Test #1 Flashcards
Cynodont changes
- 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
What was a significant feature in early Therians?
- Tribosphenic molar (became basic pattern for later mammals)
- Can crush and shear food
- Key to mammalian diversification
- Diphyletic origin
What is the primitive mammalian phalangeal formula?
2-3-3-3-3
What are the changes between reptilian and mammalian shoulders?
What do these allow for?
- Coracoid is reduced
- Interclavicle is absent
- Clavicle reduced in cursorial mammals
- Allows for improved muscle attachment and back-and-forth motion
What are the main characteristics of modern mammals?
- 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)
Of the two cetacean families, which have symmetrical skulls and which have asymmetrical skulls?
What is this linked to?
- 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
What is the carnassial pair?
P4/M1
In the jaw, which muscles are more deveoped in carnivores vs. herbivores?
Where does the bite force go?
- 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)
What are the four levels in the hierarchy of the distribution of species?
- 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)
What are the faunal regions?
- Palearctic
- Nearctic
- Neotropical
- Ethiopian/Afrotropic
- Oriental/Indomalay
- Australian
- Oceanic
- Bolded have higest number of endemic families
What is vicariance?
- Existence of closely related forms (vicariants) in different geographical areas which have been separated by formation of natural barriers
What is the difference between ecological dispersal and species dispersal?
- 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)
What are the three types of routes in dispersal?
- 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)
What is Rapoport’s rule?
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)
What is Bergmann’s Rule?
- 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
What is Allen’s rule?
- 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)