Crinoid House in Hannibal, Missouri
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Please look at the pictures of the crinoid fossils if you need to know what they look like.
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Geology and Description
A large proportion of the crinoid species are restricted to the Burlington Formation. The crinoids began to assume a front rank in the beginning of the Osage, as shown by the rich crinoid faunas of the Fern Glen and other beds. The Burlington contains a record of the continuation and acceleration of crinoidal development; the clear, shallow waters of the Mississippi Valley being apparently a region of maximum differentiation and dispersal of crinoids exhibit evolution along several lines-species of Burlington age being broadly distinguished from those of the Keokuk and both of these from Warsaw types.
The Osage epoch marks the culmination of the great division of the crinoids known as the Camerata, and it is remarkable that immediately following this maximum deployment the group vanished.
Crinoids flourished because they were filter feeders, and most of the particles in the clear oceans would have been bits of food. They also needed warm water to produce their elaborate skeletons, since warm water can hold more dissolved calcium carbonate than cold, making it easier to precipitate (Thompson, 1982).
One can imagine the crinoids growing in extensive marine meadows, rippling in the waves on their long, thin, graceful columns, like garden flowers in the wind. On rare occasions, they were preserved whole, flattened to the bottom by a storm and quickly covered with lime mud. Unfortunately, the organic matter connection the plates and columnals of
the stem nearly always rotted in the water and plates were scattered and sorted by the waves to form crinoidal limestones (Clark and Stearn, 1960).
The Burlington contains more species of crinoids than any other formation in the Mississippi Valley. About 260 species have been identified, some of which may be descriptions studied only casually. Brachiopods are next in abundance. About 110 species have been identified. Bryozoa are abundant but only a few species have been recognized. Blastoids are more abundant in the Burlington than any other formation in Missouri. Thirty-three species have been listed, mostly in northeast Missouri near Louisiana (Branson, 1944). Colonial corals declined in some areas, but solitary corals were diversified and
abundant. Gastropods, pelecypods and cephalopods are rare. Sharks
greatly increased their numbers and variety, which may have contributed to the decline of the trilobites, (Shroud and Wagenek, 1969), as only a few specimens of trilobites have been found. Shark's teeth are widely
distributed, but rare. About 100 species have been described from the Burlington of the Mississippi Valley, but of these, not more than 20 are known from the Burlington of Missouri.
Crinoid Description
Crinoids, also known as sea lilies or feather-stars, are marine animals that make up the class Crinoidea of the echinoderms (phylum Echinodermata). Crinoidea comes from the Greek word krinon, "a lily", and eidos, "form". [1] They live both in shallow water and in depths as great as 6,000 meters.[citation needed]
Crinoids are characterized by a mouth on the top surface that is surrounded by feeding arms. They have a U-shaped gut, and their anus is located next to the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognized, most crinoids have many more than five arms. Crinoids usually have a stem used to attach themselves to a substrate, but many live attached only as juveniles and become free-swimming as adults.
There are only a few hundred known modern forms, but crinoids were much more numerous both in species and numbers in the past. Some thick limestone beds dating to the mid- to late-Paleozoic are almost entirely made up of disarticulated crinoid fragments.
1. How many different Crinoids can you count within eye level to the sidewalk?
(depending on your height answer will vary)
2.How many different species are in the Burlington Limestone?
3. How many different types of fossils can you see in the stone building?
4. What is the average size of all the crinoid
and other fossils combined?
Additional Hints
(No hints available.)