Astraspis (Greek for "star shield"); pronounced as-TRASS-pis
Shores of North America
Late Ordovocian (450-440 million years ago)
Size and Weight:
About 6 inches long and a few ounces
Small marine organisms
Small size; lack of fins; thick plates on head
Like other prehistoric fish of the Ordovician period--the first true vertebrates to appear on earth--Astraspis looked like a giant tadpole, with an oversized head, flat body, wriggling tail and lack of fins. However, Astraspis seems to have been better-armored than its contemporaries, with distinctive plates along its head, and its eyes were set on either side of its skull rather than directly in front. This ancient creature's name, Greek for "star shield," derives from the characteristic shape of the tough proteins that composed its armored plates.