Invertebrate Palaeontology and Evolution

adductor ambulacra ammonites ammonoids animals aperture appendages aragonite arthropods bivalves brachial valve brachiopods bryozoans burrowing calcareous calcite CALIFORNIA/SANTA CRUZ Cam.-Rec Cambrian Carboniferous central cephalon cephalopods coiled colony corallites corals Cretaceous crinoids CRUZ The University cystoids Devonian dissepiments dorsal echinoderms echinoids environment evolution evolutionary extinct fauna Figure functional gastropods genera genus geological gills graptolites graptoloids grooves groups growth hinge hypostome internal invertebrates Jurassic known later layer living lophophore mantle cavity marine Mesozoic molluscs morphology mouth muscles Nautilus normally Order Ordovician organs pair Palaeontology Palaeozoic pedicle pedicle valve Permian plates polyp pores posterior preserved pygidium radial redrawn reef Rugosa sea floor sediment segments septa shell Silurian siphuncle skeleton species specimens spines sponges stratigraphical stromatoporoids structure SUBCLASS SUBORDER Superfamily surface suture taxonomic tentacles thecae tissue trace fossils Treatise trilobites tube tube-feet types University Library UNIVERSITY UNIVERSITY OF CALIFORNIA/SANTA Upper usually vertical whilst zone zooids