Chapter 27: Aves Flashcards
What is Archaeopteryx?
- an animal that died 147 million years ago leaving an imprint at the bottom of a lagoon.
Similarities between birds and reptiles?(6)
- occipital condyle
- single middle ear bone, the stapes
- both have a lower jaw composed of 5 or 6 bones
- excrete nitrogenous waste as uric acid
- lay similar yoked eggs and embryo developing on the surface by shallow cleavage divisions
- feathers are modified scales
What physical characteristic distinguishes them from all other vertebrates?
- feathers
Birds anatomy is completely designed around what?
flight
What are some characteristics that reflect their ability to fly?(6)
- light bones
- wings for support and propulsion
- enhanced respiratory system
- high body temp
- rapid and efficient digestive system
- high pressure circulatory system
What are the two theories for the origin of flight?
- Arboreal (trees down)
- Cursorial (ground up)
Describe the Cursorial hypothesis!
- fast running animals with long tails sued their arms to keep balance while running. Increasing the surface area of outstretched arms could have helped
Describe the Aboreal hypothesis!
- animals sprung from branch to branch, favouring the evolution of lengthened metatarsals and backwards directed hallux to grasp them
- front limbs were for climbing (front limbs remained long)
- back limbs for leaping
What are Paleognathe’s?
- can they fly?
- size?
- other name?
- sternum description?
- speeds?
- pectoral muscles development?
- large flightless birds
ex: ostrich, kiwis and emus - also called ratite birds
- flat sternum and poorly developed pectoral muscles
- some can run up to 60 MPH
What are Neognathae’s?
- can they fly?
- sternum?
- pectoral muscles description!
- what are also included in this despite the answer to the first question!
- flying birds
- keeled sternum
- large pectoral muscles for flight
- does include flightless birds such as penguins
L> keel is lost reduces size of flight muscles
Aves ___ sweat glands, ____ is at the base of the tail.
- do not possess
- oil gland
What kind of cavities are in their bones?
- air cavities
Do they possess teeth?
- no
How many cranial nerves do they have?
12
How many chambers does their heart have? What acts as the dorsal aorta? (is this different in mammals?)
- 4
- right aortic arch ( in mammals its left)
Are their red blood cells nucleated?
- yes as are all other vertebrates up to this chapter
Do they have a bladder?
no
Do females possess two functioning ovaries?
- no only one and its the left one
Young can be classified in two ways what are they?
- precocial (active)- 3 Downy, open eyed, mobile on hatching, follows parents and is shown food.
- altricial (helpless)- naked, blind and helpless hatchling
Example of Precocial young?
Example of Altricial young?
- Ruffed Grouse Hatchling
2. House Sparrow hatchling