Examining affinities of the Taung child by developmental simulation

Kieran P. McNulty, Stephen R. Frost, David S. Strait

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60 Scopus citations

Abstract

As a well-preserved juvenile and the type specimen of Australopithecus africanus, the Taung child figures prominently in taxonomic, ontogenetic, and phylogenetic analyses of fossil hominins. Despite general agreement about allocation of Sterkfontein and Makapansgat fossils to this species, limited morphological comparisons have been possible between these adult specimens and the juvenile Taung. Here, we used developmental simulation to estimate the adult form of the Taung child, and directly compare its morphology to that of other fossil hominins. Specimens were represented by 50 three-dimensional landmarks superimposed by generalized Procrustes analysis. The simulation process applied developmental trajectories from extant hominine species to the Taung fossil in order to generate its adult form. Despite differences found in the developmental patterns of these modern species, simulations tested on extant juveniles-transforming them into "adults" using trajectories from other species-revealed that these differences have negligible impact on adult morphology. This indicates that morphology already present by occlusion of the first permanent molar is the primary determinant of adult form, thereby supporting use of extant trajectories to estimate the morphology of an extinct species. The simulated Taung adult was then compared to other adult fossils. As these comparisons required assumptions about the pattern and magnitude of developmental change, additional analyses were performed to evaluate these two parameters separately. Results of all analyses overwhelmingly rejected the possibility that the Taung child was a juvenile robust australopith, but were consistent with the hypothesis that the Taung and Sterkfontein fossils are conspecific. Between Sts 5 and Sts 71, the latter is more likely to resemble the adult form of the Taung child.

Original languageEnglish (US)
Pages (from-to)274-296
Number of pages23
JournalJournal of Human Evolution
Volume51
Issue number3
DOIs
StatePublished - Sep 2006
Externally publishedYes

Bibliographical note

Funding Information:
We are grateful to all those who provided generous access to and assistance with specimens in their care: Bob Randall, Ross MacPhee, Richard Thorington, Linda Gordon, Judith Chupasko, David Pilbeam, John Harrison, Malcolm Harman, Manfred Ade, Wim Van Neer, Francis Thackeray, Stephanie Potze, Meave Leakey, Christopher Kiarie, and Kevin Kuykendall. Special thanks to Karen Baab for use of her OH 5 data. This manuscript benefited greatly from conversations with and comments from Dennis Slice, William Harcourt-Smith, Philip Mittereocker, Philip Gunz, Jim Rohlf, Eric Delson, and especially Bill Kimbel, Becky Ackermann, Sam Cobb, Michelle Singleton, and an anonymous reviewer. Funding for this project was provided in part by Baylor University, New York College of Osteopathic Medicine, and the New York Consortium in Evolutionary Primatology. This is NYCEP Morphometrics contribution number 17.

Keywords

  • African apes
  • Australopithecus africanus
  • Developmental simulation
  • Morphometrics
  • Ontogeny
  • Permutation tests
  • Taung

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