Pikaia is a early fish that is very similar to lanclets of today, and had no fins or armor, and still had no backbone, only a notachord.


Haikouichthys and Myllokunmingia live slightly after Pikia, and are still extremely similar to Pikia, but their vague, undeveloped head now has eyes, and a jawless mouth instead of tentacles. Still, no fins, no backbone, no jaws.


Arandaspis appears a few million years later, and is very similar to our previous fish, but one exception. It's grown a large plate of armor on it. A bit of a backbone is starting to appear, but it's still finless and jawless.

Astraspis appears almost immediately after, similar to Arandaspis but instead now having traces of sensory organs on it's skin near the skull. Still jawless and finless.

Cephalaspis is next, and is similar to Astraspis, but now has FINS! Hurray, fish have grown fins for the first time....only took until the Siluran Period ;)

I'll continue on the simplified fish fossil record soon, but soon both modern fish, sharks, and tetropodomorphs willa appear...