The Cambrian Explosion was a period in which animal life on earth went from a few less-than-thrilling blobs of cells to an immensely complex group of highly mobile creatures including trilobites, Emeraldella, and this crazy shrimp-like beast. It was a period in which most of the basic body elements for all animal life – legs, guts, mouths – were first evolved. It is also the period in which the first cardiovascular systems arose. A specimen of a 4.5″ critter called Fuxianhuia protensa was recently unearthed with a remarkably well-preserved cardiovascular system. This preserved set of soft tissue represents the oldest cardiovascular system ever found, shedding light on a biological structure that is crucial to nearly all living animals today.

The fossil of F. protensa shows a central, tubular heart with blood vessels branching off towards the eyes, antennae, and brain. This is an especially significant find, since it’s pretty rare that a fossilized animal’s soft tissues can actually be preserved. Usually all that paleontologists are left with are the bones – or in the case of Cambrian critters, shells and exoskeletons, of a given animal. Just consider how you don’t see T. rex eyeballs on display at most of the museums you visit.

“It is an extremely rare and unusual case that such a delicate organ system can be preserved in one of the oldest fossils and in exquisite detail,” said Xiaoya Ma of London’s Natural History Museum, adding that “under very exceptional circumstances, soft tissue and anatomical organ systems can also be preserved in fossils.”

F. protensa. While F. protensa’s cardiovascular system is the oldest we’ve ever found, researchers suspect blood was pumping through early Cambrian creatures well before this guy came onto the scene. (Xiaoya Ma)

The appearance of a cardiovascular network is a significant evolutionary step towards more complex animals. This new body system meant a more effective way of delivering oxygen and nutrients to different areas of an animals body. The high amount of vascular networking found in the head of F. protensa indicates that the brain of this ancient sea dweller required a lot of oxygen, so, whatever you do, don’t call him primitive.

HT: Discovery News