Lab 7: Primate Dietary and Locomotive Anatomy Flashcards
Gumnivores
Group of primates (with hight metabolic rate and small body size) who chiefly feed on tree gum
Includes many callitrichids, especially marmosets
Insectivores
Group of primates who rely heavily on insects for energy.
Includes platyrrhines and some of the callitrichids, and many strepsirhines
folivores
Group of primates that rely primarily on leaves for food
frugivores
Group of primates that rely heavily on fruits
Primate dental morphology
Includes adaptations that enable primates to consume various foods
Cheek Teeth
premolars and molars
reflect structural properties associated with primate diet because they function primarily as grinding instruments, breaking down food before it is chemically processed in the gut.
May include variations of cusps and shearing crests, or dental blades, which function to process different food types.
Folivores’ teeth
typically have molars with high shearing crests and sharp cusps, relatively small central incisors
might have other adaptations to help them digest leafy foods.
Insectivores’ teeth
typically have molars with high shearing crests and sharp cusps
Frugivores’ teeth
typically possess molars with low, rounded cusps, rather than the high shearing crests of most folivores and insectivores
tend to have large, spatulated incisors for scooping fruit with their teeth
Gumnivores
Stout procumbent incisors (projecting forward in a V-shape), allowing them to scrape tree bark and access the underlying sap
bilophodont molars
molars with two anterior cusps and two posterior cusps that are aligned to form two ridges (or lophs)
differences in bilophodont molars reflect differences in primates’ diets
Gingerich’s formula
mathematically formula for determine a primate’s diet.
provides an estimated body weight based on measurements of the second mandibular molar using equation
Body Weight (in grams) = exp [3.92 + (1.31 * ln(length*width))] / 10
based on relatively strong relationship between body size and diet.
Kay’s threshold
Kay’s threshold suggests primates weighing less than 500g usually are insectivores or gumnivores, while primates over 500g tend to be either folivores or frugivores. This occurs largely due to energy demands associated with digesting different types of food as well as to the quantity and quality of food needed to support primates of different body sizes
Primate locomotion
Ambulation characteristics distinctive to primates:
1) Vertical clinging and leaping
2) Quadrupedalism
a) Arboreal quadrupedalism
b) Terrestrial quadrupedalism
c) Knuckle-walking quadrupedalism
3) Suspensory behavior (including brachiation)
4) Bipedalism
Primate locomotion: Vertical clinging and leaping
used by a variety of primate taxonomic groups
Strepsirhines employ vertical clinging and leaping as their primary means of mobility between separated trees in the forest or between tree trunks in the understory.
Leapers typically have long hindlimbs (legs), short, slender forelimbs (arms), and elongated tarsal bones.
Primate locomotion: quadrupedalism (Arboreal)
employed across many primate taxa and is the most common form of locomotion
suitable for moving across a continuous network of tree branches
less dangerous than leaping, especially for large- bodied primates
Primates that are habitually arboreal quadrupeds have body proportions that provide stability and balance while allowing them to move quickly across tree branches
They generally have gracile arms and legs that tend to be more equal in length than the limbs of leapers (enabling their center of gravity to be closer to the tree branch, thereby helping them maintain balance)
Also have more flexed (bent) limbs for climbing on branches
Primate locomotion: quadrupedalism (Terrestrial)
relatively uncommon among primates.
terrestrial quadruped primates are primarily large-bodied cercopithecoids (baboons, some macaques, the patas monkey).
Limb proportions of terrestrial quadrupeds, unlike arboreal quadrupeds, function less to maintain balance and more to attain long strides and speed while moving on the ground.
unlike their arboreal counterparts, terrestrial quadruped limbs tend to be less flexible.
tend to have long, robust limbs, narrow trunks, and short tails.
several forms of terrestrial quadrupedalism: primates walk on the palms of their hands (palmigrade), or knuckle-walking quadrupedalism where they walk on the back of the intermediate phalange
Primate locomotion: Suspensory
includes brachiating (swinging from arm to arm).
Typically, used by larger-bodied species
allows them to move quickly across tree- branches that would not support them if they were arboreal quadrupeds.
The apes, and some platyrrhines, most notably the atelines (e.g., spider monkeys), employ suspensory locomotion.
tend to have long, slender upper limbs and long, curved phalanges, particularly in their hands.
Primate locomotion: Bipedalism
most unique form of primate locomotion
walking on the hindlimbs without the use of the forelimbs.
only humans are obligate bipeds.
intermembral index (IMI)
formula for calculating likelihood of a particular locomotive form based on forelimb:hindlimb length
[(length of humerus+length of radius)/(length of femur +length of tibia)]*100
