| P number: | P549486 |
|---|---|
| Caption: | An early Devonian cephalaspid fish. |
| Description: | Cephalaspidomorphs, which first evolved during Silurian times (about 420-430 million years ago), were jawless fish. One group (the osteostracans or cephalaspids) had a large, heavy head shield, but this was reduced in the second, more advanced, group (the anaspids). The osteostracans evolved in the seas, but later colonised fresh water environments. The illustrated cephalaspid lived in Wales during early Devonian times, about 410 million years ago. Only the head shield, which was made up of a single plate of bone, is preserved. The fish lived on the sea floor where it sucked up food particles through a round mouth underneath the head. It had small eyes on the upper surface and sensory organs on the sides and top of the head which may have detected vibrations through the water. Fish are cold-blooded vertebrates with a braincase, fins for swimming and gills to take oxygen from the water (although some also have lungs). They therefore differ from other aquatic creatures like invertebrate molluscs or crabs; amphibians and reptiles, which have lungs and limbs rather than gills and fins; and whales and dolphins which are warm-blooded mammals. Fish are the first vertebrates, having evolved during the early Cambrian over 500 million years ago. |
| Photographer: | Unknown |
| Copyright statement: | NERC |
| Orientation: | Landscape |
| Size: | 686.49 KB; 1000 x 992 pixels; 85 x 84 mm (print at 300 DPI); 265 x 262 mm (screen at 96 DPI); |
| Average Rating: | Not yet rated |
| Categories: | Best of BGS Images/ Fossils |
Loading...
Loading...
Reviews
There is currently no feedback