Macroevolutionary consequences of developmental mode in temnopleurid echinoids from the Tertiary of southern Australia.

Taxonomic revision and cladistic analysis of a morphological dataset for Australian Tertiary temnopleurids resolve the phylogeny of the group and allow the testing of a series of hypotheses about the evolution of larval development and consequences of changes in development. Australian Tertiary temnopleurids encompass all three major developmental types found in marine invertebrates (planktotrophy, lecithotrophy, and brooding). Planktotrophy is plesiomorphic for this clade, and nonplanktotrophic larval development evolved independently at least three times during the Tertiary.

Phylogeny and evolution of developmental mode in temnopleurid echinoids.

The phylogenetic relationships of 24 nominal species of temnopleurid echinoid were established using molecular and morphological data sets. The analysis combined sequence data from mitochondrial 16S rRNA and cytochrome c oxidase subunit I genes and the nuclear 18S-like small subunit rRNA gene with morphological data concerning coronal, lantern, spine, and pedicellarial traits. All four data sets contain similar phylogenetic information, although each provides support at a different taxonomic level.