(1) Geophysical Sciences, University of Chicago, Chicago, IL, USA, (2) Geological Sciences, University of Colorado, Boulder, Boulder, CO, USA, (3) University of Colorado, Boulder, Boulder, CO, USA, (4) Geological Sciences, University of Colorado, Boulder, Boulder, CO, USA, (5) Geologial Sciences, University of Colorado, Boulder, Boulder, CO, USA,
Abstract:
Evidence suggests sponge groups diverged in the Cryogenian, but their silicious spicule skeletons only appear in the fossil record after a hundred million year gap, a span termed the spicule gap. Due to their early branching position in animal phylogeny and the important role sponges play in regulating ocean chemistry through biomineralization and carbon burial, a taphonomically controlled global spicule gap would have major implications for the tempo and mode of changes to the Earth system as animals radiate. We find no evidence for a spicule gap. Rather, convergent evolution of siliceous spicules is likely as we find spicules evolved when they appear in the fossil record. Siliceous skeletons, consequently, also evolve at the same geological time as all other types of animal skeletons.
Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025