What to know?Characteristics of Coelurosaurs (When did they live? What did they look like? What characteristics did they share with birds?)-Cretaceous-Small-Used hands or feet-Possess some characteristics of living birdsLate Triassic-late Jurassic Furcula, fused bony sternum, t-rex proteins, bird like egg brooding pastureWithin–> tetanurans > theropodomorpha > saurichia> dinosauria>archosaurs > diapsida>saurapsida> amniota> tetrapoda etc. Contain: maniraptorans which contains tyrannosaurids,dromeosaurs & birdsCharacteristics of Dromeosaurs (When did they live? What did they look like?)-Cretaceous-Small-Large toe and claw, 2nd digit-Feet similar to birds-Remarkable tail structure-Used fore feet to seize preyLate Cretaceous -bipdeal, cursorial & terrestrial predators-arms used to aid in bipedal running for balance like chicken eventually evolved to shorts flightsTHIS THEORY DROPPED-terrestrial origin – arms used to catch prey by swatting it down or for horizontal jumps & inclinerunning*arm & wrist movements seem to be consistent w/ prey seizing & feathered forelimbs poorlysuited 4 flight1st airsacs & endothermyCharacteristics of Pterosaurs (When did they live? What did they look like? How did theydiffer from modern birds?)-Box 16-3-Triassic-Wing different than birds-Flight mechanically demandingSome similarities with birdsLate Triassic-end of Cretaceous periodWalked on four legs when they were on land, compared to birds' strictly bipedal posturesMost pterosaur skulls had elongated jaws with a full complement of needle-like teeth.Shared characteristics between theropods and birdsHollow, pneumatic bones; Elongate, mobile S-shaped neck; Tridactyl foot; Digitigrade posture;Ankle joint forms between tarsal bones rather than tarsals and tibia/fubula; Feather precursorsor true feathers; Reduced genome sizeFeathers – how did they evolve? Know the differences (and the importance of these differences) between filamentous feathers, symmetrical vane, and asymmetrical vaneGenes of interest-Sonic hedgehog-bone morphogenetic protein 2Stage 1: feather follicle precursor (placode)Stage 2: follicle differentiation 2 layersStage 3: Rachies & barbules formStage 4: Distal & proximal barbules developStage 5: sheetlike surface of pennaceous vaneArchaeopteryxHypotheses for the origin of flightExamples of extinct “birds”Jeholornis primaEarly cretaceous from chinaBird like wings, thorax, skillDinosaur tailTeethShort rounded wingsConfuciusornis-early cretaceouscrow sizedelongated tail feathersseveral species in the genusfish eatingtoothless beak convergent w/ ornithurniespygostyleDromeosaurs – cursorial terrestrial predators-grasping arms-swivel wrist joint-posteriorly directed pubisCaudipteryx – Basically terrestrial w/ flapping flight- Symmetrical vaned feathers on wings & tail-Down like feathers on body*-long tail Archaeopteryx – basically terrestrial w/ flapping flight- asymmetrical vaned wing & tail feathers-longer arms-reduced tailIberomesornis – arboreal-strut-like coracoid-fused pelvis-pygostyle-reduced foot clawsEnantiornithes – improved low speed flight-increased skeletal fusion-deeper sternum-alula-shorter tail-metatarsals fused diffently + different articulation b/w scapula & coracoid as compared tomodern birds-teeth-small & medium sized-ecologically diverseIchthyornithiformes – essentially modern flight-shorter back & tail-deeper sternum & keel-more compact back & hipNeornithes – extant birdsWhat class do birds belong to?Time periods that major radiations were/are present-Late Jurassic – archaeopteryx-early cretaceous – iberomesornis-late cretaceous – enantiornithines & ornithurines & neornithes-Paleocene – neognathae then