Week 9: Early Homo Flashcards
1
Q
problematic defintion of genus homo
leakey, tobias and napier
A
“…it would be necessary to revise the diagnosis of the genus Homo. In particular, it has become clear that it
is impossible to rely on only one or two characters, such as the cranial capacity or erect posture, as the
necessary criteria for membership of the genus.”
2
Q
cerebral rubicon
A
the minimum brain size (cranial capacity) required for a specimen to be classified as a member of a specific human genus or species
3
Q
more complicated definition of genus
A
- no non-arbitrary yard stick available for the genus as reproductive isolation is for the species
- a genus is a monophyletic grorup whose members occupy a single adaptive zone
- for species to belong to a genus it should belong to the same monophyletic group as the type of species of that genus
- a clade are all of the taxa that are descended from a recent common ancestor
- the type of species of the genus homo is homo sapiens
4
Q
definiton of genus homo
A
- locomotion - bipedal
- body size - tall
- body shape - short arms and long legs
- brain - large
- hand - precision grip
- stone tools - habitual use
- masticatory apparatus - reduced, further apart temporal lines
- face - small and retracted
- jaws and teeth - small
5
Q
in the cranium
morphological features of homo habilis
A
- reduced prognathism
- slightly increased cranial volume
- less postorbital constriction
- enlarged occipital contribution to the sagittal arc
- laterally expanded parietals with greater coronal than sagittal chord
- upper premolars reduced, two rooted
- lower postcanine teeth buccolingually narrow and long, reduced P4 talonid, M3 reduces, premolars mostly single rooted
6
Q
“homo” rudolfensis: facial morphology
A
- face wide and tall
- flat, dished midface
- broad and flat nasoalveolar clivus
- incisors on bicanine line
- shallow palate
- likely large molars
- large neurocranium
- no marked supraorbital torus
- quite vertical face
