15 Topic: Mesozoic Monsters of the Sea and Sky PDF

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15 Topic: Mesozoic Monsters of the Sea and Sky last time… -Ordovician Mass Extinction -cause: glaciation/ ice age -killing agents: marine regression, ocean anoxia -Devonian mass extinction -cause: land plants -killing agents: global cooling, ocean anoxia -end permian mass extinction -cause: siberian flood basalts -killing agents: global warming, ocean acidification, ocean anoxia, ozone depletion, etc Euryapsids -defined by the euryapsid skull… diapsids that lost the lower skull hole -marine reptiles -Ichthyosaurs and Plesiosaurs -Triassic to Cretaceous early ichthyosaur -Cartorhynchhus: early triassic -adapted to both land and sea- flexible limbs; poor swimmer -bottom dweller, fed on invertebrates Ichthyosaurs -“fish lizard” -limbs evolved into strong paddles for swimming -lived entirely in water, but breathed air -Triassic to Cretaceous (dominant in Triassic and Jurassic) -large Sclerotic ring: bony plates around the eyes -helps large eye maintain shape in deep pressures -great eyesight underwater -(all vertebrates have these, except crocodiles and mammals) -Opthalmosaurus Plesiosaurs and Pliosaurs -“near lizard” -not dinosaurs! -two varieties: long-necked Plesiosaurs, and short-necked Pliosaurs -Gastroliths are common -live birth of a single offspring, in open ocean -Jurassic to Cretaceous (replied ichthyosaurs as dominant group) -largest plesiosaur was 46 feet, with a very long neck

-couldn’t support head out of water -largest pliosaur was 52 feet, with an 8 foot skull Lepidosaurs -lizards, snakes, and mosasaurs -“scaled lizards” -reptiles with overlapping scales of keratin -diapsid skull -shed scales or skin -teeth feud to jaw bone (no sockets) -triassic to today -sprawling stance: not standing upright -movement controlled by wiggling spine Mosasaurs -marine lepidosaurs -related to snakes or monitor lizards -propelled by long, flat tail -double-hinged jaw, like a snake -live young in open water -cretaceous -Jurassic World (movie)? Archosaurs -“rullino lizard” -triassic to today -diapsid skull, with two additional holes: -between eye and nasal cavity (antorbital fenestra) -lower jaw (mandibular fenestra -holes lighten skull and room for muscles -another synapomorphy: socket teeth -mammals and euryapsids also have these early archosaurs -small reptiles with long tails and short forelimbs -upright stance -Bipedal, allowing front limbs to serve other purposes (eg catching, holding) two subdivisions -crocodiles and relatives: can sprawl like lepidosaurs or stand upright -pterosaurs, dinosaurs, and birds: upright stance -defined based on location of ankle joint crocodyliforms -dominant carnivores in the triassic -died out late triassic mass extinction, except for the modern groups -filled many niches: ocean crocs, herbivore crocs, running crocs…

Anatosuchus/ Duck Croc -2 ft long -Laganosuchus/ Pancake Croc -20 ft long -flat head Dematosuchus -15 ft long -herbivores: the buffalo of the triassic -eaten by Postosuchus Postosuchus -13 ft long -carnivore: shaped like a theropod (think t-rex) -long neck, short head, theropod hips, bipedal crocodiles -triassic to today -Sarcosuchus: up to 40 ft long the end triassic mass extinction -a mini end permian -casual agent: central atlantic magmatic province (CAMP) -associated with the breakup of Pangea/ opening of atlantic ocean -lots of basalt, but not as much gas release -killing agents: same as before -hurts corals, mollusks, early plants -kills off most therapsids -kills off most crocodyliforms -early Pterosaurs, dinosaurs, take over pterosaurs + dinosaurs -archosuars that aren’t crocs -sister groups (pterosaurs are not dinosaurs or birds) -synapomorphies: -ankle joint -longer legs and metatarsals -longer necks (s-curve)...