Ossification sequence of the avian order anseriformes, with comparison to other precocial birds

Abstract

Ossification sequences are poorly known for most amniotes, and yet they represent an important source of morphogenetic, phylogenetic, and life history information. Here, the author describes the ossification sequences of three ducks, the Common Eider Somateria mollissima dresseri, the Pekin Duck Anas platyrhynchos, and the Muscovy Duck Cairina moschata. Sequence differences exist both within and among these species, but are generally minor. The Common Eider has the most ossified skeleton prior to hatching, contrary to what is expected in a subarctic migrant species. This may be attributed to a tradeoff between growth rate and locomotory performance. Growth rate is higher in hatchlings with more cartilaginous skeletons, but this may compromise locomotion. No major ossification sequence differences were observed in the craniofacial skeleton when compared with Galliformes, which suggests that the influence of adult morphology on ossification sequence might be relatively minor in many taxa. Galliformes and Anseriformes, while both highly ossified at hatching, differ in the location of their late-stage ossification centers. In Anseriformes, these are most often located in the appendicular skeleton, whereas in Galliformes they are in the thoracic region and form the ventilatory apparatus.

Insight into the early evolution of the avian sternum from juvenile enantiornithines

“…4c) possess lateral trabeculae of comparable morphology to living taxa where the process ossifies from the corporis (for example, Merula - Fig. 4e, Cairina) 5,8 . The morphology of the 'caudal trabeculae' in Cretaceous ornithothoracines, although similar in that they extend to approximately the caudal margin of the sternum and an intermediate pair is additionally present, also differ greatly; the ornithuromorph trabeculae extend to the same level and in some cases enclose fenestrae, whereas in enantiornithines the lateral trabeculae demarcate deep caudal embayments with the xiphoid process and the intermediate trabeculae are very short.…”

“…We also recognize that the developmental pathways that lead to a superficial morphotype may have changed through time and in clade-specific ways. Furthermore, a majority of recent research on living birds focuses on embryological development 4,5,[14][15][16][17][18] , which is poorly known for extinct taxa. However, a review of literature dating back over a century creates the basis for comparison with enantiornithines 5,6,8,13,14,16,19 .…”

Timing of Ossification in Duck, Quail, and Zebra Finch: lntraspecific Variation, Heterochronies, and Life History Evolution

“…Welten et al, 2005; Eames and Schneider, 2008; Kerney et al, 2010), to observations of morphogenetic movements of cranial neural crest cells (e.g., Olsson and Hanken, 1996; Vaglia and Smith, 2003; Tokita, 2006; Mitgutsch et al, 2008, 2009), to analyses of the temporal appearance of cartilaginous and skeletal elements. In particular, the temporal appearance of mineralized individual bones in a species – the ossification sequence of the species – has attracted much interest and the timing of the onset of ossification of skeletal elements has been investigated and analyzed in a wide variety of taxa throughout the Craniota, both extant and extinct, including teleosts, amphibians, sauropsids, and mammals (e.g., Trueb, 1985; Starck, 1989; Mabee and Trendler, 1996; Maisano, 2002a, b; Sánchez-Villagra, 2002; Rose, 2003; Sheil, 2003, 2005; Schoch, 2006; Fröbisch, 2008; Maxwell, 2008a, b, 2009; Maxwell and Harrison, 2008; Sánchez-Villagra, et al 2008, 2009; Weisbecker et al, 2008; Werneburg et al, 2009; Hugi et al, 2010; Maxwell et al, 2010; Weisbecker and Mitgutsch, 2010). …”

“…Although early developmental heterochronies could be shown in some cases to characterize certain higher clades and to coincide with certain specific life history modes or anatomical peculiarities of the corresponding adults (e.g., Vaglia and Smith, 2003; Tokita, 2006; Weisbecker et al, 2008), such connections are not always easy to make (e.g. Chipman et al, 2000; Maxwell, 2008b; Mitgutsch et al, 2008, 2009; Werneburg and Sánchez-Villagra, in press), suggesting that characteristics in embryonic timing should rather be seen in connection with embryonic anatomy and demands, rather than with those of temporally distant developmental stages (Mitgutsch et al, 2008, 2009). Comparative embryological studies covering different taxa and different character complexes have gathered increasing evidence for intraspecific and, even among closely related taxa, interspecific variability in timing of early embryogenic events (Mabee and Trendler, 1996; Chipman et al, 2000; Moore and Townsend, 2003; Sheil and Greenbaum, 2005; Mitgutsch et al, 2008, 2009; Wilson et al, 2010).…”

Cellular preservation of musculoskeletal specializations in the Cretaceous bird Confuciusornis

“…The ridge occurs at the position of the hypotarsus in ornithuromorph birds31, but it is less distinct and more cartilaginous compared with the latter structure, even with those seen in early ornithuromorph birds, such as the Late Cretaceous Patagopteryx, Pengornis , Yixianornis , Apsaravis and Ichthyornis , which have a flat bony projection or unprojected discrete surface without canals and sulci323334. In contrast, the ridge resembles an intermediate state of the hypotarsus in the ontogeny of extant birds, in which the hypotarsus remains cartilaginous until the latest stages or after hatching, when it ossifies from a separate centre located on its distal medial corner3536.…”