paleozoic era

amphibian animals archaeopteris art arthropleura biology brachiopod cambrian carboniferous chain coral cooksonia devonian dimetrodon edestus heinrichi eps10 era evolution extinct fish geologic time scale geological haikouichthys hallucigenia hylonomus ichthyostega life meganeura mississippian ordovician paleontology paleozoic pennsylvanian period permian plant pneumodesmus poster prehistoric shark silurian tiktaalik line timeline tree trilobite vector