The evolution of long bone microstructure and lifestyle in lissamphibians

Abstract

The compactness profile of femoral cross-sections and body size of 105 specimens of 46 species of lissamphibians was studied to assess the effect of lifestyle (aquatic, amphibious, or ter restrial). Several tests that incorporate phylogenetic information (permutational multiple linear re gression incorporating phylogenetic distances, logistic regression using phylogenetic weighting, concentrated-changes tests) show that the return to a fully aquatic lifestyle is associated with an increase in the compactness of the femur and an increase in body size. However, amphibious taxa cannot be distinguished from terrestrial ones solely on the basis of size or compactness. Body size and compactness profile parameters of the femur exhibit a phylogenetic signal (i.e., closely related taxa tend to be more similar to each other than to distantly related taxa). Mathematical equations obtained from our data by using logistic regression with phylogenetic weighting are used to infer the lifestyle of four early stegocephalians. The results are generally congruent with prevailing paleontological interpretations, which suggests that this method could be applied to infer the lifestyle of early taxa whose lifestyle is poorly understood.

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

“…This finding, based on bone microstructure, contrasts with the skeletal designs of the trematosaurids and paracyclotosaurids (Schoch and Milner, 2000;Steyer, 2002). However, Laurin et al (2004) in a recent study on Paleozoic temnospondyls have shown that these animals were terrestrial, and were secondarily adapted to water. Moreover, Damiani et al (2000) and Damiani and Welman (2001) suggested that trematosaurids occupied varied ecological niches ranging from near shore regions to fluvial settings.…”

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

“…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.…”

Comparative limb bone loading in the humerus and femur of the tiger salamander Ambystoma tigrinum: testing the ‘mixed-chain’ hypothesis for skeletal safety factors

“…This shift may have made the evolution of long, tubular limb bone shafts advantageous compared with their blocky precursors (Currey, 2002). Microanatomical analyses of a wide range of tetrapods have differentiated aquatic and terrestrial lifestyles from limb bone histology (Laurin et al, 2011), facilitating the inference of the locomotor biomechanics of fossil taxa such as the Devonian fish Eusthenopteron (Laurin et al, 2007) and stem stegocephalians (Laurin et al, 2004). Identifying stronger form-function relationships between limb morphology and locomotor movements would facilitate efforts to reconstruct the transition from water to land by tetrapods (Nyakatura et al, 2014;Standen et al, 2014).…”