Variation of the outer circumferential layer in the limb bones of birds

Fleur Ponton, Andrzej Elzanowski, Jacques Castanet, Anusuya Chinsamy, Emmanuel de Margerie, Armand de Ricqlès, Jorge Cubo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


The core of the limb bone cortex of mammals and birds is made of rapidly deposited, fibro-lamellar bone tissue (also present in non-avian theropods), which is usually surrounded by an avascular outer circumferential layer (OCL) of slowly deposited parallel-fibered bone. We present the first comparative allometric study of the relative OCL thickness (expressed as a fraction of the diaphyseal radius) in modern birds. Body size explains 79% of the OCL variation in thickness, which is inversely correlated with size, that is, shows negative allometry (slope -0.799). This may explain the apparent absence of OCL in the ratites. Since the OCL is deposited at the end of growth, we propose that its relative thickness probably correlates with the amount of slow, residual growth, which our results suggest to be on the average larger in small birds.

Original languageEnglish
Pages (from-to)137-140
Number of pages4
JournalActa Ornithologica
Issue number2
Publication statusPublished - Dec 2004
Externally publishedYes


  • Bone histology
  • Ossification
  • Periosteal bone
  • Phylogenetically independent contrasts
  • Postnatal growth
  • Skeleton


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