Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Strolling through life Tetrapods, amphibians, and life on land Tetrapods - the clade of four- limbed terrestrial vertebrates Living tetrapod groups: * amphibians * mammals (including humans) * lizards and snakes * crocodilians * birds Eurypos , early Permian temnospondyl (painting by Douglas Henderson, 1990) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Lobe-finned fish (Sarcopterygia) Living coelacanth Fossil sarcopterygians Late Cretaceous (ca. 65 mya) Carboniferous (ca. 300 mya) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Comparison of pectoral fins Actinopterygian Sarcopterygian (ray finned) (lobe finned) Scapulocoracoid Humerus Ulna Radius Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Coelacanth pectoral fins Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Ancestral characteristics of living tetrapods • Pelvic and pectoral girdles • Forelimb with humerus, radius, and ulna bones • Hindlimb with femur, tibia, and fibula bones • five digits on the feet • sprawling posture • undulating locomotion • skull with no fenestra Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Tetrapoda: vertebrates more closely related to living Phylogeny of Bony Fish amphibians and amniotes than to their nearest living relatives Fossil taxa coelocanths and Fish-like amphibian-like lung fish Tetrapods Tetrapods Actinopterygia Coelocanths Dipnoans (lungfish) Osteolepis Eusthenopteron Pandericthyes Acanthostega Icthyostega tetrapods Derived Tetrapoda Sarcopterygia Osteichthyes After Coates and Ruta, 2007. Fins into Limbs. Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Living amphibians • Begin life as larvae, metamorphose into adults • Larvae typically respire through gills, adults typically breath through lungs and moist skin Frogs Caecilians Salamanders Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Smallest living vertebrate is a frog Paedophryne amauensis (Rittmeyer et al, 2012) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Giant salamander walking https://www.youtube.com/watch?v=XgtkMVAIodA Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Ancestral vertebrate locomotion: Undulation Fish Salamander Note “sprawling” posture Snake Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 First Tetrapods on Land Devonian Period (c) Ron Blakey (http://jan.ucc.nau.edu/~rcb7/nam.html) Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Early amphibian skull from Carroll, 2009. The Rise of Amphibians Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Early amphibian skeleton Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Xiphactinus Cretaceous Kansas Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Limb and skull evolution in tetrapods Coates, M. I., M. Ruta, and M. Friedman. 2008. Ever since Owen: changing perspectives on the early evolutio of tetrapods. Annual Review of Ecology, Evolution, and Systematics, 39: 571-592. Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Synapomorphies (homologies) Actinopterygia Coelocanths Dipnoans (lungfish) Osteolepis Eusthenopteron Pandericthyes Acanthostega Icthyostega tetrapods Derived • reduction to five digits Tetrapoda • flattened head • humerus with muscle attachment Sarcopterygia Osteichthyes • muscular pectoral and pelvic limbs with substantial bones Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Challenges for a fish out of water Respiration. gills collapse in air, reducing surface area and inhibiting gas exchange. Solution: cutaneous respiration, lung respiration. Support against gravity. Original vertebrate skeleton not able to support the body off the ground. Solution: limbs and vertebral column. Sensory perception. Ever see a fish with ears? Solution: transformation of hyomandibula to stapes, reorganization of skull for forward sight, improvements to sense of smell. Reproduction 1. Fish typically spawn. Solution: internal fertilization. Reproduction 2. Fish eggs dry out. Solution: amniotic membrane surrounding embryo in egg to prevent desiccation. Communication. Ever hear a fish scream? Solution: vocalizations come along with hearing, new sense of smell signals, and new visual signals. Food. Fish are typically predatory and have prey capture strategies that often involve sucking prey into mouth with water. Solution: reorganization of jaws and differentiation of neck Department of Geological Sciences | Indiana University Dinosaurs and their relatives (c) 2015, P. David Polly Geology G114 Paleozoic amphibian trackway from Indiana.