![]() We review how these peculiarities shape fossil inclusion in bryophyte systematics. Bryophytes present a special case: deep evolutionary history but sparse fossil record and phenotypic diversity encompassing small dimensional scales. Current consensus in evolutionary biology emphasizes fossil integration in total-evidence analyses, requiring in-depth understanding of fossils - age, phenotypes, systematic affinities - and a detailed morphological framework uniting fossil and extant taxa. #Sylvain sagequoia timing update#Instead, we sample its products - phenotypes, genotypes - to generate phylogenetic hypotheses, which we sequentially reassess and update against new data. The staggering duration and complexity of evolution, coupled with loss of information (extinction), render exhaustive reconstruction of the evolutionary history of life unattainable. ![]() Systematics reconstructs tempo and mode in biological evolution by resolving the phylogenetic fabric of biodiversity. To illustrate these methods, we analyze three‐dimensional human face shape based on data from the Avon Longitudinal Study of Parents and Children (ALSPAC). We outline promising directions for further research and for the evaluation of new developments, such as “landmark‐free” approaches. We focus on recent developments and current methodological challenges, especially those arising from the increasing number of landmarks and semilandmarks, and emphasize the importance of thorough exploratory multivariate analyses rather than single scalar summary statistics. Here we review the building blocks of modern geometric morphometrics: the representation of organismal geometry by landmarks and semilandmarks, the computation of shape or form variables via superimposition, the visualization of statistical results as actual shapes or forms, the decomposition of shape variation into symmetric and asymmetric components and into different spatial scales, the interpretation of various geometries in shape or form space, and models of the association between shape or form and other variables, such as environmental, genetic, or behavioral data. What has remained as a central thrust and source of debate in the morphometrics community is the shared goal of meaningful biological inference through a tight connection between biological theory, measurement, multivariate biostatistics, and geometry. The foundations of geometric morphometrics were worked out about 30 years ago and have continually been refined and extended. ![]() The importance of trends, extinction, and chance as factors in the evolution of disparity remains relatively underexplored and needs more attention. There have also been increasing efforts to identify the determinants of disparity, from developmental to functional and ecological considerations, leading to conceptual extensions such as allometric disparity. Currently, active areas of methodological development focus on characterizing the geometric properties of morphospaces, devising indices that describe the structure of disparity, and incorporating phylogenetic information. ![]() Disparity studies have led to improved understanding of the evolutionary history of major clades and fostered new research on adaptive radiations, rates of evolution, and morphological innovation. ![]() This unique focus on the morphological component of clade dynamics has promoted disparity as a distinct measure of biodiversity complementing traditional taxonomic proxies. Two main classes of indices are routinely used to describe the distribution of taxa in morphospace in terms of their spread and spacing. Its quantification is based on the construction and exploration of morphospaces, multidimensional spaces spanned by a set of morphological descriptors, and benefits from a well-established analytical protocol. Morphological disparity, the measure of morphological variation among species and higher taxa, has been at the core of an important research program in paleobiology over the last 25 years. ![]()
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