Primate Classification Flashcards by Rhiannon E

Systematics

A field of evolutionary biology concerned with organizing the diversity of life

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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)

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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”

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Who created the taxonomic system still in use today?

Linnaeus

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Hierarchical nature of taxonomic classification

Multiple lower-level taxonomic divisions are grouped into one higher-level division

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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

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Hierarchical classification

Kingdom
Phylum
Class
Order
Family
Genus
Species

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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

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Taxonomy Rulebook

International Code of Zoological Nomenclature (ICZN)

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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)

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PRIMATES is an ORDER within the class Mammalia

All primates are mammals
BUT primates take the mammal lifestyle to the extreme!

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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

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Reproductive investment

Trade-off between number of offspring and investment in offspring
- prenatal and postnatal parental investment

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Reproductive strategy

Suite of adaptations (behavior, morphology, physiology) that increase the chance of mating and fertilization, and infant survival

K-selected!

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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

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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

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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

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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