How the dinosaurs appeared is clear, but it's not so clear how they dissapeared. One thing's for sure, they ruled this planet for a significant amount of time. But how much truth is behind this avalanche of publicity and fiction, and which dinosaurs are the true leaders of these amazing lizards?? Here's just a small list, by no means comprehensive of these vertebrates which dominated the earth for a period of about 160 millions of years. As a matter of fact, there are about 10 000 species of dinosaurs living today, but we know them as birds.
- Amphicoelias fragillimus
There's a really big chance this name won't say anything to you; it didn't to tell anything to scientists until a few years ago. Despite the fact that no full fossils have been found, it is widely regarded as the larges dinosaur to have ever lived, coming close to the biggest animal of all time, the blue whale. It's believed to be the larges vertebrade, varying in length from 40 to 60 meters. The femur of Amphicoelias is unusually long, slender, and round in cross section, and it is very fragile, which is why scientists have nick named it the crumbling giant.
Jumping from the biggest to a (relatively) small dinosaur, you'd never suspect that this "little" dinosaur was in fact the most feared predator for most dinosaur herbivores. Measuring about 2 meters, it walked on two legs and were similar in construction in many ways to birds. Actually, there are some reasons to believe that these dinosaurs were covered in feathers, which would mean that our perception of them could be totally wrong. If we were to see one of these cooperative hunters today, perhaps we would think that we are looking at a very strange bird.
Brachiosaurus is another huge creature, actually the tallest of all dinosaurs. Its name means "armed lizard", and it was named in this way because its forelimbs are bigger than the hind limbs. It is not certain if it was cold blooded or warm blooded, which leads to the fact that scientists are not sure how much it would take to mature (in the first case 100 years, in the second 10 years). It is believed that due to the size and the fact that it walked in herds, it had nothing to fear from even the biggest predators.
- Tyrannosaurus rex
With a name that means tyrant king, T. Rex is the most known dinosaur in the world today, but not just due to its amazing characteristics. It had a huge massive had, which was balanced only by the huge tail in the back. Still, the general image of this creature is not accurate, because research showed that it was mostly a scavenger, hunting only on rare ocasions; still, that debate is not yet settled. This fact could have other implications, showing how well it could turn and how fast it could run. Still, it remains one of the biggest predators ever, and it's definitely a badge for the jurassic period.
- Spinosaurus aegyptiacus
T Rex may be the well known, but Spinosaurus was by far the biggest predator of all dinosaurs. The bad thing is that many remains have been destroyed so scientists are not very sure just what its appearance was, but they made some pretty accurate appreciations, using the few remains they found. This dinosaur had a sail which was formed of very tall neural spines growing on the back vertebra; these spines were huge, growing up to eleven times the height of the vertebrae from which they grew, reaching two meters. There is also some speculation that Spinosaurus was a fisher, but the most probable thing is that ate terrestrial and aquatic.
Triceratops was one of the latest herbivorous dinosaurs that appeared, and it's very easy to recognize because of the horns which resemble a rhinoceros. Actually, the name means three horned. They probably had up to 9 meters, and the head could be to about a third of the body. The classic believe is that horns were used for defence against predators, but more recently, the theory is that they were used as to court the females, in a pretty similar way to deers or other horned animals today.
It's time to move to the aquatic dinosaurs; Ichthyosaurs in particular were giant marine reptiles that resembled fish and dolphins, reigning pretty much in all of the mesozoic period. That is until they were surpassed in efficiency by the plesiosaurs. Some species of Ichthyosaurs lived to huge sizes, up to 15 meters, but the latest ones were a bit smaller.
Plesiosaurs were the best aquatic predators that the jurassic period had to show. Imposing in the dangerous waters of the age was by no means an easy task, and it truly required some amazing abilities. They developed and thrived with no real opposition, until the Cretaceous–Tertiary extinction event, which occured approximately 65.5 million years ago. They had a small head and long neck, and were actually slow swimmers. But they used the neck to create really fast movements of the head, grabbing fish or cephalopods. Also, they presented an unbelievable evolutionary trait, four flippers, which gave them great mobility so they could rotate their body too.
Archaeopteryx was not a dinosaur, but rather the link between dinosaurs and birds. Similar in size to modern day birds, it was just about 0.5 metres long. It has broad wings, feathers, and is able to fly, but it still has more in common with dinosaurs, such as jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest homeothermy), and various skeletal features. It is a key element in the evolutionary debate, and one of the most studied creatures of all time.