Bone surface texture as an ontogenetic indicator in long bones of the Canada goose Branta canadensis (Anseriformes: Anatidae)

Abstract

Growth series of femora, tibiotarsi, and humeri of the Canada goose Branta canadensis were examined to evaluate whether bone surface textures are reliable indicators of relative age and skeletal maturity in this taxon. The relationship between surface texture and skeletal maturity was analysed by comparing element texture types with both size-based and size-independent maturity estimates. A subsample of hindlimb elements was thin sectioned to observe histological structures underlying various surface textures. Three relative age classes of elements are identifiable based on surface texture. Juvenile and subadult bone textures have fibrous and/or porous areas on the bone shaft and are distinguished by the presence (in juveniles) or absence (in subadults) of coarse longitudinal striations in proximal and/or distal regions. Adult bone texture lacks surface porosity. Immature textures are caused by channels in fibrolamellar bone intersecting the bone surface; the presence or absence of striations is determined by channel orientation. Mature textures may be underlain by fibrolamellar bone with little to no surface exposure of channels, or by lamellar bone deposited after rapid growth ceases. The utility of the textural ageing method appears intimately related to the uninterrupted determinate growth regime of Branta . This suggests that bone surface textures may prove useful as skeletal maturity indicators in both modern and fossil taxa with similar growth regimes, but may not necessarily be reliable for taxa with interrupted and/or indeterminate growth.

Anomalously high variation in postnatal development is ancestral for dinosaurs but lost in birds

“…Because of missing data, many sequences were highly unresolved, and so this number of sequences is a lower bound for the amount of variation in the sample during life. OSA for the 10 femoral ontogenetic characters of C. bauri resulted in 82 developmental sequences ( In contrast, the extant birds possess low levels of intraspecific variation relative to early theropods, consistent with other studies (10,11). The OSA of 36 ontogenetic characters of B. canadensis returned 9 equally parsimonious developmental sequences ( …”

“…The avian taxa analyzed possessed an extremely low number of reconstructed developmental sequences, with the majority of specimens represented by semaphoronts on the modal sequences ( Fig. 3 A-C), and this level of variation is supported in other Aves (11). A. mississippiensis possessed a higher level of intraspecific variation than the birds, but this level was still at a far lower level than that of the early theropods analyzed (Fig.…”

“…Although a taphonomic study has not been undertaken on the M. rhodesiensis localities, the Coelophysis Quarry is thought to have undergone almost no time averaging and represents individuals buried in only one to two events (31), making the time and geographic averaging on the C. bauri sample potentially less than that of the sample of B. canadensis and M. gallopavo, the skeletons of which do not represent individuals from a single population but were collected from wild populations across Illinois and Wisconsin, over a period of several decades (reposited in the Field Museum of Natural History). The specimens comprising the femoral dataset of B. canadensis were collected from wild populations across several northeastern and mid-Atlantic states (11).…”

“…In addition to their extremely rapid rates of growth, avian ontogeny possesses a characteristically low level of morphological variation within a species relative to that of other reptiles. The majority of individuals in a given avian species undergoes the same morphological changes during ontogeny in the same order at similar body sizes (10,11), whereas their closest living relatives, crocodylians, possess higher variation (10,(12)(13)(14). How and when this feature of avian biology evolved is poorly constrained.…”

Preliminary observations on the bone microstructure, growth patterns, and life habits of some Triassic temnospondyls from India

“…Efforts were made to examine skeletal elements belonging to adult individuals only, and the adult stage was deduced from size-independent criteria such as welldeveloped muscle scars, ossification of the limb bones, and bone surface texture Tumarkin-Deratzian et al, 2006). This ontogenetic stage as deduced from morphological features was later verified from bone microstructure.…”