brachiopod01
Lingulella chenjiangensis (soft pedicle)
1 of 20
brachiopod02
Anomaloglossa porca (lingulid part and counterpart)
2 of 20
brachiopod03
Platystrophia ponderosa (original shell orthid)
3 of 20
brachiopod04
Kirkidium knighti (original shell pentamerid)
4 of 20
brachiopod05
Desquamatia zonata (original shell atrypid)
5 of 20
brachiopod06
Stringocephalus burtini (original thick shelled pentamerid)
6 of 20
brachiopod07
Australospirifer ceres (internal mold of spiriferid)
7 of 20
brachiopod08
Paraspirifer brownockeri (pyritized spiriferid)
8 of 20
brachiopod09
Mucrospirifer mucronatus (internal mold of spiriferid)
9 of 20
brachiopod10
Cyrtospirifer thalattodoxa (original shell spiriferid)
10 of 20
brachiopod11
Dictyoclostus portlockianus (original shell productid)
11 of 20
brachiopod12
Neospirifer dunbari (original shell spiriferid)
12 of 20
brachiopod13
Cyclantharia kingorum (prorichthofenid or brachiopod)
13 of 20
brachiopod14
Collemataria elongata (leptodid or brachiopod)
14 of 20
brachiopod15
Paucispinifera auriculata (productid silicified)
15 of 20
brachiopod16
Johndearia isbelli (original shell of thick shelled spiriferid)
16 of 20
brachiopod17
Lingula sp. (original shell of lingulid)
17 of 20
brachiopod18
Magellania grandis (original shell terbratulid)
18 of 20
brachiopod19
Magasella sanguinaria, Waltonia inconspicua
19 of 20
brachiopod20
Terebratella sanguinea (living terbratulid)
20 of 20

View the entire gallery or click the above images to enlarge.

The most common seashells at the beach today are bivalves: clams, oysters, scallops, and mussels. From the Cambrian to the Permian (542-252 million years ago), however, fossil seashells are dominated by another group of organisms with two hinged valves, Phylum Brachiopoda. Over 12,000 fossil species of brachiopods have been described, but only 330 species remain alive today. Bivalves and brachiopods are both sessile filter feeders, sitting on the seafloor and filtering water for food and oxygen. Their abundance reversed at the end of the Permian, when the greatest of all known mass extinctions eliminated more than 95% of Earth’s ocean species. The Permian extinction involved a crisis of low oxygen in the atmosphere that favored the more muscular and actively respiring mollusks over the passively respiring brachiopods. Clams and their relatives are much more efficient at extracting oxygen from seawater, so they were more successful after the extinction. Unlike bivalves, brachiopods are symmetrical along the midline of the shell, which inspired the Chinese name "stone butterflies." Their beauty and variety is illustrated by this selection from the recently acquired Retallack collection. Photography by Win McLaughlin, text by Greg Retallack, and web development by Keith Hamm. Images © Museum of Natural and Cultural History.