Introduction

   This week we explore the most common macroinvertebrate fossil group, the Brachiopod Phylum.  Brachiopods are exclusively marine, shelled invertebrates that are members of the Superphylum Lophophorata,a  group of organisms that feed with a ciliated hollow, crown shaped structure called the lophophore.  Other members of the Lophophorata are the worm-like Phoronids and the colonial Bryozoans, which we examined last week.  Brachiopods are easily the most common fossil macroinvertebrate, and therefore have tremendous use as guide fossils, as paleoecological indicators, as sources for information on functional morphology and phylogeny, and as sources for geochemical and isotopic analyses.   In life, they are notably characterized by the presence of the  lophophore,  as well as a pedicle (a stalk) for anchoring to the substrate (the pedicle can be a pronounced, fleshy structure as in the Inarticulates, or reduced to a hardly visible rough area on the pedicle valve, as in the Articulates).  As fossils, the opening for the pedicle is often visible, and the internal structures of the shell indicate the location of the lophophore.  Although they are not very common today, they underwent considerable diversification in the Paleozoic, and are a subject of many phylogenetic and cladistic studies.
 
 
 
 
 
 
 
 
 

The Lophophore:  the distinguishing structure found in the Phylum Brachiopoda and also in the Phylum Bryozoa

This interior view of an articulate brachiopod clearly shows the ciliated lophophore feeding structure, coiled in pairwise fashion inside the brachial (dorsal) valve.
In life, this structure extracts food particles from the water column, and thus depends on water that has a current and is free of suspended sediment.
 

Image shown with permission from the University of California Museum of Paleontology
 

Phylum Brachiopoda, Class Inarticulata (Cambrian-Recent) and Class Articulata (Cambrian-Recent)

Basic Facts & Terms to Know about Brachiopods:  They are:
1.	Eukaryotes
2.	Metazoans with organs, true tissues, nervous, muscular, and reproductive systems
3.	characterized by a  Lophophore feeding structure for benthic filter feeding, pedicle structure for anchoring to substrate, and a bivalved shell
4.	Bilateral in symmetry, symmetry plane passing vertically through the valves
5.	free-swimming in larval stage (larvae):  sessile (attached or burrowing)as adults
6.	able to reproduce  sexually
7.	structurally supported by calcium carbonate or calcium phosphate shell
8.	found in marine environments,   Sessile (Attached) or burrowing.
9.	divided into two groups based on presence of toothed hinge in shell:  Articulata-with a toothed hinge, or Inarticulata, without a toothed hinge structure.

What ecological factors can you expect to be important to their survival?  Consider the problems of substrate type, respiration, feeding, and avoiding predation.

Label the  Ventral (Pedicle) valve, the Dorsal (Brachial) valve, the beak, the sulcus, the fold, growth lines, and costae, as well as the Order, Genus (if provided), and time range for the specimen.  For some specimens, you may find that you can't label all these areas because they are not visible.
What is...
Ventral (Pedicle) valve:  The larger of the two valves, and the valve that may have an opening for the pedicle.
Dorsal (Brachial) valve:  The smaller of the two valves, and the valve that holds the calcareous support for the lophophore, the brachidium.
Beak-the pointed portion of the ventral (pedicle) valve near the hinge.
Sulcus-a very deep trough on one valve
Fold-a high ridge on one valve that corresponds to the sulcus on the other valve
Growth Lines-concentric lines of continual growth of the shell as the animal increases in size
Costae-rib-like ridges that run radially from the beak to the edge (commissure) of the shell.

Part II.  Group Assignment: A first look at Caesar's Creek Fossils - 20 pts

Each group should examine the slab(s) of fossiliferous limestone from Caesar's Creek (Upper Ordovician) and note the presence of corals (what order?), bryozoans (what growth habit?), brachiopods (what order?) and sponges (what class?).  Can you find examples of these specimens, with names, in Fossils of Ohio?  Record this information on a single sheet of paper, put the names of the group members on that, and turn it in at the end of the lab.

Notes and Images of the Brachiopoda

Class Inarticulata Range Cambrian-Recent

Order Lingulata

Genus Lingula (Cambrian-Recent)

    This is a typical example of the genus Lingula.  Lingula sp. are "living fossils", organisms that have changed very little since their first appearance in the fossil record (in this case, since Cambrian time).  Shown clearly here to the right of the bivalved shell is the pedicle, a fleshy structure that anchors the brachiopod into the mud and permits it to live in a vertical burrow.  The inarticulate valves are opened and closed entirely with muscular support:  there are no hinge structures beyond the muscles to aid in this.

Image shown with permission from the University of California Museum of Paleontology
 
 

Class Articulata   You will find most of the fossil brachiopods are in this Class.
Order Orthida (Cambrian-Permian)

Image shown with permission from the University of California Museum of Paleontology
 

Order Strophomenida  Ordovician-Triassic

Image shown with permission from the University of California Museum of Paleontology
 

Order Pentamerida (Cambrian-Devonian)

Image shown with permission from the University of California Museum of Paleontology
 
 
 
 

Order Spiriferida  (Ordovician-Jurassic)

Image shown with permission from the University of California Museum of Paleontology

Order Rhynchonellida (Ordovician-Recent)
+
Image shown with permission from the University of California Museum of Paleontology
 

Order Terabratulida (Devonian-Recent)

Image shown with permission from the University of California Museum of Paleontology
 
 
 

Want to know more about how Brachiopods are used in geological research?
Try these references and links

Kowalewski, M., Simoes, M.G., Carroll, M., Rodland, D.L., 2002.  Abundant Brachiopods on a Tropical, Upwelling-Influenced Shelf (Southeast Brazilian  Bight, South Atlantic),  Palaios Volume: 17, Issue: 3, June 1, 2002. pp. 277-286.

Craig, Robert S., 2002.  The palaeobiogeography of Late Cretaceous and Cenozoic brachiopods from Western
                      Australia.  Palaeogeography, Palaeoclimatology, Palaeoecology Volume: 179, Issue: 3-4, pp. 267-292.

James, N.P.; Bone, Y.; Kyser, T.K., 1997.  Brachiopod d18O values do reflect ambient oceanography: Lacepede Shelf, southern
                      Australia.  Oceanographic Literature Review Volume: 44, Issue: 12, December, 1997. pp. 1467.

Rao, C. Prasada; Huston, D., 1996.  Temperate shelf carbonates reflect mixing of distinct water masses, eastern Tasmania,
                      Australia.  Oceanographic Literature Review Volume: 43, Issue: 1, January, 1996. pp. 48.

Bickert, Torsten; Pätzold, Jürgen; Samtleben, Christian; Munnecke, Axel, 1997.  Paleoenvironmental changes in the Silurian indicated by stable isotopes in brachiopod shells from Gotland, Sweden.  Geochimica et Cosmochimica Acta Volume: 61, Issue: 13, July, 1997. pp. 2717-2730.
                        .
Don't forget about the Paleontology Portal, which shows images of fossils, including brachiopods, found in the U.S.  Check out the Ohio Brachiopods at the Paleontology Portal here.

A nice web page on Kentucky Brachiopods...
http://www.uky.edu/KGS/coal/webfossl/pages/brachs.htm