Within the shell is a pair of "arms," often long and spirally coiled, bearing rows of ciliated tentacles by which a current of water is made to flow into the mantle cavity, bringing the microscopic food to the mouth between the bases of the arms. The shell is both opened and closed by special muscles. They form two orders; Lyopoma, in which the shell is thin, and without a distinct hinge, as in Lingula; and Arthropoma, in which the firm calcareous shell has a regular hinge, as in Rhynchonella.
Brachiopods feed by filtering small particles from the water using a specialized organ called a lophophore, which is a feeding structure with tentacles that capture food particles. The particles are then transported to the mouth for digestion.
During the Ordovician period, many organisms emerged that are now extinct. Notable examples include the trilobite Asaphus, the brachiopod Orthoceras, the graptolite Didymograptus, the conodonts like Iapetognathus, and the nautiloid Endoceras. Other extinct organisms include the coral Favosites, the crinoid Cameroceras, the bivalve Pecten, the echinoderm Clypeus, and the bryozoan Fenestella. These groups illustrate the diversity of life during this time before their eventual extinction.
Cambrian Period
brachiopod
Brachiopod
The Brachiopod is the official state fossil. After lobbying by students and teachers at a Louisville middle school, the Kentucky State Legislature designated the brachiopod the state fossil in 1986; aspecific species was not named. Though they resemble clams, brachiopods are not related to them. There are hundreds of species of brachiopod found in Paleozoic strata throughout Kentucky. They lived attached to the sea bottom or some object on the sea bottom. A few brachiopods survive in the deep oceans today.
A bivalve. A clam (A brachiopod)
David Alexander Taylor Harper has written: 'The brachiopod faunas of the upper Ardmillan succession (upper Ordovician), Girvan'
Helen Marguerite Muir-Wood has written: 'On the morphology and classification of the Brachiopod suborder Chonetoidea' -- subject(s): Chonetoidea
Thomas W. Amsden has written: 'Late Ordovician through Early Devonian annotated correlation chart and Brachiopod range charts for the Southern Midcontinent region, U.S.A'
Brachipods evolved about 540 million years ago during the Cambrian period. They still exist today, so they also were alive during all of periods between now and the Cambrian.
Janet Waddington has written: 'An introduction to Ontario fossils' -- subject(s): Fossils, Paleontology 'Upper paleozoic brachiopod subfamily spiriferellinae from the Canadian Arctic and its significance for paleogeography, paleoclimatology, and continental drift'
Absolute age differs from relative age in that it states exactly how old something is, instead of how old it is compared to something else. The age of most fossils, including those of brachiopods, are determined using the carbon dating method.
Thomas W. Henry has written: 'The brachiopod Antiquatonia coloradoensis (Girty) from the upper Morrowan and Atokan (lower Middle Pennsylvanian) of the United States' -- subject(s): Animals, Fossil, Antiquatonia coloradoensis, Fossil Animals, Paleontology