title: Morphological and developmental macroevolution: a paleontological perspective.
abstract: Evidence of the morphological evolution of metazoans has been preserved, in varying degrees of completeness, in the fossil record of the last 600 million years. Although extinction has been incessant at lower taxonomic levels, genomic comparisons among surviving members of higher taxa suggest that much of the developmental systems that pattern their bodyplans has been conserved from early in their history. Comparisons between the origin of morphological disparity in the record and patterns of genomic disparity among living taxa promise to be interesting. For example, Hox cluster composition varies among major taxa, and the fossil record suggests that many of the changes in Hox clusters may have been associated with late Neoproterozoic evolution among minute benthic vermiform clades, from which crown bilaterian phyla arose just before or during the Cambrian explosion. Study of genomic differences among crown classes and orders whosetiming and mode of origin can be inferred from morphological data inthefossil record should throw further light on the timing and mode of origin of genomic disparities.
authors.affiliation: Center for Integrative Genomics and Department of Integrative Biology, University of California, Berkeley, California 94720, USA. jwvsossi@socrates.berkeley.edu
authors.forename: James W
authors.initials: JW
authors.lastname: Valentine
authors.forename: David
authors.initials: D
authors.lastname: Jablonski
mesh_terms: D000818:Animals; D019521:Body Patterning; D016000:Cluster Analysis; D019143:Evolution, Molecular; D005580:Fossils; D005786:Gene Expression Regulation; D005801:Genes, Homeobox; D014644:Genetic Variation; D016678:Genome; D007448:Invertebrates / Q000033:anatomy & histology* / Q000235:genetics; D010163:Paleontology