turiasaurus Turiasaurus. Nobu Tamura Name Turiasaurus (Greek for "Teruel lizard"); pronounced TORE-ee-ah-SORE-us Habitat Plains of western Europe Historical Period Late Jurassic (150 million years ago) Size and Weight About 100 feet long and 50-60 tons Diet Plants Distinguishing Characteristics Large size; long neck and tail; relatively small head At the end of the Jurassic period, 150 million years ago, the largest dinosaurs on earth could be found in North America: sauropods like Diplodocus and Apatosaurus. But western Europe wasn't totally bereft of behemoths: in 2006, paleontologists working in Spain and Portugal discovered the remains of Turiasaurus, which at 100 feet long and over 50 tons was in a weight class all by itself. (Turiasaurus did, however, possess an unusually small head, so it wasn't the brainiest sauropod on its Jurassic block.) Its closest relatives were two other Iberian sauropods, Losillasaurus and Galveosaurus, with which it may have formed a unique "clade" of enormous plant-eaters.

63 of 66 Vulcanodon Vulcanodon. Wikimedia Commons Name: Vulcanodon (Greek for "volcano tooth"); pronounced vul-CAN-oh-don Habitat: Plains of southern Africa Historical Period: Early Jurassic (208-200 million years ago) Size and Weight: About 20 feet long and four tons Diet: Plants Distinguishing Characteristics: Squat, thick body; long front limbs The plant-eating Vulcanodon is usually seen as occupying an intermediate position between the smaller prosauropods of the Triassic period (such as Sellosaurus and Plateosaurus) and the huge sauropods of the later Jurassic, such as Brachiosaurus and Apatosaurus. Despite its volcanic name, this dinosaur wasn't all that big by later sauropod standards, "only" about 20 feet long and 4 or 5 tons. When Vulcanodon was first discovered (in southern Africa in 1969), paleontologists were puzzled by the small, sharp teeth scattered among its bones. At first, this was taken as evidence that this dinosaur might have been a prosauropod (which some experts think ate meat as well as plants), but it was later realized that the teeth probably belonged to a theropod that tried to have the Vulcanodon for lunch.

64 of 66 Xenoposeidon Xenoposeidon. Mike Taylor Name: Xenoposeidon (Greek for "strange Poseidon"); pronounced ZEE-no-poe-SIGH-don Habitat: Woodlands of western Europe Historical Period: Early Cretaceous (140 million years ago) Size and Weight: About 50 feet long and 5-10 tons Diet: Plants Distinguishing Characteristics: Large size; strangely shaped vertebrae More often than you might think, dinosaurs are "rediscovered" decades after their fossils were first unearthed. Such is the case with Xenoposeidon, which was recently assigned to its own genus based on a single, partial bone dug up in England in the late 19th century. The problem is, although Xenoposeidon was clearly a type of sauropod, the shape of this vertebra (specifically, the forward slope of its neural arch) doesn't fit comfortably into any known family, prompting a pair of paleontologists to propose its inclusion in an entirely new sauropod group. As to what Xenoposeidon looked like, that remains a mystery; depending on further research, it may have been built along the lines of either Diplodocus or Brachiosaurus.

65 of 66 Yizhousaurus Yizhousaurus. Wikimedia Commons Yizhousaurus is the earliest sauropod to be represented in the fossil record by a complete skeleton, a very rare event for these types of dinosaurs, since their heads were easily detached from their spinal columns after they died. See an in-depth profile of Yizhousaurus