Test #2 Flashcards

Question

Orrorin

Answer 1

Kenya, ~6 mya Thick enamel Large jaws Large molars Large canines (compared to Sahelanthropus) - Canine reduction compared to great apes Possible biped - Large hip joint - Australopithecine-like femur Possible climber - Curved phalanges - Powerful climbing muscle attachments on the humerus

Answer 2

Ethopia, 5.8 mya ``` Thin enamel compared to earlier Large jaws Large molars Large, honing canines Possible biped - Toe bones short, thick Possible climber - Curved phalanges - Humerus ```

Answer 3

Ethopia (Aramis) 4.4 mya Forested setting ``` Canine reduction - non-sectorial premolars Chimp size, brain & limb proportions Abducted big toe - Suggests arboreal with enhanced capacity for bipedalism Small molars Thin enamel Prognathic face ```

Answer 4

Kenya (Kanapoi & Allia Bay) 4.2 - 3.9 mya Forest ecology Hard fruit frugivore ``` Large canines - Compared to other Australopithecines Strong sexual dimorphism Vertical palate Inclined symphasis - Helps withstand high bite forces Small external auditory meatus - Not sure about significance Short arms Robust knee & tibia - Robust tibial plateau Strong sexual dimorphism Size of a large chimp Large molars w/ flat cusps Thick enamel Vertically oriented premaxilla Large, vertical malleolus Strong hands Deep carpal tunnel Big medial epicondyle (compared to A. afarensis) ```

Answer 5

``` Ethopia (Hadar) & Tanzania (Laetoli) - Wide distribution 3.9 - 3.0 mya Mixed forest-open ecology - More open in Laetoli ``` ``` Sexual dimorphism Smaller canines Large anterior dentition Larger premolars Large molars Long, large jaw Flat palate U-shaped dental arcade Large, broad face Small sagittal crest in some individuals Small brain - A little bit bigger than Ardipithecus - Chimp-sized Anterior foramen magnum Massive zygomatics Broad, short, lateral pelvis Large sacrum Valgus angle Robust knees (large tibial plateau) Short arms Straight fingers Size of a chimp ```

Answer 6

Tend to get smaller as time progresses in the hominin lineage Can be standardized by looking at size if incisors compared to nasal aperture - if incisors take up same or less space, then they are reduced As incisors get smaller, begin to see tool use

Answer 7

Footprints of A. afarensis Two individuals walking side-by-side (male/female?) - Foot had arch - Heel-strike motion Basically the same as a walking human

Answer 8

``` Kenya (West Turkana) 3.5 mya River floodplains, lake margins - more forested than Hadar Cranium is extremely distorted ``` ``` Flat, broad lower face Small molars Small brain Broad, flat palate Flat cheek area Strongly inclined lateral side of braincase ```

Answer 9

South Africa (Sterkfontein & Makapansgat) 3.5 - 2.5 mya Mixed forest-open ecology Obligate biped w/ climbing abilities First discovered Australopithecine - Tuang Baby - A little under 3 years old ``` Human features in the brain Same as A. afarensis except: - Larger molars - Smaller anterior teeth (at nasal margin) - Bigger face - Larger brain - More robust jaw - Shorter face Postcranially the same ```

Answer 10

Compared to Homo, Australopithecus has: - Long femoral necks - Low neck shaft angle - Small femoral heads - Small acetabulum - Flared ilia - Small bodies (approx. 3ft tall) - 6 lumbar vertebrae

Answer 11

Australopithecine - Short sacrum - Flared ilium - Long lever arm for gluteal muscles - Fewer strains; efficient pelvic balance Homo - Broader birth canal - Greater distance between acetabula - Loss of gluteal efficiency - More strains (larger femoral heads; thicker, shorter necks)

Answer 12

Ethiopia (Bouri) 2.5 mya Lake margin-grassland ecology Tough foods (tubers, roots) Possible tool use - Tools found near A. garhi sites, but not at - Means something was using tools at the time ``` Prognathic face Small brain Large posterior teeth (like in Paranthropus) - Close to P. boisei - Grit in diet means more surface area Intermediate anterior teeth ```

Answer 13

Usually later in time than Australopithecus (2.5-1.0 mya) East and South Africa Bigger faces, larger chewing muscles Larger postcanines than A. Smaller front teeth and larger brains - In later taxons Similar in body mass, dimorphism, and postcranial morphology to Australopithecus

Answer 14

Kenya (West Turkana) 2.5 mya Lake margins, grassland ecology Dramatic postorbital constriction Posterior temporalis Sagittal crest Primitive traits: - Small brain (chimp-sized) - Prognathic face - Large anterior dentition - Flat cranial base - Australopithecus-sized brain Derived traits: - Huge posterior dentition - Huge chewing muscles - Very large face - Projecting zygomatics

Answer 15

Direction of the temporalis muscle If angled, moves the front teeth a lot and gives them more strength Size of anterior teeth greatly correlated with bite force & angle of line of action

Answer 16

``` South Africa (Swartkrans, Kromdraai) 2.0-1.0 mya Mixed forest & grassland More folivorous - Isotopic signatures Possible tool maker/user - Tools found at Swartkrans, also H. erectus - 90% fossils P. robustus Overlaps with H. erectus ``` ``` Orthognathic Broad face Facial pillars Flexed cranial base Small front teeth Larger brain Massive chewing muscles Large postcanines Massive, tall mandible Anterior sagittal crest ```

Answer 17

Kenya, Ethopia, Malawi (East Africa) - wide geographical distribution 2.0-1.0 mya Mixed lake margin, river margin, forest, open ``` Massive orthognathic face Huge chewing muscles Gigantic postcanines - Molarized premolars Very small anterior dentition Thick mandible Sagittal crest Largest brain of Australopithecines Short, broad palate Vertical line of action ```

Answer 18

Omnivorous - At least as diverse as Pan diet Known from anatomy, microwear, isotopes Tools?

Answer 19

Forest mosaic | Specialized generalists

Answer 20

Strongly dimorphic in body size - 2:1 Reduced canine dimorphism Unlike modern primates - Males less antagonistic? - Female choice?

Answer 21

Uganda 20-15 mya (disputed) Probably closely related to Afropithecus Transverse processes on the lumbar vertebrae show different range of movement than Proconsul - moving toward Homo Probably an evolutionary dead end

Answer 22

Turkey (Ankara) 10.6 mya Frugivore Beginning of the pongid line - May be right before or right after divergence

Answer 23

China ~10 mya 3 species Teeth are similar to Pongo, face isn't - Crenulated molars

Answer 24

Premolars that are so large they take on the appearance of molars I.e. P. boisei premolars look like A. africanus molars