Scientists have found a fossil in China of a creature that appears to be a worm with spikes protruding out from its back. The age of the fossil was determined to be about 500 million years old, which corresponds to about the middle of the Cambrian period, the time when unicellular life was thought to have first started.
This fossils defining feature is the spikes on its back but it also has hairy appendages. Most researchers actually think it is a distant cousin of the velvet worms that inhabit tropical forests.
The creature has been named Collinsium ciliosum which is named not after its discoverer, but after Canadian paleontologist Desmond Collins, who in the 1980’s hypothesized that these types of spiked worms might exist. And sure enough they do!
Collinsium lived about 500 million years ago in what is now modern day China in the Xiaoshiba deposit. The Cambrian period is the time when atmospheric oxygen levels were high enough to allow the evolution of multicellular organisms. This was a period of explosive evolution which lead to many interesting life forms including, apparently, spiked worms.
The origin of the spikes on Collinsium is easy to explain. Researchers say Collinsium stuck out to predators and had a sedentary lifestyle. It did not hide under rocks or have a speedy getaway so these spikes were needed to protect against predators. It has very heavy armored, which indicated it was probably slow and relied on its armor for protection.
Although it doesn’t look like in it the fossil possibly because not all of the spikes were preserved in the fossil, Collinsium can have up to 72 spikes on its back and grow to a length of 10cm. What is very interesting about Collinsium is that it is believed to be one of the first armored soft-bodied animals to evolve.
The scientists involved in this study find themselves very lucky to have found this fossil. Soft-bodied organisms without internal skeletons very rarely fossilize because there are few ‘hard parts’ in them.
Evidence of Collinsium being relatively closely related to velvet worms comes from both of them having a similar sedentary lifestyles and body organization. It also seems to be very closely related to another Cambrian creature, Hallucigenia, which has similar spikes and was living in about the same time period.