CH 6 Sarcopterygii monophyletic Sarcopterygian bony fish classified as osteolepiformes are sister group to all terrestrial vertebrates tetrapoda Tetrapod ancestor was some type of osteolepiform fish Early devonion present Fish non verts tetrapods 1 complex coating enamel surrounding oral teeth 2 pectoral pelvic fins lobate single basal bone Actinistia 1 2 dorsal fins 2 diphycercal caudal fin 3 soft anatomy Rostral organ senses electrical currents snout top 4 Coelacanth known mid Devonian thought extinct until 1938 a Latimeridae 2 kinds Chalumnae menadoensis b only 2 living reps of actinistia Dipnoi 1 Diphycercal caudal fin 2 Upper jaw fused to cranium autostylic jaw suspension holocephalans 3 Large well developed lung singular One Order Ceratodontformes Ceratodontidae Australia lungfish Lepidosirenidae south America protopteridae Tetrapoda 1 pectoral girdle separated from shell 2 presence of zygaphyses on vertebrae 3 limbs w carpels tarsals digits phalanges 4 pelvic girdle attached to vertebral column Zygopophyses tetrapods allow vertebrae to interlock allow twist bend reinforce vert column to support weight prezygapophyses anterior post Lateral Line System sense movement in water around them main cell of system Hair Cell Hair cells excited by mechanical stimuli which pass over their surface stimulate tiny hairs Largest of these hairs are kinocilia Secondary Lamellae where O2 exchange takes place in gill filaments Collapse in air no exchange Solution o Gas filled bladder extension of anterior gut lungfishes o Gills to lungs req change to circulatory system Include a double circuit to include a pulmonary loop o Higher blood pressure req to prevent blood from pooling low points b c of weight of blood in air o Gill arches adapted to make cartilage to support larynx thyroid gland Sacral Rib connect the acial skeleton to the pelvic girdle allowing weight to be transmitted to hind limb OSTEOLEPIFORMES DIDN T HAVE Panderichthys tiktaalik Derived Elpistostegids Lacked dorsal anal fin reduced caudal Still had developed gills Pectoral girdle still attach to cranium but prob allowed partial rotation Pectoral fin Pelvic girdle unknown Eyes on top of head like croc Tiktaalik skull w eyes on top pectoral fin w lepidotrichia MAJOR DIFFERENCE pectoral girdle completely separate from cranium Panderichthyidae some of these appear truly intermediate between osteolepiforms and tetrapods Dorsolaterally flattened body with long snout eyes on top of head Vertebrae Large ribs project laterally and ventrally Early Osteolepiform fish Eusthenopteron another Osteolepiform known from a fossil is a cylindrical osteolepiform that was a good candidate to be the sister to tetrapods for a while Cylindrical body 4 unpaired fins 2 dorsal caudal and anal fin Vertebrae neural arches do not articulate short ribs Skull Area anterior to parietals on skull is mosaic of small bones Order Panderichthyes tiktaalik acanthostega Two earliest stem group tetrapods Acanthostega most basal FIRST VERTEBRATE WITH A NECK couldn t support body out of water Weak zygaphyses connection b w pelv girdle vert column More complex pectoral girdle now separate from head Paired limbs lacking in lepidotrichia had up to 8 digits Prob still aquatic Icthyostega BEST CANDIDATE FOR 1ST TERRESTRIAL VERTEBRATE Vert columns w strong zygapophyses like extant tetrapods Good connection w pelvic girdle for support of weight Well developed ribs overlapped forming cage around viscera o Adaptation prob protected viscera from being crushed under weight of body on land Lacked gills dunno if semi aquatic or full terrestrial prob like crocodile terrestrial traits Chonae How did the Choanae evolve Posterior nostril migrated from its external to internal position over evolutionary time Critics This would involve migrating across a field of teeth in the upper jaw is unlikely no fossil intermediates found for support of hypothesis Nasal ways dif in tetrapods Have noses that open to world through a singe pair of external nostrils Open to throat through a pair of Internal NostriLS called CHONAE choana sing Ch 7 KenIchThys 395 myo Osteolepiform fish china I Vomeronasal Organ Jacobsons organ a In anterior roof of mouth b Well developed in snakes in some mammals i Flehman Behavior in ungulates where the head is lifted high the upper lip is curled likely a way of inhaling pheromones into the vomeronasal organ Olfactory receptors associated w mouth throat pass air over olfactory epithelium every breath receptors can be very sensitive amongst extant mammlas have most sensitive due partly to presence of thin scrolls of bones called TURBINATES Turbinates highly developed in mammals significantly increase the surface area available for olfactory epithelium Lepospondyli 1 of 2 major tetrapod lineages Lepospondyli 1 Diverse tetrapods semi aqua terrestrial forms 2 Many body forms some similar to extant suggest similar ecologies life hisotries 3 Relation to other tetrapods unclear a 5 GROUPS OF LEPOSPONDYLI i NECTRIDIA ii Microsauria iii Aistopoda iv Adelogyrinidae v Lysorophia Nectridian Lepospondyls 1 bad devel Limbs prob aquatic 2 DiploCAUluS well known lepos From NA 3 up to 1 m in length 4 boomerang shaped head The Batrachomorpha Aq semi aq terr Forms MID CORBONIFEROUS PERIOD 340 mya Reduced of digits on the forelimbs 4 vs 5 as in other crown group tets Two Groups Temnospondyli Extinct Paraphyletic some gave rise to amphibians now Large 2 m prob look act like crocodlies 2 Lissamphibia a some extant Anurans Salamanders Caecilians The Reptilomorpha 1 Third major lineage of tetrapoda a Origins in Early carboniferous b Majority of extant tetra s Sensory systems water vs air lateral line system good watr bad air b c water is denser than air Electroreception better in water b c it conducts electricity Air better for vision hearing Chemical senses Olfactory work better in air than water Ch 8 The names frogs and toads do not refer to monophyletic groups Anura frogs toads MOST ABUNDANT tetrapod group most diverse in tropics majority terrestrial as adults Skeleton Defining Characteristics associated w jumping Tailless as adults Short vertebral column w few presarcal vertebrae Long hind limbs toes Modified sarcal area Urostyle Massive mouths Almost all lack teeth on the lower jaw Urodela Caudata salamanders 1 N hemisphere 2 Majority adult terr But many full aqua 3 UNLIke aquatic anurans the majority of aquatic salamanders retain larval characteristics are referred to as paedomorphic or