Reconstructing early sponge relationships by using the Burgess Shale fossil Eiffelia globosa , Walcott

• DOI: 10.1073/pnas.0405867102
• Publication Date: 2005-01-22T01:41:41Z
• Authors: Joseph P. Botting; Nicholas J. Butte...
• Keywords: Sponge; Taphonomy; Spicule; Lagerstätte

The relationships of the sponge classes are controversial, particularly between calcareous and siliceous sponges. Specimens putative calcarean Eiffelia globosa Walcott from Burgess Shale show presence diagnostic hexactinellid spicules integrated into skeletal mesh. arrangement these in is shown to be precisely equivalent that early protospongioid hexactinellids, growth occurred through an identical pattern produce body morphology. difference spicule composition interpreted observation taphonomic features suggest at least two mineralogically distinct layers within spicules. These results support molecular analyses identify calcarean-silicisponge transition as earliest major branch heteractinids were paraphyletic with respect Hexactinellida.