Prosauropod Dinosaur Pictures and Profiles

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Meet the Prosauropod Dinosaurs of the Mesozoic Era

jingshanosaurus
Jingshanosaurus. Flickr

Prosauropods were the small, ancient, bipedal progenitors of the giant, four-legged sauropods and titanosaurs that dominated the later Mesozoic Era. On the following slides, you'll find pictures and detailed profiles of over 30 prosauropod dinosaurs, ranging from Aardonyx to Yunnanosaurus.

02
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Aardonyx

aardonyx
Aardonyx. Nobu Tamura

Name:

Aardonyx (Greek for "earth claw"); pronounced ARD-oh-nix

Habitat:

Woodlands of southern Africa

Historical Period:

Early Jurassic (195 million years ago)

Size and Weight:

About 20 feet long and 1,000 pounds

Diet:

Plants

Distinguishing Characteristics:

Long neck and tail; long, low-slung body

 

Only "diagnosed" in 2009 based on two juvenile skeletons, Aardonyx was an early example of a prosauropod--the plant-eating precursors of the huge sauropods of the late Jurassic period. What makes Aardonyx important from an evolutionary perspective is that it seemed to pursue a mostly bipedal lifestyle, dropping occasionally to all fours to feed (or perhaps mate). As such, it captures an "intermediate" stage between the lighter, bipedal herbivorous dinosaurs of the early and middle Jurassic periods and the heavier, quadrupedal plant eaters that evolved later.

 

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Adeopapposaurus

adeopapposaurus
Adeopapposaurus. Nobu Tamura

Name:

Adeopapposaurus (Greek for "far-eating lizard"); pronounced AD-ee-oh-PAP-oh-SORE-us

Habitat:

Woodlands of South America

Historical Period:

Early Jurassic (200 million years ago)

Size and Weight:

About 10 feet long and 150 pounds

Diet:

Plants

Distinguishing Characteristics:

Long neck and tail; horny beak

 

When its type fossil was discovered a couple of years ago in South America, Adeopapposaurus was believed to be a species of a more famous prosauropod of the early Jurassic period, the African Massospondylus. Later analysis showed that this medium-sized herbivore deserved its own genus, though its close relationship to Massospondylus remains beyond dispute. Like other prosauropods, Adeopapposaurus possessed a long neck and tail (though nowhere near as long as the necks and tail of later sauropods), and it was probably capable of walking on two feet when circumstances demanded.

 

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Anchisaurus

anchisaurus
Anchisaurus. Wikimedia Commons

The famous paleontologist Othniel C. Marsh identified Anchisaurus as a dinosaur in 1885, though its exact classification couldn't be pinned down until more was known about the evolution of sauropods and prosauropods. See an in-depth profile of Anchisaurus

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Antetonitrus

antetonitrus
Antetonitrus. Eduardo Camarga

Name:

Antetonitrus (Greek for "before the thunder"); pronounced AN-tay-tone-EYE-truss

Habitat:

Woodlands of Africa

Historical Period:

Late Triassic (215-205 million years ago)

Size and Weight:

About 30 feet long and two tons

Diet:

Plants

Distinguishing Characteristics:

Long neck; thick trunk; grasping toes on feet

 

You'd have to be in the know to get the joke, but the person who named Antetonitrus ("before the thunder") was making a coy reference to Brontosaurus ("thunder lizard"), which has since been renamed Apatosaurus. As a matter of fact, this Triassic plant-eater was once thought to be a specimen of Euskelosaurus, until paleontologists took a closer look at the bones and realized they might be looking at the first-ever true sauropod. In fact, Antetonitrus seems to have possessed anatomical characteristics reminiscent of both prosauropods ("before the sauropods"), such as movable toes, and sauropods, such as relatively small feet and long, straight thigh bones. Like its sauropod descendants, this dinosaur was almost certainly limited to a quadrupedal posture.

 

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Arcusaurus

arcusaurus
Arcusaurus. Nobu Tamura

Name

Arcusaurus (Greek for "rainbow lizard"); pronounced ARE-koo-SORE-us

Habitat

Woodlands of southern Africa

Historical Period

Early Jurassic (200-190 million years ago)

Size and Weight

Undisclosed

Diet

Plants

Distinguishing Characteristics

Long neck; occasional bipedal posture

 

Way back during the late Triassic and early Jurassic periods, southern Africa teemed with prosauropods, the distant cousins of the giant sauropods that arrived on the scene tens of millions of years later. Recently discovered in South Africa, Arcusaurus was a contemporary of Massospondylus and  a close relative of the better-known Efraasia, which is somewhat surprising since this latter dinosaur lived at least 20 million years earlier. (Exactly what this means for theories of sauropod evolution is still a matter of debate!) By the way, the name Arcusaurus--Greek for "rainbow lizard"--doesn't refer to this dinosaur's bright coloring, but to Archbishop Desmond Tutu's characterization of South Africa as the "Rainbow Nation."

 

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Asylosaurus

asylosaurus
Asylosaurus. Eduardo Camarga

Name

Asylosaurus (Greek for "unharmed lizard"); pronounced ah-SIE-low-SORE-us

Habitat

Woodlands of western Europe

Historical Period

Late Triassic (210-200 million years ago)

Size and Weight

Undisclosed

Diet

Unknown; possibly omnivorous

Distinguishing Characteristics

Slender build; bipedal posture

 

Its name may be the most interesting thing about Asylosaurus: this dinosaur's moniker translates from the Greek as "unharmed lizard," a reference to the fact that its remains avoided destruction during World War II when they were shipped to Yale University, while the "type fossil" of its close relative, Thecodontosaurus, was bombed to pieces in England. (Originally, Asylosaurus was assigned as a species of Thecodontosaurus.) Essentially, Asylosaurus was a plain vanilla "sauropodomorph" of late Triassic England, from a time when these ancient ancestors of the sauropods didn't look all that much different from their meat-eating cousins.

 

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Camelotia

camelotia
Camelotia. Nobu Tamura

Name

Asylosaurus (Greek for "unharmed lizard"); pronounced ah-SIE-low-SORE-us

Habitat

Woodlands of western Europe

Historical Period

Late Triassic (210-200 million years ago)

Size and Weight

Undisclosed

Diet

Unknown; possibly omnivorous

Distinguishing Characteristics

Slender build; bipedal posture

 

Its name may be the most interesting thing about Asylosaurus: this dinosaur's moniker translates from the Greek as "unharmed lizard," a reference to the fact that its remains avoided destruction during World War II when they were shipped to Yale University, while the "type fossil" of its close relative, Thecodontosaurus, was bombed to pieces in England. (Originally, Asylosaurus was assigned as a species of Thecodontosaurus.) Essentially, Asylosaurus was a plain vanilla "sauropodomorph" of late Triassic England, from a time when these ancient ancestors of the sauropods didn't look all that much different from their meat-eating cousins.

 

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Efraasia

efraasia
Efraasia (Nobu Tamura).

Name:

Efraasia (Greek for "Fraas' lizard"); pronounced eff-FRAY-zha

Habitat:

Woodlands of central Europe

Historical Period:

Late Triassic (215-205 million years ago)

Size and Weight:

About 20 feet long and one ton

Diet:

Plants

Distinguishing Characteristics:

Slender trunk; long fingers on hands

 

Efraasia is one of those dinosaurs that paleontologists would rather file in a back cabinet, in some dusty museum, and forget. This Triassic-period herbivore has been misidentified a record number of times--first as a crocodilian, then as a specimen of Thecodontosaurus, and finally as a juvenile Sellosaurus. By 2000 or so, Efraasia had been conclusively identified as an early prosauropod, the evolutionary branch it occupied eventually giving rise to the giant sauropods of the late Jurassic period. This dinosaur is named after Eberhard Fraas, the German paleontologist who first unearthed its fossil.

 

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Euskelosaurus

euskelosaurus
Euskelosaurus. Getty Images

Name:

Euskelosaurus (Greek for "well-limbed lizard"); pronounced YOU-skell-oh-SORE-us

Habitat:

Woodlands of Africa

Historical Period:

Late Triassic (225-205 million years ago)

Size and Weight:

About 30 feet long and two tons

Diet:

Plants

Distinguishing Characteristics:

Thick trunk; long neck and tail

 

Fifty million years before its sauropod descendants roamed the earth, Euskelosaurus--which is classified as a prosauropod, or "before the sauropods"--must have been a common sight in the woodlands of Africa, judging by the number of fossils that have been recovered there. This was the first dinosaur ever to be discovered in Africa, in the mid-1800's, and at 30 feet long and two tons it was certainly one of the largest land creatures of the Triassic period. Euskelosaurus was a close relative of two other large prosauropods, Riojasaurus in South America and its fellow African plant-eater Melanorosaurus.

 

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Glacialisaurus

glacialisaurus
Glacialisaurus. William Stout

Name

Glacialisaurus (Greek for "frozen lizard"); pronounced GLAY-shee-AH-lah-SORE-us

Habitat

Plains of Antarctica

Historical Period

Early Jurassic (190 million years ago)

Size and Weight

About 20 feet long and one ton

Diet

Plants

Distinguishing Characteristics

Slender build; long neck; bipedal posture

 

Only a handful of dinosaurs have been discovered in Antarctica, not because this was an inhospitable place to live during the Mesozoic Era (it was actually rather mild and temperate) but because conditions today make excavation so difficult. What makes Glacialisaurus important is that it's the first prosauropod, or "sauropodomorph," to be identified on this frozen continent, which has given paleontologists valuable insight into the evolutionary relationships of these distant sauropod ancestors. Specifically, Glacialisaurus seems to have been most closely related to the Asian Lufengosaurus, and coexisted with the fearsome predator Cryolophosaurus (which may occasionally have had it for lunch).

 

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Gryponyx

gryponyx
Gryponyx. Getty Images

Name

Gryponyx (Greek for "hooked claw"); pronounced grip-AH-nix

Habitat

Plains of southern Africa

Historical Period

Early Jurassic (200-190 million years ago)

Size and Weight

About 16 feet long and half a ton

Diet

Plants

Distinguishing Characteristics

Slender build; bipedal posture

 

Named by the famous paleontologist Robert Broom in 1911, Gryponyx has never quite cemented its place in the official dinosaur record books--possibly because Broom mistook his find for a type of theropod, whereas later consensus places Gryponyx as a prosauropod, an ancient, slender, bipedal ancestor of the massive sauropods that evolved millions of years later. For much of the past century, Gryponyx has been lumped in with one or another species of Massospondylus, but a more recent analysis claims that this slender African plant-eater may actually deserve its own genus after all.

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Ignavusaurus

ignavusaurus
Ignavusaurus. Wikimedia Commons

Name:

Ignavusaurus (Greek for "cowardly lizard"); pronounced ig-NAY-voo-SORE-us

Habitat:

Woodlands of Africa

Historical Period:

Early Jurassic (190 million years ago)

Size and Weight:

About five feet long and 50-75 pounds

Diet:

Plants

Distinguishing Characteristics:

Small size; long neck and tail

 

Despite its name--Greek for "cowardly lizard"--there's no reason to believe that Ignavusaurus was any less brave than any other early prosauropod, the ancient cousins and distant progenitors of the sauropods (though at only five feet long and 50 to 75 pounds, this gentle herbivore would have made a quick snack for the larger and hungrier theropods of its day). The "coward" part of its moniker actually derives from the region of Africa where this dinosaur's remains were found, the name of which translates roughly as "home of the coward's father."

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Jingshanosaurus

jingshanosaurus
Jingshanosaurus. Flickr

Name:

Jingshanosaurus (Greek for "Jingshan lizard"); pronounced JING-shan-oh-SORE-us

Habitat:

Woodlands of Asia

Historical Period:

Early Jurassic (190 million years ago)

Size and Weight:

About 30 feet long and 1-2 tons

Diet:

Plants

Distinguishing Characteristics:

Large size; long neck and tail

 

One of the largest prosauropods--the herbivorous, four-footed, distant uncles of the later sauropods--ever to walk the earth, Jingshanosaurus tipped the scales at a respectable one to two tons and was about 30 feet long (by comparison, most prosauropods of the early Jurassic period only weighed a few hundred pounds). As you might guess from its advanced size, Jingshanosaurus was also among the last of the prosauropods, an honor it shares with its fellow Asian plant-eater Yunnanosaurus. (It may yet be the case that Jingshanosaurus will be reassigned as a species of this more well-known prosauropod, pending further fossil evidence.)

 

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Leonerasaurus

leonerasaurus
Leonerasaurus. Wikimedia Commons

Name

Leonerasaurus (Greek for "Leoneras lizard"); pronounced LEE-oh-NEH-rah-SORE-us

Habitat

Woodlands of South America

Historical Period

Middle Jurassic (185-175 million years ago)

Size and Weight

Undisclosed

Diet

Plants

Distinguishing Characteristics

Long neck and tail; longer hind than front legs

 

At some point during the early Jurassic period, the most advanced prosauropods (or "sauropodomorphs") started to evolve into the true sauropods that dominated the world's continents millions of years later. The recently discovered Leonerasaurus possessed a unique and confusing combination of basal (i.e., primitive) and derived (i.e., advanced) characteristics, the most important of the latter being the four vertebrae connecting its pelvis to its spine (most prosauropods had only three), and the most important of the former being its relatively puny size. For now, paleontologists have classified Leonerasaurus as a close relative of Anchisaurus and Aardonyx, and very close to the emergence of the first true sauropods.

 

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Lessemsaurus

lessemsaurus
Lessemsaurus. Wikimedia Commons

Name:

Lessemsaurus (Greek for "Lessem's lizard"); pronounced LESS-em-SORE-us

Habitat:

Woodlands of South America

Historical Period:

Late Triassic (210 million years ago)

Size and Weight:

About 30 feet long and two tons

Diet:

Plants

Distinguishing Characteristics:

Large size; long neck and tail; bipedal posture

 

Described by the famous Argentinean paleontologist Jose Bonaparte in 1999--who named his find after the popular dinosaur-book author and science popularizer Don Lessem--Lessemsaurus was one of the largest prosauropods of late Triassic South America, measuring a full 30 feet from head to tail and weighing in the neighborhood of two tons (which still wasn't much compared to the giant sauropods of the late Jurassic period). This plant-eater shared its habitat with, and may have been closely related to, another plus-sized South American prosauropod, the better-known Riojasaurus. Like other prosauropods, Lessemsaurus was distantly ancestral to the giant-sized saurpods and titanosaurs of the later Mesozoic Era.

 

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Leyesaurus

leyesaurus
Leyesaurus. Wikimedia Commons

Name:

Leyesaurus (after the Leyes family that discovered it); pronounced LAY-eh-SORE-us

Habitat:

Woodlands of South America

Historical Period:

Late Triassic (200 million years ago)

Size and Weight:

About 8 feet long and a few hundred pounds

Diet:

Plants

Distinguishing Characteristics:

Low-slung body; long neck and tail

 

Announced to the world in 2011, based on the discovery of a fossilized skull and bits and pieces of leg and backbone, Leyesaurus is the latest addition to the prosauropod roster. (Prosauropods were the slender, plant-eating dinosaurs of the Triassic period whose closest cousins evolved into the gigantic sauropods of the Jurassic and Cretaceous.) Leyesaurus was comparatively more advanced than the much earlier Panphagia, and about on a par with the contemporary Massospondylus, to which it was closely related. Like other prosauropods, the slender Leyesaurus was probably capable of sprinting on its hind legs when pursued by predators, but otherwise spent its time on all fours, nibbling low-lying vegetation.

 

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Lufengosaurus

lufengosaurus
Lufengosaurus. Wikimedia Commons

Name:

Lufengosaurus (Greek for "Lufeng lizard"); pronounced loo-FENG-oh-SORE-us

Habitat:

Woodlands of Asia

Historical Period:

Early Jurassic (200-180 million years ago)

Size and Weight:

About 20 feet long and two tons

Diet:

Plants

Distinguishing Characteristics:

Long neck and tail; quadrupedal posture

 

An otherwise unremarkable prosauropod (the line of quadrupedal, herbivorous dinosaurs that preceded the giant sauropods) of the late Jurassic period, Lufengosaurus had the honor of being the first dinosaur ever mounted and displayed in China, an event that was commemorated in 1958 with an official postage stamp. Like other prosauropods, Lufengosaurus probably nibbled on the low-lying branches of trees, and may have been capable of (occasionally) rearing up on its hind legs. About 30 more-or-less complete Lufengosaurus skeletons have been assembled, making this herbivore a common exhibit in China's natural history museums.

 

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Massospondylus

massospondylus
Massospondylus. Nobu Tamura

In the past few years, convincing evidence has come to light that the prosauropod dinosaur Massospondylus was primarily (and not only occasionally) bipedal, and thus faster and more agile than was previously believed. See an in-depth profile of Massospondylus

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Melanorosaurus

melanorosaurus
Melanorosaurus. Wikimedia Commons

Name:

Melanorosaurus (Greek for "Black Mountain lizard"); pronounced meh-LAN-oh-roe-SORE-us

Habitat:

Woodlands of South Africa

Historical Period:

Late Triassic (225-205 million years ago)

Size and Weight:

About 35 feet long and 2-3 tons

Diet:

Plants

Distinguishing Characteristics:

Large size; thick legs; occasional bipedal posture

 

Just as its distant cousins, the sauropods, dominated the later Jurassic and Cretaceous periods, Melanorosaurus was one of the largest prosauropods of the Triassic period, and very possibly the largest land creature on the face of the earth 220 million years ago. Save for its relatively short neck and tail, Melanorosaurus displayed all the nascent adaptations typical of later sauropods, including a heavy trunk and sturdy, tree-trunk-like legs. It was probably a close relative of another contemporary South American prosauropod, Riojasaurus.

 

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Mussaurus

mussaurus
Mussaurus. Getty Images

Name:

Mussaurus (Greek for "mouse lizard"); pronounced moo-SORE-us

Habitat:

Woodlands of South America

Historical Period:

Late Triassic (215 million years ago)

Size and Weight:

About 10 feet long and 200-300 pounds

Diet:

Plants

Distinguishing Characteristics:

Small size; long neck and tail; occasional bipedal posture

 

The name Mussaurus ("mouse lizard") is a bit of a misnomer: when the famous paleontologist Jose Bonaparte discovered this Argentinean dinosaur in the 1970's, the only skeletons he identified were of newly hatched juveniles, which measured a mere foot or so from head to tail. Later, Bonaparte established that these hatchlings were actually prosauropods--distant Triassic cousins of the gigantic sauropods of the late Jurassic period--that grew to lengths of about 10 feet and weights of 200 to 300 pounds, much bigger than any mouse you're likely to encounter today!

 

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Panphagia

panphagia
Panphagia. Nobu Tamura

Name:

Panphagia (Greek for "eats everything"); pronounced pan-FAY-gee-ah

Habitat:

Woodlands of South America

Historical Period:

Middle Triassic (230 million years ago)

Size and Weight:

About six feet long and 20-30 pounds

Diet:

Probably omnivorous

Distinguishing Characteristics:

Small size; bipedal stance; long tail

 

Sometime in the middle Triassic period, probably in South America, the very first "sauropodomorphs" (also known as prosauropods) diverged from the earliest theropods. Panphagia is as good a candidate as any for this important transitional form: this dinosaur shared some important characteristics with early theropods like Herrerasaurus and Eoraptor (notably in its small size and bipedal posture), but also had some traits in common with early prosauropds like Saturnalia, not to mention the giant sauropods of the late Jurassic period. Panphagia's name, Greek for "eats everything," refers to its presumed omnivorous diet, which would make sense for a dinosaur perched between the carnivorous theropods that preceded it and the herbivorous prosauropods and sauropods that came after.

 

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Plateosaurus

plateosaurus
Plateosaurus. Alain Beneteau

Because so many fossil specimens have been discovered in western Europe, paleontologists believe Plateosaurus roamed the late Triassic plains in sizable herds, literally eating their way across the landscape. See an in-depth profile of Plateosaurus

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Riojasaurus

riojasaurus
The skull of Riojasaurus. Wikimedia Commons

Name:

Riojasaurus (Greek for "La Rioja lizard"); pronounced ree-OH-hah-SORE-us

Habitat:

Woodlands of South America

Historical Period:

Late Triassic (215-205 million years ago)

Size and Weight:

About 35 feet long and 10 tons

Diet:

Plants

Distinguishing Characteristics:

Large size; quadrupedal posture

 

As far as paleontologists can tell, Riojasaurus represents an intermediate stage between the small prosauropods of the Triassic period (such as Efraasia and Camelotia) and the huge sauropods of the Jurassic and Cretaceous periods (typified by such giants as Diplodocus and Brachiosaurus). This prosauropod was very large for its time--one of the biggest animals to roam South America during the late Triassic period--with the long neck and tail characteristic of later sauropods. Its closest relative was probably the south African Melanorosaurus (South America and Africa being joined together in the supercontinent Gondwana 200 million years ago).

 

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Sarahsaurus

sarahsaurus
Sarahsaurus. Matt Colbert & Tim Rowe

The amusingly named Sarahsaurus possessed unusually strong, muscular hands capped by prominent claws, the kind of adaptation you'd expect to see in a ravenous meat-eating dinosaur rather than a gentle prosauropod. See an in-depth profile of Sarahsaurus

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Saturnalia

saturnalia
Saturnalia. University of Maryland

Name:

Saturnalia (after the Roman festival); pronounced SAT-urn-AL-ya

Habitat:

Woodlands of South America

Historical Period:

Mid-Late Triassic (225-220 million years ago)

Size and Weight:

About five feet long and 25 pounds

Diet:

Plants

Distinguishing Characteristics:

Small head; slender legs

 

Saturnalia (named, because of the time of year it was discovered, after the famous Roman festival) is one of the earliest plant-eating dinosaurs yet discovered, but aside from that its exact place on the dinosaur evolutionary tree is a matter of dispute. Some experts classify Saturnalia as a prosauropod (the line of small, slender plant eaters distantly related to the giant sauropods of the Jurassic and Cretaceous periods), while other maintain that its anatomy is too "undifferentiated" to merit this conclusion and simply lump it in with the earliest dinosaurs. Whatever the case, Saturnalia was much smaller than most of the herbivorous dinosaurs that succeeded it, only about the size of a small deer.

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Seitaad

seitaad
Seitaad. Nobu Tamura

Name:

Seitaad (after a Navajo deity); pronounced SIGH-tad

Habitat:

Plains of North America

Historical Period:

Middle Jurassic (185 million years ago)

Size and Weight:

About 15 feet long and 200 pounds

Diet:

Plants

Distinguishing Characteristics:

Small size; long legs, neck and tail

 

Seitaad is one of those dinosaurs that's more famous for how it died than for how it lived: the near-complete fossil of this deer-sized reptile (lacking only the head and tail) was found curled up in a way that indicates it was buried alive in a sudden avalanche, or possibly caught inside a collapsing sand dune. Aside from its dramatic demise, Seitaad is important for being one of the earliest prosauropods yet discovered in North America. Prosauropods (or sauropodomorphs, as they're also called) were small, occasionally bipedal herbivores that were distantly ancestral to the giant sauropods of the late Jurassic period, and coexisted with the earliest theropods.

 

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Sellosaurus

sellosaurus
Sellosaurus. Wikimedia Commons

Name:

Sellosaurus (Greek for "saddle lizard"); pronounced SELL-oh-SORE-us

Habitat:

Woodlands of western Europe

Historical Period:

Late Triassic (220-208 million years ago)

Size and Weight:

About 10 feet long and 500 pounds

Diet:

Plants

Distinguishing Characteristics:

Bulky torso; five-fingered hands with large thumb claws

 

It sounds like the caption to a New Yorker cartoon--"Now get out there and be a Sellosaurus!"--but this early herbivorous dinosaur of the Triassic period was in fact a fairly typical prosauropod, the remote precursors of huge plant-eaters like Diplodocus and Argentinosaurus. Sellosaurus is fairly well represented in the fossil record, with over 20 partial skeletons cataloged so far. It was once thought that Sellosaurus was the same animal as Efraasia--another Triassic prosauropod--but now most paleontologists believe that this dinosaur is best classified as a species of another famous prosauropod, Plateosaurus.

 

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Thecodontosaurus

thecodontosaurus
Thecodontosaurus. Wikimedia Commons

Thecodontosaurus was discovered very early in the modern history of dinosaurs, in southern England in 1834--and was only the fifth dinosaur ever to receive a name, after Megalosaurus, Iguanodon, Streptospondylus and the now-dubious Hylaeosaurus. See an in-depth profile of Thecodontosaurus

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Unaysaurus

unaysaurus
Unaysaurus. Joao Boto

Name:

Unaysaurus (indigenous/Greek for "black water lizard"); pronounced OO-nay-SORE-us

Habitat:

Woodlands of South America

Historical Period:

Late Triassic (225-205 million years ago)

Size and Weight:

About eight feet long and 200 pounds

Diet:

Plants

Distinguishing Characteristics:

Small size; probably bipedal posture

 

As far as paleontologists can tell, the first meat-eating dinosaurs evolved in South America about 230 million years ago--and these small theropods then branched off into the very first prosauropods, or "sauropodomorphs," the ancient cousins of the giant sauropods and titanosaurs of the Jurassic and Cretaceous periods. Unaysaurus may well have been one of the first true prosauropods, a slender, 200-pound plant-eater that probably spent much of its time walking on two legs. This dinosaur was closely related to Plateosaurus, a slightly later (and much more famous) prosauropod of late Triassic western Europe.

 

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Yimenosaurus

yimenosaurus
Yimenosaurus. Wikimedia Commons

Name:

Yimenosaurus (Greek for "Yimen lizard"); pronounced yih-MEN-oh-SORE-us

Habitat:

Woodlands of Asia

Historical Period:

Early Jurassic (190 million years ago)

Size and Weight:

About 30 feet long and two tons

Diet:

Plants

Distinguishing Characteristics:

Large size; long neck and tail; occasional bipedal posture

 

Along with its close contemporary, Jingshanosaurus, Yimenosaurus was one of the largest prosauropods of the Mesozoic Era, measuring about 30 feet from head to tail and weighing as much as two tons--not much compared to the plus-sized sauropods of the late Jurassic period, but beefier than most other prosauropods, which only weighed a few hundred pounds. Thanks to its numerous (and near-complete) fossil remains, Yimenosaurus is one of the better known plant-eating dinosaurs of early Jurassic Asia, rivaled only by another Chinese prosauropod, Lufengosaurus.

 

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Yunnanosaurus

yunnanosaurus
Yunnanosaurus. Getty Images

Name:

Yunnanosaurus (Greek for "Yunnan lizard"); pronounced you-NAN-oh-SORE-us

Habitat:

Woodlands of Asia

Historical Period:

Early Jurassic (200-185 million years ago)

Size and Weight:

About 23 feet long and one ton

Diet:

Plants

Distinguishing Characteristics:

Slender build; long neck and tail; sauropod-like teeth

 

Yunnanosaurus is important for two reasons: first, this is one of the latest prosauropods (the distant cousins of the gigantic sauropods) to be identified in the fossil record, prowling the woodlands of Asia well into the early Jurassic period. And second, the preserved skulls of Yunnanosaurus contain over 60 relatively advanced, sauropod-like teeth, an unexpected development in such an early dinosaur (and one that may well have been the result of convergent evolution). The closest relative of Yunnanosaurus appears to have been another Asian prosauropod, Lufengosaurus.