ALLOSAURUSNAME: Allosaurus (AL –uh-SOR-us)NAME MEANS: Different LizardPERIOD: Late Jurassic - 150 million years agoWHERE: Midwest USA: Colorado, Montana, New Mexico, Oklahoma, South Dakota, Utah, Wyoming; also Europe (Portugal) and AfricaSIZE: Length: 12 meters (39 feet) Height: 5 meters (16 feet) Weight: 1,700 kg (3,800 lbs)

As the largest North American predator for more than 10 million years, Allosaurus could reach 30 years of age but was able to reproduce at 10 years. Like Yangchuanosaurus it had two ridged crests running along its snout which may have indicated its good health and breeding potential to prospective mates. Allosaurus mates needed to be careful -- recent research shows interactions with others of its species were largely aggressive rather than co-operative.

A two-legged meat-eater, Allosaurus could open its jaws extra wide, like some modern snakes, to gulp down massive chunks of meat. A rather intelligent animal, with eyes twice as large as those of any other carnivore, Allosaurus probably hunted in company with others of its species and raised its young in family groups. It may even have established nurseries watched over by a few adults, just like some mammals of today.

Allosaurus was on the scene at the same time as the herbivores Stegosaurus and Apatosaurus, which were likely prey.

APATOSAURUSNAME: Apatosaurus (uh-PAT-uh-SOAR-us)NAME MEANS: Deceptive LizardPERIOD: Late Jurassic - 150 million years agoWHERE: North America: Mexico, USA (Utah, Wyoming, Colorado)SIZE: Length: 21 meters (70 feet) Height at hips: 4.5 meters (15 feet) Weight: 18,000 kg (40,000 lbs with a full belly)

Apatosaurus is the modern scientific name for the more familiar Brontosaurus, a term which is no longer used. It used to be thought that, because this animal was so huge, it must have spent most of its life in water just to support its weight. It is now believed to have lived mostly on land. Apatosaurus was incredibly long – 70 feet from the tip of its head to the tip of its tail. No wonder it was called “thunder lizard”! The ground (not to mention the shrew-sized mammals around at the time) must have literally trembled when it walked.

Lumbering through the broad flatlands of the plain Apatosaurus ate vast amounts of plant material (200 kilos, or 440 lbs!) each day to satisfy the needs of its huge size. Size was one of the best forms of protection that Apatosaurus had from predators. That, and the 50 ft tail which may have been cracked like a whip creating a deafening sound and warning others in the group of danger. In terms of locomotion, its size would have probably rendered it fairly slow moving.

BARYONYXNAME: Baryonyx (BEAR-ee-ON-ix)NAME MEANS: Heavy ClawPERIOD: Early Cretaceous - 125 million years agoWHERE: Europe: England, Northern Spain, MoroccoSIZE: Length: 9 meters long (30 feet) Height: 2.5 meters (8 feet) Weight: 1,800 kg (4,000 lbs)

Plunging into the river in pursuit of food, much like a modern grizzly bear, Baryonyx used its 12” curved, hooked-like claw on its largest digit, or finger, to catch a fish before 96 teeth clamped down on the hapless victim. Or did it hunt stealthily from the bank like a heron or egret do today? Scientists hold differing views but either way we do know that Baryonyx was one of the few fishermen of the dinosaur world.

In 1983 William Walker, an amateur fossil hunter, spotted an enormous claw sticking out of a clay pit near Dorking in Surrey, England. Eventually the site yielded an almost complete skeleton of this new species of dinosaur. The long, strong arms of the Baryonyx suggest that it could walk on all fours, and if so, would make it the only theropod known to do so.

DEINONYCHUSNAME: Deinonychus (dy-NON-ih-KUS)NAME MEANS: Terrible ClawPERIOD: Mid-Cretaceous – 110-100 million years agoWHERE: US: Montana, Wyoming and OklahomaSIZE: Length: 3 meters long (10 feet) Height: 1.2 meters (4 feet) Weight: 70 kg (150 lbs)

Bird-like dinosaur or dinosaur-like bird… paleontological opinion is inconsistent. Possessing a unique foot weapon – a 13 centimeter (5inch) sickle shaped claw, the relatively small Deinonychus was a fearsome killer. Coupled with the fact that it was agile and intelligent for a dinosaur (as shown by the high ratio between brain size and body weight) prey would have had to fight back or run from a hunting pack of Deinonychus. The disembowelling feature of the terrible claw and the ability to rip of large chunks of flesh with the serrated teeth, while the hands held the victim, meant that once caught, escape would have been difficult. Deinonychus is thought to have been able to run quickly on its slender legs possibly sprinting at 25 mph.

METRIACANTHOSAURUSNAME: Metriacanthosaurus (MET-re-ah-CAN-thut-SOAR-us)NAME MEANS: Medium Spine LizardPERIOD: Mid-Jurassic – 160-155 million years agoWHERE: Europe, UKSIZE: Length: 8 meters long (27 feet) Height: 1.8 meters (6 feet) Weight: 1 tonne (2,205 lbs.)

Metriacanthosaurus was a large, bipedal carnivore that is truly a mysterious dinosaur, due to the fact that there have only been a few partial specimens found to date. Although the skull of Metriacanthosaurus has been missing from the fossil remains, scientists can conjecture that the shape was much like all theropods of the Mid-Jurassic Period - long, flat topped and with a rounded snout. The long neural spines may have supported a “skin sail” which could have helped to regulate heat and body temperature and given the dinosaur a slightly hump-backed appearance. In the Cretaceous Period these skin sails evolved into enormous displays.

PARASAUROLOPHUSNAME: Parasaurolophus (PAIR-uh-so-ROL-uh-PHUS)NAME MEANS: Close to Crested Lizard (i.e., a close relative of Saurolophus)PERIOD: Late Cretaceous - 72 million years agoWHERE: North America: New Mexico, Utah, AlbertaSIZE: Length: 12 meters (40 feet) Height at hips: 3 meters (10 feet) Weight: 1.8 tonnes (3,900 lbs)

Danger! Run! The calls emitted from the crests of Parasaurolophus warned the others in the herd of the approach of predators. Running was the only natural defence for a Parasaurolophus. The dinosaur could move quickly on its two strong hindlimbs and when grazing it could crouch down on all four legs, its duck-like beak with the hundreds of tiny teeth grinding the fibrous conifers and ferns into a digestible pulp. Parasaurolophus were so plentiful that they were known as the “cows of the Cretaceous”.

PARASAUROLOPHUS JUVENILEA juvenile Parasaurolophus had many pairs of eyes watching out for its well-being, especially while it was small and vulnerable to predator attack. As a herd animal Parasaurolophus lived in a large social network but that wouldn’t have deterred an errant youngster from being called to dinner. A young Parasaurolophus may have been able to find its mother by recognizing her distinct call which may have sounded like a fog horn.

STEGOSAURUSNAME: Stegosaurus (STEG-o-sawr-us)NAME MEANS: Roof LizardPERIOD: Late Jurassic - 150 million years agoWHERE: Western North America and Europe (Portugal)SIZE: Length: 9 meters (30 feet) Height: 4 meters (14 ft) Weight: 7 tonnes (15,000 lbs)

Stegosaurus is an iconic dinosaur because of the two walls of bony plates along its back that gave it a distinctive profile. His wide array of defence equipment was necessary because this slow, heavy herbivore needed to eat for most of the day. Whether battling one of its own kind or a predator, Stegosaurus could swing the two pairs of spikes (each up to 4 feet long) projecting from its tail as an awesome defensive weapon. The 17 bony dorsal plates arranged alternately along its spine may have acted like armor, been a mating display, helped to regulate heat, or all three. These plates may have made the Stegosaurus look larger to its enemy and therefore discouraged attack.

TRICERATOPSNAME: Triceratops (try-SER-uh-TOPS)NAME MEANS: Three-horned FacePERIOD: Late Cretaceous - 65 million years agoWHERE: North America: Colorado, Montana, South Dakota, Wyoming, Alberta, SaskatchewanSIZE: Length: 9 meters (25 – 30 feet) Height: 3 meters (10 feet) Weight: up to 10,000 kg (22,000 lbs)

Triceratops is one of the most famous dinosaurs. The most distinctive feature is their large skull, the largest of all land animals. The skull could grow to be over 7 ft in length and could reach almost a third of the length of the entire animal.

Triceratops was no gentle, plant-eating giant. Many fossil records show damage to Triceratops bones which could have occurred in combat with both rivals and predators. Aside from inter-group displays of domination and as weapons against predators, horns could also be used in mating displays. The neck frill would have offered some protection against the bite of the Tyrannosaurus rex and perhaps would have regulated body temperature.

TYRANNOSAURUS REXNAME: Tyrannosaurus rex (tuh-RAN-uh-SOR-us)NAME MEANS: King of the Tyrant LizardsPERIOD: Late Cretaceous - 65 million years agoWHERE: North America: Colorado, Montana, New Mexico, Wyoming, Alberta SIZE: Length: Over 13 meters (over 40 feet) Height: 4 meters tall (13 ft) at the hips Weight: 6,000 kg (14,000 lbs)

As the last great carnivore of the Cretaceous Period, Tyrannosaurus rex was an efficient killing machine stalking the North American landscape. With a specially strengthened nose structure that enabled it to deliver bone splintering, crushing bites to both captured prey and during combat with others of its species, a Tyrannosaurus rex lower jaw could deliver 10,000 newtons of force – the equivalent of being able to lift a semi-trailer.

This deadly killer with the toothy smile might seem like a Hollywood creation but it was quite real, as any of the plant eaters of the time could tell you. It had powerful jaws, highly efficient teeth, each the size of a small screwdriver, good sight and sense of smell, and 20 cm talons on its forward-pointing toes. Its massive skull was balanced by a long, heavy tail. Tyrannosaurus rex bite marks found on the bones of other dinosaurs prove that its teeth could crunch right through bone, leading to the conclusion that plant-eating and even other meat-eating dinosaurs likely gave the “king of the tyrant lizard ” a wide berth.

TYRANNOSAURUS REX FEATHERED JUVENILENo fluffy and helpless chick, recent research indicates that Tyrannosaurus rex juvenile, (male and female), most likely had a fine downy covering resembling a hair-like structure. This covering was shed before the animal reached adulthood. Feathers most likely developed to regulate body heat and as the dinosaur became larger it was important to be able to quickly shed stored body heat.

YANGCHUANOSAURUSNAME: Yangchuanosaurus (Yang-chew ON-uh-SOR-us)NAME MEANS: Yang-ch’uan LizardPERIOD: Late Jurassic - 160 million years agoWHERE: China: Sichuan ProvinceSIZE: Length: 10 meters (34 feet) Weight: 2,300 kg (5,000 lbs)

Yangchuanosaurus is one of the most complete fossil dinosaur skeletons ever found in China. Unable to inflict the kill through its bite alone because, al-though its teeth were sharp and plentiful, they were not large, Yangchuano-saurus instead likely used the massive claws on its hindlimbs to slash and tear. As the largest Late Jurassic theropod in China, Yangchuanosaurus was a powerfully-built dinosaur, in many ways resembling the fearsome Allosaurus. The long low crests over the snout may have been an indication of health to a potential mate.

PROTOCERATOPSNAME: Protoceratops (proto-SER-uh-TOPS)NAME MEANS: First horned facePERIOD: Late Cretaceous - 75 million years agoWHERE: Mongolia: Gobi desertSIZE: Length: 1.5 - 2.5 meters (5 - 8 feet) Weight: 400 kg (900 lbs)

The safety of the herd offered Protoceratops protection from predators and the opportunity to attract a mate. Males may have had larger frills than females, indicating that the frill may have been used in courtship and mating. What better to impress a potential mate than a showy neck frill? As the first of the horned-face dinosaurs that eventually gave rise to Triceratops, many of the features of ceratopsians are present in Protoceratops. Without any defensive weapons the neck frill may have made Protoceratops look larger and less vulnerable. The ceratopsians lived exclusively in the northern hemisphere and survived until the end of the reign of the dinosaurs.

OMEISAURUSNAME: Omeisaurus (Oh-MY-ee-SOAR-us)NAME MEANS: Mount Emei LizardPERIOD: Mid- to Late Jurassic - 160 million years agoWHERE: Western China (named after Mount Emei)SIZE: Length: 20 meters (60 feet) Weight: 3,600 kg (8,000 lbs)

The best protection Omeisaurus had from predators looking for a high protein meal was its sheer size (up to 3,600 kilos or 8,000 lbs) which may have deterred all but the most determined. As long as Omeisaurus remained healthy it was unlikely that it would find itself under attack from its main predator, Yangchuanosaurus. Consuming up to a ton (1000 kilos, or 2200 lbs) of plants each day, Omeisaurus swallowed food whole and digestion was aided by gastroliths (stomach stones).