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Sections
of stems from stalked echinoderms are rare in the Fort Apache
Limestone at all three of our sites east of Payson. This could
include Crinoids, blastoids, and cystoids. There is really no
way to identify the exact genus and species from scattered stem
ossicles, so here I present to you anything that even remotely
resembles a stem piece. The most common shapes are the small
ovals with a round central axial hole, followed by more conventional
round crinoid stem ossicles which are the larger sizes here.
The extreme mud present on the bottom and raining down on the
benthic community most likely prevented a large population of
filter feeding crinoids from taking hold in this formation.
Click on images
for full size.
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This
represents a low power view of nearly every recognizable stem
fragment we ever found in over 200 pounds of limestone. Some
are round, some are star shaped. Many are ovals. A few ring shaped
pieces are questionably stems, however they are included here
for completeness. 7x |
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Oval
to round thick walled ossicles with very small central openings. |
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Round
doughnut shaped pieces with larger central round holes. |
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Crinoid
stem ossicles. These are single specimens. |
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A
three stack of crinoid ossicles, we can almost can call this
one a stem! |
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Side
view of above specimen. The crinoids must have been quite diminutive. |
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Very
strange piece, a crinoid stem ossicle covered with an encrusting
bryozoan. Few hard grounds existed in the Fort Apache, and we
find quite a few shells, urchin parts and gastropods covered
with such an encrustation. |
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