Mesozoic Marine Life Invertebrate Vertebrate
Cenozoic Marine Life - Invertebrates (Mollusks) Cenozoic Marine Life - Invertebrates (Arthropods)
Cenozoic Marine Life - Vertebrates Marine fossils are abundant from the Mesozoic Late Triassic to Late Cretaceous - time of high sea levels Large regions of the continents flooded by epicontinental (epeiric) seas. Marine sandstone, shale, limestone, and chalk deposited over large areas of the continents Middle - Late Jurassic Sundance Sea
Middle - Late Cretaceous Zuni Sea Atlantic shoreline far inland of present position Mesozoic Marine Invertebrates Mollusks (clams, snails, cephalopods) Arthropods (shrimp, crab, lobster) Echinoderms (sea urchins, heart urchins, crinoids) Brachiopods (lamp shells) Paleozoic Dominants Corals Ammonites Shelled cephalopods related to squid Extremely diverse and abundant in the Mesozoic Completely extinct by the Paleocene
Ammonites Ammonites
Ammonites Belemnites Squid-like animals with an internal shell (guard) Common in the Jurassic and Cretaceous Completely extinct by the Paleocene Pelecypods - Clams burrowing clams Trigonids Inoceramids Gryphaeid oysters (coiled, free-lying) Rudistids (reefforming clams)
A group of Jurassic and Cretaceous pelecypods with a distinctive triangular outline. Trigonid clams Oysters evolve in the Triassic Gryphaeid Oysters The first evolutionary radiation is of forms that have a coiled shell adapted for lying unattached on the seafloor. coiled left valve lid-like right valve Inoceramid clams Oyster - like Very abundant in some black shale deposits Some grew to enormous size
Rudistid clams Bizarre reef-forming clams Organ-pipe clusters Conical or tubular right valve, lid-like left valve Rudistid reefs under the Gulf of Mexico form important petroleum reservoirs Hippurites side view left valve right valve Rudistid clams
intergrown cluster of rudistid bivalves - a reef made out of clams! Gastropods - Snails evolutionary radiation of drilling snails (predators on clams) in the Jurassic and Cretaceous Mesozoic radiation of decapod crustaceans - shrimps, crabs and lobsters. Crabs and lobsters are predators on bivalves and prey for cephalopods. Arthropods
Jurassic lobster Jurassic horseshoe crabs Evolutionary radiation of sea urchins and heart urchins Crinoids are abundant, but not as much as in the Paleozoic Echinoderms Cretaceous crinoid
Regular sea urchin Irregular or heart urchin Brachiopoda Lamp shells - not related to clams Much reduced in abundance and diversity in the Mesozoic from their heyday in the Paleozoic.
Mesozoic Marine Vertebrates Sharks and Rays Bony Fish Turtles (Archelon) Marine Crocodilians Ichthyosaurs (fish-lizards) Plesiosaurs (long-necked and shortnecked) Mosasaurs (related to lizards and snakes) Sharks and Rays Species of cartillagenous fish similar to modern rays and sharks diverge and radiate in the Jurassic. Teeth are common fossils in marine deposits. Teleosti - Bony Fish Teleosts begin their evolutionary radiation in the Late Triassic.
Xiphactinus Marine Turtles Archelon - a Late Cretaceous marine turtle from the Niobrara Chalk of Kansas. 12 feet in length Geosaurus - a marine crocodile
Evolve in the Early Triassic and go extinct in the Early Cretaceous. Fully-adapted to a marine existence, never venturing onto land. Gave birth to live young. Ichthyosaurs Jurassic Ichthyosaur Triassic Ichthyosaur Jurassic Ichthyosaur
Plesiosaurs and Pliosaurs Plesiosaurs radiate in the Jurassic into two main groups. Elasmosaurs - longnecked forms with small heads. Pliosaurs - shortnecked forms with huge heads. Elasmosaur Pliosaur primitive plesiosaur Pliosaur
Elasmosaurus
Mosasaurs Late Cretaceous group of marine reptiles most closely related to living snakes.