Primate Classification Flashcards
Systematics
A field of evolutionary biology concerned with organizing the diversity of life
What are the three tasks of systematics?
1.) Naming and defining different kinds of organisms (alpha taxonomy)
2.) Discovering the evolutionary relationships among the groups (phylogenetics)
3.) Classifying the groups into hierarchically more inclusive groups (beta taxonomy)
- These groups should reflect the evolutionary relationships (beta)
Famous sketch from Darwin’s “Notebook B”
This is the first illustration of his new idea of descent with modification– the first depiction of what we now know as the “Tree of Life”
Who created the taxonomic system still in use today?
Linnaeus
Hierarchical nature of taxonomic classification
Multiple lower-level taxonomic divisions are grouped into one higher-level division
The hierarchical structure contains information about evolutionary relationships
~ All of the species in a single genus should be more closely related to each other than to a species in a different genus
~ All genera in a family should be more closely related to each other than to a genus in a different family
Hierarchical classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
Levels of taxonomic hierarchy that will be on your test (spelling counts!)
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Superfamily: Hominoidea
Tribe: Hominini
Genus: Homo
Species: sapiens
Taxonomy Rulebook
International Code of Zoological Nomenclature (ICZN)
Rules for writing taxonomic names
1.) Binomial nomenclature: each species has a scientific name that consists of two parts
- Scientific names are italicized
- Genus name is capitalized and the species name is not capitalized
- Genus name can be abbreviated (H. sapiens)
2.) Higher order taxonomic groupings are capitalized when they are used formally (ex. Hominoidea)
3.) In informal usage, the names can be shortened by dropping the Latin ending (-oidea, -idea, -inae, -ini) and then you do not capitalize (ex. hominoids)
PRIMATES is an ORDER within the class Mammalia
All primates are mammals
BUT primates take the mammal lifestyle to the extreme!
Characteristics of Living Mammals (CLASS: Mammalia)
1.) Reproduction
- Parents invest heavily in their offspring
2.) Brain organization
- Higher order brain structures make learning possible
3.) Temperature regulation
4.) Diet
Reproductive investment
Trade-off between number of offspring and investment in offspring
- prenatal and postnatal parental investment
Reproductive strategy
Suite of adaptations (behavior, morphology, physiology) that increase the chance of mating and fertilization, and infant survival
K-selected!
Mammals invest more in each offspring
“K-selected” (as opposed to “r-selected”) reproductive strategy
- Primates tend to have only 1 dependent offspring at a time
- Apes are an extreme version of K-selection
Brain organization
1.) Mammals share development of the limbic brain, which is not present in more primitive animals
- Emotions and feelings are biology’s mechanism to encourage offspring care
- Mammals have a greater reliance on sensory input
2.) Mammals– and especially primates– have a relatively large cerebrum
- Ability to learn
- Thoughts
3.) The neocortex is a part of the cerebrum associated with rational thought
- Conscious behavioral control
~ These last two especially are vital to living in social groups
Characteristics of Primates
1.) Grasping hands and feet
- 5 fingers and toes
- thumb and “big” toe position
2.) Nails instead of claws
- distal phalanx
3.) Pronation and supination ability
- radius and ulna
- tibia and fibula
4.) Binocular and stereoscopic vision
- Eye orbits facing anteriorly (forward)
5.) Color vision (cones)
- ability to see red
- for fruit? for sex?
6.) Reduced reliance on smell
- reduced snout
Traditional Taxonomy
Evolutionary systematics:
Anthropoids: Apes and Monkeys
- in the human form
- derived primates (higher primates)
Prosimians: Lemurs, Lorises, Tarsiers
- before the monkey form
- primitive primates (lower primates)
Cladistic Taxonomy
Haplorhines (suborder: Haplorhini)
Strepsirrhines (suborder: Strepsirrhini)
Sub- or Semiorder Strepsirrhini (strepsirrhines)
1.) Wet nose
2.) Retains primitive features
- lacks color vision
- rely on smell (large snout)
- Nocturnal
- Grooming claw
- Partially open orbits
- Mandible with suture at midline
3.) Variety of dental formulas
4.) Derived dental comb
- Lorises, Galago (bushbabies), Lemurs
Dental formula
Describes how many teeth of each type are present in each quadrant of the upper and lower jaws (incisors, canines, premolars, molars)
Dental formula
2.1.2.3
2.1.2.3
Strepsirrhine hands have a claw-like feature used for what?
Grooming
(ex. left hind foot of the Galago)
Strepsirrhines have partially open what?
Orbits
“Orbital closure”
When the bony ring around the orbit is closed and a thin sheet of bone covers back of orbits
- can’t see through eye socket to back of cranium
Ex. Gibbon cranium: fully closed eye orbits
Ex. Lemur cranium: ring around eye orbits closed, but no sheet of bone
Strepsirrhines have a pretty big snout and wet nose, which is similar to one of the most primitive mammals known as what?
The tree shrew
What makes the Aye-aye so unique
“Sixth finger” used for tap scanning for foot
- Aye-aye was first mistaken for a rodent because of its long incisors
Sub- or Semiorder Haplorhini (haplorhines)
1.) Dry nose
2.) Tarsiers
- Traditionally grouped with strepsirrhines because they retain some primitive features (mandibular suture, nocturnal)
3.) New world monkeys, old world monkeys, and apes
- monkeys and apes are derived in all features discussed to this point
Infra-order Platyrrhini (platyrrhines)
The meaning of Platyrrhini is flat nose with nostrils facing out
- more commonly called “new world monkeys”
- Superfamily Ceboidea (cebids)
1.) Prehensile tail
- all species are arboreal
- quadrupedal
2.) Dental formula is 2.1.3.2-3/2.1.3.2-3
Split from old world monkeys 35 Ma
Almost all primates give birth to only one offspring at a time, but who are the exceptions?
Humans
Marmosets
Tamarins
- these are all cooperative breeders!
Infra-order Catarrhini (catarrhines)
Catarrhini means nostrils facing down
- contains 2 superfamilies:
I ~ Cercopithecoidea (cercopithecids) are the old world monkeys
II ~ Hominoidea (hominoids) are apes and humans
1.) All catarrhines have the dental formula 2.1.2.3/2.1.2.3
2.) Can be terrestrial and/or arboreal
- all are quadrupedal
3.) Dietary specializations
- grass eating
- leaf eating
Superfamily Hominoidea (hominoids)
Includes:
I ~ Gibbons and siamangs (lesser apes)
II ~ Chimps, bonobos, gorillas, orangutans (greater apes)
III ~ Humans
1.) Hominoids have large body size and large brain size
- slow growth and development
2.) Extreme investment in offspring
3.) Hominoids are orthograde animals
- the body is held upright
- hominoids can move around in the trees by hanging below branches
4.) Lower molar cusp is “Y-5” pattern
5.) Hominoids are tail-less
Split from monkeys
- Molecular: 30+ Ma
- Fossils: 23 Ma
Apes are what kind of primates?
Tropical forest primates
In forelimb-dominated, below-branch suspension, the body is…?
Orthograde
In quadrupedal locomotion, the body is…?
Pronograde
Adaptations to below-branch locomotion in hominoids
1.) Long arms relative to the legs
- brachial index
2.) Short, stiff back
3.) Very mobile wrist (bone reduced so the wrist rotates almost like a ball-and-socket joint)
4.) Wide, shallow chest with shoulder blades on back
5.) Long, curved fingers
Hominoids have a specific shape of the molar teeth called the Y-5 pattern
Lower molars only
- “Bifurcation is buccal” (cheek side)
- can’t always see on all M3s
In monkeys, mesial and distal cusp pairs are separated bilophodontly
Life History
How different stages of growth and development are typically distributed across the lifetime of an animal
- How much time is spent as an infant?
- How much time is spent growing?
- when do teeth erupt (weaning; independence from mother)
- when do bones fuse (adult size)
- When does reproduction start?!
Generally thought about as a trade-off
- life history theory predicts that certain strategies are optimal in certain situations
~ grow quickly, reproduce early, be small
~ grow slowly, reproduce late, be big
Hominoids have extended periods of growth and development
Gestation longer
Dependent period longer
Growth longer
Reproductive period longer
Life longer
Primates are super-mammals
investment in offspring
brain structure (social living)
There are many different species of primates, organized taxonomically by shared biology and degree of evolutionary relatedness
- anatomy: vision, hands as manipulatory organs; tooth number and tooth type
- geography
- diet
The suborder division separates strepsirhines and haplorhines
- Strepsirrhines retain some primitive features (smell, grooming claw)
- Haplorrhines have more derived features (vision, manipulatory hands)
- Tarsiers are haplorrhines, despite having some primitive features
The infraorder division separates platyrrhines and catarrhines
There was an entirely independent evolutionary radiation of primates in South and Central America beginning in the Oligocene
Cercopithecoids and hominoids are very different kinds of animals
- Body posture: pronograde vs orthograde
- Tail: present vs absent
- Size: smaller vs larger
- Intelligence: less vs more
