Microanatomy of the amniote femur and inference of lifestyle in limbed vertebrates

Abstract

The femoral microanatomy of 155 species of extant amniotes (57 species of mammals, 15 species of turtles, 56 species of lepidosaurs, and 27 species of birds) of known lifestyle is studied to demonstrate a possible link between some basic parameters of bone structure and specific lifestyles, as well as phylogenetic relationships between taxa. Squared change parsimony with random taxon reshuffling and pairwise comparisons reveal that most compactness and size parameters exhibit both phylogenetic and ecological signals. A discriminant analysis produces several inference models, including a ternary model (aquatic, amphibious, terrestrial) that yield the correct lifestyle in 88% of the cases. These models are used to infer the lifestyle of three extinct Permian temnospondyls: Eryops megacephalus, Acheloma dunni, and Trimerorhachis insignis. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 644–655.

Microstructural features of the femur in early ophiacodontids: A reappraisal of ancestral habitat use and lifestyle of amniotes

“…The value of parameter S (steepness of the transition between Min and Max) for Clepsydrops (0.012) is low, which reflects an abrupt transition between the cortex and the medulla and a fairly even thickness of the cortex. A low value of this parameter is typical of terrestrial and (to a lesser extent) amphibious taxa (supplementary on line Table 2 of Quémeneur et al, 2013). The S value for Ophiacodon (0.047), though clearly higher, remains inside the range (0.008 ≤ S ≤ 0.13) that characterizes the femur of terrestrial taxa (Quémeneur et al, 2013).…”

“…A low value of this parameter is typical of terrestrial and (to a lesser extent) amphibious taxa (supplementary on line Table 2 of Quémeneur et al, 2013). The S value for Ophiacodon (0.047), though clearly higher, remains inside the range (0.008 ≤ S ≤ 0.13) that characterizes the femur of terrestrial taxa (Quémeneur et al, 2013).…”

“…These data were then used to obtain inferences about the lifestyle of ophiacodontids using the ternary inference model based on the femur produced by Quémeneur et al (2013). This model requires data on snout-vent length (Supplementary On line Materials [SOM]).…”

“…However, long bone microanatomy of slightly more recent, Permo-Carboniferous stegocephalians, including amniotes, has started yielding clues about the lifestyle of the first amniotes (Canoville and Laurin, 2010;Germain and Laurin, 2005;Huttenlocker and Rega, 2012;Kriloff et al, 2008;Laurin et al, 2004;Quémeneur et al, 2013). Among Permo-Carboniferous amniotes, ophiacodontids are especially relevant to assess the primitive amniotic condition, for two reasons.…”

Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru

“…Inference models (using respectively the humerus [26], radius [27], tibia [28] and femur [29]) were tentatively applied to our data. Pilosans, which are currently not included in these models, were often incorrectly interpreted as aquatic or amphibious, owing to the high compactness generally displayed by their bones.…”