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Flashcards in chapter 9 Deck (23)
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1
Q

megadont

A

large teeth; megadont hominids are characterized by expansion of the posterior teeth

2
Q

synchronic

A

at the same time; thus synchronic species coexist in time

3
Q

mosaic habitats

A

areas characterized by a range of habitat types, from forrest to grassland

4
Q

aridification

A

a drying trend resulting from lower seasonal or annual precipitation levels

5
Q

savannah hypothesis

A

the now discredited idea that the development of open savannah grass-land created conditions leading to the evolution of hominins

6
Q

gallery forest

A

dense, canopied forest found along water courses such as rivers and lakeshores

7
Q

forest hypothesis

A

the suggestion that the hominid clade diverged from pains while still occupying a woodland/forest habitat, as suggested by paleoecological reconstruction of fossil localities

8
Q

variability selection hypothesis

A

a model that suggests that the operating factor in hominin evolution was environmental disparity, rather than stability, which promoted adaptive flexibility in hominin traits, including locomotion, dental adaptations, and technology

9
Q

genetic divergece

A

an estimate of the time since two genomes diverged, based on the number of differences observed and assuming a constant rate of mutation

10
Q

species divergence

A

an estimate of time since speciation; because genetic differences are constantly accumulating within lineages, estimates of genetic divergence time will always be older than species divergence time

11
Q

assemblages

A

the collection of all remains of pants or animals from paleontological contexts

12
Q

stem hominin

A

the progenitor of all later hominin species within a clade, arising from the last common ancestor

13
Q

foramen magnum

A

“large passage”, the foramen magnum is the largest hole in the cranium, though which the brain stem passes to become the spinal cord

14
Q

eurytopic

A

organisms that are able to live in diverse habitats and geographic ranges; the prefix “eury” means “broad, wide” and the affix “topic” refers to “place”

15
Q

gracile

A

small or slightly built; among australopithecines, refers to those species lacking the skeletal and dental features associated with the megadont adaptation

16
Q

robust

A

rugged or strongly built; several australopithecine species possess skeletal and dental features associated with large chewing muscles and crushing and grinding of hard foods

17
Q

phyletic sequence

A

an unbroken lineage of ancestor- descendent species

18
Q

mandibular symphysis

A

the midline of the lower jaw, where the left and right sides of the dental arcade meet

19
Q

orthognathic

A

“ortho” refers to verticle or flat, and gnathic to the jaws, so means flatfaced

20
Q

prognathic

A

refers to the degree to which the lower face projects forward

21
Q

competitive exclusion

A

a phenomenon in which two species closely related in phenotype and ecology come into direct competition or resources. in these cases one species will either become extinct or adopt a new phenotype, allowing it to exploit other resources

22
Q

Liem’s paradox

A

a model in biology that describes the apparent paradox between a specialized phenotype and a generalized behaviour; the paradox is resolved if the specialized phenotype does not restrict an organism from nonspecialized behaviours

23
Q

fallback foods

A

resources on which a species relies when its preferred, more easily acquired and processed foods are unavailable