This is the "Fossil Friday" post #20. Expect this to be a somewhat regular feature of the website. We will post any fossil pictures you send in to [email protected]. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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Today, we have a real treat... blastoids. These specimens were contributed by ESCONI Paleo Group Leader John Catalani. You might remember he sent along some Nautiloids for our first Fossil Friday. Enjoy!
Blastoids are stemmed echinoderms with 18-21 major plates and hundreds to thousands of smaller plates. Adults were attached to the seafloor by root-like structures called holdfasts. Food gathering involved a set of brachioles that are seldom preserved. Respiration was accomplished using internal, calcareous folds termed hydrospires. Blastoids appeared in the Late Ordovician or Middle Silurian and went extinct in the Late Permian.
Age of blastoids:
Silurian: Troosticrinus reinwardti
Pennsylvanian: Pentremites rusticus
Permian: Deltoblastus verbeeki
Mississippian: remaining specimens
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