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Lophophorates: Brachiopods

Lophophorates: Brachiopods. Hinge is pin-in-socket type Separate adductors and diductors Valves tend to stay articulated post mortem. Brachidia – lophophore supports, diagnostic shapes Pedicle may exit in notch between valves (primitive) or from opening in pedicle valve.

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Lophophorates: Brachiopods

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  1. Lophophorates: Brachiopods

  2. Hinge is pin-in-socket type Separate adductors and diductors Valves tend to stay articulated post mortem

  3. Brachidia – lophophore supports, diagnostic shapes Pedicle may exit in notch between valves (primitive) or from opening in pedicle valve.

  4. 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

  5. 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 Order Spiriferida O-Jr Order Rhynchonellida O-R Order Terebratulida D-R

  6. Lingulida & Acrotretida

  7. Orthida

  8. Strophomenida

  9. Rhynchonellida

  10. Pentamerida

  11. Atripida

  12. Spiriferida

  13. Terebratulida

  14. Phylogeny

  15. 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)

  16. 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.

  17. Zig-zag commisure Classical functional morphology by Rudwick

  18. Convergence (homeomorphy) 1 orthid, 2 productid, 3 spirifer, 4 terebratulid See also Terebratula and Composita

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