Community College (LRCCD)

Geology & Earth Science Instructor: Arthur Reed, P.G.

Happy Fossil Friday!

Friday July 2, 2021

Blastoids

Blastoids are extinct, stalked, invertebrate animals (not plants) that appeared during the Ordovician Period. They were successful species that survived 145 million years until the end of the Permian Period (about 252 million years ago) when they became extinct (compared to us hominins at less than five million). Their close ‘cousins’, the modern-day crinoids, lived at the same time but still thrive in today’s ocean as sea lilies, feather stars and others, some of which float through the water.

The blastoids were not mobile, once mature they would anchor themselves and strain passing water for nutrients. The above illustration show the main body at the end of the ‘anchoring’ stem with the straining limbs attached. The small walnut-sized body is normally all that gets fossilized.

Blastoid fossils (1-2cm ea)

Short video of hunting for blastoid fossils

These sea lilies (crinoids) are close ‘cousins’ to the blastoids but they have survived since the Paleozoic…the blastoids did not survive. (remember, they are animals, not plants).

Short video of a crinoid moving along the seafloor.

Crinoids:

These unusual, beautiful and graceful animals are living fossils. That is, they have been around for about 450 million years and can still be found in the oceans today.