Allosaurus (meaning “Other reptile”) was one of the largest carnivores of the Jurassic period. Running on two muscular, bird-like legs, Allosaurus preyed upon the large herbivores of the period, including large sauropods and smaller plant eaters. It may have been a pack hunter, possibly lying in wait to ambush prey. The forelimbs were short but muscular, each of the three fingers tipped with a sharp curved claw up to 25cm (10 inches) long for holding prey. The powerful jaws were lined with over seventy sharp 8cm (3 inch) long teeth. Movable joints and elastic ligaments in Allosaurus’s jaw and skull flexed to help the teeth tear and slice through the prey. The flexible jaws stretched widely to allow the creature to swallow large mouthfuls of flesh.
The last and largest of the tank-like armoured dinosaurs, Ankylosaurus (meaning “Fused reptile”) was well protected from big meat eaters. Large bony plates, which probably had additional horn-like coverings, protected its flanks. The skull was thick with two pairs of sharp horns at the back of the head. Parts of the tail vertebrae were fused like the handle of a club, while the base of the tail remained flexible. The end of the tail was a large bony club which would have been a devastating defensive weapon wielded against attacking predators. Analysis of Ankylosaurus’s brain cavity indicates the most highly developed part of its brain was devoted to its sense of smell.
Named for the large bones of its foreleg, Brachiosaurus was an enormous sauropod, one of the largest dinosaurs known from a complete skeleton. Brachiosaurus stood over ten metres high, was twenty-two metres long and weighed around eighty tonnes. Brachiosaurus was adapted to live on land, with similarities to a giraffe, browsing in treetops. Its peg-like teeth were used to strip leaves from the high branches. Unlike many of its sauropod relatives, Brachiosaurus had very long forelegs, indicating that its neck was held in a more vertical position. Some paleontologists have suggested that the most well known species, Brachiosaurus brancai, is actually a separate genus, Giraffatitan. Whatever its name, this giant was feeding almost constantly to sustain its enormous bulk.
Liliensternus was an active hunter, agile and fast, running on two powerful hind-legs, balanced by a long, graceful tail. It was a lightly built carnivore and was the largest meat eater of its time. Skull details suggest that Liliensternus is related to the Jurassic carnivore Dilophosaurus. The jaws were lined with sharp, blade-like teeth. The skull shows evidence of distinctive fin like crests along the snout. These may have been for species recognition or as a display to attract a mate. Like many early theropods, Liliensternus has a five fingered hand, with a smaller fourth and fifth digit. Later theropods have three fingered hands. Liliensternus is known from two incomplete specimens found in the Kueper Formation, Saschen-Anhalt in Germany. Named for German paleontologist Hugo Ruele von Lilienstern.
One of the largest flying creatures ever, Ornithocheirus is known from a variety of bone fragments on different continents. Like many larger pterosaurs, Ornithocheirus had an enormous head relative to its body length. The jaw supported numerous long, slender, pointed teeth, useful for catching a slippery diet of fish and squid. The crest of the Ornithocheirus may have offered some aerodynamic advantage in flight or it may have been an indicator of gender or for species recognition. Some of the best Pterosaur fossils have come from the Araripe Plateau in north-west Brazil.
Plateosaurus (meaning “broad reptile” or “flat reptile”) was the first and best known of the early giant herbivores. Probably travelling in herds, Plateosaurus was able to move on all fours and could also rear up into a bipedal posture. Balanced on its long hind legs and reaching up with its long neck, Plateosaurus was able to feed on higher branches of conifers and ferns. It had distinctive hands with small fingers and a large clawed thumb. The hands had effective grasping ability and the claw was possibly used for ripping up roots or tearing at branches. Rearing up, Plateosaurus was also able to use its long thumb claws for defense against predators such as Postosuchus. This Triassic dinosaur was first described in 1837 by H. von Meyer. Plateosaurus is known from over one hundred partial to complete skeletons , including ten skulls. Plateosaurus is the most common and well known European Triassic vertebrate fossil from the late Triassic and was the largest land animal of the period.
Stegosaurus (meaning “roof lizard”), is one of the most easily-identifiable dinosaurs, due to the distinctive double row of kite-shaped plates rising vertically along its arched back and the two pairs of long spikes extending horizontally near the end of its tail. “Stegosaurus tails were without question one of the most dangerous weapons ever evolved by a plant-eating animal”. (Bakker) Such a weapon appears necessary considering Stegosaurus coexisted with large predatory theropod dinosaurs, such as the fearsome Albosaurus. The function of the plates has been much debated. Initially thought of as some form of armour, researchers have also proposed that they may have helped to control body temperature. Wind tunnel tests have suggested that the plates are well shaped to gather and dissipate heat. Stegosaurus is also known for its remarkably tiny brain, at only 80 grams, apparently sufficient for its needs.
With its formidable horns and powerful, muscular body, Torosaurus (meaning “Bull reptile”) was like a dinosaur version of a rhinoceros. Featuring an enormous neck frill, Torosaurus had the largest skull of any terrestrial animal. The bony frill had large fenestrae, or holes, to reduce weight and may have been brightly coloured and used for display. Apart from the large frill, Torosaurus was similar in appearance to its close relative, Triceratops. Both ceratopsians had two long horns sprouting above the eyes with a smaller horn on the snout. Torosaurus used its sharp beak and rows of shearing teeth to munch tough vegetation. Fossilized footprints identified as ceratopsian trackways indicate that the forelegs were slightly splayed, with the hind legs straight under the body, similar to a rhinoceros.
Tyrannosaurus (meaning “Tyrant Lizard”), was one of the largest terrestrial carnivors of all time being roughly six tonnes in weight. Tyrannosaurus’s massive skull was balanced by a long, heavy tail. The heavily reinforced skull of T.rex suggests that it was a devastating predator, with bone-crushing bite strength. The jaws were armed with 150mm long, sharp, serrated teeth. Relative to the large and powerful hind limbs, Tyrannosaurus forelimbs were small and retained only two digits. Recent specimens have shown the tiny arms to have been well-muscled, presumably to enable the animal to anchor itself to the ground as it attempted to straighten its hind legs and stand up from a prone position. It was among the last dinosaurs to exist prior to the Cretaceous-Tertiary extinction event. More than 30 specimens of T.rex have now been identified, some nearly complete, which has allowed significant research into many aspects of its biology, including its life history and biomechanics.
Utahraptor (meaning “Utah thief”) is the largest known member of the theropod dinosaur family Dromaeosauridae. Utahraptor is known from a well-preserved skeleton found in 1991 in Utah, USA and fragmentary remains from South America. It was the largest of a group of lightly-built carnivores, called the dromaeosaurs (‘swift lizards’). Utahraptor had large eyes, long grasping hands with large, sharp ripping claws. Its toe joints were specially enlarged so that its massive claw could be raised upward and backward to avoid damage while running. But when used in attack, its claw flexed forward as the animal kicked out. Swinging in a wide arc its huge 20 cm slashing claw would produce terrible wounds enabling a Utahraptor to cripple and kill animals much larger than itself. The unique wrist-joints of the dromaeosaurs allowed the hands to pivot sideways, an action similar to the folding of a bird’s wing.