The following will provide you with some information of the major dinosaur families found in Alberta during the Cretaceous Period. Alberta lay at the crossroads of dinosaurs travelling north to the Arctic, south to the tropics, or between Asia and North America.

Hadrosaurs (Duck-billed dinosaurs)

The hadrosaurs, commonly known as duckbills, were the most abundant group of dinosaurs in Alberta during the late Cretaceous period. On average, they were about 9-10m long and weighed between 3-4 tons. They wandered through lowland forests munching on low tough vegetation with their duck-like bill which gave them their popular name. Although there were no teeth in the front of the hadrosaur's mouth, there were numerous cheek teeth arranged in rows in the upper and lower jaws, these dinosaurs may have had up to 2000 teeth at one time. All hadrosaurs had long hind legs and shorter fore legs, both equipped with hoof-like nails for walking. They likely spent most of their time browsing on all fours, but when chased by predators they would have reared up on their hind legs and sprinted away, balanced by their long tail.

Reaching the size of modern elephants, all hadrosaurs had similar body structures, and many had distinctive crests. It is believed that some of these head crests probably functioned as resonating (sound) chambers to help the animals communicate with their own species (ie. warning, attracting a mate, etc.), or for species recognition.

Since hadrosaurs had few natural defences, it would have been beneficial for them to herd together for protection. Evidence of this behavior comes form nesting sites which contain eggs, embryos and the remains of juveniles, indicating parental care. In fact, discoveries at Devil's Coulee, Alberta and Egg Mountain, Montana have uncovered nesting sites of hadrosaurine dinosaurs.

At least twelve species of hadrosaurs have been discovered in Alberta, with some examples being Corythosaurus, Lambeosaurus, Hypacrosaurus, and Parasaurolophus.

Pachycephalosaurus (Thick-headed dinosaurs)

The skulls of the "thick-headed" dinosaurs were dome-shaped, giving them a very unique appearance They had high foreheads and thick skull caps made up of enormously thickened bones up to 30 cm. However, the brain inside the skull was no bigger than an average doughnut hole. Some species also had bony knobs and/or spikes on the sides and back of their head, as well as on the snout. Smaller than the hadrosaurs (ranging from 2-4.5m long, and weighing 1-2 tons), the pachycephalosaurs had short fore limbs and small blunt teeth. They walked on their hind legs, although they may have dropped to all fours as they searched for plants.

Like many animals that lived in herds, pachycephalosaur males may have engaged in non-lethal combat to establish dominance and attract mates. They probably buttted heads like bighorn sheep and other ungulates do today.

Three different kinds of thick-headed dinosaurs have been found in Alberta -- Stegoceras, Ornatotholus, Pachycephalosaurus.

Ornithomimids (Bird-mimic dinosaurs)

The skulls of the "thick-headed" dinosaurs were dome-shaped, giving them a very unique appearance They had high foreheads and thick skull caps made up of enormously thickened bones up to 30 cm. However, the brain inside the skull was no bigger than an average doughnut hole. Some species also had bony knobs and/or spikes on the sides and back of their head, as well as on the snout. Smaller than the hadrosaurs (ranging from 2-4.5m long, and weighing 1-2 tons), the pachycephalosaurs had short fore limbs and small blunt teeth. They walked on their hind legs, although they may have dropped to all fours as they searched for plants.

Dromaeosaurs (Raptors)

The name dromaeosaurs means "running lizard". They are now more commonly known to the public as the "raptors" since the popularity of Jurassic Park. These dinosaurs were agile creatures with a light body and a low centre of gravity. They also had a long tail which acted as a stabilizer as they ran. Generally, they were about 2m long, and probably weighed less than 50kg (except for Deinonychus which weighed about 70kg).

Members of this dinosaur family must have been fearsome predators as they were equipped with a large sickle-shaped claw (raptorial talon) on the second toe of each hind foot. These claws could easily have killed small dinosaurs. They were also armed with sharp, recurved teeth and clawed, grasping hands.

The dromaeosaurs were among the most important carnivores to evolve in the late Cretaceous. It is believed that they hunted in packs, so the dromaeosaur patrol would have sent most animals scurrying for cover.

Two species that lived in Alberta included Dromaeosaurus and Sauronitholestes. Another well-known species, Deinonychus, lived earlier in the Cretaceous period and has not been found in Alberta, but in Montana. The very popular Velociraptor lived in the Cretaceous period in Mongolia, and Utah raptor was found in Utah.

The dromaeosaurs were the group of dinosaurs most closely related to birds.

Tyrannosaurs (Large carnivores)

The largest terrestrial carnivores that ever lived belonged to this group of dinosaurs. As a group they were short-lived, appearing in late Cretaceous time and disappearing at the end of that period in the mysterious extinction of all the dinosaurs. However, while they lived, they ruled! Weighing as much as elephants, 6-7 tons, and measuring between 8-12 metres long, tyrannosaurs had large skulls, some of which were up to 1.3 metres long. Their jaws were massive and armed with sharp, serrated teeth each measuring 10-15cm long. Their hind limbs were powerful, but their two-fingered front limbs were short and unable to reach their mouth. Only the largest horned dinosaurs may have been a match for the awesome predators. Although they were clearly meat eaters, it is possible that scavenging may have been a large part of their diet.

Three species of tyrannosaurs could be found in Alberta during the late Cretaceous -- Albertosaurus, Daspletosaurus and Tyrannosaurus rex. They may have hunted on the deltas and in the forests, ambushing ceratopsians and duckbills, or scavenging food wherever they could.

Dromaeosaurs and Tyrannosaurs are known collectively as theropods (bipedal, carnivorous dinosaurs). There are many other theropods that have been discussed, however, one worth mentioning is Troodon. This group of dinosaurs is one of the rarest theropods, with only 20 fragmentary specimens known. In the early 1920's it was believed the Troodon was closely related to the Pachycephalosaurid dinosaurs (dome-headed dinosaurs). After complex studies, Troodon is now considered to be a lightly-built theropod weighing approximately 50kg. Troodon is believed to be the most intelligent dinosaur because of its large brain. The size of the brain implies a high activity level in Troodontids. This is also indicated by the large eyes, stereoscopic vision, and long, slender legs. Troodontids had a large claw present on their second toe that was similar , though not as large, to the Dromaeosaurs. Many scientists believe the diet of Troodon consisted of small mammals, lizards, hatchlings of other dinosaurs, and insects.

Ceratopsians (Horned dinosaurs)

The horned dinosaurs were the last major group of dinosaurs to evolve, and they were among the most abundant in Alberta late in the Cretaceous period. Most of them were heavy (between 3-6 tons and measuring 5.5-9m long), four-legged herbivores with powerful jaws that ended in parrot-like beaks. Ceratopsians had many teeth that were only found in the cheek section of the jaw. There were no teeth found in the beak portion. Ceratopsian had such large heads that their necks had to be specially reinforced with muscle to support the weight. The pelvis and shoulders were both sturdy, and the tail was held off the ground.

They were well protected from attack as they sported a variety of frills and horns. Besides serving an intimidation function, these structures may have been used for display in attracting mates. Both male and females had horns and frills.

There was also safety in numbers, and there is evidence that the horned dinosaurs moved in great foraging herds through the forests, chopping off vegetation with their sharp, toothless beaks. Huge dinosaur graveyards provide clear indication that ceratopsians travelled in herds. The jumbled bones in these bonebeds are often from a single species, and sometimes include dinosaurs of all ages. This suggests that the herd perished together due to some disaster. Centrosaurus bonebeds have been uncovered in Dinosaur Provincial Park, Alberta.

In Alberta, at least fourteen species of ceratopsians have been identified. Most of them have been found along the Red Deer River. Examples include: Centrosaurus, Chasmosaurus, Styracosaurus, Triceratops, Arrhinoceratops, and Anchiceratops.

Ankylosaurus (Armoured dinosaurs)

The ankylosaurs, or amoured dinosaurs, were built like battle tanks with stocky legs and squat, heavy bodies. On average, they weighed between 2-4 tons, and measured form 5-10 metres long, depending on the species. A variety of armour and scales protected their bodies and small heads, while some species even had armour in their eyelids! An array of studs, plated, spikes and tail clubs (in one group) kept their enemies at a distance. Made of bone and controlled by powerful tail muscles, the clubs were very dangerous weapons. Not all species of Ankylosaurs had these powerful tail clubs.

Ankylosaurs were plant-eaters, cropping low growing plants with their stubby teeth. Their heads were somewhat triangular-shaped and rested on the end of a short neck.

Four species of armoured dinosaurs roamed Alberta in the late Cretaceous -- Ankylosaurus, Euoplocephalus, Panoplosaurus and Edmontonia.

Sauropods (Long-necked dinosaurs)

The sauropods were perhaps the most spectacular of all dinosaurs. They were the long necked, long-tailed giant herbivores of the Jurassic and Cretaceous Periods. In fact, they were the largest land animals to have ever lived. As a group they survived for over 50 million years. The body plan of all sauropods was structurally similar. They had a small head on top of an extra long neck; a long, deep body to accommodate an enormous stomach; thick, pillar-like legs with five-toed feet; and long, thick tail tapering to a point.

Two special adaptations of the skeleton were evident in all sauropods. First, great cavities were hollowed out of the vertebrae to help lighten the load of the animal while still retaining the structural strength of the skeleton. Secondly, the massive hip girdle was firmly fused to the backbone by four or five sacral vertebrae, which formed a solid support for the heavy body and tail.

Sauropod remains have been frequently found in the western United States, but never in Canada. This is probably due to the different environmental conditions during the Mesozoic Era. The western United States was drier and had more exposed land surface, while Canada had more seas, lakes, swamps, and marshes which appear not to have been suitable sauropod habitat.

Some sauropods that children are familiar with include: Apatosaurus (also known as Brontosaurus), Brachiosaurus, Deplodocus, and Camarasaurus.