Bone histological correlates of soaring and high-frequency flapping flight in the furculae of birds

Abstract

The furcula is a specialized bone in birds involved in flight function. Its morphology has been shown to reflect different flight styles from soaring/gliding birds, subaqueous flight to high-frequency flapping flyers. The strain experienced by furculae can vary depending on flight type. Bone remodeling is a response to damage incurred from different strain magnitudes and types. In this study, we tested whether a bone microstructural feature, namely Haversian bone density, differs in birds with different flight styles, and reassessed previous work using phylogenetic comparative methods that assume an evolutionary model with additional taxa. We show that soaring birds have higher Haversian bone densities than birds with a flapping style of flight. This result is probably linked to the fact that the furculae of soaring birds provide less protraction force and more depression force than furculae of birds showing other kinds of flight. The whole bone area is another explanatory factor, which confirms the fact that size is an important consideration in Haversian bone development. All birds, however, display Haversian bone development in their furculae, and other factors like age could be affecting the response of Haversian bone development.

Dinosaur paleohistology: review, trends and new avenues of investigation

“…Skeletal tissues can shed light on cranial biomechanics and function. Although some functional aspects of the postcranium in both fossil and extant archosaurs have been investigated using histology (De Ricqlès et al, 2000; Ponton et al, 2007; Zhao et al, 2013; Cubo et al, 2015; Tsai & Holliday, 2015; Mitchell et al, 2017), in comparison, very few functional histological studies on cranial elements exist. Histological analyses of cranial skeletal tissues conducted to reconstruct skull biomechanics are still in their infancy, but they have the potential to be highly informative.…”

Bone cortical compactness in ‘tree sloths’ reflects convergent evolution

“…; Mitchell et al. ), and it is thus of high interest to explore and compare this microanatomical feature of tetrapod long bones. The extent and pattern of distribution of Haversian tissue has hence been investigated in various clades, e.g.…”

“…The cortex of long bones of adult (non-osteoporotic) mammals usually feature a compact structure, comprising the socalled compacta, or compact bone, with relatively few resorption cavities and immature secondary osteons (Amprino & Godina, 1947;Francillon-Vieillot et al 1990;Cambra-Moo et al 2014;Mitchell, 2016). Investigation of bone remodeling can yield ecological, functional, and phylogenetic information (Cubo et al 2005;Mitchell et al 2017), and it is thus of high interest to explore and compare this microanatomical feature of tetrapod long bones. The extent and pattern of distribution of Haversian tissue has hence been investigated in various clades, e.g.…”

“…The extent and pattern of distribution of Haversian tissue has hence been investigated in various clades, e.g. in relation to locomotion in primates (Schaffler & Burr, 1984) and birds (Ponton et al 2007;Mitchell et al 2017), and more generally in relation to lifestyle (Mitchell, 2016).…”

Does bone preparation impact its shape: consequences for comparative analyses of bone shape

“…Two types of functions in scapular girdle of birds were identified previously: (1) bones that need to resist the action of the muscles attached and that thus need to be robust and (2) bones that play a role of protection of the internal organs such as the heart and viscera. Both of these functions may also be related to bone flexibility, like the spring function of the furcula, which can absorb and return energy during the wingbeat (Goslow, Dial & Jenkins, 1989; Kardong, 2012; Mitchell et al, 2017).…”