Lecture 18: Marine reptiles Flashcards
Turtles
Anapsids, most primitve group of living reptiles (ancestry is poorly known_) Odontochelys from china 10 mil years older than Proganochelys- late triassic europe-
common during jurassic and creteaceous, seas and estuaries
Modern sea turtles
Limbs are modified into Hydrofoils, using all 4 limbgs as wings under water, precise migration (over 1000s km) warm blooded
Archelon- the giant
cretaceous, 3m long, 4m in flipper span, no complete bony carapace due to weight, bony framework
Crocodiles
Archosaurs, ancestors were terrestrial, late triassic, since early jurassic living at the water edge
Postosuchus, late triassic crurotarsi 4 to 5 m long fast hunter
Phobosuchus
Late cretaceous, Texas. Largest crocodile, 2m skull 11m in length, possibly 15, 6 tons possibly 18 tons. Duckbill dinosaurs as prey?
Position of Holzmaden during Jurassic time a site of ______marine reptile preservation
extraordinary
Jurassic in Southern Germany
Over 60 million years Europe partly covered by water forming smaller basins, stagnant- reduced oxygen exchange, posionienschiefer lower jurassic, rich in well preserved fossils
Icthyosaurs
Diapsids, similarity to doplhins. But tail flukes are vertical, not horizontal. Spine is running into lower tail fin, allowing steep vertical diving, limbs are small stiff fins. Good vision-large eyes, long and thin jaw in advanced species, piercing conical teeth for catching fish, early species had blunt shell crushing teeth (hunting cephalopds)
Shonisaurus
Late triassic, Nevada. Up to 20m long, largest found in Canada, strong deep body, 37 specimens were found fossilized together with all facing in the same direction
Sauroptygeria (order)
Nothosaurs, plesiosaurs, small heads and long necks, preying on small fish
Nothosaurs
Triassic, alps and china, only a few well preserved specimens, powerful tail for propulsion, hind limb acted as rudders, strong limbs possibly allowing moving on land for egg laying
Plesiosaurs
replaced nothosaurs in early jurassic, stronger limbs highly modified for swimming, True plesiosaurs: elasmosaurus cretaceous (12m neck and 76 neck vertebrae)
Pliosaurs: large, kronosaurus 12m, 4m skull, australia
Plesiosaurs
Powerful 4 limbs, powerful ligaments to move limbs, comparable to flying through water like penguins, prey small fish due to their small heads
Pliosaurs
Jurassic & cretaceous, short necks, massive toothed jaws, 4 to 15 m in length, Kronosaurus and pliosaurus
Mosasaurs
Late cretaceous, 10m length, main propulsion through flexing, skulling with tail, large heads and powerful jaws,some had stabbing teeth and som had blunt teeth, carnivores, rigid elbow joint, shoulder joint designated for up and down movement
Air breathers
such as modern marine animals, dangerous process at time of birth, turtles lay eggs on land and doplhins young are born tail first, then pushed by adults to sruface to breathe
Icthyosaur behavior
Fetuses of icthyosaurs have long jaws, born tail first, live birth, requirement of parental care
Mosasaur behavior
No juvenilles were found, unusual pelvis possible giving birth to live large offsprings, 1996 mosasaur found with 2 juvenilles inside was found in south dakota
All marine animals became ________except turtles and crocodiles
extinct
