Table 2 EDJ shape differences between Australopithecus and later Homo, and their condition in Olduvai specimens

From: Dental morphology in Homo habilis and its implications for the evolution of early Homo

Shape characteristics in later Homo

OH 7

OH 13

OH 16

OH 24

Increased relative dentine body height (all teeth)

Dentine body short (M2) or intermediate (P3, P4, M1)

Dentine body short (M2), intermediate (P3, P4, M3, P3) or tall (M1, P4, M1, M2, M3)

Dentine body tall (all teeth)

Dentine body intermediate (P4) or tall (M1)

Talon/talonid reduction (P3, P4, P3, P4)

No talonid reduction (P3 and P4)

No talonid reduction in P3, P3 slight/moderate talon/talonid reduction in P4, P4

Talon/talonid clearly reduced (P3,P4) or slightly reduced (P4,P3)

Squared distolingual crown corner, no talon reduction (P4)

Metaconid reduced relative to protoconid (P3, P4)

No metaconid reduction (P3, P4)

Metaconid reduced (P3) or slightly reduced (P4)

Metaconid reduced in P3, not in P4

-

Protocone relatively taller and more distally placed (M1, M2, M3)a

-

Intermediate protocone placement, but height as in Australopithecus (M1, M2, M3)

Protocone taller and distally placed in M3, taller and intermediately placed (M2) or as in Australopithecus (M1)

Protocone placement intermediate but taller (M1)

Reduced distal marginal ridge (DMR) (M1, M2, M3)

-

No DMR reduction in M1, moderate reduction in M2, clear reduction in M3

No DMR reduction in M1, but clear distal reduction in M2 and M3

No DMR reduction (M1)

Protoconid are relatively taller and more distally placed (M1, M2, M3)a

Protoconid moderately taller and more distally placed (M1, M2)

Protoconid not distally placed, and variable in height (M1 moderately tall, M2 tall, M3 not taller)

Protoconid tall but not distally placed (M1, M2, M3)

-

Rounded crown—EDJ ridge mesiodistally shorter and buccolingually wider (M1, M2, M3)b

Less rounded crown, mesiodistally elongated (M1, M2)

M1 marginally more rounded, M2 similar to Australopithecus, M3 mesiodistally longer

M1 mesiodistally elongated, M2 and M3 more rounded

-

  1. The features listed are those identified through GM analyses that distinguish between Australopithecus and later Homo. The condition in later Homo is described in the first column and the condition in the Olduvai H. habilis specimens in the subsequent columns. A dash indicates that the specimen does not preserve the relevant tooth positions.
  2. aFirst molars of H. habilis show wear on protocone/protoconid, these results are based on dentine horn reconstructions.
  3. bH. habilis has mesiodistally elongated mandibular molars at the OES relative to Australopithecus; for more discussion of this trait, see Supplementary Note 1.
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