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Lecture 2

Lecture 2.pdf

4 Pages
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Department
Ecology & Evolutionary Biology
Course Code
EEB386H1
Professor
Michael Denny

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Lecture'2:'Origins'and'Evolution'of'Birds'
Solnhofen!Limestone!Quarries!
2 limestones!were!cut!into!slants!
2 these!slants!were!used!for!etching!!!fine!and!mallable!with!extremely!smooth!surfaces!
2 have!fossils!well!preserved!
!
Archaeopteryx!
2 one!of!the!first!bird!fossils!discovered!was!the!preserved!impression!of!a!flight!feather!found!in!the!lithographic!
limestone!rock!at!Solnhofen,!Germany!–!the!skeleton!was!later!discovered!
2 vonMeyer!named!it!the!Archaeopteryx,lithographica!(Ancient!wing)!
2 !the!specimen!was!initially!owned!by!a!medical!doctor,!then!sold!to!the!British!Museum!
Basic!Features!
2 date!back!to!150!million!years!ago,!there!are!10!specimens!found!
2 key!feature!is!the!feathered!wings!with!asymmetric!flight!feathers!
o strongly!suggested!the!Archaeopteryx!could!fly,!or!even!flap!fly!
2 possessed!a!round!furcula!–!fused!clavicles!(initially!was!thought!to!be!a!unique!bird!trait!!!but!now!known!from!
theropods!dinosaurs!
2 London!specimen!showed!a!reversed!digit!1!(“big!toe”)!or!hallux!!!a!feature!of!perching!birds!
o A!dinosaur!feature!is!a!fully!perforated!acetabulum!(seen!in!the!London!specimen)!
2 The!Thermopolis!specimen!(in!Wyoming),!shows!3!forelimb!digits!clearly,!but!metacarpals!are!unfused!
2 The!Archaeopteryx!retained!reptilian!features!(teeth,!long!tail,!and!semilunate!carpal!at!the!hand)!
2 The!Archaeopteryx!(like!us)!is!a!mosaic!of!old!and!new!
characters!!!consequence!of!differential!rates!of!evolution!for!
traits!!!reptilian!origin!
Technology!and!the!Fossil!!
2 Fluorescence!X2ray!analysis!revealed!there!is!actual!feather!
remnants!in!there!and!not!just!impressions!
2 Brain!endocast!analysis!using!micro!X2ray!computer!tomography!
(CT!scans)!revealed!lobe!microstructure!and!relatively!large!
sensory!lobes!!!supported!the!view!that!Archaeopteryx!flew!
o No!skull,!only!an!endocast!
!
2 Can!also!see!that!the!teeth!has!“waste”!on!them!!!not!like!close!relatives!(dinosaurs),!more!like!crocodiles!
2 In!the!Synchroton!X2ray!Fluorescence,!we!see!the!teeth,!hand!with!claws,!diffused!clavicles!
o Picks!up!different!elements!(ex.!Phosphorus)!
o There!are!phosphorus!in!bones!
o Chemical!composition!
o See!packages!of!melanin!in!feathers!
!
Brain!Cast!Neuroanatomy!
2 motor!area!controls!flight!muscles!
2 cerebrum:!lots!of!complex!processing!
2 optic:!large!optic!lobe!(have!large!eyes)!!!to!spy!on!predators!and!
finding!prey!!
2 !
Bird!Relationships!
2 Thomas!Huxley:!proclaimed!it!to!be!a!bird!(based!on!its!feathers)!
but!an!intermediate!form!!!closely!related!to!dinosaurs!based!on!

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Description
Lecture 2 Origins and Evolution of Birds Solnhofen Limestone Quarrieslimestones were cut into slantsthese slants were used for etchingfine and mallable with extremely smooth surfaceshave fossils well preservedArchaeopteryxone of the first bird fossils discovered was the preserved impression of a flight feather found in the lithographic limestone rock at Solnhofen Germanythe skeleton was later discoveredvonMeyer named it the Archaeopteryx lithographica Ancient wing the specimen was initially owned by a medical doctor then sold to the British Museum Basic Featuresdate back to 150 million years ago there are 10 specimens foundkey feature is the feathered wings with asymmetric flight feathers o strongly suggested the Archaeopteryx could fly or even flap flypossessed a round furculafused clavicles initially was thought to be a unique bird traitbut now known from theropods dinosaursLondon specimen showed a reversed digit 1 big toe or halluxa feature of perching birds o A dinosaur feature is a fully perforated acetabulum seen in the London specimenThe Thermopolis specimen in Wyoming shows 3 forelimb digits clearly but metacarpals are unfusedThe Archaeopteryx retained reptilian features teeth long tail and semilunate carpal at the handThe Archaeopteryx like us is a mosaic of old and new charactersconsequence of differential rates of evolution for traitsreptilian origin Technology and the Fossil Fluorescence Xray analysis revealed there is actual feather remnants in there and not just impressionsBrain endocast analysis using micro Xray computer tomography CT scans revealed lobe microstructure and relatively large sensory lobessupported the view that Archaeopteryx flew o No skull only an endocast Can also see that the teeth has waste on themnot like close relatives dinosaurs more like crocodilesIn the Synchroton Xray Fluorescence we see the teeth hand with claws diffused clavicles o Picks up different elements ex Phosphorus o There are phosphorus in bones o Chemical composition o See packages of melanin in feathersBrain Cast Neuroanatomymotor area controls flight musclescerebrum lots of complex processingoptic large optic lobe have large eyesto spy on predators and finding preyBird RelationshipsThomas Huxley proclaimed it to be a bird based on its feathers but an intermediate formclosely related to dinosaurs based on
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