| P number: | P549530 |
|---|---|
| Caption: | Goniorhyncha boueti, an important Jurassic brachiopod. Specimen GSM114050/13b. |
| Description: | Goniorhyncha boueti is a small species, the illustrated one being only 2.5 cm. across. It lived during the mid-Jurassic (Bathonian) and is found particularly commonly in one marker bed, the Bouetti Bed, which was deposited almost 170 million years ago. Finding this species is useful to corellate geographically separate rocks. Goniorhyncha boueti has a very convex brachial valve with a fold in the central part, whereas the larger pedicle valve is flattened and slightly concave. Ribs radiate from the umbo (the pointed 'beak' at the top of the illustrated specimen) and have a chevron-like appearance when the two valves are firmly closed. Brachiopods have a very long history. The oldest species lived during the earliest Cambrian time (545 million years ago) although strange animals that look like worms, but with a brachiopod-like shell each end suggest they evolved during the late Precambrian. They were particularly commmon during the Palaeozoic times (248 to 545 million years ago), but today they are rather rare. These animals are almost entirely marine, although some live in brackish waters. They have a shell usually attached to a firm substrate like a rock, by a pedicle, a fleshy stalk that extends out of an opening in one of the valves (the pedicle valve). The two valves are hinged so that they can be opened to allow water and food particles to wash through. Calcareous supports for the internal organs are sometimes preserved in fossils. |
| Photographer: | Unknown |
| Copyright statement: | NERC |
| Orientation: | Portrait |
| Size: | 398.88 KB; 792 x 1000 pixels; 67 x 85 mm (print at 300 DPI); 210 x 265 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Best of BGS Images/ Fossils |
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