Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
The Palaeozoic fauna 1. Sepkoski’s Curves 2. The Palaeozoic fauna 3. Brachiopods 4. Corals 5. Graptolites 6. Predators 7. Ecological overview 1. Sepkoski’s Curves Family diversity Palaeozoic diversity plateau Palaeozoic fauna Ordovician radiation End Permian extinction 2. Palaeozoic fauna Lie-in-wait predators Corals and other barrier builders Brachiopods and other filter feeders Graptolites and other plankton 3. Brachiopods Shell composition Hinge mechanism Pedicle Digestive tract Phylum Brachiopoda Subphylum Subphylum Linguliformea Craniiformea L.Cam.-Rec. L.Cam. – Rec. Organophosphate Calcareous Lacking teeth and Lacking teeth and sockets sockets Present Reduced or absent Gut with anus Gut with anus Pedicle - used to attach the animal to the sea floor A. Diductor muscle – muscles which contract to open the shell Posterior Subphylum Rhynchonelliformea L.Cam-Rec. Calcareous Teeth and sockets present Present Gut without anus Lophophore – food gathering and respiratory mechanism. Two arms (brachia) fringed with cilia generate currents that bring in food and oxygen Anterior Dorsal Adductor muscle – muscles which contract to close the valves Stomach Ventral Mouth Teeth B. Muscle scars – can be used to identify certain species Mantle – sheets of tissue which line the shell Cardinal process – diductor muscle attachment site Dorsal valve Ventral valve Brachidium – lophophore support 4. Corals Medusoid stage Sexual reproduction Swimming larva Corals are cnidarians like jellyfish and sea anemones Asexual reproduction Polyp stage Outer cell layer, with stinging cells on tentacles Inner cell wall, responsible for digestion Calcareous skeleton Basic coral morphology Coral diversity through time 5. Graptolites Carboniferous Benthic diversity Planktonic diversity Faunal description Dendroid graptolites become extinct. Devonian Pterobranch Monograptid fauna Devonian A., B., simple ‘Monograptus’ Silurian Morphologically simple monograptids undergo a series of minor radiations and extinctions. Monograptid fauna - Upper Silurian C. Retiolites D. Saetograptus Saetograptids, robust monograptids, often with spines on their early thecae, radiate. Retiolitids, unusual graptoloids with a skeletal framework around the rhabdosome, become common. Monograptids radiate into a variety of forms with curved or spiral stipes and complicated thecae. Thecae become isolated, asymmetrical, hooked, spinose. Cyrtograptids evolve; monograptids that produce branches from spines on their thecae and have a spiral form. Monograptid fauna - Lower Silurian F. Normalograptus G. Spirograptus H. ‘Monograptus’ E. Cyrtograptus Cambrian Ordovician Only one genus of diplograptids survives the end-Ordovician extinction event. This group evolves into monograptids, which have a single stipe. Fauna dominated by graptoloids with two thecae arranged back-to back. These diplograptid species showed more variety of thecal shape than had been seen before, with boxy thecae and curved thecal walls becoming common. V- and Y- shaped graptoloids evolve. Diplograptid fauna I.’Climacograptus’ J. Dicellograptus K. Dicranograptus Maximum diversity of graptolites, around 200 species worldwide. High degree of faunal provinciality with two major provinces, a low latitude Pacific province and a higher, southern hemisphere Atlantic province. Four and two stiped graptoloids common. Dendroid graptolites move from the benthos into the plankton. Different thecal types are lost. Number of stipes reduces, but degree of regularity of the rhabdosome increases rapidly. True graptoloids, dominated by forms with a virgella, quickly appear. Benthic graptolites evolve from a common ancestor of graptolites and pterobranchs. Maximum diversity of benthic forms in the late Cambrian and early Ordovician. Planktonic graptoloid Dichograptid fauna L. Didymograptus M. ‘Isograptus’ N. Phyllograptus Anisograptid fauna O. Clonograptus P. Staurograptus First planktonic graptolites are dendroids Q. Rhaphidonema Benthic dendroid 6. Predators Trilobites Nautiloids Conodonts 7. Ecological overview 1. Palaeozoic fauna takes over slowly 2. Fauna reaches higher diversity than before 3. Includes mud grubbers like trilobites from Cambrian fauna 4. Includes filter feeders and macrozooplankton 5. Increased niche space above seafloor 6. Includes greater predator pressure 7. Survives mass extinctions at end Ordovician and end Devonian 8. Wiped out at end Permian