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Anomalocaris Life of the Paleozoic Tuesday, November 22, 11 Life of the Paleozoic • Overview: • Cambrian, Vast expansion of shelly marine life forms and jawless fish • Ordovician - most modern phyla established • Late Paleozoic- land plants and vertebrates (tetrapods and amniotes) Tuesday, November 22, 11 Invertebrates • Marine environments • Nektic, planktic, benthic • Adaptions: • Epifaunal- animals living on the sea floor • Infaunal – animals that burrow into the sea floor Tuesday, November 22, 11 Early cambrian • Small Shelly fossils • Rarely more than a few millimeters long • A- Anabarella • B- Camanella • C- Aldanella • D- Sponge Spicule • E- Formitchella • F- Lapworthella Tuesday, November 22, 11 Early Soft-body fossils • The Burgess shale: • Most fossils reduced to shiny black impressions What type of fossilization is this? • Viewed as one of the most important finds of the fossil record • Altogether, over 60,000 species have been collected Tuesday, November 22, 11 The Burgess shale • Four Groups of Arthropods • Trilobites • Crustaceans • Scorpions • Insects • Sponges • Onycophorans • Crinoids • Sea Cucumbers • Chordates Tuesday, November 22, 11 Chordates • Shows evolution of early notochord • Notochord- dorsally situated nerve cord Why is this important? • Pikaia- small animal that has notochord and also shows evidence of v-shaped muscle bands (this indicated sinosoidal swimming motion THESE ANIMALS ARE ANCESTORS TO ALL MODERN VERTEBRATES Tuesday, November 22, 11 Other Notable Fossils • Anomalocaris- fierce predator over 50cm long (~2ft) • Opabinia- five eyes, flexible nozzle • Hallucigenia- seven pairs of legs, seven dorsal spines, claws, cylindrical trunk. (Considered to be a onycophoran) • Marrella- Four spines extended back from cephalon The most common arthropod found in the burgess shale Tuesday, November 22, 11 Tuesday, November 22, 11 Protista (unicellular groups) • Foraminifera (Calcerous Microfossils) • Range from Cambrian to present • More numerous and varied by Carboniferous • Global distribution during Pennsylvanian-Permian • Radiolarians (Siliceous Microfossils) • Range early Paleozoic to present • Most abundant in Mesozoic rocks Tuesday, November 22, 11 Porifera • Pore-bearing animals • Appear to evolved from colonial flagellated unicellular creatures • Cambrian representatives of all but one modern class are known as fossils (Have not changed much) Tuesday, November 22, 11 Fossil Porifera Modern Sponges Tuesday, November 22, 11 Corals and Cnidarians • Main Groups • Sea Anemonies • Sea Fans • Jelly Fish • Hydra • Reef-forming Corals Tuesday, November 22, 11 Brachiopods • Most abundant, diverse, and useful Paleozoic fossil group • Braciopods are bivalves, however, each valve (shell) differs in shape and size. • Unlike clam shell which can be considered right and left brachiopod shells are distinguished between dorsal and ventral. • Most valves are made of Calcium Carbonate. • Ornamented with radial ridges, grooves, spines, nodes and growth lines. Tuesday, November 22, 11 Groups of Brachiopod • Articulate Brachiopods • Valves are hinged along the posterior margin and are prevented by sliding sideways by teeth and grooves • Inarticulate Brachiopods • Lack a definite hinge structure • Valves held together by muscle • Both are filter feeders attached to sea floor by fleshy stalk (pedicle) • Lophophore: hair like structures that circulate water and food toward mouth Tuesday, November 22, 11 Fossil Brachiopods Tuesday, November 22, 11 Mollusks • Gastropods (snails) • Earliest forms constructed small conical shells, by late Cambrian/early Ordovician most had developed the more recognizable coiled shell. • By Pennsylvanian gastropods extremely abundant and even air-breathing species had developed • Cephalopods- may be the most advanced and complex of all invertebrates Tuesday, November 22, 11 Cephalopods • Represented today by: • Squid • Cuttlefish • Octopods • Chambered Nautilus Tuesday, November 22, 11 Ammonites • Goniatites, the first ammonite, appears during the Devonian • Other Ammonites Tuesday, November 22, 11 Arthropods • Includes: • Lobsters • Spiders • Insects • All animals that have chitonous exterior skeletons, segmented bodies, and paired,jointed appendages Tuesday, November 22, 11 Trilobites Tuesday, November 22, 11 Trilobites Tuesday, November 22, 11 Eurypterids • Scorpion like bodies • Found in Ordovician- permian Marine and Brackish facies • Recent finds suggest that some eurypterids reached a length of 9ft. Tuesday, November 22, 11 Eurypterids • Scorpion like bodies • Found in Ordovician- permian Marine and Brackish facies • Recent finds suggest that some eurypterids reached a length of 9ft. Tuesday, November 22, 11 Echinoderms • Spiny-skinned animals • Five way symmetry • Exclusively marine- typically bottom dwelling, either attached or mobile • Group includes • Starfish • Sea Urchins • Crinoids • Crystoids Tuesday, November 22, 11 Echinoderms • Appear to have developed during late proterozoic • Ediacaran, also had five way symmetry • Stemmed or stalked echinoderms first occur in mid cambrian (not abundant until Ordovician) Tuesday, November 22, 11 Echinoderms • Appear to have developed during late proterozoic • Ediacaran, also had five way symmetry • Stemmed or stalked echinoderms first occur in mid cambrian (not abundant until Ordovician) Tuesday, November 22, 11 Continental Invertebrates • Fossil evidence is less complete Why? • However as plants begin to invade continent so do animals • Record begins with possible Millipede tracks in Ordovician rocks. • Body Fossils of Centipedes and Millipedes occur in Silurian rock • In New York, Devonian rocks have yielded fossil centipedes, spiders and other wingless arthropods • Insects do not become common until the late Missipian • The Pennsylvanian witnessed the arrival of flying insects like the dragon fly • Coal swamps from the Pennsylvanian yielded a dragon fly with a wingspan of over 2 ft. Tuesday, November 22, 11 Vertebrates • Evolution of Fish • Dermal Plates (Upper Cambrian) • Scales and Plates (Ordovician) • Four Taxonomic classes: • Agnatha (jawless fish) • Acanthodii (Archaic jawed fish) • Chondrichthyes (cartilaginous fish) • Osteichthyes (Bony fish) Tuesday, November 22, 11 Agnatha • Earliest known (early Cambrian) species include Theolodus, Jamoytius, Pteraspis (armored) and Hemicyclapsis Tuesday, November 22, 11 Acanthodii • Arose during Silurian • Most numerous during Devonian • Extinct during Permian Tuesday, November 22, 11 Chondrichthyes • Late Devonian to Present • Represent shark, rays, and skates • Cladoselache- late paleozoic shark Tuesday, November 22, 11 Osteichthyes • Bony Fish can be divided into two groups • Actinoptergians • Lack a muscular base to their paired fins • Also lack nasal passage to the throat • Sarcoptergians • Had sturdy, fleshy lobe-fins • A pair of openings in upper mouth that led to external nostrils • Were able to rise to surface to take in air that was passed onto functional lungs (Lung Fish) Tuesday, November 22, 11 Sarcoptergians • Two major roups lived during the Devonian • Dipnoans • Dipnoans- include some present day freshwater living species of lungfish in Australia and Africa • Crossopterygians • Because of the pattern of skull elements, arrangement of bones in their fins, and the structure of their teeth, Crossopterygians are considered to be the ancestor of the earliest land inhabitants (tetrapods). Tuesday, November 22, 11 Sarcoptergians • Two major roups lived during the Devonian • Dipnoans • Dipnoans- include some present day freshwater living species of lungfish in Australia and Africa • Crossopterygians • Because of the pattern of skull elements, arrangement of bones in their fins, and the structure of their teeth, Crossopterygians are considered to be the ancestor of the earliest land inhabitants (tetrapods). Tuesday, November 22, 11 Crossopterygians & Tetrapods Tuesday, November 22, 11 Tetrapods • Tetrapods are four- footed vertebrates • Amphibia, Reptilia, Mammalia Tuesday, November 22, 11 Tetrapods • First to come ashore did not leave the water completely • Amphibians • Return to water to lay eggs • From eggs come fish-like larvae that develop in water • Number of changes had to accompany the shift to land Tuesday, November 22, 11 Shift to land • A three chambered heart developed • Limb and girdle bones had to be modified to overcome gravity • Spinal column became more sturdy but yet flexible • To better assist hearing the Hyomandibular (fish) transformed into an ear ossicle-the stapes Tuesday, November 22, 11 Fossil Record of Basal Tetrapods • Late Devonian • Ichthyostegids • Retained many features of their fish ancestor • Tail fin • Bony gill covers • Fish-like vertrbae • Skull bones similar to crossopterygians • Labyrinthic folding of enamel • Due to this following species are referred to as Labyrinthodonts • During the Carboniferous large numbers of these Labyrinthodonts wallowed in swamps and streams Tuesday, November 22, 11 Tuesday, November 22, 11 Evolution of the Tetrapods • Development of the amniotic egg • These animals are referred to as amniotes • During the Carboniferous Amniotes diverged into two groups • Reptilia: anapsids, diapsids, and archosaurs • Synapsids- Mammal-like reptiles Tuesday, November 22, 11 Synapsids • Although the synapsids are called “mammal- like reptiles, cladistic analysis shows that they are not reptiles • Some sported big sail-like structures (pelycosaurs) • Varied group • Carnivores: Dimetrodon • Herbivores: Edaphosaurus Tuesday, November 22, 11 Synapsids • Although the synapsids are called
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