Lab VI: Survey of the Living Archosaurs Flashcards
Describe the characteristics of the bird skull
- Upper and lower fenestra in temporal region of skull (diapsid) and additional opening in front of eye
- Skull bones are fused with one occipital condyle
- Loss of teeth on maxilla and dentary; well developed beak with keratinized covering
- Single bone in middle ear
Describe the characteristics of the bird skeleton
- Ossified skeleton; many bones hollow
- Ribs with strengthening processes
- Sternum (breastbone) with well-developed keel in most
- Keel = anchor for wing muscles to attach to
- Forelimbs modified for flying; hindlimbs modified for perching, walking, swimming
- Foor with four toes (most); hand with three fingers
- Sacral vertebrae fused to each other and to pelvic girdle (synsacrum)
- Overall reduction in size and number of skeletal elements
Describe the integument of birds
- Outer covering of feathers; scales on legs
- Thin skin with few skin glands
- Oil gland (uropygial) at base of tail
Describe bird circulation and respiration
- Four-chambered heart; persistent right aortic arch
- Nucleated RBCs
- Respiration by slightly expansible lungs with air sacs among the viscera and skeletal elements
- Syrinx (voice box) near junction of trachea and bronchi (air duct to lungs)
Are birds endotherms or ectotherms?
- Endotherms
Describe the excretory system of birds
- Paired kidneys; duct from kidney open into cloaca
- No urinary bladder
- Uric acid main nitrogenous waste
Describe reproduction in birds
- Sexes separate; males with paired testes; females with left ovary and oviduct only
- Internal fertilization
- Amniotic egg with large amount of yolk and calcareous shell; incubation always external (oviparous)
- Young born active and covered in feathers (precocial) or helpless and naked (altricial)
What are feathers?
- Highly modified epidermal scales
- (Birds have more typical epidermal scales on their legs and feet)
What type of feather is this?
What is its function?
- Filoplume
- Sensory function
- Provides feedback on contour feather activity
What type of feather is this?
What is its function?
- Contour feather
- Outer feathers; give colour and shape to bird; strong and stiff - aid in flight; provide some insulation
What type of feather is this?
What is its function?
- Down
- Function is to insulate bird by trapping air
What type of feather is this?
What is its function?
- Semiplume
- Mix between a contour and down feather
- Provides shape (by streamlining bird) and insulation
What type of feather is this?
What is its function?
- Bristle feather
- Sensory function
- Small and stiff contour feathers like whiskers
What are the two main factors that affect feather colouration?
- Pigments: Carotenoids and melanins
- Structural colour: Resulting from breaking up and reflection of light by physical structure of feather itself (e.g., blue feathers rely on structure of feather and rarely on pigments)
What are the three uses of colour that birds employ?
What are the different types of these colourations?
- Anti-predation colouration
- Concealment or cryptic
- Countershading (e.g., penguin)
- Deflective (e.g., rump patch on killdeer)
- Social colouration
- Sexual dimorphism (physical differences between sexes)
- E.g., mallards, pheasants
- Status signaling (mate attraction)
- E.g., peacocks
- Sexual dimorphism (physical differences between sexes)
- Physiological colouration
- Reduction of wear and tear (e.g., increase melanin granules (black) at tip of feather in many migratory birds to make feathers tougher
What is referred to as when individuals of the same birds species display different adult morphs?
Do these morphs breed with each other?
- Polymorphism
- Yes, morphs interbreed
What are the three times that molting occurs?
- Natal
- Juvenal
- First winter
Give an example of a type of sexual dimorphism with respect to changes in plumage in adult birds?
- Plumage changes with age in adult birds and can vary dramatically between sexes
What is seasonal molting?
- In some species there is a marked difference in adult’s breeding plumage and plumage outside breeding season
- Molting is energetically expensive and most adults molt only twice annually
What are the characteristics of the crocodile skull?
- Skull with upper and lower fenestra (openings) in temporal region of skull (diapsid) and additional opening in front of eye
- Skull elongate and massive
- Nares terminal
- Secondary palate present
- Jaws with teeth set in sockets
What are the characteristics of crocodile skeletons?
- Limbs are well developed and paired with forelimb ending in five digits and hindlimb ending with four digits
- Limbs extend laterally from the side of the body
Describe crocodile integument
- Epidermal scales cover feet and ventral surfaces; bony dermal plates cover the back
Describe respiration and circulation in crocodiles
- Four-chambered heart
- Secondary palate allows animal to eat and breathe simultaneously
Are crocodiles endotherms or ectotherms?
- Ectotherms
Describe the excretory system of crocodiles
- Paired kidneys
- Uric acid main nitrogenous waste
Describe reproduction in crocodiles
- Sexes separate
- Amniotic egg with shell; oviparous