Where's the glass? Biomarkers, molecular clocks, and microRNAs suggest a 200‐Myr missing Precambrian fossil record of siliceous sponge spicules

SPERLING, E. A.; ROBINSON, J. M.; PISANI, D.; PETERSON, K. J.

doi:10.1111/j.1472-4669.2009.00225.x

Where's the glass? Biomarkers, molecular clocks, and microRNAs suggest a 200‐Myr missing Precambrian fossil record of siliceous sponge spicules

The earliest evidence for animal life comes from the fossil record of 24‐isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are a…