Term
| What two groups make up the Saurischians, and which do birds fall in? |
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Definition
| Sauropods and theropods, birds are theropods |
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Term
| List some of the skeletal characteristics of modern flying birds |
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Definition
Furcula - fused clavicle bones
Pygostyle - fused caudal vertebrae
Synsacrum - fusion of sacral and trunk vertebrae and pelvic bones
Tibiotarsus + tarsometatarsus - bones of lower leg and foot fused
Keeled sternum for wing muscle attachment
Modification/loss of digits in wings |
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Term
| What features did archaeopteryx have that separates it from modern birds? |
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Definition
| Long tail, teeth, sternum not keeled, no synsacrum, no pygostyle, no fusion of hind limb elements, claws on tips of wing "fingers". Only classified as a bird (and not a dromeosaur) because of feathers |
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Term
| What are the main characteristics of theropods? |
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Definition
| Bipedal, elongate, mobile, S-shaped neck, hollow pneumatic bones, tridactyl foot with digitigrade posture |
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Term
| What characteristics are shared by dromeosaurs and birds? |
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Definition
| Furcula, feather structures, lunate wrist (allows twisting) |
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Term
| What is the most probable scenario for the evolution of feathers in birds? |
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Definition
Started out as modified scale, coloured for camouflage/signalling
Developed into tufts of unbranched barbs, may function in insulation or waterproofing
Developed further into bipinnate structure typical of bird flight |
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Term
Name and describe the three types of feathers found in birds
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Definition
Contour feathers: Outer feathers and flight feathers, asymmetrical, central rachis with hundreds of barbs and branching barbules that interlock
Down feathers: Lack prominent rachis and barbules - fluff for insulation, under feathers and on some chicks
Filoplumes: Hairlike long rahchis with tuft of short barbs at tip - for display only |
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Term
| What indicated that the Aniornus climbed trees? |
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Definition
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Term
| Describe the transition from 1 to 3 locomotor modules in birds |
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Definition
Basal quadrapedal tetrapod: one module (4 limbs, trunk and tail)
Early therapod: one module (2 limbs and tail, forelimbs free)
Modern bird: 3 modules (wings (lift+thrust), hind limbs (ground movement) and tail (balance and steering)) |
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Term
| Why do birds need a tail? |
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Definition
| Because bird wings involve only forelimbs, tail with lift needed to balance centre of gravity |
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Term
| Name and describe the two main hypotheses of powered flight evolution and their weaknesses |
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Definition
Arboreal (Trees down) hypothesis: tree dwelling, leaped from branch to branch, increased surface areas cushion falls/improve glides/aided catching insects. Weakness = Most dromeosaurs ground dwelling (except aniornus)
Cursorial (ground up) hypothesis: a) lightweight agile theropod chased flying insects, developed forelimb surface area to act as a net and enable run and jump gliding. Weakness = No living terrestrial vertebrate gliders ground launch.
b) Tree climbing cursorial hypothesis (vs traditional) - flapping wings used to assist tree climbing |
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Term
| Describe the shape of bird wings and how they are associated with flight |
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Definition
Shaped as airfoils (camber shape)
Distal part of the wing associated with forward thrust (flat)
Proximal part of wing associated with lift (camber) |
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Term
| What is the name of the feathered membrane that spans the angle in front of the elbow? |
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Definition
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Term
| Where do primary and secondary feathers attach? |
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Definition
Primary - carpel and 3rd digit
Secondary - ulna (forearm) |
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Term
| Which principle stats that the difference in air-flow speed creates low pressure above the wing and high pressure below the wing, causing lift? |
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Definition
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Term
| What three components can lift be resolved into? |
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Definition
Effective lift (opposes gravity)
Induced drag
Forward thrust |
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Term
| When the wing angle is decreased, lift is increased but drag is also increased. True or false? |
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Definition
| False, this happens when the wing angle is increased |
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Term
| What is the name of the first digit in the wing (thumb) and its feathers that form a wing-slot over part of the wing to reduce drag? |
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Definition
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Term
| Wing lift is dependent on what factors? |
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Definition
Area of wing
Square of air speed
Wing angle
Aspect ratio: wing span/average chord width (varies within birds reflecting lifestyle) |
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Term
| Name the types of aspects found in birds and give an example |
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Definition
Low aspect fast manoeuvrer - flycatcher
High aspect fast flyer - swallow
High aspect dynamic soarer - albatross
Intermediate aspect static soarer - hawk |
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Term
| How much lift is generated in each wing stroke and which muscles are associated with them? |
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Definition
Downstroke - most thrust, pectoralis muscle
Upstroke - Recovery stroke, supracoracoidous muscle |
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Term
| A wing is extended laterally to full length during down stroke to minimise wing area, true or false? |
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Definition
| False, this maximises wing area. Wing tips are then drawn towards body during up-stroke |
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Term
| Where is the origin and insertion of the two muscles association with strokes of bird wings |
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Definition
Pectoralis: Origin = distal part of keel of sternum. Insertion = ventral surface of humerus
Supracoroideus: Origin = proximal part of keel of sternum. Insertion = dorsal surface of humerus, passes through foramen triosseum near shoulder joint |
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Term
| Explain altricial and precocial chicks |
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Definition
Altricial: Derived condition, naked, no feathers at hatching, poorly developed neuromuscular coordination, good mouth opening and beggind reflex, dependant on parents for food and warmth, ectothermic and no homeothermic reaction to chilling, High water content, small yolk size, low energy density
Precocial: Basal condition, well developed plumage (good insulation), well developed neuromuscular coordination, feed themselves, homeothermic response to chilling, low water content, large yolk size, high energy density |
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Term
| Female birds are usually the individuals that incubate eggs and care for the chicks, true or false? |
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Definition
| False, usually it's both male and female |
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Term
Name and describe the "ancient birds"
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Definition
| Paleognathae (emu, cassowary, ostrich, rhea, kiwi): reduced wings, retain theropod-like bony palate, flightless |
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Term
| Name and describe the "modern birds" |
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Definition
| Neognathae: neognathous palate (flesh instead of bone, allows greater cranial kinesis), diverse specialisations in beak/wing/feet structure |
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Term
| Name the perching birds and their suborders (describe) |
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Definition
| Passeriformes, comprised of 3 suborders: Acanthisittidae (New Zealand wrens), Oligomyodi (suboscines) and Passers (oscines or song birds, all bar 4 Australian species) |
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Term
| The suborder Passeres consists of what two sub groups? |
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Definition
Corvida - Most confined to Australia and New Guinea, originated in Australian region of Gondwanaland. Members in other countries derived from 'escapees' through Indonesian archipelago
Passerida: Australo-papuan region, moved to asia and radiated, dispersed into Africa and North America, some groups re-invading Australia |
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