Geo Lab Exam (1)

Tabulate Corals

- Skeleton calcitic - Exclusively colonial - Tightly packed, tubular corallites (chambers of individual coral polyp); horizontal dividers along length of tube (tabulae) - Septa absent OR short - Early Ordovician to Permian (Paleozoic) - 280 genera - Important Silurian and Devonian reef-makers

Mollusca: Gastropods (snails & slugs)

- as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda - Cambrian to Today

Mollusca: Bivalves

- clams, oysters, mussels, scallops have an external covering that is a two-part hinged shell that contains a soft-bodied - Cambrian to Today - Two valves - No head, few sense organs, foot used for burrowing =, gills modified for respiration and filter feeding - Aquatic filter feeders

Rugose Corals

- "Horn Corals" - Skeleton calcitic - Some solitary, some colonial - Middle Ordovician to Permian (Paleozoic) - Most diverse (800 genera) and abundant Paleozoic corals

Brachiopods

- "Lamp shells" - Two calcitic valves - Marine; sessile, intertidal to abyssal - Filter feeders (using lophophore) - Cambrian to Today

Crinoids

- "Sea lilies" - Ordovician to Today - "Starfish on a stick": arms, calyx, stem, root - Filter feeders: tube, feet on arms move food to mouth - Stem segments have produced "crinoidal limestones"

Ammonoids & Ammonites

- "Serpent Stones" / "Horns of Ammon" - Ammonoids with very complex sutures are known as ammonites - Ammonites lived during the Jurassic and Cretaceous period

Echinoderms

- "Spiny skin" - Five-fold symmetry - Cambrian to Today - Weird - All marine - Typically gregarious - Two subgroups with great fossil records: Crinoids, Echinoids

Vertebrates

- Animals with bones - Cambrian: first vertebrates - Devonian: first tetrapods (four-limbed vertebrates) - Triassic: first mammals - Cretaceous: first placental mammals (major group of mammals still alive today)

Trilobites

- Arthropod phylum (bug-like animals) - Cambrian to Permian (Paleozoic) - Most important fossils for dating Cambrian rocks - Exoskeleton: mostly calcite - Cephalon (=head; facial sutures), thorax, pygidium (=tail); thoraxes show trilobation

Corals

- Corals belongs in the Phylum Cnidaria along with jellyfish and sea anemones - 3 major groups: Tabulate corals: Paleozoic, Rugose corals: Paleozoic, Scleractinian corals: Mesozoic and Cenozoic

Echinoids

- Echinoids; sea urchins and sand dollars - Late Ordovician to Today - Burrowing creatures - Spines - Eat algae

Oldest Fossils: Stromatolites

- Oldest known fossil group: ~ 3.5 billion years old; Australia - Mat-like structures formed mostly by photosynthesizing bacteria called cyanobacteria - Slimy layers + sediment - Oxygen by-product of photosyntheis - Fossil record: Archean to Today - Mostly found today where grazing animals like snails cannot eat them

Mollusca

- Second most diverse phylum (after anthropoids) - 3 major groups which are known from the Paleozoic, Mesozoic, and Cenozoic eras: Bivalves, Gastropods, Cephalopods

Fusulinids

- Single-celled - Fossil Record: Pennsylvanian to end-Permian - Primary guide fossils for late Paleozoic - Some very large (1-10cm) - Make up the bulk of some late Paleozoic rocks

Scleractinian Corals

- Skeleton aragonite in modern corals - Some solitary, some colonial - Six primary septa (divisions) within corallites - Middle Triassic to Today - 600 genera - Wide variety of forms - Major producers of reefs since the Triassic

Mollusca: Cephalopods

- ny member of the molluscan class Cephalopoda such as a squid, octopus, cuttlefish, or nautilus - marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the рrimitive molluscan foot - Late Cambrian to Today - subclasses: squids, octopi, cuttlefish), nautiloids, endoceratoids, and ammonoids