"Terrible plant-eating lizards"

From about 240 to 65 million years ago, dinosaurs roamed the Earth. They were a group of reptiles (cold-blooded animals who had a backbone), with scaly skin, and they laid eggs. They were first called "dinosaurs" in 1841 by Dr Richard Owen - the word is Greek and means "terrible lizard". The earliest dinos had deadly, slashing teeth and claws which they used to kill, and eat other reptiles. These were the carnivores and they liked their meat.

"We've vegetarians now, thanks very much"

Among their prey was the new breed of herbivore (plant-eating) dinosaurs which evolved from one or more breed of predatory dinosaur during the Triassic Age (248-213 million years ago) and which over the next hundreds of millions of years were to develop into huge, long-necked beasts, with immense armoured protection against the carnivore predators.

"A little of both, please."

There was also a third group of dinosaurs which - like the human beings who were to succeed them many millions of years later - were both meat-eating and plant-eating. These were the omnivores.

Triassic Dino

The Age of Dinosaurs began in the Triassic period (248-213 million years ago). The first-known dinosaurs, in the late Middle Triassic period, evolved from a rabbit-sized creature. By the end of this period, meat-eating dinos were as heavy as cows.

From two legs to four

From the early predatory dinosaurs came plant-eaters and from small bipedal (two-legged) herbivores there emerged four-legged creatures as big as a bus.

Jurassic Dino

In the Jurassic Period (213-144 million years ago - the name comes from the Jura Mountain rocks of France and Switzerland), new, enormous dinosaurs emerged. Herbivores were the prey of megalosaurids, allosaurids and other huge sharp-fanged predators.

Cretaceous Dino

In the last, longest Age (144-65 million years ago), toothless birdlike dinosaurs emerged. Tyrannosaurids, the heaviest land predators, were ranged against new, powerful plant-eaters. At the end of this Age, dinosaurs became extinct.

The sauropods were the largest animals ever known on land. They were plant-eaters and they lived all over the world, from about 185 to 64 million years ago. Their five-toed hands and feet were made like elephants' feet and had a large, fleshy heel.

Prehistoric giraffes

Pillar-like arms and legs supported a body that was bigger than several elephants put together. All of the sauropod dinos had very long necks - they were a sort of prehistoric giraffe - and equally long tails. Their heads were very small compared with their bodies.

A life of non-stop guzzling

As plant-eaters, they probably spent much of their time eating. The sauropods defended themselves against predators by using their long, whiplash tails and large stamping feet.

Believe it or not …

Eating plants gave animals greater problems than eating meat.

Inside the belly of a sauropod

Sauropods had spoon-shaped or peg-shaped teeth with which they cropped leaves. They didn't chew but swallowed raked-in food, which was passed to their stomach where it was digested by "gastroliths" - gizzard stones which they deliberately swallowed to break up their food. Its bulky digestive system helped it to bear its own huge body weight on all fours.

Apatosaurus - "deceptive lizard"

Apatosaurus belonged to a group of sauropods that included Diplodocus, Barosaurus and Mamenchisaurus. Apatosaurus was 23 m (76 ft) long, 5 m (17 ft) high at its hips and weighed 41.3 tonnes (42 tons). For a long time scientists believed that the sauropods were so big and heavy that they could only have lived in water by using their nostrils like a snorkel. The water would have helped to support their weight. But when Apatosaurus footprints were found in rock in Texas, they changed their minds. The huge footprint had not been made in mud deep under water but in sand, damp enough to keep the print sharp.

Among the strangest dinosaurs, the hadrosaurs, or duck-billed dinosaurs, were also some of the last alive on earth. The "duck-bill" nickname comes from their wide, flat, toothless beak, which had a horny cover and was used for biting off twigs and leaves.

Would you wear an inflatable balloon on your head?

Strange though it was, this beak was quite ordinary when compared with some of the head decorations of the duck-bills. Tsintausaurus had a bony spike sticking up from its skull and some hadrosaurs from North America had trumpet-like crests of hollow bone. Saurolophus, from China and North America, had an inflatable balloon of skin over the top of the skull and some hadrosaurs like Edmontosaurus from North America had inflatable areas of skin over the nostrils.

Prehistoric walkie-talkies

These bony crests and blown-up balloons may have been used to "talk" to each other. The inflated skin and bony passages were connected to the nostrils and helped to make loud calls.

I'd know that bony spike anywhere

It was also possible that the shape of bony spikes, like the aerial of Tsintausaurus, would have been a visual signal to other hadrosaurs.

An ancient, exclusive club

The duck-bills were plant-eating dinosaurs that usually walked on broad-footed rear legs. They first appeared about 100 million years ago and lived in eastern Asia and western North America, which were probably connected at the time. The hadrosaurs were a very distinct group of dinosaurs, and were probably later relatives of the group that included Iguanadon.

Biggest hadrosaur ever

Excavated in the Shandong province of eastern China in 1964-8, and 15 m (50 ft) long, Shantungusaurus may have been the largest of the hadrosaurs. This flat-headed giant of the duck-billed world had large, strong, rear legs. Three "hoofed" toes on each foot spread out to carry its weight.

Click here to find out more about Hadrosaurus and the hadrosaurids (a group of hadrosaurs).

Ceratopsians were a group of ornithischian (bird-hipped), herbivorous (plant-eating) dinosaurs with short, deep, parrot-like beaks. These dinosaurs flourished during the Cretaceous period (144-65 million years ago) and their sometimes alarming protective features made them a worthy adversary of ferocious meat-eaters such as T. rex. They were able to tackle tough plants with their extra strong jaws, formidable beaks and scissor-like teeth. There were three subgroups of ceratopsians: protoceratopsids, ceratopsids and psittacosaurids.

Protoceratopsids: frightening or attractive?

Protoceratopsids, such as Protoceratops, Bagaceratops and Microceratops, were relatively small, ranging from 76 cm (30 in) to 3 m (10 ft) long. They had a bony frill around the neck that may have been used to frighten predators, protect the neck, or attract mates; the frill may also have served as an anchor for the jaw muscles. Some species of protocerapsid also had brow ridges and small horns on their noses and cheeks.

Ceratopsids: the big heads - not just frills but horns too

Ceratopsids, such as Torosaurus ("Bull Lizard") and Triceratops ("Three-Horned Face") had neck frills that were larger than protoceratopsids and horns on their brow and nose. In some cases, ceratopsid brow horns were up 90 cm (3 ft) long. These were the rhinoceroses of their time with huge heads (Torosaurus' head, relative to its body, was larger than any other animal's), bulky bodies and pillarlike limbs with hooflike claws. They probably roamed in herds, browsing on low-growing vegetation. When threatened, they charged their enemies.

Psittacosaurids: horns in the cheek

Psittacosaurus, the only psittacosaurid known, was 2 m (6 ft 6 in) long. In addition to the parrot-like ceratopsian beak, it had small cheek horns (though it didn't have a bony neck frill) and its eyes and nostrils were located high up in its head. It had long hindlimbs and strong short forelimbs with blunt claws suitable for walking on or grasping leaves. Its long tail counterbalanced the fore part of its body when it walked or ran.

Prosauropods: small heads with leaf-shaped teeth

The first plant-eaters appeared in Late Triassic time. They most likely evolved from some early predatory dinosaur and the first large group of herbivores was the prosauropods. These were saurischian (lizard-hipped) dinos that lived from 231-188 million years ago until Early Jurassic times and they were distributed throughout the world.

Big ones and small ones

The prosauropods may have had the same ancestors as sauropods (remember them? - the biggest land beasts ever!). But the prosauropods varied greatly in size. Typical features included a small head containing leaf-shaped teeth, a relatively long neck and tail, and hind limbs that were longer than the forelimbs. All known prosauropods had large, curved thumb-claws.

Anchisasaurus ("Near Lizard"): this was one of the smaller prosauropods, at about 2.1 m (7 ft) long and weighing 27 kg (60 lb). It had a small, slim-snouted head with ridged teeth suitable for shredding leaves. It probably walked on all fours, but could have reared to feed.

Bigger than a tennis court?

Melanurosaurus ("Black Mountain Lizard") was one of the largest prosauropods at about 12.2 m (40 ft) long - which is longer than a tennis court is wide! A four-legged plant-eater with a small head and long neck, it had a bulky body, elephantine legs and long tail.

Bigger and bigger

The small early bipedal (two-legged) prosauropods probably gave rise to the huge, bulky quadrupedal (four-legged) variety during the Triassic Period. By the end of Jurassic times, the tendency towards increasing size reached its climax in colossal sauropods. Their later decline was probably due to competition from the ornithischians (bird-hipped dinos in the Late Triassic to Cretaceous period (220-65 million years ago) and the spread of plants that sauropods were badly equipped to eat.

Or maybe the prosauropods just got too big to move!

Heterodontosaurus ("Different Teeth Lizard")

This ornithischian was a small, fast plant-eater 1.2 m (3ft 11 in) long, with small, sharp cutting teeth, short, curved tusks (maybe only in males), and close-packed, grinding cheek teeth that chewed from side to side as well as up and down.

Life was no picnic for the prehistoric plant-eaters. Eating a diet of plants causes animals many more problems than eating meat. Plants are made of tough materials like cellulose and woody lignin, and need to be broken down before digestion can take place in the animal's stomach. Plant-eating dinosaurs coped with their diet in a variety of ways.

Triceratops: powerful jaws and teeth

Dinosaurs like Triceratops ate tough, fibrous plants. Triceratops, like many ceratopsians, had extremely powerful jaws and sharp scissor-like teeth to help it to cope with its diet. After tearing off the vegetation with its beak, it would then have sliced it up with its teeth. The rough grooves and pits on the cropping beak marked the place where the horny covering of keratin was attached. The lower wider part of the bone (called the predentary) fitted tightly against the lower jaw.

Sauropods: no chewing … and not just of gum

The sauropods didn't chew at all, but simply swallowed raked-in vegetation. This passed directly to the stomach, and was ground up by deliberately swallowed "gizzard stones" (gastroliths), or fermented by bacteria, as in a cow's stomach. Sauropods' teeth were either spoon-shaped, for nipping, or peg-like, for raking in leaves.

Hadrosaurs: chopped before swallowing

The hadrosaurs, or duck-billed dinosaurs, had special teeth which ground and chopped their food before they swallowed it. They could also store extra food in their cheeks, like hamsters. Edmontosaurus (a duck-billed dino) had about 1000 strong teeth in its cheek region. It may have blown up the loose skin on its flat face to make a loud bellowing call.

Ankylosaurs: small teeth - soft plants only

The ankylosaurs, or armoured dinosaurs, had small teeth which were only good for eating soft plants. No dinosaur had flat teeth like human molars, which we use to crush and grind our food.

First plate-back dino

Stegosaurus was the first plate-back dinosaur ever found. A four-legged, plant-eating vegetarian, Steggy is most easily recognised by its narrow snout, short front legs and thin, spiny vertical plates jutting from its back.

Solar-plated Steggy

These triangular plates resembled armour and allowed the animal to appear bigger and tougher than it really was. The plates may have worked like solar panels, storing sunlight and helping to regulate internal body temperature.

Sting in the tail

Stegosaurus' tail was thick and heavy. At its base were four tall spines, arranged in pairs and angled back towards the tip. These spikes were effective weapons against predators like Allosaurus and Ceratosaurus.

Golf-ball-sized brain

One of the fascinating mysteries about Stegosaurus is its very small brain compared to its large body size. Its tiny brain was only about the size of a golf ball, weighing approximately 78 gm (2.5 oz).

Pinhead

Steggy's head was small too, only 40 cm (16 in) long, narrow in shape, with a rounded beak like a turtle. Its thick hind legs were long and powerful and its front legs were very short.

Stegosaurus' family ties - the "Roof Lizard"

Steggy belonged to the stegosaur family, a group of ornithischian (bird-hipped) dinosaurs that lived from Middle Jurassic to Late Cretaceous times (188-65 million years ago) in what are now North America, Europe, Africa and Asia. They were generally medium-sized dinosaurs, between 3 m (10 ft) and 9.1 m (30 ft) long, with bulky bodies that weighed up to about 1.5 tonnes (1.47 tons).

Other stegosaurs

There were two main subgroups of stegosaurs: stegosaurids, such as Stegosaurus, Tuojiangosaurus, Kentrosaurus and Wuerhosaurus, and huayangosaurids. Huayangosaurus, the only known huayangosaurid, resembled stegosaurids but is thought to be more primitive.

Biggest of the breed

Stegosaurus was certainly the biggest stegosaur - in fact it was also the largest known plated dinosaur - measuring up to 9 m (30 ft), which was three times the average size of a stegosaur.

When did it live? And where?

Steggy thrived in the late Jurassic period (150 million years ago) in what is now the United States. Remains have been found in Colorado, Oklahoma, Utah and Wyoming. Though it became extinct before the end of the Cretaceous period, this great beast walked the Earth for 50 million years. It was named in 1877 from an incomplete skeleton from Colorado.

Another brain in its hip?

Although Steggy had a tiny tubular skull with a brain the size of a small golfball - or a big walnut - it is thought that it may have had a second brain in its hip region.

More about those strange plates

Stegosaurus had small flat plates on its neck and bigger diamond-shaped plates on its back and the first part of its tail. These are usually shown in two rows, but there may have only been a single row, or they may have stuck out sideways like a protective shield over the back. The exact function of these plates or spikes is not known. They may have been for defence, for display, or for regulating body temperature by absorbing or radiating heat.

Steggy's foes

Allosaurus ("Different Lizard") was one of the predators which may have fallen foul of Steggy's spikes. This large flesh-eater - the most abundant predator in Late Jurassic North America - was 11 m (36 ft) long and weighed about 1.5 tons. It had a big head, S-shaped "bulldog" neck and bulky body, balanced by a long, deep tail. The top of its head had bony ridges and bumps, and its jaws held serrated, bladelike teeth.

Pachycephalosaurus was the most advance dinosaur in a group known as bone-heads. This dome-headed dinosaur's skull had a very thick and bony top, just behind and above the eyes, covered with bumps and nodules at the front and back of the neck. The density of the skull - 25 cm (10 in) thick - was designed like a crash helmet to protect the animal's brain during head-butting contests. Pachy had a short, narrow face and ate only plants.

Head to head

Today male deer and goats batter each other head-on, fighting for mates, and it is believed that this is just what Pachy leaders did - defending their territory by charging and butting heads like mountain goats.

The bony head spikes may have also been used to dig up vegetation. Pachycephalosaurus ran on two legs with its tail extended horizontally. It roamed the plains in herds and may have moved into mountainous areas to avoid competition for food.

Pachy's family ties

Pachycephalosaurus belonged to the pachycephalosaurs, a relatively rare and puzzling group of dinosaurs which lived towards the end of the Cretaceous period, 65 million years ago. The first possible pachycephalosaur remains that were discovered consisted of a single tooth from the Judith River Beds of Montana in the late 19^th century. This was named Troödon formosus ("wounding tooth") and over the next ten years similar teeth were discovered.

Mistaken for an armadillo

In 1920 a skull and partial skeleton were discovered which were linked to Troödon, but it wasn't until 1940 that the almost complete, beautifully well-preserved skull of another thick-headed dinosaur was discovered and the name Pachycephalosaurus was finally given to it. In fact, when Pachy's bones were first discovered in Montana they were misidentified as part of the Tylosteus family, a giant armadillo-like reptile!

High domes and low domes

Pachycephalosaurs have been divided into high-domed forms (pachycephalosaurid, such as Pachy and Stegoceras); and low-domed forms (homalocephalid, such as Homalocephale).

Remains have also been found in Madagascar, China and Mongolia.

How big was Pachy?

As the largest of the bone-heads, Pachy was 4.6 m (15 ft) long. His name means "Thick-Headed Lizard".

How did that compare with other bone-heads?

Stegoceras ("Horny Roof") was much smaller - a mere 2.5 m (6 ft 6 in).

Were all bone-heads the same?

No. The difference between pachycephalosaurids and homalocephalids, which were the two kinds of pachycephalosaurs, probably reflected their different behaviour patterns.

Head-butters vs head pushers

Whereas Pachy and Stegoceras belonged to the pachycephalosaurids who had high domed heads and the males practised head-butting, Homalocephale (the name means "Even Head") belonged to the sub-order of homalocephalids which were flat-headed bone-heads. They had a large, flat, fairly smooth skull roof with nodes along the back. Rival males probably pushed against each other like bighorn sheep. The homalocephalids may not have been a single family but a sequence of increasingly advanced design.

Pachy's lifestyle

All pachycephalosaurids such as Pachycephalosaurus walked with level back and were not designed for running fast. They ate leaves, fruits, seeds and perhaps insects. They would detect danger with sharp eyes and a keen sense of smell. The winners of the males' head-butting contests mated with and ruled the herds of females.

What do their teeth have to tell us?

The first specimens of pachycephalosaurs were their teeth. Their compressed, slightly curved and serrated nature suggests that they belonged to a herbivorous (plant-eating) animal and that they were used to shred plants. In many ways, Pachy's lifestyle was something like that of modern sheep and goats: they probably lived in small groups in upland areas.

Pachy's enemies

Undoubtedly Pachy's head-down charging was also used to fend off enemies, as well as in fighting for dominance within its own group. A typical adversary would have been Abertosaurus, a Late Cretaceous saurischian - like a smaller version of T. rex.

Parasaurolophus was one of the most distinctive of all the crested dinosaurs. This crest was a long, curved, hornlike tube that arced back from its head towards its shoulders. This amazing bone structure was double the length of the dinosaur's head. Its elaborate crest was filled by hollow air passages which may have emitted low-frequency sounds, that could have been useful in communicating with other dinosaurs. Parasaurolophus was huge, weighing over 2 tons, but highly adaptable. It could walk upright or move about on all fours.

All beak and teeth

This dinosaur probably ate tough tree material like pine needles and oak leaves. Like all hadrosaurs, it had a duck-like beak. Behind the beak were several rows of teeth, used for crushing and grinding. It had the ability to replace old teeth as they became worn out. Because the beak was scoop-shaped, scientists believe Parasaurolophus also ate plants from shallow water sources.

All-round athlete

Parasaurolophus had keenly developed senses, with remarkable vision and acute hearing. While browsing in herds, its well-developed senses kept it alert to approaching danger. It had strong, muscular legs and toed hooves. Its front legs were short with webbed fingers. It could run and was probably also able to swim.

Family ties

Parasaurolophus was a hadrosaur - a group of ornithischian (bird-hipped) dinosaurs that lived during Late Cretaceous times (97.5-65 million years ago). All hadrosaurs had duck-billed beaks, and although these were toothless, they had large numbers of cheek teeth - sometimes more than 300 in each jaw.

Flat skulls vs bony crests

There were two main subgroups of hadrosaurs: hadrosaurids (such as Gryposaurus and Maiasaura) and lambeosaurids (such as Corythosaurus and Parasaurolophus itself). The main difference between the subgroups was the shape of the skull: hadrosaurids had flat skulls, some with bumps of solid bone on the snout, whereas the skulls of lambeosaurids had large, hollow, bony crests.

How long? Parasaurolophus was 10 m (33 ft) long. From its head a 1.5 m (5 ft) curved hollow tube (the crest) projected back above the shoulders.

Evidence: Remains have been found in Alberta, New Mexico and Utah.

Dinner-plate crest

Parasaurolophus' overall length was about the same as that of another lambeosaurid, Corythosaurus; one striking difference between these two crested hadrosaurs was in the crest itself: whereas Parasaurolophus' was tube-shaped, Corythosaurus' was shaped like a large dinner plate set up on end on top of the skull.

Forward-pointing crest

Another unusual crested hadrosaur was Tsintaosaurus whose crest pointed forward. It took the form of a hollow tube that pointed straight up between the eyes.

Teeth, teeth and yet more teeth

Incredible as it may seem, Parasaurolophus may have grown up to ten thousand teeth in its liftetime!

There have been a number of theories about the function of Parasaurolophus' extraordinary crest.

Underwater snorkel: it allowed Parasaurolophus' to breathe underwater while feeding on submerged plants. (Drawback: there was no actual hole at the tip of the crest through which air could have passed!)

Air storage tank: it helped Parasaurolophus' to stay submerged for long periods while feeding. (Drawback: the amount of air that could have been stored was very small!)

Salt glands: it housed salt glands to regulate salt balance in Parasaurolophus' body.

Smelling device: it was an advanced smell detector.

Signalling device: the crests of individual species of hadrosaurids helped them to signal to members of their own species - especially useful for courtship and mating!

Foliage deflector: perhaps Parasaurolophus lived in quite heavily wooded areas, using its crest as a deflector to crash through heavy foliage to escape their predators without damaging their heads. And just as the elaborate crests of lambeosaurids like Parasaurolophus indicate that they lived in dense forests, did flat-headed hadrosaurids live in open areas where deflectors were not necessary?

The massive Triceratops ("Three Horned Face") is the most well-known of the horned dinosaurs. It was the largest, measuring up to 9 m (30 ft) long, heaviest and most visually distinctive. Named for the three horns on its nose and brow, it had an extremely elaborate head frill, like a huge, open fan. Some Triceratops' horns measured 100 cm (40 in), about the length of a golf club.

Prehistoric rhino

Triceratops had a large brain and sharp vision. Scientists believe it could run fairly well for its large size. With its stout stature and massive head, it resembled a larger, modern-day rhinoceros. Triceratops weighed approximately 5 tonnes (5.5 tons) and required a lot of plant material to sustain its enormous bulk. Its teeth were like long blades, operated like shears, but functionally unable to crush or grind. This great dinosaaur ate palm leaves and may have knocked over tall trees to get to the top, tender branches.

The best form of defence

Though Tricer had an aggressive nature, it had no lasting enemies because it could outmanoeuvre opponents with its facial horns, a strategically well-designed defence mechanism.

Family ties

Triceratops horridus ("Terrible Three-Horned Face") belonged to the ceratopsid subgroup of the ceratopsians (horned dinosaurs, see pages 8-9) and was among the last-known dinosaurs on the planet. Ceratopsians seem to have grown bigger and bigger as they evolved. An early ceratopsian Protoceratops ("First Horned Face") was not much bigger than a large dog. What they had in common was the large bony neck frill pointing backwards from the skull and masking the neck, horns on the nose or over the eyes, and a narrow hooked beak. Most were four-legged and stocky, like today's rhinoceroses, and all were plant-eaters.

Pack animals

Many fossils of ceratopsians found in the same area suggest that they roamed in herds, confronting a threatening meat-eater as a pack.

The evidence

Remains of Triceratops have been found in Colorado, Montana, Wyoming and Canada.

Tyrannosaurus meets Triceratops

Sometimes, even the mighty T. rex can meet its match. Triceratops is well-protected against the fierce predators, such as Tyrannosaurus, that track the herds of plant-eaters across the great plain. Triceratops' giant, bony frill also makes its head look huge and frightening to deter any prowling carnivore or meat-eater. Triceratops has long, sharp horns on its forehead and snout. In addition, the dinosaur has specially strengthened bones on its neck and hip area and on the roof of its skull to withstand great shocks if it charges into an attacker.

The monster attacks

A hungry T. rex spots a Triceratops, feeding away from its herd. The meat-eater rushes at its prey, hoping to knock it down. It will try to wound Triceratops with one fatal bite from its dagger-like teeth. Tricer shakes its head, bellows, and lunges towards its attacker …

Tricer charges

As Triceratops rises from the ground, its long back legs push its hips upwards. Huge muscles support Tricer's great 6-tonne (6 ton) body over its front and rear legs. Its hip bones take the strain of its heavy body weight. Breaking into a run, perhaps as fast as 25 km/h (over 15 mph), it charges forward, trying to stab Tyrannosaurus' belly with its horns. If it succeeds, Triceratops may escape from death - this time.

Standing its ground

Tricer may look a little like a rhinoceros - but it's twice the size and a reptile, not a mammal, though it may have had similar ways of defending itself. Pawing the ground, its legs kicking up a cloud of dust to confuse its attacker, it hisses at T. rex, looking for a way to escape the terrible hunter's razor-sharp, slashing teeth. But Tyrannosaurus is growing tired and may decide to give up and hunt a weaker animal.

Mamenchisaurus had a neck three times the size of a giraffe. It belonged to a group called the sauropods and had a tiny head compared to its long neck and tail. Its body was perfectly designed for its lifestyle, allowing it to feed from the tops of the tallest trees. It munched on leafy vegetation few other dinosaurs could reach.

Hoovering up, Jurassic style

Its neck was strong and flexible, capable of raising and lowering with ease. Built like a modern-day crane, its head was lightweight and compact, allowing freedom of movement and quick manoeuvring in close quarters. It may have eaten the plants from shallow lakes, swinging its neck along the sides like a powerful vacuum hose. Its body was designed to support its enormous weight. Backbones were strong and hollowed out for lightness. Its muscular legs supported its body structurally like the architectural pillars on buildings.

Mamenchisaurus grazed and when the vegetation was gone, it moved on to the next lake.

Family ties

Mamenchisaurus belonged to the euhelopodid family ("Good Marsh Feet") of sauropods. They lived in the Late Jurassic Age (95-60 million years ago). These large four-legged plant-eaters have only been found in China, and are sometimes grouped with the camarasaurids. Like those, euhelopodids had chisel-shaped (or spoon-shape) teeth and a tall blunt snout. Like Mamenchisaurus, many euhelopodids had amazingly long necks with 17 vertebrae.

Highest number: In fact, Mamenchisaurus had 19 neck vertebrae, more than any other known dinosaur. Many of these vertebrae overlapped with long, thin, reinforcing bony struts.

Evidence: Remains have been found in Sichuan, Gansu and Xingjiang, China.

Size: Mamenchisaurus was possibly 27 m (89 ft) long - yes, 89 feet! - with the world's longest known neck perhaps measuring up to 15 m (49 ft). As Winston Churchill said, "Some neck."

Close relatives

Euhelopus ("Good Marsh Feet"): half its length, a mere 10-15 m (33-50ft), weighing up to 25 tons. Other euhelopodids: Omeisaurus, 20 m (66 ft) ; and Tienshanosauraus, 12 m (40 ft) .

Diplodocus - long neck, long tail

Another massive long-necked sauropod was Diplodocus (26 m, 86 ft) long whose neck, unlike Mamenchisaurus, was balanced by a long tail.

Prehistoric ostrich

Gallimimus ("Fowl Mimic") was the largest of the birdlike dinosaurs. With its toothless beak and long tail, it resembled a modern-day ostrich. It had large eyes, a small head with a narrow beak, long, slender S-shaped neck and powerful long, slim hind limbs. Its thin front "arms" had elbow joints that bent for flexible movement. The structure of its internal anatomy was similar to a bird's.

Scratching and scraping

Gallimimus had non-grasping clawed "hands" that could not have torn meat. It may have scratched and scraped the soil and eaten the eggs of other animals. Its body was covered with scaly skin and its feet were clawed, front and back. Its long tail extended over the ground. When it ran, its tail was stiff, held horizontally for balance.

One of the fastest

Gally was one of the fastest of all the birdlike runners, with speeds up to 40 km/h (25 mph).

Evidence

Remains have been found in Southern Mongolia.

Family ties

Gallimimus lived in Late Cretaceous times (95-65 million years ago) and belonged to the ornithomimosauria group of the ornithomimidae ("bird mimics") family. The ornithomimidae were saurischians ("lizard-hipped dinosaurs") and all looked like ostriches with small, light head, relatively big brain, large eyes and long narrow beak. They had long, slim, curved, mobile necks, compact bodies and fairly long arms with grasping, clawed, three-fingered hands.

Speedy getaway

They had long, strong legs, with longer shins than thighs and long feet, each with three toes tipped with claws. The stiffly held tapered tail positioned level with the back balanced the forepart of the body when they ran. Ornithomimids ate low-growing plants, eggs and maybe insects and small reptiles. They might have kicked enemies but their chief defence was a speedy getaway.

Biggest of the breed

Measuring up to 6 m (20 ft) long, Gallimimus was the biggest in its family.

Close relatives

How did Gallie compare with other ornithomimids?

Dromiceiomimus ("Emu Mimic"): half the size of Gallie but half again as fast; it was 3.5 m (11 ft) long and weighed 100 kg (230 lb), with big, keen eyes, toothless beak, long neck and tail, short back, slim arms with three-fingered hands, and long legs capable of running up to 64.4 km/h (40 mph), compared with Gallie's 40 km/h (25 mph) speeds.

Elaphrosaurus ("Lightweight Lizard"): reputedly an ancestral ostrich dino 3.5 m (11 ft 6 in) long, with light, hollow bones, but, compared with later ornithomimids, shorter arms and legs and a shorter running speed.

Ornithomimus ("Bird Mimic"): 3.5 m (11 ft 6 in) long, with small head, toothless beak, long curved neck, thinner arms than Struthiomimus, three clawed fingers on each hand, long sprinter's legs and long tail occupying more than half its length.

Struthiomimus ("Ostrich Mimic"): ostrich-like predator (or herbivore) 3.5 m (11 ft 6 in) long, with fairly strong arms.

What big eyes you've got, Gallie…

Galliminus' eyes were bigger than ostriches, yet its skull was narrower. Its eyeballs were actually flattened and could not move much in its socket. This means that Gallie and all the other ostrich-mimics (ornithomimids) must have had to flick their heads to and fro to sight in on various objects.

Look out … it's behind you!

Because Gallie's eyes faced sideways, its binocular vision (ability to use both eyes together at the same time which enhances vision) was more limited than in some other protobirds (early bird-like dinosaurs). However, to compensate for this, it was better adapted to detect predators from behind.

Advantages of a full belly

Gallimimus' abdominal ribs show that the belly's lower contour is not as hollow as in hungry predator theropods (meat-eaters). This is because ostrich dinos always kept their bellies at least partly filled with digesting plant material in order to support the flora of micro-organisms that do the actual breaking down of plant materials.

Hadrosaurus was a member of the hadrosaurids (a type of hadrosaur). Confused? Then see Family ties for an explanation!

Prehistoric waste disposal

Hadrosaurus was a duck-billed dinosaur that lived during the Late Cretaceous era. Though its beak was toothless, Hadrosaurus had up to 300 cheek teeth in each powerful jaw. It could grind tough vegetation like a waste disposal unit. Which was fortunate because Hadrosaurus was a browser, which grazed continuously.

Kangaroo dino

Haddie's body was heavy with a long head that ended in a flat, horny bill. It resembled a large, oddly shaped kangaroo, standing on its hind legs, with shorter front legs dangling in front. Its toothless beak indicates that this dinosaur was primarily a land feeder, dining on palm fronds and needles.

First mounted dino

Hadrosaurus was the first mounted dinosaur skeleton ever displayed - at Philadelphia in 1868.

Family ties

Hadrosaurus was a member of the hadrosaurids (a type of hadrosaur). That might sound like: "A human being is the member of the human race (a type of human)", but actually it's rather different. What it means is that Hadrosaurus was a species of hadrosaurid, which was a particular subgroup of the larger group of hadrosaurs, which were duck-billed dinosaurs. (Click here to find out more about hadrosaurs.)

So what on earth were hadrosaurids?

Hadrosaurids ("big lizards") were a family of medium to huge, heavily built bipedal (two-footed) or quadrupedal (four-footed) plant-eaters; they were among the last and largest of all bird-footed, bird-hipped dinosaurs. There were two such families of hadrosaurs or duck-bills, so nicknamed because of their broad, flat, toothless beaks. Both groups had powerful jaws and pavements of self-sharpening cheek teeth chewing leaves and twigs stored in roomy cheeks. Most were big and heavy, with longer limbs and deeper tails than their forebears. Each hand had only four fingers, cushioned in a padded paw.

The difference between hadrosaurids and hadrosaurs

Unlike other hadrosaurs, hadrosaurids had a flat skull or one with crests or bumps of solid, and a relatively longer lower jaw and longer, slimmer limbs.

Hadrosaurus: some facts and figures

Haddie was 8-10 m (26-32 ft) long; its mode of attack was head-butting. Remains have been found at Alberta in Canada; and New Jersey, Montana and New Mexico in the USA.

Close relatives

How did Hadrosaurus compare with other hadrosaurids?

Aralosaurus ("Aral Lizard"): early hadrosaurid, known from an incomplete skull with a Hadrosaurus-like low bulge in front of the eyes.

Brachylophosaurus ("Short-Crested Lizard"): this primitive hadrosaurid was about 7 m (23 ft) long, with long forelimbs, deep snout, low nasal crest and (between the eyes) a bony plate forming a short, backward-pointing spike.

Claosaurus ("Broken Lizard"): a small, early hadrosaurid 3.7 m (12 ft) long with long hind limbs, slender feet and body, and rows, not batteries, of teeth behind the toothless beak.

More of Haddie's relatives

Edmontosaurus ("Edmonton Lizard"): large, flat-headed hadrosaurid, bigger than Hadrosaurus, being 13 m (42 ft 6 in) long and weighing nearly 3.2 tonnes (3.5 tons)

Maiasaura ("Good Mother Lizard") : this bipedal (two-legged)/quadrupedal (four-legged) plant-eater was about 9 m (30 ft) long, with short, broad, toothless beak, batteries of cheek teeth in shallow jaws, and a short bony crest between the eyes. It was found near nests that were 2 m (7 ft) across, containing the fossil young of different ages.

Bumps and bellows

Hadrosaurus walked on all fours but stood on hind legs, balancing its body with the aid of its long, stiff tail. Its skin was tough and leathery and its skull was flat, often with bumps on the snout. Scientists believe that it had a very loud voice.

Hadrosaur bones - they're all over the place

Hadrosaur fossils make up about 75% of all land animal bones that have been found.

Palaeontology: looking for clues

Palaeontology is the study of the geological past. Scientists have made maps to show the different ages of rocks. Dino fossils are found throughout the world in 210-64 million-year-old rocks.

How are fossils made?

When most animals die, their remains are broken up and destroyed by the weather and by other animals. Sometimes, however, their bodies are washed into a river or lake and quickly covered in sand and mud; in a desert the remains might be covered by wind-blown sands. This is how some dinosaurs became preserved.

Permineralization - minerals reinforced the bones

Over millions of years more and more sand and mud piled on top of the remains. The sediments gradually turned into sandstone, limestone and shale, the soft parts of the dinosaurs' scaly skin lasted long enough to leave its impression in the fine mud, and fragile egg shells were also turned into fossils.

Petrification - turned to stone

The fossils discovered by scientists are different from the dinosaurs' original remains. Chemicals have changed them into stone, or they may have been crushed. Sometimes minerals replaced the bone itself until the bone was turned to stone.

Different types of remains

Teeth: the hardest parts of all, often surviving with little change at all; the fossilized teeth of plant-eating dinosaurs are blunt and flat

Moulds: certain minerals dissolved some bones but left bone-shaped hollow fossils called moulds

Casts: a mould that was later filled by other minerals became a cast; some moulds or casts even show a dinosaur's scaly skin

Trace fossils: other traces left by dinosaurs, including:

Ichnites: fossil footprints, left in lakeside mud that dried out in the sun; fossil trackways show where dinos walked on two or four limbs, whether they trudged or sprinted, and travelled singly or in herds. Click here for more information

Coprolites: these fossil droppings are moulds showing the shape of the intestines

Ooliths: fossil eggs

What fossil tracks tell us

Fossil tracks reveal that dinosaurs stood, walked and ran with limbs beneath bodies. They also show where, when and how sauropods, hadrosaurs and others moved and rested on the muddy sides of lakes.

Herds of herbivores

Big herbivores (plant-eaters) such as sauropods walked in herds. Washtub-sized depressions left by huge feet in mud and now hardened into rock show where sauropods once roamed. Finds from Texas and other places suggest sauropods and other herbivores trudged in herds, perhaps in seasonal migration.

Tracks of the theropods

Theropods were meat-eaters, and large and small predatory dinosaurs left birdlike tracks on the muddy shores of lakes and rivers in the Connecticut valley and elsewhere. Some were probably scavenging corpses washed ashore; others ambushed herbivores that had come to drink.

Sitting down

Tracks other than footprints indicate where a dinosaur sat down to rest or doze.

Running, walking … hopping?

Running dinosaurs left footprints far apart - the faster they ran, the greater the gaps. One set of tracks indicates that large theropods (meat-eating predators) could run at 40 km/h (25 mph). Small prints usually mean they were small animals. An Early Jurassic trackway in Arizona revealed that a theropod no heavier than a whippet had sprinted as quickly as a galloping horse.

Swimming dinos: fossil tracks with incomplete footprints suggested that dinos sometimes swam. A hindfoot print marked where a big herbivore kicked off to change direction, the limb functioning as a kind of punter's pole to push off from a lake bed.

Walking dinos: tracks with short distances between footprints indicate slow speeds. Traces left by sauropods suggest they always ambled and never hurried.

Tails raised: where tracks show no groove left by a dragging tail, it has been deduced that the tail was held aloft to balance the body and prevent the tail's being trodden on by other members of the herd.

The tools of the trade

Dinosaur discoveries are rare, often lying buried in layers of rock until exposed on a hillside, a quarry or perhaps a rocky beach. Only then can a team of experts go to work to excavate fossil dinosaur. They use pick-axes and shovels to clear away rock; hammers and sharp chisels to work close to the bone without damaging it, and brushes to sweep away the dust. Workers wear protective goggles to keep their eyes safe. Hard-hats are essential near cliffs.

Protecting the fossils

Wet tissue paper is spread over the fossil to protect the surface. Thick bandages or sacking are soaked in plaster and spread over the paper. When this has hardened the fossil is carefully turned over. Its other side is also covered in paper and plaster bandage. When the plaster has hardened, the fossil, wearing its "jacket", can then be lifted out.

Putting dinos together again

After the hard work of excavation, the precious fossils are taken back to the laboratory for preparation, study and display. They are removed from their protective jackets; then the remaining rock or earth is cleaned away with chisels, delicate power-driven tools and chemicals. The cleaned

bones are then studied to understand how they fitted together - and therefore how the dinosaur lived. Tell-tale clues can be found on the bone surface: muscles sometimes leave clear marks where they were attached.

Adding the flesh

It may take some time to work out how the bones fitted together and missing bones may have to be modelled from plaster. Skin impressions have sometimes been preserved to aid the model-maker, but colour is a matter of guesswork.

A load of old bones

During the 19^th century, when dinosaurs had just been discovered, the sculptor Benjamin Waterhouse Hawkins built models of dinosaurs first in Britain, then in America.

Europe

The remains of herbivore (plant-eating) dinosaurs have been found all over Europe, but the fossilized skeletons tend to be less complete than elsewhere. Among those discovered are: Plateosaurus ("Flat Lizard"), 6-8 m (20-26 ft); Iguanodon ("Iguana Tooth"), 9 m (30 ft); and Scelidosaurus ("Limb Lizard"), 4 m (13 ft).

North America

This part of the world has been popular with dinosaur hunters since the mid-19^th century. Famous plant-eating finds include: Camarasaurus ("Chambered Lizard"), 18 m (59 ft); Parasaurolophus, 10 m (33 ft); Triceratops (see pages 26-9), Euoplocephalus ("Well-Armoured Head"), 7 m (23 ft); Stegosaurus (see pages 14-17) and Apatosaurus ("Deceptive Lizard"), 21 m (69 ft). New dinosaur remains are still being discovered here.

South America

Much of South America is covered with dense vegetation, making it difficult to dig for dinosaur remains. But important finds have been made in the more barren areas further south. Plant-eating finds include: Mussaurus ("Mouse Lizard"), 3 m (10 ft); Amargasaurus, 9 m (30 ft); and Riojasaurus, 10 m (33 ft).

Africa

This huge continent has been home to many different kinds of dinosaurs. The oldest are found in the south; younger dino remains are further north. Among important finds: Massospondylus ("Massive Vertebrae"), a two-legged/four-legged plant-eater 4 m (13 ft) long, with long neck and tail, bulky body, massive hands, rounded front teeth, flat-sided back teeth, and possibly a horny lower beak.

Asia

Some of the most recent and exciting finds have been made in Asia, including Yingshanosaurus, 5 m (16 ft); Tuojiangosaurus, 7 m (23 ft); Saurolophus ("Ridged Lizard"); 9 m (30 ft); and Shantungosaurus, 15 m (49 ft). Fossilized dino bones (once thought to belong to dragons!) are found all over China. Many dinosaur remains, including dino eggs, have been discovered in the Gobi Desert.

Australia

Not many dino fossils have been found: the most complete dinosaur discovered here was the plant-eating Muttaburrasaurus, 7 m (23 ft).

Antarctica

Only two dinosaurs have been excavated here so far, in 1988 and 1889, but there may well be many dino fossils under Antarctica's icy waters.

Extinct theories …

Before people understood how old the Earth was, they entertained ideas about fossils that now seem very funny: they were put there by the devil to confuse people; or they were the remains of animals drowned in the Flood when Noah escaped in his ark. The explanation nearest to the truth was the suggestion that fossils were mistakes that God made while creating all the animals.

… and theories of extinction

About 65 million years ago dinosaurs, plesiosaurs, pterosaurs and many other animals of land or sea became extinct. Just why remains a mystery that many scientists have tried to solve. Among the theories: dinos evolved such awkward bodies that they couldn't move or breed; predatory dinos ate the rest then starved; tiny mammals gobbled up dino eggs. But the most likely explanations have been drastic global change or relatively slow extinction as shifting continents, rising mountains and shrinking seas helped new creatures evolve who outcompeted the old.