Morphometric analysis of lumbar vertebrae in extinct Malagasy strepsirrhines.

Published

Journal Article

Previous research on subfossil lemurs has revealed much about the positional behavior of these extinct strepsirrhines, but a thorough quantitative analysis of their vertebral form and function has not been performed. In this study, 156 lumbar vertebrae of Pachylemur, Archaeolemur, Megaladapis, Mesopropithecus, Babakotia, and Palaeopropithecus (11 species in all) were compared to those of 26 species of extant strepsirrhines and haplorhines. Lumbar shape was compared among species, using a principal components analysis (PCA) in conjunction with selected vertebral indices. The first principal component revealed strong separation between Palaeopropithecus at one extreme, and Archaeolemur/Pachylemur at the other, with Babakotia, Mesopropithecus, and Megaladapis in an intermediate position. Palaeopropithecus has markedly shorter spinous processes and wider laminae than do the other subfossil taxa, consistent with sloth-like, inverted suspensory postures. The moderately reduced lumbar spinous processes of Babakotia, Mesopropithecus, and Megaladapis are convergent with those of lorisids and Pongo, reflecting antipronogrady, but a less specialized adaptation than that of Palaeopropithecus. Archaeolemur and Pachylemur share relatively elongated spinous processes, in conjunction with other features (e.g., transverse process orientation and relatively short vertebral bodies) indicative of pronograde, quadrupedal locomotion characterized by reduced agility. All subfossil taxa exhibit adaptations emphasizing lumbar spinal stability (e.g., relatively short vertebral bodies, and transverse processes that are not oriented ventrally); we believe this probably reflects convergent mechanical demands connected to large body size, irrespective of specific locomotor mode. Reconstructions of positional behavior in subfossil lemurs based on lumbar vertebrae are largely consistent with those based on other aspects of the postcrania.

Full Text

Cited Authors

  • Shapiro, LJ; Seiffert, CVM; Godfrey, LR; Jungers, WL; Simons, EL; Randria, GFN

Published Date

  • December 2005

Published In

Volume / Issue

  • 128 / 4

Start / End Page

  • 823 - 839

PubMed ID

  • 16110476

Pubmed Central ID

  • 16110476

Electronic International Standard Serial Number (EISSN)

  • 1096-8644

International Standard Serial Number (ISSN)

  • 0002-9483

Digital Object Identifier (DOI)

  • 10.1002/ajpa.20122

Language

  • eng