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Animal Diversity > 17: Birds > Flashcards

17: Birds Flashcards

1
Q

2 theories of where birds came from

A

Birds evolved from theropod dinosaurs (most probable)

Birds evolved from earlier thecodont reptiles

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2
Q

Similarities between birds and reptiles

A 
Lay eggs
Lower jaw consists of several bones
Scales on legs
Pneumatised bones
Single middle ear bone
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3
Q

Differences between birds and reptiles

A 
Birds are endothermic
Have a 4 chambered heart
Have feathers (only different to extant non-avian reptiles)
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4
Q

What is the semilunate carpal?

A

The ‘half moon shaped’ bone in the therapod wrist

Formed by the fusion of distal carpals 1 and 2

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5
Q

What is the function of a semilunate carpal?

A

Flexible wrist

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6
Q

What was the first feathered non-avian dinosaur?

A

Sinosauropteryx prima

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7
Q

Features of Sinosauropteryx prima

A

Small theropod dinosaur
Up to 1.07m, 0.55kg
Had downy filamentous feathers, probably for insulation

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8
Q

Another important feathered dinosaur

A

Protarchaeopteryx

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9
Q

Features of protarchaeopteryx

A 
A non-avian theropod
1m in length, 4kg
Pneumatised feathers (air cells/cavities)
Feathers with symmetrical veins
Also had a furcula (wishbone)
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10
Q

What was the earliest bird?

A

Archaeopteryx lithographica

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11
Q

Features of Archaeopteryx lithographica

A

Both bird and reptile features (transitional form)
Reptile: long bony tail, claws on forelimbs, small sternum
Gastralia

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12
Q

What is a gastralia?

A

Dermal bones found between sternum and pelvis
Provide support for abdomen
Attachment for abdominal muscles

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13
Q

Skulls of Archaeopteryx vs extant birds

A

Long nasal opening in birds
Birds have much larger brains relative to body size
Many cranial bones in birds are fused

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14
Q

What is a pygostyle?

A

Triangular plate made of fused caudal vertebrae

Supports tail feathers

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15
Q

What were the Enantiornithines?

A

Toothed jaws (a few had beaks)- reptiles
Shortened hand with claws- reptiles
Pygostyle
No keeled sternum

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16
Q

What was the K-Pg extinction event and who survived?

A

Cretaceous-Palaogene

Water birds and crocodiles survived

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17
Q

How many extant species of bird are there?

A

9,000-10,000

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18
Q

What are the two super orders of bird?

A

Palaeognaths

Neognaths

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19
Q

What do Palaeognaths include?

A

Ratites and tinamou

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20
Q

What do Neognaths include?

A

Game birds and ducks
Water birds and soarers
Forest birds

21
Q

Features of palaeognaths

A

The vomer is fused with the palatine bone (morphology of the palatte)
Mostly flightless eg. ostrich, but the tinamou can fly

22
Q

What is a ratite?

A

Bird with a keel-less breastbone

So can’t fly

23
Q

What was the moa?

A

Extinct ratite
Endemic to New Zealand
Human driven extinction

24
Q

Features of the bird skull

A

One occipital condyle
Large optic lobes and cerebellum, well developed brain
Single bone in the middle ear- the columella

25
Q

What is the columella?

A

Single bone in the middle ear

Equivalent to our stapes

26
Q

Bird vision

A

Very good vision
3 eyelids- upper and lower, and a nictitating membrane
Membrane keeps out dirt and water in diving birds
Large eyes relative to skull
Supported by sclerotic eye ring- bony plates also seen in reptiles and icthyosaurs

27
Q

What is an indented fovea?

A

Magnifies central part of visual field

Some have 2 fovea in each eye

28
Q

What can birds see that we can’t?

A

UV part of light spectrum

Used in mate choice in starlings- look drab to us

29
Q

Bird beak structure

A

Upper jaw (maxilla) and lower jaw (mandible)
Both made of bone, usually hollow or porous
Sheath of keratin over the bone called the rhamphotheica
Continuous growth

30
Q

What is special about a toucan beak?

A

Vascular controlled thermal radiator
Open capillaries to heat up/cool blood
Only adults

31
Q

Bird circulatory system

A

Heart has 2 atria and 2 ventricles (4 chambered)

There are separate pulmonary and systemic circuits

32
Q

What is the syrinx?

A

How birds produce sound
Change diameter where the trachea branches
Vibrate a pressulus
Can generate more than one sound at once

33
Q

Bird respiratory system

A

No diaphragm
Air moves in and out of lungs by pressure changes in air sacs
Air sacs are only involved in air movement, not gas exchange

34
Q

Air sac hypothesis

A

Inhalation:
Air moves into posterior air sac, lungs, through parabronchi andinto anterior air sacs
Exhalation:
Out of posterior airsacs, through parabronchi, out of anterior and out of body

Would require valve

35
Q

What is the crop?

A

Part of digestive system
Softens and regulates flow of food
Can store food temporarily
In some birds, produces milk to feed young

36
Q

Bird stomach features

A

2 parts:
Proventriculus- glandular stomach
Produces mucus, pepsin and HCl for digestion

Gizzard- muscular stomach
Some contain stones/grit to ‘chew’
Safety valve blocks bits that might damage- owl pellets

37
Q

What is the caeca?

A

Part of the digestive system
Contains bacteria that break down cellulose
In birds that digest fibrous plant food
eg. pheasants

38
Q

What is the cloaca?

A

Opening for intestinal, urinary and reproductive tracts

Excrete as uric acid, like reptiles

39
Q

Bird skin features

A

Thin epidermis and dermis
No sweat glands
Feathers
Antibacterial secretion for cleaning

40
Q

How did feathers evolve?

A

From reptilian scales
For insulation or display originally
Flight came after

41
Q

2 types of feather

A

Vaned feathers- exterior

Down feathers- not vaned

42
Q

What are feathers made of?

A

B-keratin

43
Q

Feather functions

A

Flight/contour feathers- flight
Filoplumes- sensory information
Downy feathers- insulation
Also visual display, sound, nest lining

44
Q

Pigmentation

A

Melanins- water and bacterial resistant, blacks, browns, greys
More melanin in tips to protect from wear
Carotenoids- died derived, yellows, orange, reds
Porphyrins- greens, pinks

45
Q

Reproduction in birds

A

Internal fertilisation
Amniotes
Oviparous

46
Q

What is an egg shell made of?

A

Calcium carbonate

47
Q

What are altricial young?

A

Born undeveloped, require care and food from parents

eg. robins

48
Q

What are precocial young?

A

Born developed, can feed themselves immediately

Eg. mallard ducks

Animal Diversity (12 decks)

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