Microanatomical diversity of the humerus and lifestyle in lissamphibians

Abstract

A study of body size and the compactness profile parameters of the humerus of 37 species of lissamphibians demonstrates a relationship between lifestyle (aquatic, amphibious or terrestrial) and bone microstructure. Multiple linear regressions and variance partitioning with Phylogenetic eigenVector Regressions reveal an ecological and a phylogenetic signal in some body size and compactness profile parameters. Linear discriminant analyses segregate the various lifestyles (aquatic vs. amphibious or terrestrial) with a success rate of up to 89.2%. The models built from data on the humerus discriminate aquatic taxa relatively well from the other taxa. However, like previous models built from data on the radius of amniotes or on the femur of lissamphibians, the new models do not discriminate amphibious taxa from terrestrial taxa on the basis of body size or compactness profile data. To make our inference method accessible, spreadsheets (see supplementary material on the website), which allow anyone to infer a lissamphibian lifestyle solely from body size and bone compactness parameters, were produced. No such easy implementation of habitat inference models is found in earlier papers on this topic.

Histological study of karaurids, the oldest known (stem) urodeles

“…Unfortunately, we could not apply the inference models that we proposed earlier (e.g. Canoville and Laurin 2009) to assess the habitat of our specimens because these models were based on adult individuals, and the sections described above appear to be from individuals that were still in an active phase of growth. They possibly had lifestyles similar to those of extant neotenic urodeles, such as cryptobranchids, sirenids, proteids or Amphiuma.…”

“…The fact that karaurid taxa (including the two sampled here) are neotenic and aquatic does not necessarily imply that this is primitive for Caudata because the fossil record is known to be strongly biased towards aquatic taxa (Shipman 1981). The individuals of Marmorerpeton sampled here, as well as 'salamander A', were probably aquatic because a great compactness (absence of a free medullary cavity) and the presence of multiple resorption cavities in long bones is a characteristic of aquatic lissamphibians (Laurin et al 2004Canoville and Laurin 2009). Unfortunately, we could not apply the inference models that we proposed earlier (e.g.…”

Evolution of bone compactness in extant and extinct moles (Talpidae): exploring humeral microstructure in small fossorial mammals

“…The humerus was sampled because of its abundance and easy recognition in the fossil record as well as its relatively simple bone growth pattern and morphology, with the mid-diaphyseal region yielding the strongest ecological signal (Figure 2) [17,19,20,37]. Bones were photographed prior to preparation following standard petrographic preparation techniques [38,39].…”

Emerging onto a Tangled Bank

“…Similarly, the operations of a particular physical device (or process) on an arbitrary state can be measured by process tomography (4,5), as can the action of a measuring device, by detector tomography (6,7). Once the quantum state has been determined, all the properties of the system, including its entanglement, can be computed (8). This approach, however, requires a data set that grows exponentially with the number of subsystems.…”

“…Quantitative study is needed to evaluate these qualitative scenarios; comparative research that draws on living animals in addition to fossils provides a template for future work (7,8).…”