Palaeontology 

About: Palaeontology is an academic journal published by Palaeontological Association. The journal publishes majorly in the area(s): Devonian & Ordovician. It has an ISSN identifier of 0031-0239. Over the lifetime, 2578 publications have been published receiving 74202 citations.

Disparity: morphological pattern and developmental context

Abstract: The distribution of organic forms is clumpy at any scale from populations to the highest taxonomic categ- ories, and whether considered within clades or within eco- systems. The fossil record provides little support for expectations that the morphological gaps between species or groups of species have increased through time as it might if the gaps were created by extinction of a more homogen- eous distribution of morphologies. As the quantitative assessments of morphology have replaced counts of higher taxa as a metric of morphological disparity, numerous stud- ies have demonstrated the rapid construction of morpho- space early in evolutionary radiations, and have emphasized the difference between taxonomic measures of morphologi- cal diversity and quantitative assessments of disparity. Other studies have evaluated changing patterns of disparity across mass extinctions, ecomorphological patterns and the pat- terns of convergence within ecological communities, while the development of theoretical morphology has greatly aided efforts to understand why some forms do not occur. A parallel, and until recently, largely separate research effort in evolutionary developmental biology has established that the developmental toolkit underlying the remarkable breadth of metazoan form is largely identical among Bilate- ria, and many components are shared among all metazoa. Underlying this concern with disparity is a question about temporal variation in the production of morphological innovations, a debate over the relative significance of the generation of new morphologies vs. differential probabili- ties of their successful introduction, and the relative importance of constraint, convergence and contingency in the evolution of form.

Autecology and the filling of ecospace: key metazoan radiations

Abstract: All possible combinations of six tiering positions in relation to the substratum/water interface, six motility levels and six feeding strategies define a complete theoretical ecospace of 216 potential modes of life for marine animals. The number of modes of life actually utilized specifies realized ecospace. Owing to constraints of effectiveness and efficiency the modern marine fauna utilizes only about half the potential number of modes of life, two-thirds of which (62 of 92) are utilized by animals with readily preserved, mineralized hard parts. Realized ecospace has increased markedly since the early evolution of animal ecosystems. The Ediacaran fauna utilized at most 12 modes of life, with just two practised by skeletal organisms. A total of 30 modes of life are recorded in the Early and Middle Cambrian, 19 of which were utilized by skeletal organisms. The other 11 are documented from soft-bodied animals preserved in the Chengjiang and Burgess Shale Konservat-Lagerstatten. The number of modes of life utilized by skeletal organisms increased by more than 50 per cent during the Ordovician radiation to a Late Ordovician total of 30. Between the Late Ordovician and the Recent the number of utilized modes of life has doubled again. The autecological and taxonomic diversity histories of the marine metazoa appear to be broadly parallel, and future studies of theoretical ecospace utilization should provide more detailed tests of pattern and process in the ecological history of the metazoa.