Lab 8 _ Mesozoic Cenozoic Fossils

Lab 8 _ Mesozoic Cenozoic Fossils - Fossils Mesozoic&...

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Unformatted text preview: Fossils Mesozoic & Cenozoic Eras Phylum Mollusca Class Gastropoda Class Bivalvia Class Cephalopoda Class Gastropoda Largest class of Mollusca Head with mouth, radula, prominent foot, Fleshy mantle in shell Occupy various habitats marine freshwater Terrestrial Class Gastropoda- The Shell Support for visceral mass, space for retraction of head and foot Basic plans of coiling - planispiral (planar) - trocospiral (helicoid) Class Gastropoda Diverse styles of feeding - scavengers - suspension or detritus feeders - parasitic - herbivores, carnivores... Class Gastropoda- Geologic Range Archaeogastropoda- late Cambrian to Recent Mesogastropoda- Mesozoic, Cenozoic Neogastropoda- Jurassic & younger Class Bivalvia Laterally compressed bodies Hinged calcareous shell Lack head, radula, sense organs Modified foot (burrowing) Expanded gills (respiration & filter feeding) Teeth & sockets in both valves Mostly marine, some freshwater Paleo-ecological indicators Class Bivalvia- The Living Animal Double- valved shell Plane of symmetry between the valves Soft anatomy Epifaunal, Infaunal filter-feeders Class Bivalvia- Geologic Range Cambrian to present 7,000 Paleozoic species 15,000 Mesozoic species 20,000 Pre- Holocene Cenozoic Minor losses Permian & K- T extinctions Class Cephalopoda Class includes organisms such as: - Nautilus - Cuttlefish - Squid, Octopus - Ammonoids Class Cephalopoda Late Cambrian- recent Greatest diversity during Paleozoic & Mesozoic Ammonoids - INDEX FOSSIL, Devonian to Permian & Mesozoic (Cretaceous) The Cephalopod shell External (most fossil cephalopods) or Internal (cuttlefish, squid) No shell (octopods) Most cephalopods coil in a plane External conchs; coiled & chambered Class Cephalopoda- Shell & Suture Outer edge of the septum (wall divisions) Usually expressed in outer wall of shell Relatively straight or fluted with saddles & lobes - saddles: convex toward aperture - lobes: concave away from aperture Cephalopoda Suture Suture patterns: - Agoniatitic -Goniatitic: Most Paleozoic forms -Ceratitic: Triassic -Ammonitic: Most complex, Jurassic & Cretaceous Cephalopoda Suture Patterns PROTISTA Greek protos, very first; ktistos, to establish CATCH-ALL FOR THE MULTICELLULAR ORGANISM WHICH DON'T FIT INTO THE ANIMAL, PLANT, OR FUNGUS KINGDOM. Overview 5 "Kingdoms" of life on Earth: Bacteria Protista Animals Fungi Plants All but bacteria are eukaryotic (meaning that most of their DNA is organized into chromosomes & found within a nucleus). Eukaryotic Microorganisms One of the two major groupings (superkingdoms) into which all organisms are divided. Bacteria and cyanobacteria (blue-green algae), which belong to the prokaryote grouping. Clearly defined nucleus Protoctista Currently 30 phyla Existed for approximately 1.2 billion years. Zooplankton: Small aquatic animals that are suspended or swimming in water. Heterotrophic. Phytoplankton: Microscopic floating plants, mainly algae, that live suspended in bodies of water. Autotrophic. Coccolithophores Calcareous nannoplankton Photosynthetic 15- 100 microns Marine Environment; tropical seas Mesozoic/ Cenozoic stratigraphy Paleoclimate indicators Triassic- Recent Coccolith Functions FUNCTION of coccoliths (the plates or scales) is not known but may be one or more of four basic possibilities: Protection Flotation and buoyancy; Light regulation Biochemistry The White Cliffs of Dover were made by coccolithophores Dinoflagellates 20- 150 microns `dinoflagellate' means whirling tail swimming phytoplankton Cysts of organic matter Aquatic environments Silurian to Recent Bioluminescent dinoflagellate: When a predator of plankton is sensed through motion in the water, the dinoflagellate luminesces. This in turn attracts even larger predators which will consume the wouldbe predator of the dinoflagellate. dinoflagellate. Dinoflagellates can also bloom "Red Tide" Diatoms Diatoms Photosynthetic Most important primary producer in the oceans...consume Carbon Dioxide Found in wide variety of environments Aquatic Soils, ice, rocks Highest concentrations in sub-polar to temperate conditions Diatoms Important! Base of food chain Biostratigrapghy Paleoclimate & Oceanographic indicators Silica Diatomaceous rocks kitty litter mineral filler (flat paint) filtering agent Diatoms are widely noted for their beauty Radiolarians Animal- like proctista Siliceous Survive at depth Cambrian- present 60-200 microns in size Paleoclimate & oceanographic indicators Marine environments; planktonic Great fossil record because silicon skeletons preserve well Foraminifera Majority planktonic; some benthic Calcareous; 14-300 microns About 60,000 species Cambrian to recent (important for modern fauna) Geologic Importance: Paleosalinity Paleoclimate Paleobathymetry Biostratigraphy: Mesozoic & Cenozoic stratigraphy Paleoclimatic studies (Planktonic) Different coiling directions are dependent upon temperature Some live in warm water, some in cold Oxygen isotope ratios are used for paleotemperature Paleobathymetry (Benthic) Goes by looking at species of forams Coring of the ocean floor Relative dating of the core based on forams Oil & gas exploration References ...
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