Bone histology yields insights into the biology of Aepyornithidae (1 Viewer)

[Fred Ruhe]

Anusuya Chinsamy, Delphine Angst, Aurore Canoville, & Ursula B. Göhlich, in press.

Bone histology yields insights into the biology of the extinct elephant birds (Aepyornithidae) from Madagascar

Biological Journal of the Linnean Society. in press. doi:10.1093/biolinnean/blaa013

Abstract: https://academic.oup.com/biolinnean...nnean/blaa013/5815707?redirectedFrom=fulltext

Given that the biology of the recently extinct aepyornithids is poorly understood, we undertook a histological study of 29 skeletal elements of adult and juvenile specimens of Aepyornithidae, i.e. Aepyornis maximus, Aepyornis hildebrandti and Vorombe titan, in addition to a group of taxonomically unidentifiable juvenile Aepyornithiformes. Comparative analysis of the histology of the different skeletal elements showed that although the femur retained a good record of growth during early ontogeny, the tibiotarsus provided the best record of growth. Our data showed that, like other insular birds and their extant relative, the kiwi, Aepyornithidae experienced protracted growth. We also found that intracortical remodelling began early in ontogeny and continued throughout their lives, becoming more extensive throughout the compacta with age, albeit more restricted to the perimedullary region in the femora. We also deduced that the different skeletal elements experienced variable amounts of intracortical remodelling, which was most likely to be related to biomechanical constraints, size of the element and ontogenetic age. Additionally, we documented the occurrence of an unusual endosteal tissue within the large perimedullary erosional spaces of a femur of A. maximus. Overall, our study provided a lot of new information about the life history of these giant, recently extinct ratites.

Enjoy,

Fred

 

[Fred Ruhe]

Figure 1. A, B, femur, NHMW 2014/0238/0052, transverse section. A, a low-magnification image of the overall histology of the bone wall. Abbreviation: m, medullary cavity. B, higher magnification of the boxed part of the cortex in panel A, showing the inner and outer layers of bone tissue separated by a line of arrested growth (white arrows). Note that the inner layer, closest to the medullary cavity (m), comprises reticular fibrolamellar bone, whereas the outermost layer consists of more laminar bone tissue. C–G, tibiotarsus NHMW 2014/0238/0015, transverse section. C, low magnification, giving an overall view of the bone wall. Abbreviation: m, medullary cavity. D, higher magnification of the boxed region in panel C, showing the highly secondary reconstructed inner part of the bone wall, with many secondary osteons (arrowheads), and the outer region, with largely unremodelled fibrolamellar bone tissue interrupted by growth rings (arrows). E–G, different transverse sections of bone fragments of the tibiotarsus. E, the reticular fibrolamellar bone tissue interrupted by two narrow annuli (arrows). F, higher magnification, showing the fibrolamellar bone and a few secondary osteons (arrows). G, transverse section of a different shaft fragment, showing a more extensively remodelled cortex. Several large resorption cavities (arrows) are visible.

Fred