Ontogeny of Surface Texture of Limb Bones in Modern Aquatic Birds and Applicability of Textural Ageing

Abstract

Despite its importance in various disciplines, a general method to assess ontogenetic ages of skeletal and fossil specimens has been lacking for birds. Although the textural ageing method was formulated to assess relative ontogenetic ages of specimens from inspection of bone surface textures, the exact correspondence of surface textures to ontogenetic stages has not yet been clear. In this study, bone surface textures of six major limb bones (humerus, ulna, carpometacarpus, femur, tibiotarsus, and tarsometatarsus) were described in postnatal ontogenies of four species of modern birds (Calonectris leucomelas, Phalacrocorax capillatus, Larus crassirostris, and Cerorhinca monocerata) from 14 to 28 individuals of known ontogenetic stages for each species. Consistently with the previous postulation, it was found that bones of chicks were characterized by rough surface textures with numerous grooves/depressions that host minute foramina. Bones of fledglings/juveniles, which are generally as large as those of adults but more slender, were characterized by the occasional presence of depressions and foramina. Histological observations confirmed that these rough surface textures were underlain by fibrolamellar bone tissue which is associated with active periosteal ossification. These results indicate that the smooth surface texture in adults is formed after the cessation of circumferential bone growth, which probably takes place between fledging and the attainment of sexual maturity. The available evidence suggests that the textural ageing is probably applicable to the entire Neognathae, a clade containing most crown-group birds. Anat Rec, 301:1026-1045, 2018. © 2017 Wiley Periodicals, Inc.

Clade‐specific evolutionary diversification along ontogenetic major axes in avian limb skeleton

“…Only skeletally mature individuals, as assessed by inspection of surface textures of long bones (Tumarkin‐Deratzian et al. ; Watanabe and Matsuoka ; Watanabe ), were included in the calculation of species means. For the purpose of this study, it is notable that a smooth surface texture on a long bone is almost exclusively seen after the cessation of longitudinal and circumferential bone growth in birds (Watanabe ).…”

“…; Watanabe and Matsuoka ; Watanabe ), were included in the calculation of species means. For the purpose of this study, it is notable that a smooth surface texture on a long bone is almost exclusively seen after the cessation of longitudinal and circumferential bone growth in birds (Watanabe ). In calculating species means, collection localities and sexes were pooled, except where prominent size variation of body size is known among subspecies (e.g., in Branta canadensis – hutchinsi complex).…”

Pleistocene fossils from Japan show that the recently extinct Spectacled Cormorant (Phalacrocorax perspicillatus) was a relict

“…All specimens described here are now formally deposited at NSMT PV. All the limb bones described are skeletally mature, as confirmed by the smooth surface texture that is observed after the cessation of active bone growth (Tumarkin-Deratzian et al 2006, Watanabe and Matsuoka 2013, Watanabe 2018.…”

“…However, changes in oceanographic conditions in the subsequent Last Glacial Maximum resulted in a drop of oceanic productivity (Kuroyanagi et al 2006, Minoshima et al 2007, Matsuzaki et al 2014, which would have seriously affected the population of P. perspicillatus in this area. The effect of this event may not be limited to this species; other unique components of the Shiriya paleoavifauna, including a flightless duck (Shiriyanetta hasegawai) and a large murre (Uria onoi), became extinct since the Late Pleistocene (Watanabe andMatsuoka 2015, Watanabe et al 2016). Although this is an admittedly simplistic scenario that needs further evaluation, it is conceivable that such local oceanographic changes have affected population dynamics of such large-bodied, and hence slowly breeding, seabirds in many local communities worldwide since the Late Pleistocene.…”

“…The cormorant fossils co-occur with various vertebrate remains, including land and marine mammals, birds, amphibians, and fish (Hasegawa et al 1988). The avian material is currently under revision by the authors (Watanabe andMatsuoka 2015, Watanabe et al 2016).…”