1
Q
Cynodont changes
A
- Post-canine cheek teeth with accessory cusps to aid chewing
- Zygomatic arch (chewing)
- Double rooted cheek teeth
- Jaw structure and masseter muscle
- Hearing
- Atlas and axis (first two vertebrae) (increase range of motion)
- Pectoral and pelvic girdle
- Partial secondary bony palate
- Lumbar ribs reduced or lost
- Calcaneal heel
2
Q
What was a significant feature in early Therians?
A
- Tribosphenic molar (became basic pattern for later mammals)
- Can crush and shear food
- Key to mammalian diversification
- Diphyletic origin
3
Q
What is the primitive mammalian phalangeal formula?
A
2-3-3-3-3
4
Q
What are the changes between reptilian and mammalian shoulders?
What do these allow for?
A
- Coracoid is reduced
- Interclavicle is absent
- Clavicle reduced in cursorial mammals
- Allows for improved muscle attachment and back-and-forth motion
5
Q
What are the main characteristics of modern mammals?
A
- Hair
- Mammary and other skin glands
- Birth of altricial young
- Viviparity
- Enucleate RBCs
- 4-chambered heart
- Muscular diaphragm
- One bone in lower jaw, 3 in inner ear (reptiles have one bone in ear; multiple bones in lower jaw)
- Limbs rotate 90° from splayed reptilian stance (mechanically more efficient)
- Corpus callosum (not in monotremes or marsupials)
- True placenta (only in eutherians)
6
Q
Of the two cetacean families, which have symmetrical skulls and which have asymmetrical skulls?
What is this linked to?
A
- Mysticetes (baleen) are symmetrical
- Linked to low-frequency hearing, bulk-straining predation
- Odontocetes (toothed) are asymmetrical
- Linked to high-frequency hearing, echolocation
- Pan-bone thinning of lower jaws, fat pads, isolation of ear region
7
Q
What is the carnassial pair?
A
P4/M1
8
Q
In the jaw, which muscles are more deveoped in carnivores vs. herbivores?
Where does the bite force go?
A
- Carnivores with well developed temporalis muscle with bite force going to tip of jaw (mandibular condyles line up with tooth plane)
- Herbivores have well developed masseters with bite force going to molars (mandibular condyles above the tooth plane)
9
Q
What are the four levels in the hierarchy of the distribution of species?
A
- 1st order selection: Selection at physical/geographical range of a species (species range)
- 2nd order selection: Home range of an animal
- 3rd order selection: Use of habitat components within home range
- 4th order selection: Procurement of foods/micro-habitat from that site (resources from habitat)
10
Q
What are the faunal regions?
A
- Palearctic
- Nearctic
- Neotropical
- Ethiopian/Afrotropic
- Oriental/Indomalay
- Australian
- Oceanic
- Bolded have higest number of endemic families
11
Q
What is vicariance?
A
- Existence of closely related forms (vicariants) in different geographical areas which have been separated by formation of natural barriers
12
Q
What is the difference between ecological dispersal and species dispersal?
A
- Ecological dispersal: Movement of individuals or groups that leave natal to breed elsewhere (demographically important)
- Occurs within lifetime of individual, must be successful
- Species dispersal: Extension of a species range into a previously unoccupied area (important with vicariance) ( = range extension)
13
Q
What are the three types of routes in dispersal?
A
- Corridor routes: Minimal resistance
- Filter routes: Only certain species can pass through (e.g., Beringia)
- Sweepstakes routes: Some unusual occurrence carries an organism beyone the limits of normal ecological dispersal (rafting or wing event for bats)
14
Q
What is Rapoport’s rule?
A
Latitudinal breadth of species tends to be larger for species at higher latitudes than for species at lower latitudes (higher latitude species are adapted to broader range of conditions)
15
Q
What is Bergmann’s Rule?
A
- Races from cooler climates in species of warm-blooded vertebrates tend to be larger than races of the same species living in warmer climates
- Mass to surface area ratio will decrease with increasing size - more difficult to dissipate heat
- Temperature almost as good as latitude for explaining size trends
16
Q
What is Allen’s rule?
A
- Races in warm and humid areas are more heavily pigmented than those in cool and dry areas
- Questionable and poorly studied (could be cryptic colouration, areas could select for different colours)
17
Q
What is the “resource rule”?
A
- Mammals will increase or decrease body size with respect to geography or time depending on abundance, availability, and size of resources
18
Q
What are the three main layers of the epidermis?
A
- Outer layer is the stratum corneum (dead keratinized cells)
- Stratum granulosum - cells become keratinized
- Stratum basale - innermost layer where cells are produced by mitosis and move upwards
- Also have stratum lucidum between stratum corneum and stratum granulosum but only on thick skin
19
Q
What is the dermis layer of skin made up of?
A
- Connective tissue and vascularized glands
- Hair follicles
- Sweat glands
- Sebaceous glands
- Nerve endings
20
Q
What is the hypodermis made up of?
A
- Innermost layer
- Consists of fatty (adipose) tissue
- Base of hair follicles
- Fat serves as:
- Energy store
- Body contouring
- Cushion against blows
- Insulation
21
Q
What are armadillo tiles connected by?
A
- Non-mineralized collagen fibers called Sharpey’s fibres
22
Q
What are the three types of guard hairs?
A
- Spines: Stiff, enlarged guard hairs with determinate growth
- Bristles: Stiff, enlarged guard hairs with angora growth
- Awns: Definitive growth, expanded distal end, firm tips, weak base
23
Q
What are the four types of underhairs?
A
- Wool: Long, soft, curly (angora growth)
- Fur: Most common underhair, closely spaced, fine, short hair
- Velli: Very short, very fine hair; includes embryonic fur
- Lanugo: Embryonic fur shed in utero or shortly after birth
24
Q
What is the Flehmen response?
A
- Lip curling in mammals to facilitate transfer of scent to Jacobson’s organ
25
What are the four requirements for walking or running?
1. Support and stability
2. Propulsion
3. Maneuverability
4. Endurance
26
What are the main evolutionary changes seen in horses over time?
27
What are the differences between an ambulatory gait and a cursorial gait?
* Ambulatory animals have each foot on the ground at least half of the time
* Cursorial animals have each foot in contact with the ground less than half the time
28
Symmetrical vs. asymmetrical gaits
* Symmetrical: Spacing of feet is equal and makes contact with ground at even time intervals (walking, pacing, trotting)
* More stable
* Asymmetrical: Contact with ground at uneven intervals (galloping or bounding)
29
Difference between fast twitch and slow twitch
* Fast twitch: Contract quickly and powerfully but fatigue quickly (strength)
* Slow twitch: Contract for long periods with little force (endurance)
30
Difference between jumping and ricocheting
* Jumping uses all four feet
* Ricocheting involves only hind limbs
* Collectively known as saltatorial locomotion
* Gain efficiency in locomotion using elasticity in tendons
* Posterior shift in centre of body mass
* Enlarged hip muscles
* Pelvic girdle modified to accommodate shift in body mass
* Larger hind feet
* Longer tail for balance
31
Difference between amphibious, aquatic, and marine mammals?
* Amphibious: Spend time in both terrestrial and aquatic habitats
* Aquatic: Live most of the time in water but come on land for some activities (e.g., seals)
* Marine: Mammals that never come onto land
32
How does pectoral and pelvic oscillation differ in pinnipeds in aquatic and land environments, specifically the phocids and oteriids?
* Otariids:
* Aquatic - Pectoral oscillation - flap forelimbs, no hind limbs
* Terrestrial - Pectoral oscillation - posture (hind facing forward) allows for weight on all four limbs
* Phocids:
* Aquatic - Pelvic oscillation - alternating hind limbs, forelimbs for steering; or hind limbs used in alternating force with forelimbs as rudders or paddles
* Terrestrial - Pelvic oscillation - do not use hind limbs in terrestrial locomotion - vertical or lateral undulations called "gallumphing"; or hind limbs can be rotated forwards (like otariids) with belly supporting more of body than limbs
33
What are the three ways to counteract loss of stability in marine mammals?
* Pitch (for slip)
* Roll (for surge)
* Yaw (for heave)
34
What are chevron bones?
* Site for muscle attachment for downward tail motion in cetaceans
35
What is Dehnel's phenomenon?
What is Cope's rule?
* Dehnel's phenomenon: Observation that the reduction in the body size of the common shrew in autumn is accompanied by shrinkage in the size of the skull
* Cope's rule: Population lineages tend to increase in body size over evolutionary time
36
What is the peninsular effect?
* Mammal species decline toward terminal end of peninsulas
37
What is crypsis?
* Colouration where mammal's colour matches colour of substrate
38
What are scent glands?
* Modified hair or sweat glands that may release pheremones (chemical signals that convey information between members of the same species)
39
What are the differences between claws, nails, and hooves?
* Claws: Most primitive form
* Two parts: Dorsal unguis and ventral subunguis
* Nails: Cover only dorsal portion of phalanx
* Hooves: Characteristic of ungulates and are derived from claws, unguis completely surrounds subunguis
40
Differences between horns and antlers
* Horns are only found in bovid species and have an inner core of dermal bone covered by a keratinized sheath
* Antlers are branched ornaments made entirely of bone and are highly vascularized; shed annually
41
What is the hyoid apparatus?
* Located in throat region and consists of H-shaped array of small bones that support the tongue and larynx
42
What are somatic muscles?
* Muscles that orient the body in the external environment
* Either striated (presence of sacromeres), skeletal (attached to bones and tendons), and voluntary (can be contracted at will)
ZOOL 408
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