Chapter 6: Physiology II

Question 1

Premaxilla

Answer 1

• upper end of top beak
• The primary bone of the upper jaw
• Amniote phylogeny showing major clades and configuration of the premaxillae
• The avian rostrum is formed from fused, elongate premaxillae

Question 2

Dentary

Answer 2

• upper end of bottom beak/mandible

Question 3

Rhamphotheca

Answer 3

• layer over the beak made up of keratin

Question 4

Nasofrontal hinge

Answer 4

point in the head region where the head ends and beak begins

Question 5

What kind of teeth would birds have if they were still able to develop them?

Answer 5

multiple premaxillae, dentin and enamel teeth

Question 6

Calmodulin effect on beak

Answer 6

• creates longer beak

Question 7

Bmp4 effect on beak

Answer 7

• wider and deeper beak

Question 8

Describe predicted evolution of premaxillae

Answer 8

• Expression of Fgf8 and Lef1 and adult skeletal phenotypes in reptiles, showing ancestral paired gene expression preceding small, paired premaxillae in turtles and alligators and median zone of expression preceding elongate, fused premaxillae in birds
• six genes (1 dentin, 5 enamel genes)

Question 9

Cranial Kinesis

Answer 9

The closed, resting position of a bird’s jaw shows that the maxilla and dentary are in
contact. The cranium sits on the craniofacial hinge in a neutral position.

The articular and the quadrate are also in neutral positions, held in place by the slight pressure of the jugal arch and palatine bones

Question 10

Describe how quadrate, jugal arch, and palatine moves the premaxilla

Answer 10

• When the quadrate bone pivots forward, it begins to push on the jugal arch and palatine, lifting the premaxilla and opening the jaw from the craniofacial hinge
• When the bill begins to close again, the actions are reversed: the craniofacial hinge rotates down, the premaxilla and maxilla drop, and the quadrate rotates back

Question 11

Rhynchokinesis

Answer 11

Movement of the distal part of the upper jaw with respect to the cranium

Question 12

Nasal Coverings

Answer 12

IMAGE

Question 13

Herbst Corpuscles

Answer 13

• pressure receptors
• The most widely distributed mechanoreceptors in birds
• Present in the deep dermis all over the body, occur adjacent to joint capsules and feather follicles and are present in muscles and tendons
• Especially numerous in the beak and oral cavity

Question 14

Bristles

Answer 14

• Rictal bristles are specialized rigid, whisker‐like feathers that are usually evenly spaced at the base of the bill

Most conspicuous in birds that pursue insects, including nightjars, flycatchers, and some New World warblers such as redstarts - may also have a tactile function

Question 15

Bill shape: length

Answer 15

• short: fine movement
• longer: betterr reach but less precision

Question 16

Wide bill shape

Answer 16

• larger capture area
• swift

Question 17

Bill depth shape

Answer 17

• can give more or less power
• more power: macaw

Question 18

Tongue morphology

Answer 18

• relates to diet
• varies for fish, probing, fruit, filtering, nectar, etc.

Question 19

How does the hummingbird tongue work?

Answer 19

• A close‐up view of its forked tongue reveals tiny hair‐ like plates (lamellae). As the tongue retracts, the lamellae fold in and funnel captured nectar into the mouth
• mouth pieces rotate to provide opening and closing in lamellae