Natural History And Fossils

The Story Of Life On Planet Earth

What Are Life Before Dinosaurs?

Life before dinosaurs are creatures that existed before the Mesozoic era (see what are dinosaurs?) The creatures first evolved about 600 million years ago. The time life before dinosaurs inherit is called the Palaeozoic era. Even further back is the Precambrian, not much life at all. In the Palaeozoic era there are 6 periods. There is the Cambrian (543-490 MYA), Ordovican (490-443 MYA), Silurian (443-417 MYA), Devonian (417-354 MYA), Carboniferous (354-290 MYA) and lastly the Permian (290- 248 MYA).

The Cambrian (543-490 MYA) And The Ordovican (490-443 MYA)

The Cambrian- The Cambrian was one of the first time periods to have life (not including bacteria). Were once there were simple celled creatures, complex organisms now swim in the oceans of 543 MYA (million years ago). The very first proper predator on earth was Anomalocaris. Anomalocaris looked like an armoured cuttle fish. Anomalocaris's strong jaws were useful for cracking open the shells of Trilobites and sucking up the juicy inside. Trilobites were very common in the Cambrian seas. Anomalocaris and Trilobites were among the first creatures to evolve complex eyes with simple lenses. Others had no eyes and relied on other senses. Having eyes in the Cambrian seas was a great advantage but unfortunately Anomalocaris did not live on into the next time period which is the Ordovican. Trilobites did however. Trilobites lived on until the start of the dinosaur age, they were the Palaeozoic's big succes story. The Ordovican- The Ordovican was full with life in the oceans unlike the periods that came before. Giant Orthocones rule the oceans. The largest carnivore in the Ordovican is Cameraceras. Cameraceras was a huge squid like animal that lived inside a long straight shell and grew to 11m in length, more than 9m of its body length is shell. People used to think that fossil orthocone shells were unicorn horns. Cameraceras fed on trilobites and Megalograptus. Megalograptus was a giant spiny sea scorpion growing to 1m in length. Megalograptus hunted fish and trilobites. The previous predator Anomalocaris (see the Cambrian) is no longer alive. Megalograptus did its best to stay out of the way of the Orthocones (Cameraceras). The ancient oceans quickly became a scarier place.

The Silurian (443-417 MYA) And The Devonian (417-354 MYA)

The Silurian- The Silurian was an important part of the Earths history as it is the period when life (plants and animals) first crawled out onto land. These primitive plants would have only been about ankle high and probably resembled weeds. The first land animals would have not been very large. Some examples of animals during this time are: the Eurypterids which were sea scorpions. There was a variety of Eurypterid species in the Silurian but the largest was Pterygotus which was also the largest arthropod ever. Pterygotus measured 2.8m long (9.2ft)! It was probably the largest killer in the Silurian Seas. Pterygotus however did not make the journey onto land and finally died out about 410 MYA. A smaller scorpion also prowled the seas but it was not a Eurypterid. It was Brontoscorpio a 94cm long scorpion making it the biggest scorpion of all time! Brontoscorpio had a sting about the size of a light bulb and it used it to kill its prey such as Cephalaspis. Cephalaspis was an armoured fish about 60cm long. If being chased by a Eurypterid or Brontoscorpio it had to stop frequently because its armour was so heavy and straining the fish which gave The predators an advantage, However it was Cephalaspis who rapidly evolved into a different type of animal leaving the Eurypterids in the evolutionary dust. Cephalaspis evolved into an animal you will soon find out about. But it was the Eurypterids who first made it onto land and not Cephalaspis who were still swimming around in the seas. Cephalaspis's new form however could make frequent pit stops to land. For now the Eurypterids rule the oceans but that will soon change. The Devonian-

The Carboniferous (354-290 MYA) And The Permian (290 - 248)

The Carboniferous- This period was perhaps the hottest, wettest and most humid period in history. Rainforests covered almost all of the earth...something that would not occur again until the Eocene and Paleocene, some 240 million years later. As a result of the wet and lush climate, a bizzare group of animals evolved. The Carboniferous is also known as the age of amphibians, and with good reason. Various species of huge amphibians dominated the lush forests and fed on other animals there size, which was about 2m long. One such species was Proterogyrinus, which looked like a ferocious, overgrown salamander about 2.3m long. Even though the Amphibians dominate this period, there is something special about the other residents of the Carboniferous forests... GIANT INSECTS! The Carboniferous had more oxygen in the air than it does today, allowing for greater size in flying creatures, including insects. Meganeura was a GIANT dragonfly with a wingspan of 75cm! It fed on smaller insects and caught them mid flight. There were even giant spiders the size of cats! Arthropleura was a giant centipede 2.6m long! Making Arthropleura the largest Arthropod of all time! the end of the Carboniferous, there was an ice age, and the lush rainforests were killed off. Dry and arid deserts soon followed. The Giant amphibians and insects didnt survive the change...thus giving rise to the Permian. The Permian- Following the decline of rainforests, larger and more adaptable reptiles evolved. Among these were Dimetrodon and Edaphosaurus, 2 sail backed reptiles about 3m in length. Dimetrodon was a carnivore but Edaphosaurus was a herbivore. As the period progressed, larger and larger reptiles evolved. Gorgonops was a ferocious killer 3.5m in length, it hunted large herbivores like Scutosaurus and killed with its formidable jaws. Gorgonops had the body shape of a dog and could pursue prey with ease. Its prey, Scutosaurus was a giant relative of the Turtle. It was also 3.5m long, but built like a tank. The climate became so hot that even creatures like Scutosaurus and Gorgonops could not survive. It triggered a mass extinction, an extinction even larger than the one that would kill the dinosaurs in 182 million years time.

Image- Meganeura