Developmental identity versus typology

Lucy has only four sacral segments

Bibliographic Data

ID8319620
AuthorsAllison L Machnicki (0000-0002-4784-8004, Department of Anthropology Pennsylvania State University University Park PA), C Owen Lovejoy (0000-0003-0053-4523, Department of Anthropology and School of Biomedical Sciences Kent State University Kent OH), Philip L Reno (0000-0002-7053-0344, Department of Anthropology Pennsylvania State University University Park PA, corresponding author)
Year2016
Volume160
Issue4
Pages729-739
Publication date2016-08-01
Peer ReviewedYes
Open AccessYes
TypeARTICLE
VenueAmerican Journal of Physical Anthropology (JOURNAL)
Journal identifiersISSN: 0002-9483 • E-ISSN: 1096-8644
PublisherWiley (PUBLISHER • GB)
DOI10.1002/ajpa.22997
PMID27101066
OpenAlexW2342990693
LanguageEN
Citations received9
References cited72

OBJECTIVES: Both interspecific and intraspecific variation in vertebral counts reflect the action of patterning control mechanisms such as Hox. The preserved A.L. 288-1 ("Lucy") sacrum contains five fused elements. However, the transverse processes of the most caudal element do not contact those of the segment immediately craniad to it, leaving incomplete sacral foramina on both sides. This conforms to the traditional definition of four-segmented sacra, which are very rare in humans and African apes. It was recently suggested that fossilization damage precludes interpretation of this specimen and that additional sacral-like features of its last segment (e.g., the extent of the sacral hiatus) suggest a general Australopithecus pattern of five sacral vertebrae. METHODS: We provide updated descriptions of the original Lucy sacrum. We evaluate sacral/coccygeal variation in a large sample of extant hominoids and place it within the context of developmental variation in the mammalian vertebral column. RESULTS: We report that fossilization damage did not shorten the transverse processes of the fifth segment of Lucy's sacrum. In addition, we find that the extent of the sacral hiatus is too variable in apes and hominids to provide meaningful information on segment identity. Most importantly, a combination of sacral and coccygeal features is to be expected in vertebrae at regional boundaries. DISCUSSION: The sacral/caudal boundary appears to be displaced cranially in early hominids relative to extant African apes and humans, a condition consistent with the likely ancestral condition for Miocene hominoids. While not definitive in itself, a four-segmented sacrum accords well with the "long-back" model for the Pan/Homo last common ancestor. Am J Phys Anthropol 160:729-739, 2016. © 2016 Wiley Periodicals, Inc

Aesthetics · Art · Genealogy · Identity (music) · Psychoanalysis · Sociology · Typology · Anthropology · History · Morphological variations and asymmetry · Pleistocene-Era Hominins and Archaeology · Primate Behavior and Ecology · Psychology

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