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 esconi.info@gmail.com. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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
Deltoblastus verbeeki: one of the last blastoids from the Late Permian of Timor.
Diploblastus glaber: from the Mississippian of Southern Illinois.
Granatocrinus kentuckyensis: from the Mississippian Osagean Series of Northern Kentucky.
Orophocrinus stelliformis: from the Mississippian Burlington Limestone.
Pentremites godoni: from the Mississippian Paint Creek Formation of Southern Illinois.
Pentremites pyriformis: from the Mississippian Paint Creek Formation of Southern Illinois.
Pentremites pyriformis: with Brachioles: from the Mississippian of Kentucky.
Pentremites rusticus: from the lower Pennsylvanian of Oklahoma. Note the surface ornamentation.
Pentremites spicatus: with color bands: from the Mississippian of Southern Illinois.
Troosticrinus reinwardti: one of the first blastoids from the Silurian Beech River Formation of Tennessee.
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