This turns up in the Ediacaran fauna before the Cambrian explosion. It is just about what and just about when scientists predicted by looking at specimens of later chordates from the Cambrian. Eighteen specimens are known.
It is part of a growing body of evidence that body plans diversified during the Pre-Cambrian, but organisms were soft and were rarely preserved as fossils. The Cambrian explosion is more a result of developing hard body parts than any actual increase in the rate of evolution.
January 12, 2006 at 00:46
` Neat! In other words, the proper term would be the Cambrian Induration.
January 12, 2006 at 00:58
A very good word! Hi, S E E Quine!
January 12, 2006 at 01:07
` Hi-yeeee!
February 6, 2009 at 20:55
what is the specific name of this chordate? Is it something like “picaya”?
February 7, 2009 at 10:28
Lenna, you have the pronunciation right, but it’s spelled “Pikaia”—there’s a description here with animation: Understanding Evolution: Pikaia. The description says that scientists don’t know what it ate. I guess not enough soft parts are preserved.