Hadrosaurs, also known as duck-billed dinosaurs, were the most common plant-eating animals of the later Mesozoic Era. On the following slides, you'll find pictures and detailed profiles of over 50 duck-billed dinosaurs, ranging from A (Amurosaurus) to A (Zhuchengosaurus).
Amurosaurus
Name:
Amurosaurus (Greek for "Amur River lizard"); pronounced AM-ore-oh-SORE-us
Habitat:
Woodlands of Asia
Historical Period:
Late Cretaceous (75-65 million years ago)
Size and Weight:
About 25 feet long and 2 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; narrow snout; small crest on head
Amurosaurus may be the best-attested dinosaur ever to be discovered within the confines of Russia, although its fossils were unearthed on the far fringes of this vast country, near its eastern border with China. There, an Amurosaurus bonebed (which was probably deposited by a sizable herd that met its end in a flash flood) has allowed paleontologists to painstakingly piece together this large, late Cretaceous hadrosaur from various individuals. As far as experts can tell, Amurosaurus was very similar to the North American Lambeosaurus, hence its classification as a "lambeosaurine" hadrosaur.
Anatotitan
Despite its comical name, Anatotitan (Greek for "giant duck") had nothing in common with modern ducks. This hadrosaur used its broad, flat bill to nip at low-lying vegetation, of which it would have to eat several hundred pounds every day. Check out our in-depth profile of Anatotitan for more.
Angulomastacator
Name:
Angulomastacator (Greek for "bent chewer"); pronounced ANG-you-low-MASS-tah-kay-tore
Habitat:
Woodlands of North America
Historical Period:
Late Cretaceous (80-70 million years ago)
Size and Weight:
About 25-30 feet long and 1-2 tons
Diet:
Plants
Distinguishing Characteristics:
Narrow snout; oddly shaped upper jaw
You can glean everything you need to know about Angulomastacator from its clunky name, Greek for "bent chewer." This late Cretaceous hadrosaur (duck-billed dinosaur) resembled others of its kind in most ways, with the exception of its oddly angled upper jaw, the purpose of which remains a mystery (even the paleontologists who discovered this dinosaur describe it as "enigmatic") but probably had something to do with its accustomed diet. Its strange skull aside, Angulomastacator is classified as a "lambeosaurine" hadrosaur, meaning it was closely related to the much better known Lambeosaurus.
Aralosaurus
Name:
Aralosaurus (Greek for "Aral Sea lizard"); pronounced AH-rah-lo-SORE-us
Habitat:
Woodlands of Central Asia
Historical Period:
Late Cretaceous (95-85 million years ago)
Size and Weight:
About 25 feet long and 3-4 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; prominent hump on the snout
One of the few dinosaurs to be discovered in the former Soviet satellite state of Kazakhstan, Aralosaurus was a large hadrosaur, or duck-billed dinosaur, of the middle to late Cretaceous period, which is pretty much all we can say for certain, since all that's been found of this gentle herbivore is a single chunk of skull. We do know that Aralosaurus possessed a noticeable "hump" on its snout, with which it probably created loud honking noises--either to signal desire or availability to the opposite sex or to warn the rest of the herd about approaching tyrannosaurs or raptors.
Bactrosaurus
Name:
Bactrosaurus (Greek for "staff lizard"); pronounced BACK-tro-SORE-us
Habitat:
Woodlands of Asia
Historical Period:
Late Cretaceous (95-85 million years ago)
Size and Weight:
About 20 feet long and two tons
Diet:
Plants
Distinguishing Characteristics:
Thick trunk; club-shaped spines on the backbone.
Among the earliest of all the hadrosaurs, or duck-billed dinosaurs--roaming the woodlands of Asia at least 10 million years before more famous descendants like Charonosaurus--Bactrosaurus is important because it possessed certain characteristics (such as a thick, squat body) more often seen in iguanodont dinosaurs. (Paleontologists believe that hadrosaurs and iguanodonts, which are both technically classified as ornithopods, evolved from a common ancestor). Unlike most hadrosaurs, Bactrosaurus seems to have lacked a crest on its head, and it also had a row of short spines growing out of its vertebrae that formed a prominent, skin-covered ridge along its back.
Barsboldia
Name
Barsboldia (after paleontologist Rinchen Barsbold); pronounced barz-BOLD-ee-ah
Habitat
Plains of central Asia
Historical Period
Late Cretaceous (70 million years ago)
Size and Weight
Undisclosed
Diet
Plants
Distinguishing Characteristics
Crest along back; long, thick tail
Very few people have one, much less two, dinosaurs named after them — so the Mongolian paleontologist Rinchen Barsbold can be proud to claim both Rinchenia (a close relative of Oviraptor) and the duck-billed dinosaur Barsboldia (which lived in the same time and place, the late Cretaceous plains of central Asia). Of the two, Barsboldia is the more controversial; for a long time, the type fossil of this hadrosaur was considered dubious, until a re-examination in 2011 solidified its genus status. Like its close cousin Hypacrosaurus, Barsboldia was characterized by its prominent neural spines (which probably supported a short sail of skin along its back, and likely evolved as a means of sexual differentiation).
Batyrosaurus
Name
Batyrosaurus (Greek for "Batyr lizard"); pronounced bah-TIE-roe-SORE-us
Habitat
Plains of central Asia
Historical Period
Late Cretaceous (85-75 million years ago)
Size and Weight
About 20 feet long and 1-2 tons
Diet
Plants
Distinguishing Characteristics
Large size; narrow snout; claws on thumbs
A few million years before the appearance of advanced duck-billed dinosaurs like Lambeosaurus, during the late Cretaceous period, there were what paleontologists (only slightly tongue in cheek) call "hadrosauroid hadrosaurids"--ornithopod dinosaurs sporting some extremely basal hadrosaur characteristics. That is Batyrosaurus in a (very big) nutshell; this plant-eating dinosaur possessed spikes on its thumbs, like the much earlier and more famous ornithopod Iguanodon, but subtle details of its cranial anatomy point to its place lower down on the hadrosaur family tree from the later Edmontosaurus and Probactrosaurus.
Brachylophosaurus
Paleontologists have unearthed three complete fossils of Brachylophosaurus, and they're so amazingly well-preserved that they've been given nicknames: Elvis, Leonardo, and Roberta. (A fourth, incomplete specimen is known as "Peanut.") Se our in-depth profile of Brachylophosaurus for more information about them.
Charonosaurus
Name:
Charonosaurus (Greek for "Charon lizard"); pronounced cah-ROAN-oh-SORE-us
Habitat:
Woodlands of Asia
Historical Period:
Late Cretaceous (70-65 million years ago)
Size and Weight:
About 40 feet long and 6 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; long, narrow crest on head
One of the odd things about the dinosaurs of the late Cretaceous period is that many species seem to have duplicated themselves between North America and Asia. Charonosaurus is a good example; this duck-billed Asian hadrosaur was essentially identical to its more famous North American cousin, Parasaurolophus, except that it was slightly bigger. Charonosaurus also had a longer crest on its head, which means it probably blasted mating and warning calls across farther distances than Parasaurolophus ever could. (By the way, the name Charonosaurus derives from Charon, the boatman of Greek myth who ferried the souls of the recently dead across the river Styx. Since Charonosaurus must have been a gentle herbivore that minded its own business, this doesn’t seem particularly fair!)
Claosaurus
Name:
Claosaurus (Greek for "broken lizard"); pronounced CLAY-oh-SORE-us
Habitat:
Woodlands of North America
Historical Period:
Late Cretaceous (80-70 million years ago)
Size and Weight:
About 15 feet long and 1,000 pounds
Diet:
Plants
Distinguishing Characteristics:
Relatively small size; long tail
For a dinosaur that was discovered so early in the history of paleontology — in 1872, by the famous fossil hunter Othniel C. Marsh — Claosaurus has remained a bit obscure. Originally, Marsh thought he was dealing with a species of Hadrosaurus, the genus that gave its name to the hadrosaurs, or duck-billed dinosaurs; he then assigned his discovery the name Claosaurus ("broken lizard"), to which he later assigned a second species, which turned out to be a specimen of yet another duck-billed dinosaur, Edmontosaurus. Confused yet?
Nomenclature issues aside, Claosaurus is important for having been an unusually "basal" hadrosaur. This dinosaur was relatively small, "only" about 15 feet long and half a ton and it probably lacked the distinctive crest of later, more ornate hadrosaurs (we can't know for sure since no one has found a Claosaurus skull). The teeth of Claosaurus were similar to those of a much earlier ornithopod of the Jurassic period, Camptosaurus, and its longer-than-usual tail and unique foot structure also place it on one of the earlier branches of the hadrosaur family tree.
Corythosaurus
As with other crested hadrosaurs, experts believe the elaborate head crest of Corythosaurus (which looks a bit like the Corinthian helmets worn by the ancient Greeks) was used as a giant horn to signal other herd members. Check out our article on the Corythosaurus for an in-depth look at this dinosaur.
Edmontosaurus
Paleontologists have determined that the bite mark on one Edmontosaurus specimen was made by a Tyrannosaurs Rex. Since the bite wasn't fatal, this indicates that T. Rex occasionally hunted for its food, rather than scavenging already-dead carcasses. Explore our in-depth profile of Edmontosaurus for more information.
Eolambia
Name:
Eolambia (Greek for "Lambe's dawn" dinosaur); pronounced EE-oh-LAM-bee-ah
Habitat:
Woodlands of North America
Historical Period:
Middle Cretaceous (100-95 million years ago)
Size and Weight:
About 30 feet long and two tons
Diet:
Plants
Distinguishing Characteristics:
Large size; stiff tail; spikes on thumbs
As far as paleontologists can tell, the very first hadrosaurs, or duck-billed dinosaurs, evolved from their Iguanodon-like ornithopod ancestors in Asia about 110 million years ago, during the middle Cretaceous period. If this scenario is correct, then Eolambia was one of the earliest hadrosaurs to colonize North America (via the Alaskan land bridge from Eurasia); its missing-link status can be inferred from "iguanodont" characteristics like its spiked thumbs. Eolambia was named in reference to another, later North American hadrosaur, Lambeosaurus, which was itself named after the famous paleontologist Lawrence M. Lambe.
Equijubus
Name:
Equijubus (Greek for "horse mane"); pronounced ECK-wih-JOO-bus
Habitat:
Woodlands of Asia
Historical Period:
Early Cretaceous (110 million years ago)
Size and Weight:
About 23 feet long and 2-3 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; narrow head with downward-curving beak
Along with plant-eaters like Probactrosaurus and Jinzhousaurus, Equijubus (Greek for "horse mane") occupied an intermediate stage between the Iguanodon-like ornithopods of the early Cretaceous period and the full-blown hadrosaurs, or duck-billed dinosaurs, that arrived millions of years later and occupied the expanse of North America and Eurasia. Equijubus was fairly large for a "basal" hadrosaur (some adults may have weighed as much as three tons), but this dinosaur may still have been capable of running away on two legs when chased by ravenous theropods.
Gilmoreosaurus
Name:
Gilmoreosaurus (Greek for "Gilmore's lizard"); pronounced GILL-more-oh-SORE-us
Habitat:
Woodlands of central Asia
Historical Period:
Late Cretaceous (75-70 million years ago)
Size and Weight:
About 15-20 feet long and 1,000-2,000 pounds
Diet:
Plants
Distinguishing Characteristics:
Moderate size; evidence of tumors in bones
Otherwise a plain-vanilla hadrosaur of the late Cretaceous period, Gilmoreosaurus is important for what it has revealed about dinosaur pathology: the susceptibility of these ancient reptiles to various diseases, including cancer. Strangely, numerous vertebrae of Gilmoreosaurus individuals show evidence of cancerous tumors, putting this dinosaur in a select group that also includes the hadrosaurs Brachylophosaurus and Bactrosaurus (of which Gilmoreosaurus may actually have been a species). Scientists still don't know what caused these tumors; it's possible that inbred populations of Gilmoreosaurus had a genetic propensity for cancer, or perhaps these dinosaurs were exposed to unusual pathogens in their central Asian environment.
Gryposaurus
It's not as well known as other duck-billed dinosaurs, but Gryposaurus ("hook-nosed lizard") was one of the most common herbivores of Cretaceous North America. It received its name thanks to its the unusual snout, which had a hook-shaped bump on top. See our in-depth profile of Gryposaurus for more information.
Hadrosaurus
Relatively little is known about Hadrosaurus, a specimen of which was discovered in New Jersey in the 19th century. Appropriately enough for a region that boasts so few fossil remains, Hadrosaurus has become New Jersey's official state dinosaur. Check out our in-depth profile of Hadrosaurus for more on them.
Huaxiaosaurus
Name
Huaxiaosaurus (Chinese/Greek for "Chinese lizard"); pronounced WOK-see-ow-SORE-us
Habitat
Woodlands of eastern Asia
Historical Period
Late Cretaceous (70-65 million years ago)
Size and Weight
Up to 60 feet long and 20 tons
Diet
Plants
Distinguishing Characteristics
Enormous size; bipedal posture
A non-sauropod dinosaur, technically, a hadrosaur, that measured 60 feet from head to tail and weighed as much as 20 tons: surely, you think, Huaxiaosaurus must have caused a huge splash when it was announced in 2011. And so it would have, if most paleontologists weren't convinced that the "type fossil" of Huaxiaosaurus actually belongs to an unusually large specimen of Shantungosaurus, already acclaimed as the largest duck-billed dinosaur ever to walk the earth. The main diagnostic difference between Huaxiaosaurus and Shantungosaurus is a groove on the underside of its lower vertebrae, which can just as easily be explained by advanced age (and a superannuated Shantungosaurus may well have weighed more than younger members of the herd).
Huehuecanauhtlus
Name
Huehuecanauhtlus (Aztec for "ancient duck"); pronounced WAY-way-can-OUT-luss
Habitat
Woodlands of southern North America
Historical Period
Late Cretaceous (85 million years ago)
Size and Weight
Undisclosed
Diet
Plants
Distinguishing Characteristics
Squat trunk; small head with tough beak
Few languages roll as strangely off the modern tongue as ancient Aztec. That may partly explain why the announcement of Huehuecanauhtlus in 2012 attracted so little press: this dinosaur, whose name translates as "ancient duck," is nearly as hard to pronounce as it is to spell. Essentially, Huehuecanauhtlus was a standard-issue hadrosaur (duck-billed dinosaur) of the late Cretaceous period, closely related to the slightly less obscure Gilmoreosaurus and Tethyshadros. Like other members of its ungainly breed, Huehuecanauhtlus spent most of its time grazing for vegetation on all fours but was able to break into a brisk bipedal trot when threatened by tyrannosaurs or raptors.
Hypacrosaurus
Paleontologists have discovered the well-preserved nesting grounds of Hypacrosaurus, complete with fossilized eggs and hatchlings; we now know that these hatchlings attained adulthood after 10 or 12 years, faster than the 20 or 30 years of some meat-eating dinosaurs. See our in-depth profile of Hypacrosaurus for more information.
Hypsibema
Name
Hypsibema (Greek for "high stepper"); pronounced HIP-sih-BEE-mah
Habitat
Woodlands of North America
Historical Period
Late Cretaceous (75 million years ago)
Size and Weight
About 30-35 feet long and 3-4 tons
Diet
Plants
Distinguishing Characteristics
Narrow snout; stiff tail; bipedal posture
Their legislatures won't necessarily tell you, but many of the official state dinosaurs around the U.S. are based on uncertain or fragmentary remains. That's certainly the case with Hypsibema: when this dinosaur was first identified, by the famous paleontologist Edward Drinker Cope, it was classified as a small sauropod and named Parrosaurus. This initial specimen of Hypsibema was discovered in North Carolina; it was up to Jack Horner to re-examine a second set of remains (unearthed in Missouri in the early 20th century) and erect a new species, H. missouriensis, subsequently designated as the official state dinosaur of Missouri. Other than the fact that it was clearly a hadrosaur or duck-billed dinosaur, there's still a lot we don't know about Hypsibema, and many paleontologists consider it a nomen dubium.
Jaxartosaurus
Name:
Jaxartosaurus (Greek for "Jaxartes River lizard"); pronounced jack-SAR-toe-SORE-us
Habitat:
Woodlands of central Asia
Historical Period:
Late Cretaceous (90-80 million years ago)
Size and Weight:
About 30 feet long and 3-4 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; prominent crest on the head
One of the more mysterious hadrosaurs, or duck-billed dinosaurs, of the middle to the late Cretaceous period, Jaxartosaurus has been reconstructed from scattered skull fragments found near the Syr Darya river, known as the Jaxartes in ancient times. Like many hadrosaurs, Jaxartosaurus had a prominent crest on its head (which was probably larger in males than in females, and may have been used to produce piercing calls), and this dinosaur probably spent most of its time grazing on low-lying bushes in a quadrupedal posture — though it may have been capable of running away on two feet to escape pursuing tyrannosaurs and raptors.
Jinzhousaurus
Name:
Jinzhousaurus (Greek for "Jinzhou lizard"); pronounced GIN-zhoo-SORE-us
Habitat:
Woodlands of Asia
Historical Period:
Early Cretaceous (125-120 million years ago)
Size and Weight:
About 16 feet long and 1,000 pounds
Diet:
Plants
Distinguishing Characteristics:
Long, narrow hands and snout
The early Cretaceous Jinzhousaurus existed at a time when the Iguanodon-like ornithopods of Asia were just beginning to evolve into the first hadrosaurs. As a result, paleontologists aren't quite sure what to make of this dinosaur; some say that Jinzhousaurus was a classic "iguanodont," while others peg it as a basal hadrosaur, or "hadrosauroid." What makes this state of affairs especially frustrating is that Jinzhousaurus is represented by a complete, if somewhat squashed, fossil specimen, a relative rarity for dinosaurs from this period.
Kazaklambia
Name
Kazaklambia ("Kazakh lambeosaur"); pronounced KAH-zock-LAM-bee-ah
Habitat
Woodlands of central Asia
Historical Period
Late Cretaceous (85 million years ago)
Size and Weight
Undisclosed
Diet
Plants
Distinguishing Characteristics
Longer hind than front legs; distinctive head crest
When its type fossil was unearthed, in 1968, Kazaklambia was the most complete dinosaur ever to be discovered within the confines of the Soviet Union--and one imagines that this nation's science commissars were displeased with the ensuing confusion. Clearly a type of hadrosaur, or duck-billed dinosaur, closely related to the North American Lambeosaurus, Kazaklambia was first assigned to a now-discarded genus (Procheneosaurus) and then classified as a species of Corythosaurus, C. convincens. It was only in 2013, ironically, that a pair of American paleontologists erected the genus Kazaklambia, theorizing that this dinosaur lay at the root of lambeosaurine evolution.
Kerberosaurus
Name
Kerberosaurus (Greek for "Cerberus lizard"); pronounced CUR-burr-oh-SORE-us
Habitat
Woodlands of eastern Asia
Historical Period
Late Cretaceous (65 million years ago)
Size and Weight
Undisclosed
Diet
Plants
Distinguishing Characteristics
Broad, flat snout; longer hind than front legs
For such a distinctively named dinosaur — Kerberos, or Cerberus, was the three-headed dog that guarded the gates of hell in Greek mythology — Kerberosaurus is hard to get a handle on. All we know for sure about this hadrosaur, or duck-billed dinosaur, based on the scattered remains of its skull, is that it was closely related to both Saurolophus and Prosaurolophus, and lived in the same time and place as another eastern Asian duckbill, Amurosaurus. (Unlike Amurosaurus, though, Kerberosaurus did not possess the elaborate head crest characteristic of lambeosaurine hadrosaurs.)
Kritosaurus
Name:
Kritosaurus (Greek for "separated lizard"); pronounced CRY-toe-SORE-us
Habitat:
Woodlands of North America
Historical Period:
Late Cretaceous (75 million years ago)
Size and Weight:
About 30 feet long and 2-3 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; prominently hooked snout; occasional bipedal posture
Like the armored dinosaur Hylaeosaurus, Kritosaurus is more important from a historical than from a paleontological point of view. This hadrosaur was discovered in 1904 by the famous fossil hunter Barnum Brown, and an awful lot was inferred about its appearance and behavior based on very limited remains--to the extent that the pendulum has now swung the other way and very few experts talk with any confidence about Kritosaurus. For what it's worth, the type specimen of Kritosaurus will almost certainly wind up being assigned to a more solidly established genus of a hadrosaur.
Kundurosaurus
Name
Kundurosaurus (Greek for "Kundur lizard"); pronounced KUN-door-roe-SORE-us
Habitat
Woodlands of eastern Asia
Historical Period
Late Cretaceous (65 million years ago)
Size and Weight
Undisclosed
Diet
Plants
Distinguishing Characteristics
Ridged nose; stiff tail
It's very rare that paleontologists unearth a complete, fully articulated specimen of a given dinosaur. More often, they discover fragments — and if they're particularly lucky (or unlucky), they discover a whole lot of fragments, from different individuals, piled up in a heap. Unearthed in the Kundur region of eastern Russia in 1999, Kundurosaurus is represented by numerous fossil fragments and was assigned its own genus on the premise that only one dinosaur of its niche (technically, a saurolophine hadrosaur) could have occupied its ecosystem at a given time. We do know that Kundurosaurus shared its habitat with the much bigger duck-billed dinosaur Olorotitan, and that's it's closely related to the even more obscure Kerberosaurus, which lived a short distance away.
Lambeosaurus
The name Lambeosaurus has nothing to do with lambs; rather, this duck-billed dinosaur was named after paleontologist Lawrence M. Lambe. Like other hadrosaurs, it's believed that Lambeosaurus used its crest to signal fellow herd members. Check out our article on the Lambeosaurus for more information.
Latirhinus
Name:
Latirhinus (Greek for "broad nose"); pronounced LA-tih-RYE-nuss
Habitat:
Woodlands of North America
Historical Period:
Late Cretaceous (75-70 million years ago)
Size and Weight:
About 15 feet long and 1-2 tons
Diet:
Plants
Distinguishing Characteristics:
Large, broad, flat nose
A partial anagram for Altirhinus — a slightly earlier duckbilled dinosaur with an equally prominent nose — Latirhinus languished in a museum vault for a quarter of a century, where it was classified as a specimen of Gryposaurus. We may never know why Latirhinus (and other hadrosaurs like it) had such a big nose; this may have been a sexually selected characteristic (that is, males with bigger noses had the opportunity to mate with more females) or this dinosaur may have used its snout to communicate with loud grunts and snorts. Oddly enough, it's unlikely that Latirhinus had a particularly sharp sense of smell, at least compared to other plant-eating dinosaurs of the late Cretaceous period!
Lophorhothon
Lophorhothon (Greek for "crested nose"); pronounced LOW-for-HOE-thon
Habitat
Woodlands of North America
Historical Period
Late Cretaceous (80-75 million years ago)
Size and Weight
About 15 feet long and one ton
Diet
Plants
Distinguishing Characteristics
Squat torso; bipedal posture; longer hind than front legs
The first dinosaur ever to be discovered in the state of Alabama — and the only presumed hadrosaur ever to be discovered on the east coast of the U.S. — Lophorhothon has a frustratingly vague taxonomic history. The partial remains of this duck-billed dinosaur were discovered in the 1940s, but it was only named in 1960, and not everyone is convinced that it merits genus status (some paleontologists argue, for example, that the type fossil of Lophorhothon is actually of a juvenile Prosaurolophus). Lately, the weight of the evidence is that Lophorhothon was an extremely basal hadrosaur of an uncertain genus, which may explain why the official state fossil of Alabama is the prehistoric whale Basilosaurus instead!
Magnapaulia
Name
Magnapaulia (Latin for "big Paul," after Paul G. Hagga, Jr.); pronounced MAG-nah-PAUL-ee-ah
Habitat
Woodlands of western North America
Historical Period
Late Cretaceous (75 million years ago)
Size and Weight
About 40 feet long and 10 tons
Diet
Plants
Distinguishing Characteristics
Large size; bulky tail with neural spines
Not many casual dinosaur fans are aware of the fact, but some hadrosaurs approached the size and bulk of multi-ton sauropods like Apatosaurus and Diplodocus. A good example is the North American Magnapaulia, which measured about 40 feet from head to tail and weighed upwards of 10 tons (and possibly even more than that). Besides its massive size, this close relative of both Hypacrosaurus and Lambeosaurus was characterized by its unusually broad and stiff tail, which was supported by an array of neural spines (i.e., thin slivers of bone jutting out from this dinosaur's vertebrae). Its name, which translates as "Big Paul," honors Paul G.Haaga, Jr., the president of the board of trustees of the Los Angeles County Museum of Natural History.
Maiasaura
Maiasaura is one of the few dinosaurs whose name ends in "a" rather than "us," a tribute to the females of the species. This hadrosaur became famous when paleontologists unearthed its extensive nesting grounds, complete with fossilized eggs, hatchlings, juveniles, and adults. See our page all about Maiasaura for more.
Nipponosaurus
Name
Nipponosaurus (Greek for "Japan lizard"); pronounced nih-PON-oh-SORE-us
Habitat
Woodlands of Japan
Historical Period
Late Cretaceous (90-85 million years ago)
Size and Weight
About 20 feet long and 2-3 tons
Diet
Plants
Distinguishing Characteristics
Thick tail; crest on head; occasional bipedal posture
So few dinosaurs have been discovered on the island nation of Japan that there's a tendency for paleontologists to hold tight to any genus, no matter how dubious. That (depending on your perspective) is the case with Nipponosaurus, which many western experts have considered a nomen dubium since its discovery on the island of Sakhalin in the 1930's, but which is still honored in its erstwhile country. (Once a possession of Japan, Sakhalin now belongs to Russia.) It's undoubtedly the case that Nipponosaurus was a hadrosaur, or duck-billed dinosaur, closely related to the North American Hypacrosaurus, but beyond that there's not much to say about this mysterious plant-eater.
Olorotitan
One of the most romantically named dinosaurs, Olorotitan is Greek for "giant swan" (a more pleasing image than that evoked by its fellow hadrosaur, Anatotitan, the "giant duck.") Olorotitan had a relatively long neck compared to other hadrosaurs, as well as a tall, pointed crest on its head. See an in-depth profile of Olorotitan
Orthomerus
Name
Orthomerus (Greek for "straight femur"); pronounced OR-thoh-MARE-us
Habitat
Woodlands of western Europe
Historical Period
Late Cretaceous (70-65 million years ago)
Size and Weight
About 15 feet long and 1,0000-2,000 pounds
Diet
Plants
Distinguishing Characteristics
Moderate size; crest on the head; occasional bipedal posture
The Netherlands isn't exactly a hotbed of dinosaur discovery, which may be the most distinctive thing Orthomerus has going for it: the "type fossil" of this late Cretaceous hadrosaur was discovered near the city of Maastricht in the late 19th century. Unfortunately, the weight of opinion today is that Orthomerus was actually the same dinosaur as Telmatosaurus; one Orthomerus species (O. transylanicus, discovered in Hungary) was actually used as the basis of this better-known duckbill genus. Like many genera named by early paleontologists (in this case the Englishman Harry Seeley), Orthomerus now languishes on the fringes of nomen dubium territory.
Ouranosaurus
Ouranosaurus is a strange duck: this is the only known hadrosaur to have sported a prominent growth along its back, which may have been a thin sail of skin or a fatty hump. Pending more fossil discoveries, we may never know what this structure looked like, or what purpose it served. Check out our in-depth profile of Ouranosaurus for more.
Pararhabdodon
Name
Pararhabdodon (Greek for "like Rhabdodon"); pronounced PAH-rah-RAB-doe-don
Habitat
Woodlands of western Europe
Historical Period
Late Cretaceous (70-65 million years ago)
Size and Weight
About 20 feet long and 2-3 tons
Diet
Plants
Distinguishing Characteristics
Possible frill; occasional bipedal posture
Although it was named in reference to Rhabdodon, an ornithopod dinosaur that preceded it by a few million years, Pararhabdodon was a different kind of beast entirely: a lambeosaurine hadrosaur, or duck-billed dinosaur, closely related to the Asian Tsintaosaurus. Pararhabdodon is often depicted with an elaborate head crest, similar to that of its better-attested Chinese cousin, but since only fragments of its skull have been discovered (in Spain) this amounts to sheer speculation. The exact classification of this dinosaur is still disputed, a situation that can only be resolved by future fossil discoveries.
Parasaurolophus
Parasaurolophus was distinguished by its long, curved, backward-pointing crest, which paleontologists now believed funneled air in short blasts, like a trumpet--to alert other members of the herd to nearby predators, or possibly for mating displays. See article on Parasaurolophus for more about this dinosaur.
Probactrosaurus
Name:
Probactrosaurus (Greek for "before Bactrosaurus"); pronounced PRO-back-tro-SORE-us
Habitat:
Woodlands of Asia
Historical Period:
Early Cretaceous (110-100 million years ago)
Size and Weight:
About 18 feet long and 1-2 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; narrow snout with flat cheek teeth; occasional bipedal posture
As you've probably guessed, Probactrosaurus was named in reference to Bactrosaurus, a well-known hadrosaur of late Cretaceous Asia. Unlike its more famous namesake, though, Probactrosaurus' status as a true hadrosaur remains in some doubt: technically, this dinosaur has been described as an "iguanodont hadrosauroid," a mouthful that simply means it was perched midway between the Iguanodon-like ornithopods of the early Cretaceous period and the classic hadrosaurs that appeared millions of years later.
Prosaurolophus
Name:
Prosaurolophus (Greek for "before the crested lizards"); pronounced PRO-sore-OLL-oh-fuss
Habitat:
Woodlands of North America
Historical Period:
Late Cretaceous (75 million years ago)
Size and Weight:
About 30 feet long and three tons
Diet:
Plants
Distinguishing Characteristics:
Large size; minimal crest on head
As you might have guessed from its name, Prosaurolophus ("before Saurolophus") is a good candidate for the common ancestor of both Saurolophus and the more famous Parasaurolophus (which lived a few million years later). All three of these beasts were hadrosaurs, or duck-billed dinosaurs, large, occasionally bipedal quadrupeds that grazed vegetation off the forest floor. Given its evolutionary precedence, Prosaurolophus had a minimal head crest compared to its descendants — a mere bump, really, which later expanded in Saurolophus and Parasaurolophus into the huge, ornate, hollow structures used to signal herd members from miles away.
Rhinorex
Name
Rhinorex (Greek for "nose king"); pronounced RYE-no-rex
Habitat
Swamps of North America
Historical Period
Late Cretaceous (75 million years ago)
Size and Weight
About 30 feet long and 4-5 tons
Diet
Plants
Distinguishing Characteristics
Larges size; fleshy protuberance on the nose
It sounds like a brand of nasal decongestant, but the newly announced Rhinorex ("nose king") was actually a hadrosaur, or duck-billed dinosaur, equipped with an unusually thick and prominent nose. A close relative of the similarly big-nosed Gryposaurus, and only distinguishable from it by finer points of anatomy, Rhinorex is one of the few hadrosaurs to be discovered in southern Utah, pointing to a more complex ecosystem in this region than had been previously imagined. As for Rhinorex's prominent schnozz, that probably evolved as a means of sexual selection--perhaps male Rhinorex with bigger noses were more attractive to females--as well as intra-herd vocalization; it's unlikely that this duckbill had a particularly well-developed sense of smell.
Sahaliyania
Name
Sahaliyania (Manchurian for "black"); pronounced SAH-ha-lee-ON-ya
Habitat
Woodlands of eastern Asia
Historical Period
Late Cretaceous (70-65 million years ago)
Size and Weight
Undisclosed
Diet
Plants
Distinguishing Characteristics
Small head; bulky torso; occasional bipedal posture
The Amur River, which sets the boundary between China and the eastern reaches of Russia, has proven a rich source of duck-billed dinosaur fossils. Diagnosed in 2008 on the basis of a single, partial skull, the late Cretaceous Sahaliyania appears to have been a "lambeosaurine" hadrosaur, meaning it was similar in appearance to its close cousin Amurosaurus. Pending further fossil discoveries, the most notable thing about this dinosaur may be its name, Manchurian for "black" (the Amur River is known in China as the Black Dragon River, and in Mongolia as the Black River).
Saurolophus
Name:
Saurolophus (Greek for "crested lizard"); pronounced sore-OLL-oh-fuss
Habitat:
Woodlands of North America and Asia
Historical Period:
Late Cretaceous (70 million years ago)
Size and Weight:
About 35 feet long and three tons
Diet:
Plants
Distinguishing Characteristics:
Triangular, backward-pointing crest on head
A typical hadrosaur, or duck-billed dinosaur, Saurolophus was a four-legged, ground-hugging herbivore with a prominent crest on its head that it probably used to signal sexual availability to other members of the herd or alert them to danger. This is also one of the few hadrosaur genera known to have lived on two continents; fossils have been found in both North America and Asia (the Asian specimens being slightly bigger). Saurolophus shouldn't be confused with its more famous cousin, Parasaurolophus, which had a much bigger crest and likely could be heard across much longer distances. (We won’t even mention the truly obscure Prosaurolophus, which may have been the ancestor of both Saurolophus and Parasaurolophus!)
The "type fossil" of Saurolophus was discovered in Alberta, Canada, and officially described by the famous paleontologist Barnum Brown in 1911 (which explains why Parasaurolophus and Prosaurolophus, identified later, were both named in reference to this duckbill). Technically, although Saurolophus is classified under the hadrosaur umbrella, paleontologists have granted its primacy in its own subfamily, the "saurolophinae," which also includes such famous genera as Shantungosaurus, Brachylophosaurus and Gryposaurus.
Secernosaurus
Name:
Secernosaurus (Greek for "separated lizard"); pronounced seh-SIR-no-SORE-us
Habitat:
Woodlands of South America
Historical Period:
Late Cretaceous (70-65 million years ago)
Size and Weight:
About 10 feet long and 500-1,000 pounds
Diet:
Plants
Distinguishing Characteristics:
Moderate size; longer hind than front legs
As a rule, hadrosaurs were mostly confined to late Cretaceous North America and Eurasia, but there were some strays, as witness the discovery of Secernosaurus in Argentina. This small- to medium-sized herbivore (only about 10 feet long and weighing 500 to 1,000 pounds) was very similar to the bigger Kritosaurus from further north, and one recent paper makes the case that at least one presumed species of Kritosaurus properly belongs under the Secernosaurus umbrella. Reconstructed from scattered fossils, Secernosaurus remains a very mysterious dinosaur; our understanding of it should be helped by future South American hadrosaur discoveries.
Shantungosaurus
Name:
Shantungosaurus (Greek for "Shantung lizard"); pronounced shan-TUNG-oh-SORE-us
Habitat:
Woodlands of Asia
Historical Period:
Late Cretaceous (70-65 million years ago)
Size and Weight:
About 50 feet long and 15 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; long, flat beak
Not only was Shantungosaurus one of the biggest hadrosaurs that ever lived; at 50 feet from head to tail and 15 or so tons, this was one of the biggest ornithischian dinosaurs (saurischians, the other main dinosaur family, included even bigger sauropods and titanosaurs like Seismosaurus and Brachiosaurus, which weighed three or four times as much as Shantungosaurus).
The only complete skeleton of Shantungosaurus to date has been assembled from the remains of five individuals, whose bones were found mixed together in the same fossil bed in China. This is a good clue that these giant hadrosaurs roamed the woodlands of eastern Asia in herds, probably to avoid being preyed on by hungry tyrannosaurs and raptors — who could conceivably have taken down a full-grown Shantungosaurus if they hunted in packs, and would certainly have set their sights on the less bulky juveniles.
By the way, although Shantungosaurus lacked any dental equipment in the front of its jaws, the inside of its mouth was packed with over a thousand tiny, jagged teeth, which came in handy for shredding the tough vegetation of the late Cretaceous period. One of the reasons this dinosaur was so big was that it needed literally yards and yards of intestines to process its vegetable diet, and you can only pack so many guts into a certain volume!
Tanius
Name:
Tanius ("of Tan"); pronounced TAN-ee-us
Habitat:
Woodlands of eastern Asia
Historical Period:
Late Cretaceous (80-65 million years ago)
Size and Weight:
About 30 feet long and 2-3 tons
Diet:
Plants
Distinguishing Characteristics:
Long, stiff tail; longer hind than front legs
Represented by a single, headless fossil discovered in China in 1923 (by the paleontologist H.C. Tan, hence its name), Tanius was very similar to its fellow Asian duck-billed dinosaur Tsintaosaurus, and may yet wind up being assigned as a specimen (or species) of that genus. To judge by its surviving bones, Tanius was a typical hadrosaur of the late Cretaceous period, a long, low-slung plant eater that may have been capable of running on its two hind legs when threatened. Since its skull is lacking, we don't know if Tanius possessed the ornate head crest sported by Tsintaosaurus.
Telmatosaurus
Name:
Telmatosaurus (Greek for "marsh lizard"); pronounced tel-MAT-oh-SORE-us
Habitat:
Woodlands of Europe
Historical Period:
Late Cretaceous (70-65 million years ago)
Size and Weight:
About 15 feet long and 1,000-2,000 pounds
Diet:
Plants
Distinguishing Characteristics:
Small size; Iguanodon-like appearance
The relatively obscure Telmatosaurus is important for two reasons: first, it's one of the few hadrosaurs, known to have lived in central Europe (most species roamed the woodlands of North America and Asia), and second, its relatively simple body plan bears a distinct resemblance to the iguanodonts, a family of ornithopod dinosaurs (hadrosaurs are technically included under the ornithopod umbrella) typified by Iguanodon.
What's paradoxical about the seemingly less-evolved Telmatosaurus is that it lived during the end stages of the Cretaceous period, shortly before the mass extinction that wiped out the dinosaurs. The probable explanation for this is that this genus occupied one of the marshy islands that dotted central Europe tens of millions of years ago, and so was "out of step" with general dinosaur evolutionary trends.
Tethyshadros
The paleontologist who named Tethyshadros theorizes that the ancestors of this Italian duck-billed dinosaur migrated to the Mediterranean coastline from Asia, hopping and skipping across the shallow islands dotting the Tethys Sea. See an in-depth profile of Tethyshadros
Tsintaosaurus
Name:
Tsintaosaurus (Greek for "Tsintao lizard"); pronounced JING-dow-SORE-us
Habitat:
Woodlands of China
Historical Period:
Late Cretaceous (80 million years ago)
Size and Weight:
About 30 feet long and three tons
Diet:
Plants
Distinguishing Characteristics:
Large size; single, narrow crest jutting out from skull
The hadrosaurs of the late Cretaceous period sported all kinds of weird head ornaments, some of which (such as the backward-curving crests of Parasaurolophus and Charonosaurus) were used as communication devices. It's unknown as yet why Tsingtaosaurus had a single, narrow crest (some paleontologists describe it as a horn) jutting out of the top of its head, or whether this structure may have supported a sail or other type of display. Its strange crest aside, the three-ton Tsintaosaurus was one of the largest hadrosaurs of its day, and like others of its breed, it probably roamed the plains and woodlands of eastern Asia in sizable herds.
Velafrons
Name:
Velafrons (Greek for "sailed forehead"); pronounced VEL-ah-fronz
Habitat:
Woodlands of southern North America
Historical Period:
Late Cretaceous (75 million years ago)
Size and Weight:
About 30 feet long and 2-3 tons
Diet:
Plants
Distinguishing Characteristics:
Large size; prominent crest on head; occasional bipedal posture
One of the latest additions to the hadrosaur family, there's not much to say about Velafrons except that it was very similar to two better-known North American genera, Corythosaurus and Hypacrosaurus. Like its fellow, dim-witted herbivores, Velafrons was distinguished by an ornate crest on its head, which was likely used to produce sounds (and may, secondarily, have been a sexually selected characteristic). Also, despite its impressive size (about 30 feet long and three tons), Velafrons was capable of running away on its two hind legs when it was startled by raptors or tyrannosaurs.
Wulagasaurus
Name
Wulagasaurus ("Wulaga lizard"); pronounced woo-LAH-gah-SORE-us
Habitat
Woodlands of Asia
Historical Period
Late Cretaceous (70 million years ago)
Size and Weight
Undisclosed
Diet
Plants
Distinguishing Characteristics
Occasional bipedal posture; duck-like bill
In the past decade, the Amur River (which separates the easternmost reaches of Russia from the northernmost reaches of China) has proven a rich source of hadrosaur fossils. One of the latest duck-billed dinosaurs on the block, discovered at the same time as Sahaliyania, is Wulagasaurus, which oddly enough was most closely related to the North American hadrosaurs Maiasaura and Brachylophosaurus. The importance of Wulagasaurus is that it's one of the earliest identified "saurolophine" hadrosaurs and thus lends weight to the theory that duckbills originated in Asia and migrated west toward Europe and east, via the Bering land bridge, toward North America.
Zhanghenglong
Name
Zhanghenglong (Chinese for "Zhang Heng's dragon"); pronounced jong-heng-LONG
Habitat
Woodlands of Asia
Historical Period
Late Cretaceous (85 million years ago)
Size and Weight
About 18 feet long and one ton
Diet
Plants
Distinguishing Characteristics
Moderate size; quadrupedal posture; long, narrow head
The last 40 million years of the Cretaceous period presented a neat picture of evolution in action, as the large "iguanodontid ornithopods" (i.e., occasionally bipedal plant-eaters that resembled Iguanodon) gradually morphed into the first true hadrosaurs. The importance of Zhanghenglong is that it was a transitional form between the last iguanodontid ornithopods and the first hadrosaurs, presenting an intriguing mix of these two ornithischian families. This dinosaur, by the way, is named after Zhang Heng, a classical Chinese scholar who died in the second century A.D.
Zhuchengosaurus
Name:
Zhuchengosaurus (Greek for "Zhucheng lizard"); pronounced ZHOO-cheng-oh-SORE-us
Habitat:
Woodlands of Asia
Historical Period:
Early Cretaceous (110-100 million years ago)
Size and Weight:
About 55 feet long and 15 tons
Diet:
Plants
Distinguishing Characteristics:
Enormous size; small front limbs
The impact of Zhuchengosaurus on the dinosaur record books has yet to be determined. Paleontologists aren't quite certain if this 55-foot-long, 15-ton plant-eater should be classified as a gigantic, Iguanodon-like ornithopod, or as one of the first true hadrosaurs. If it winds up in the latter category, the early-to-middle Cretaceous Zhuchengosaurus would supplant Shantungosaurus (which roamed Asia over 30 million years later) as the biggest hadrosaur that ever lived! (Addendum: after further study, paleontologists have concluded that Zhuchengosaurus was really a species of Shantungosaurus after all.)