Reptile DerivativesSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Use of DNASlide 28Slide 29Slide 30Origin of MammalsSlide 32Slide 33Slide 34Synapsids = mammal like reptilesSlide 36Slide 37Slide 38Slide 39How to make a MammalSlide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66Reptile DerivativesBirds and mammalsArchaeopteryx = “first” birdReptilian features teeth, tail, pelvis – no sternum skull featuresAvian (bird) features feathers, longer front limbs.Why feathers ?; insulationWhy fly?: to glide from tree to tree or to chase insects?Mammal lung = dead end – incomplete exchange of OxygenBird lung – one way movement = flow through and current counter current = greater efficiency and lighter weight.Hespirornis = toothed, flightless, loon like diving birdRattites = worldwide, ancient flightless birds.7 is Vega island, off of James Ross Island at tip of Antarctic Peninsula.Vega Island, Antarctic PeninsulaPleisiosaur front arm (fin)Vegavis, from Vega Island in Western Antarctica – Cretaceous in age (pre-meteor)A ‘duck’Origin of Modern birds (Neornithes) before end of CretaceousUse of DNA•Gives relationship•Distance in time (if mutation at constant rate)•Does not use whole DNA but rather segments that evolve with time •Different authors use different DNA seqments.ratitesDucks and grouseUnexpected relationshipsHawks, falcons not relatedPenguins – albatrossesFlamingos – grebes !!!Origin of Mammals1. synapsids, leading to mammals are the first group of reptiles2. Based on differences from all reptiles and birds, mostly in features of soft anatomy.• ventral aorta leaves heart, splits into aortic arches to gills• in amphibians , single vessel leaves heart, then splits to left and right sides to form dorsal aorta• in mammals and birds, same system in embryo, but in adults, ventral aorta splits back to the heart so the arches come directly off heart, one to lungs, others to body. In mammals and birds, finally reduced to a single arch• in reptiles, the split involves a twist. In mammals it does not, so the remaining aortic arch in on different sides in reptiles and birds vs mammals.Synapsids = mammal like reptilesPelycosaurs = DimetrodonFunction of “sail”Camoflage?Swimming?ThermoregulationNote: nasty carnivoreTherapsidsHow to make a Mammal•Develop for carnivory = active•Hair – warm bloodedness•Limbs; under body, toes of equal length•Teeth; regionalization, multi roots, cutting•Lower jaw – one bone •Not there – change in reproductionHair, tooth regionalization, forward pointed toes of same length, limbs under body,Reptilian scales with sensory papillae in between.Papillae become hair – for insulationA definition of mammal = three bones in middle ear, one bone in lower jawMammals; monotremes, platypus and echidnaLay eggs.Echidna – egg in pouch,Hatches in 9 days – young in pouch for 12 weeks. Gets milk.Marsupials and Placentals – ParallelismAnd no shelled eggsMarsupial and placental reproduction; clevage total and equal - blastula forms with inner cell massInner cell mass forms layers of cells inside blastulaEmbryo implants into uterine wallOn plate inside embryo – primitive streak formsGet chorion, amnion, allantois and yolk sacPlacenta = chorion plus yolk sac in marsupialsPlacenta = chorion plus allantois in placentalsMarsupial pouch with ‘baby’opossum young on nipple.Marsupials not primitive, but differentDesigned for an unpredictable environment – can dump kid to save mother.The Path leading to humans: choices along the way.• bilateral symmetry• internal skeleton• active life – carnivore, omnivore? warm blooded, good senses• daylight living – visual shape perception = brains for memory storage• tropical climate – k species strategy• social organization – based on?? Food sources? Defense?This gets us to monkeys or squid. Now what to lead to humans?Suggested, upright, tools, social structure, none correlated to big brain probably speech – (no direct fossil record)Human origins – arboreal nocturnal monkeyArboreal diurnal monkeyTerrestrial monkey to terrestrial apeTo human , with what does the change correlate