Lophophorates:

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Lophophorates Brachiopods
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Hinge is pin-in-socket type Separate adductors
and diductors Valves tend to stay articulated
post mortem
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Brachidia lophophore supports, diagnostic
shapes Pedicle may exit in notch between
valves (primitive) or from opening in pedicle
valve.
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Shell composed of two layers of low Mg calcite
outer lamellar layer and inner fibrous layer,
outer layer often not preserved Shell can be
impunctate (A) without holes pseudopunctate
(B) with rods of granular calcite in fibrous
layer punctate (C) with holes penetrating
both layers Shell structure is taxonomically
restricted
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Brachiopod Taxonomy Class Inarticulata Order
Lingulida C-R Order Acrotretida C-R Class
Articulata Order Orthida C-P Order
Strophomenida O-Tr Order Pentamerida C-D Orde
r Spiriferida O-Jr Order Rhynchonellida O-R O
rder Terebratulida D-R
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Lingulida Acrotretida
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Orthida
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Strophomenida
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Rhynchonellida
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Pentamerida
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Atripida
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Spiriferida
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Terebratulida
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Order Strophic? Punctate? Brachidium Pedicle opening
Orthida yes no no open
Strophomenida yes pseudo ? closed
Rhynchonellida no no crura part open
Pentamerida no no crura open
Spiriferida/ Atrypida yes/no mostly no spiralium both
Terebratulida no yes loop In pedicle
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Phylogeny
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Ecology Inarticulates marine and brackish,
may be semi- infaunal, attached or
free-living Articulates marine, attached or
free-living (swim?) trophic suspension feeders
impingement type (not as efficient as filter,
but turbidity tolerant)
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Evolution Diversification in Paleozoic, dominant
members of level-bottom communities. Productids
(Strophomenida) developed to deal with soft
substrate (bioturbators?) Richthofenids
(Strophomenida) developed into reef forms Only
conservative forms survived P/T. Predation
pressure? Nothing eats them today. Can not be
true infauna.
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Zig-zag commisure Classical functional
morphology by Rudwick
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Convergence (homeomorphy)
1 orthid, 2 productid, 3 spirifer, 4
terebratulid See also Terebratula and Composita