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

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 determine

Fish remains, mostly otoliths, from the non-marine early Miocene of Otago, New Zealand

Fish remains described from the early Miocene lacustrine Bannockburn Formation of Central Otago, New Zealand, consist of several thousand otoliths and one skeleton plus another disintegrated skull. One species, Mataichthys bictenatus Schwarzhans, Scofield, Tennyson, and T. Worthy gen. et sp. nov., an eleotrid, is established on a skeleton with otoliths in situ. The soft embedding rock and delicate, three−dimensionally preserved fish bones were studied by CT−scanning technology rather than physical preparation, except where needed to extract the otolith. Fourteen species of fishes are described, 12 new to science and two in open nomenclature, representing the families Galaxiidae (Galaxias angustiventris, G. bobmcdowalli, G. brevicauda, G. papilionis, G. parvirostris, G. tabidus), Retropinnidae (Prototroctes modestus, P. vertex), and Eleotridae (Mataichthys bictenatus, M. procerus, M. rhinoceros, M. taurinus). These findings prove that most of the current endemic New Zealand/southern Australia freshwater fish fauna was firmly established in New Zealand as early as 19–16 Ma ago. Most fish species indicate the presence of large fishes, in some cases larger than Recent species of related taxa, for instance in the eleotrid genus Mataichthys when compared to the extant Gobiomorphus. The finding of a few otoliths from marine fishes corroborates the age determination of the Bannockburn Formation as the Altonian stage of the New Zealand marine Tertiary stratigraphy.Werner Schwarzhans, R. Paul Scofield, Alan J.D. Tennyson, Jennifer P. Worthy, and Trevor H. Worth

Dinornis - An insular oddity, a taxonomic conundrum reviewed

The taxonomic history of the extinct moa genus Dinornis (Aves: Dinornithiformes) is reviewed. Until recently limb bone dimensions and island of origin (North or South) were the pre-eminent factors in species determination within the genus Dinornis due to the expectation that flightless birds on distinct landmasses could not be the same species. Recent morphological analyses applying modern concepts of biological variation reduced the number of acceptable taxa, but size remained of paramount importance in defining species boundaries. Recent analyses of mitochondrial and nuclear DNA have resulted in a radical new explanation of the size variation in Dinornis. Here we assess the new genetics-derived hypothesis of one species per island where the size variation seen in the morphometric data is due to reversed sexual dimorphism. Length data from main limb bones is analysed by region or site and demonstrates clear bimodality where averages for the male and female forms vary between regions/sites but move up or down in parallel. The regional datasets demonstrate that in the mid-late Holocene, birds were smallest in subalpine zones and montane forests and largest in low altitude and low rainfall regions such as Canterbury (in eastern South Island) and the Horowhenua coast north of Wellington in southern North Island

Ecology and environmental history, not just genetic diversity, brings important perspectives to defining species diversity — illustrated by moas

We examine whether mitochondrial DNA (mtDNA) data can be used by itself to identify species limits in the extinct New Zealand moa, an order of birds that for the past 150 years has been difficult to classify. We argue that generally it cannot, and that a range of historical population parameters need to be considered when interpreting genetic and morphological diversity. We use the moas Emeus, Dinornis and Megalapteryx (Aves: Dinornithiformes) as examples. These taxa had very divergent palaeoecological preferences, and their ranges were affected quite differently during the glacial - interglacial cycles of the Pleistocene. We show that mtDNA diversity and genetic distances within and between these moa species is directly related to predicted population sizes over the preceding glacial period, and the likely geological longevity of populations in different areas. The interaction of these factors has produced a wide range of intraspecific diversity within moa genera, which illustrates why a simple quantitative cutoff value for genetic distance cannot be used to define species limits in moa (and potentially other taxa)

Multiple occurrences of pathologies suggesting a common and severe bone infection in a population of the Australian Pleistocene giant, Genyornis newtoni (Aves, Dromornithidae)

First published: 15 December 2021Vertebrate fossils showing pathological lesions are incredibly rare, and even more so is the identification of an ailment affecting multiple individuals in a population. However, the unique Lake Callabonna fossil deposit of South Australia has produced several such fossils from a single species of giant bird. Examination of the Lake Callabonna fossils of Genyornis newtoni, an extinct Pleistocene dromornithid, representing at least 34 individuals, has resulted in the identification of six osseous pathologies. These lesions are typical of the bone infection osteomyelitis, and affect a sternum, a tarsometatarsus and four phalanges across four individuals. The identification and description of osteomyelitis in these bones is the first of its kind for extinct galloanseres. Optically stimulated luminescence dating of host deposits shows that these animals were mired in lakebed sediments ranging from 54.2 to 50.4 kyr in age, probably becoming entrapped during a protracted drought phase previously identified as beginning at c. 48 ka and which would have resulted in the lakebed becoming exposed. Additional pathologies are recognized in phalanges of two other dromornithids, Dromornis stirtoni and Ilbandornis woodburnei, from the Miocene Alcoota deposit of the Northern Territory that are also interpreted as drought associated. It is possible that drought-driven stress and consequent immunosuppressive effects may have contributed to the high frequency of lesions observed in the sampled birds.Phoebe L. McInerney, Lee J. Arnold, Carey Burke, Aaron B. Camens and Trevor H. Worth

A new extinct species of Polynesian sandpiper (Charadriiformes: Scolopacidae: Prosobonia) from Henderson Island, Pitcairn Group, and the phylogenetic relationships of Prosobonia

We describe a new species of Polynesian sandpiper from Henderson Island, Prosobonia sauli sp. nov., based on multiple Holocene fossil bones collected during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands (1991–92). Prosobonia sauli is the only species of Prosobonia to be described from bone accumulations and extends the record of known extinct Polynesian sandpipers to four. It is readily differentiated from the extant Tuamotu Sandpiper P. parvirostris in several features of the legs and bill, implying ecological adaptations to different environments. The geographically nearest Prosobonia populations to Henderson Island were found on Mangareva, where it is now extinct. A previous record of a species of Prosobonia from Tubuai, Austral Islands, is here shown to belong to the Sanderling Calidris alba. Our analyses of newly sequenced genetic data, which include the mitochondrial genomes of P. parvirostris and the extinct Tahiti Sandpiper P. leucoptera, confidently resolve the position of Prosobonia as sister-taxon to turnstones and calidrine sandpipers. We present a hypothesis for the timing of divergence between species of Prosobonia and other scolopacid lineages. Our results further provide a framework to interpret the evolution of sedentary lineages within the normally highly migratory Scolopacidae.Vanesa L De Pietri, Trevor H Worthy, R Paul Scofield, Theresa L Cole, Jamie R Wood, Kieren J Mitchell ... et al