This all changed 600 million years ago when these ancient, primitive organisms evolved bilateral symmetry. This allowed for the creation of complex tissues and organs. This was a massive leap forward in diversity and evolutionary success, resulting in the skull, and more importantly, the brain which it protected.
The brain allowed for greater control over the body and the processing of information gathered by the limbs. This is why creatures such as squid are quite intelligent as they need high power brains to interpret all the information provided by their individual tentacles. As a result, it is possible to tell how advanced a creature is from the state of its brain. While some species of worms could easily outsmart certain species of fish in logic puzzles.
|The exquisitely preserved 520 million |
year old fossil of Fuxianhuia protensa
Discovered by researchers from the University of Arizona, the 7 and a half centimetre long branchiopod, named Fuxianhuia protensa, shows clear and well defined structures similar to antennae and eye stalks connected to a brain inside the skull. What makes it interesting is that the brain is tripartite. Such divisions are also found in the brains of many different groups of crustacean, insect and centipedes today.
|The antennae and eyes of Fuxianhuia connected to its brain|
The Cambrian Explosion, which Fuxianhuia was a part of, was the most important event in the evolution of life. It is fundamental to understanding the diversity of life. Every animal and plant can trace its roots back to this single event in the history.