Albertosaurus


The Albertosaurus was the three toed cousin of T. Rex. Although smaller than T.Rex, this relative lived a few millions of years earlier and was a carnivore. Albertosaurus lived towards the end of the Mesozoic period of the reptiles, nearly 75 million years ago.
Albertosaurus was nearly 30 feet from head to toe and about 11 feet tall at the hips! This roughly 2500 kg dinosaur walked on two legs, which had three toes each and short arms with two fingers on each. Its large head held sharp teeth. The Albertosaurus had a long tail that provided the required balance and it even aided the dinosaur while turning.

Albertosaurus' lower jaw had between 14 and 16 teeth, while the upper one had between 17 and 19. This dinosaur had replacement teeth that developed beneath each tooth! The Albertosaurus lived on the other plant-eating dinosaurs.

Albertosaurus' muscular legs enabled it to run very fast. It has been observed that the 6 tons in weight T. rex, which was 20 feet tall could only cover 20 mph, and if it did have a fall, it would have been fatal. The smaller Albertosaurus' smaller body mass would make a similar impact much less powerful. This dinosaur may have been able to recover a fall and being smaller, it must have been a fast runner.
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Allosaurus




It is interesting to note that this dinosaur's name means 'different lizard'. The 'different' in 'different lizard' probably comes from its unusual vertebrae, which was much lighter than those of other dinosaurs during the time. The Allosaurus lived in the late Jurassic period, dating back to nearly 150 million years ago!

The dinosaur was named in 1877, by Othniel Marsh who pronounced the name 'al-oh-saw-rus'. The fossils were discovered in Colorado, USA. Fossils of the Allosaurus were discovered in Colorado, Montana and New Mexico. They have been unearthed in North America, Europe, Africa and even Australia.

The Allosaurus was a carnivore that ate stegosaurs and even iguanodonts that ate plants and headed the predator list. The Allosaurus was 12 m long and 10 ft in height, at the hips. It weighed between 4 and 4.5 tons! The Allosaurus was a feared predator and made quite a scary sight with its huge head and saw edge like socket set teeth. The lizard hipped dinosaur had short arms. It had hands with three fingers on each and this feature made it an advanced theropod of the age. The Allosaurus belonged to the phylum 'chordata', which implies that it had a hollow nerve chord that culminated in a brain.
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Brachiosaurus







The Brachiosaurus was different from the other dinosaurs that roamed the earth when it did. This difference came from the fact that Brachiosaurus was a giraffe-stanced sauropod, which means that the hind legs of the Brachiosaurus were shorter than the front legs. This is also the reason why it is referred to as the 'arm lizard'. Brachiosaurus was named by Elmer S. Riggs, in 1903.

Brachiosaurus was a large plant eater. This herbivore fed on conifers, ginkgos and cycads. It was believed to have been between 80 and 85 feet long and weighed between 33 and 88 tons! Brachiosaurus was 23 feet tall, at the hips and stood between 40 and 50 feet tall at the head. The dinosaur lived during the late Jurassic period, about 156 million years ago. The fossilized remains of the Brachiosaurus have been discovered in Colorado, USA, Tanzania and Portugal.

Brachiosaurus belonged to the phylum 'chordata', which means that the dinosaurs had a nerve chord that was hollow and ended in a brain. Brachiosaurus had socket set teeth and were lizard hipped. Brachiosaurus was a warm-blooded animal, with large demands for energy by the body, on a daily basis, of probably more than 182 kg of food every day!
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Diplodocus




Diplodocus was a plant eater and had a long neck reaching around 26 feet, but it could not hold its neck beyond 17 feet off the ground. It had a very long tail (around 46 feet) that was whip-like in appearance. Diplodocus had a head, with nostrils on top that was a little less than 2 feet long. The Diplodocus' had significant short front legs when compared to its back ones. Its legs featured feet with five toes each, very elephant-like in appearance. Each foot had one thumb claw, which is believed to have been a protection mechanism.

Sauropods such as Diplodocus were believed to have dual brains. Later, it was discovered that this so-called 2nd brain was nothing more than the spinal cord that had an extension/enlargement. This enlargement, found in the hip area was even larger than the Diplodocus' already small brain. The name Diplodocus means 'Double-beamed' and the dinosaur was named in 1878. This plant eater mainly ate conifers, which were common to its natural habitat. Diplodocus also fed on secondary food sources like gingkos, cycads, seed ferns, club mosses and horsetails.

Diplodocus had blunt teeth that were useful for nipping at and stripping foliage. The dinosaur was 90 feet long, 16 ft tall at the hips and weighed between 10 and 20 tons. It lived about 155 million years ago.
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Plesiosaurus











Plesiosaurus was a large marine sauropterygian reptile that was about 3 to 5 meters long! It lived during the early Jurassic Period and its fossilized, nearly complete skeletons were discovered in England and Germany. The distinguishing feature of the Plesiosaurus was its small head, slender neck, broad body, short tail and two pairs of elongated turtle-like paddles.

Plesiosaurus means 'near lizard' and was named so by William Conybeare because of the normal reptile like structure, resembling those that had been found in the same rock strata. The snout of the Plesiosaurus was short and the jaws had a series of conical socket teeth. The neck, though long and slender, seemed rather stiff. This was probably due to the fact that vertebrae were observed to be flat-ended. The short tail of the Plesiosaurus was straight and tapered rapidly.

The pectoral and pelvic girdles were expanded and the pectoral arch was quite similar to that of the turtle. Its limbs were paddles and each had five digits. The skin of the Plesiosaurus was smooth. It is not yet known whether the Plesiosaurus laid eggs on land, like the turtles. The other possibility would be giving live birth in water. It is possible that the young ones could have lived in estuaries till they were mature enough to venture out.
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