| P number: | P549445 |
|---|---|
| Caption: | Calymene, coiled in defence, a trilobite. |
| Description: | Calymene is a trilobite that grew up to about 10 cm. in length. It can be found in Silurian to Devonian rocks (about 380 to 440 million years old) in many parts of the world. It is particularly found in shallow marine sediments that accumulated on the continental shelf. Trilobites are arthropods which had an exoskeleton for support and protection. The exoskeleton covered the animal's back, the underside appears to have been covered by a softer membrane. Trilobites such as Calymene, which lived during Silurian times, would roll into a ball in order to protect the more vulnerable underside. Trilobites were arthropods, distant relatives of crustaceans and insects that live today. They lived in the seas of the early Cambrian and they became extinct with the mass extinction at the end of the Permian times. Trilobites are divided into three parts, the cephalon (the head, which is divided into the central glabella with two cheeks each side); the thorax (body, also divided into three and comprising a number of segments); and the pygidium (the tail, also divided into three). These animals often had well-developed eyes, with many lenses made of calcite crystals, although others were blind. Some trilobites swam, most scurried about on the sea floor and yet others burrowed into the sand on the sea floor. |
| Photographer: | Unknown |
| Copyright statement: | NERC |
| Orientation: | Landscape |
| Size: | 356.93 KB; 1000 x 907 pixels; 85 x 77 mm (print at 300 DPI); 265 x 240 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Best of BGS Images/ Fossils |
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