Paleocommunity and evolutionary ecology of Paleozoic crinoids
. In: Waters JA, Maples CG, editors.
Slight micritization of crinoids
were evident along the grains margins (Fig.
Fossils of juvenile crinoids
are rare, he explains.
Although most crinoid
fossils are from "spindly, plant-like animals anchored to sea floor rocks," the 1 to 4 millimeter star-shaped parts of these crinoids
that the scientists dug up were used to grab and hold onto objects but were not found attached to anything.
The most common of these are crinoids
(sea lilies), snails, clam-like brachiopods, and ancestors of today's squids that had shells back then.
tended to grow on the edges of the reefs, so reef limestone is usually surrounded by limestone containing many crinoid
Different types of fauna, observed in the formation, include brachiopods, bryozoans, crinoids
, bivalves and foraminifera (fusulinids).
This formation is overlain by light to dark dolomite containing coral, sand and crinoids
, having less than 100 m thickness.The dolomite gradually changes from bottom to top from light grey to light green limestone, bearing trilobite fragments; such dolomite and limestone are assigned to the Mila Formation.
Gravel deposits in the creek primarily consist of siliceous lithologies including chert, jasper, geodes, agate, and silicified fossils such as bryozoans, crinoids
, corals, brachiopods, and rare cephalopods and trilobites.
Twenty-seven meters underwater we discovered an untrammeled paradise: Thousands of fish wove through brightly coloured coral peppered with striped crinoids
, small marine animals that hold their tentacles curved like flowers.
The marine organisms commonly associated with the carbonate materials deposition include; bivalves, gastropods, echinoids, crinoids
A monograph of the existing crinoids
. The Comatulids.
Several marine fossils not found in underlying formations suddenly appear here, including those of gastropods; crinoids
; rare corals; small conodonts (eel-like creatures); and armored, plate-mouthed fish known as placoderms.
These small, shelled marine animals were some of the most common inhabitants of the Late Devonian oceans, which had the most extensive reef system in Earth's history.The seas teemed with huge predatory fish such as Dunkleosteus, and smaller life forms such as trilobites and crinoids
Small corals patterned like honey bee combs, tiny rings from an unfathomable number of crinoids
, pieces of fossilized shells, and even the plain grey limestone tell the story of an ancient ocean filled with invertebrate life.