The architecture of cancellous bone in the hindlimb of moa (Aves: Dinornithiformes), with implications for stance and gait

Bishop, P.J., Scofield, R.P. & Hocknull, S.A. 6 May 2019. The architecture of cancellous bone in the hindlimb of moa (Aves: Dinornithiformes), with implications for stance and gait.. The architecture of cancellous bone in the hindlimb of moa (Aves: Dinornithiformes), with implications for stance and gait. Alcheringa XXX, X–X. ISSN 0311-5518.0311-5518.

P.J. Bishop* pbishop@rvc.ac.uk], Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hawkshead Lane, Hatfield AL9 7TA, UK; R.P. Scofield? pscofield@canterburymuseum.com], Canterbury Museum, Rolleston Avenue, Christchurch 8013, New Zealand; S.A. Hocknull? scott.hocknull@qm.qld.gov.au], Geosciences Program, Queensland Museum, 122 Gerler Road, Hendra, Queensland 4011, Australia. *Also affiliated with: Geosciences Program, Queensland Museum, 122 Gerler Road, Hendra, Queensland 4011, Australia. ?Also affiliated with: Department of Geological Sciences, University of Canterbury, Christchurch 8140, New Zealand. ?Also affiliated with: School of Biosciences, University of Melbourne, Royal Parade, Parkville, Victoria 3052, Australia.

The extinct, flightless moa of New Zealand included some of the largest birds to have existed and possessed many distinguishing pelvic and hindlimb osteological features. These features may have influenced stance and gait in moa compared with extant birds. One means of assessing locomotor biomechanics, particularly for extinct species, is quantitative analysis of the architecture of cancellous bone, since this architecture is adapted to suit its mechanical environment with high sensitivity. This study investigated the three-dimensional architecture of cancellous bone in the femur, tibiotarsus and fibula of three moa species: Dinornis robustus, Pachyornis elephantopus and Megalapteryx didinus. Using computed tomographic X-ray scanning and previously developed fabric analysis techniques, the spatial variation in cancellous bone fabric patterns in moa was found to be largely comparable with that previously reported for extant birds, particularly large species. Moa hence likely used postures and kinematics similar to those employed by large extant bird species, but this interpretation is tentative on account of relatively small sample sizes. A point of major difference between moa and extant birds concerns the diaphyses; cancellous bone invades the medullary cavity in both groups, but the invasion is far more extensive in moa. Combined with previous assessments of cortical geometry, this further paints a picture of at least some moa species possessing very robust limb bones, for which a convincing explanation remains to be determined