Relationship between the mandibular condyle and the occlusal plane during hominid evolution: Some of its effects on jaw mechanics

J.W. Osborn

85 citations0/0 files storedAmerican Journal of Physical Anthropology

No readable copy stored yet — this record is metadata only.

No open-access location is known for this record yet.

Literature note Cite in a project Citation map

Pleistocene-Era Hominins and Archaeology Evolution and Paleontology Studies Morphological variations and asymmetry

Abstract

A selection of mandibles from recent higher primates, fossil hominids, and hominoids has been studied from photographs of skulls, reproductions, and material published by others, all viewed in the sagittal plane. Tracings of each mandible were constructed so that the dentitions were all scaled to the same length (d) and superimposed. The (scaled) positions of the articular surfaces of the condyles (J = joint point) were compared. The height of each J point above the scaled dentition (h = effective condyle height) and its distance behind the dentition (r = effective ramus width) were compared. With very few exceptions d greater than r greater than d/2. There was a poor correlation between r and the amount of prognathism. The position of the J point with respect to the occlusal plane was different for different groups within the material analysed and could prove to be a useful tool to help improve the reconstruction of fragmented fossil material. Some examples are given. A. afarensis and Homo habilis shared a low and anterior J point (r approximately d/2). The later australopithecines evolved a high and anterior J point, whereas that of Homo erectus was raised and displaced posteriorly (r approximately 3d/4). The value of r was increased to d in the Neanderthals, and recent man has moved the J point forward again. The effect of the position of the J point, the slope of the preglenoid plane, and the curve of Spee on the relationship between upper and lower postcanines when the jaw is opened and then closed to process food have been analysed. The results show that the position of the J point affects the way in which the mandible moves, and this may be related to changes in diet during evolution.

Paper brief

Loading…

Cite this work

Citation unavailable for this work.

BibTeX RIS CSL-JSON

No public copy is stored for this record, so only the metadata is cited.

Citations in this library

Citation map →

Stored only when both papers are in the corpus — 85 citations exist upstream.

References

1967Olduvai Gorge 1982Morphology of the Pliocene partial hominid skeleton (A.L. 288‐1) from the Hadar formation, Ethiopia 19862.5-Myr Australopithecus boisei from west of Lake Turkana, Kenya 1984The Descent of Hominoids and Hominids 1976Australopithecus, Homo erectus and the single species hypothesis 2017Australopithecus, Homo erectus, and the Single Species Hypothesis 1972New australopithecines from East Rudolf, Kenya (II)1964ON THE MANDIBLE OF RAMAPITHECUS

Cited by

2004Dental Functional Morphology 1994Morphological adaptation to diet in platyrrhine primates 1993Enamel thickness of human maxillary molars reconsidered 1994Paranthropus boisei: An example of evolutionary stasis?1994Enamel thickness and the helicoidal occlusal plane

Explore the map →

Papers that cite the same references — the relational fallback while embeddings are still backfilling.

Imported from OpenAlex (CC0) — nothing here is generated.