Amphibians to Reptiles a Major Break from Water for the Amniotes Department of Geological Sciences | Indiana University Dinosaurs and Their Relatives (C) 2015, P

Home , Proterogyrinus

Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Amphibians to reptiles A major break from water for the amniotes Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114

Amniotes (Amniota) • Lizards + Mammals + Birds + Turtles and all related groups • Amniotic layer in egg that prevents drying and allows development completely on land • Better diﬀerentiated neck • Skin covering that prevents desiccation • Internal fertilization Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Living Mammals (Mammalia) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Living Turtles (Chelonia) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Living Lizards and Snakes (Lepidosauria) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Living Alligators and Crocodiles (Crocodilia) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Living Birds (Aves) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114

Living Mammals Turtles

Living Lizards and Snakes Living Crocodiles and Alligators Lizard-hipped dinosaurs Living Birds Bird-hipped dinosaurs Aves

Crurotarsi Ornithischian Saurischian

Dinosauria

Lepidosauria Archosauria

Diapsida Synapsida Reptilia

Fish and Amphibian eggs - ancestral egg form

Jelly

Yolk sac nutrients for developing embryo

Embryo

Amniotic egg - specialized egg of Amniotes protects the developing embryo membrane surrounding the embryo with fluid to moisten it

membrane for gas exchange and nutrients for developing embryo container for waste products Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Lizard with eggs

http://www.robertschoch.net/Tree%20Frogs%20Tadpoles %20Insects%20Colette%20Dowell%20Robert %20Schoch.htm Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Petrolacosaurus Early amniote from Carboniferous of Nova Scotia Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Amniote and non-amniote compared

Proterogyrinus Captorhinus an early anthracosaur (“amphibian”) an early amniote

Eyes facing outward

Eyes facing upward

Few bones behind parietal from Carroll, 2009. The Rise of Amphibians Many bones posterior to parietal (strongly differentiated neck) (weakly differentiated neck) (from Romer, 1966, Vertebrate Paleontology) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114

Early amphibian skeleton

Longer limbs

Early amniote skeleton mobile neck Better developed Longer limbs pectoral girdle

Better developed carpals and tarsals

“Sprawling” posture and undulating locomotion is retained in many amniotes

Captorhinus

Synapsida Living Mammals Turtles

Living Lizards and Snakes Living Crocodiles and Alligators Lizard-hipped dinosaurs Living Birds Bird-hipped dinosaurs Aves

Crurotarsi Ornithischian Saurischian

Dinosauria

Lepidosauria Archosauria

Diapsida Synapsida Reptilia

Dentary/ Squamosal jaw Quadrate/ joint articular jaw joint

Sprawling posture

Sprawling Upright (parasagittal)

Hildebrand Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Lizard vs. Mammal Skeleton Upright posture Sprawling posture Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114

Sprawling posture

No anteorbital or Only one Posterior bones of mandibular temporal mandible still present fenestra fenestra Sprawling posture

No lumbar region

(from Romer, 1966, Vertebrate Paleontology) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Thrinaxodon - a derived synapsid Single temporal fenestra modified to zygomatic Lumbar region arch (“cheek bone”)

Partially upright posture Reduction of posterior bones of mandible (from Romer, 1966, Vertebrate Paleontology) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114

Era Period Epoch Age (millions of years ago) Holocene Quaternary Pleistocene Mass Extinction 2.6 Pliocene Neogene Miocene 23 Oligocene Cenozoic Eocene Paleogene Paleocene 65 Cretaceous 145 Jurassic 199 Mesozoic Origin of dinosaurs Triassic Phanerozoic 251 Permian / Triassic extinction Permian Synapids dominant land 299 vertebrates Pennsylvanian 318 Mississippian First amniotes Carboniferous 359 Devonian Early tetrapods on land 416 Paleozoic Silurian 444 Ordovician 488 Cambrian First vertebrate fossils 542 Proterozoic 2.5 billion Archean 4.6 billion Precambrian Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114

Pangea the Late Permian (260 mya) Single continent Massive global extinction

Reconstruction by Ron Blakey http://jan.ucc.nau.edu/~rcb7/index.html Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Diversity through time (Families) Permo-Triassic extinction The greatest extinction in Earth’s 47%

history 60% 57% 82% 53% ca. 251 million years ago

Nearly 95% of the Earth’s species became extinct.

• Continental rifting (splitting) of Pangea cause eruption of Siberian trap lava, which covered an area the size of Europe with flood basalts 400 to 3000 m thick! Lasted 600,000 years and peaked at 251 million years ago.

• Rapid rise in global temperature of 6C, which combined with Pangea continent configuration, reduced ocean circulation and dissolved oxygen to create anoxic conditions on the sea floor.

• Atmospheric carbon dioxide increased because of Siberian Traps, which raised global temperature enough to melt methane hydrate deposits, which further increased atmospheric CO2 and temperature... “runaway greenhouse effect”

• Tetrapods hard hit, with the dicyondont Lystrosaurus being one of the few found in fossil record for millions of years after extinction. Forest communities absent until Middle Triassic.

Siberian traps basalt formations left by surface lava flows Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 The end of the Paleozoic