Practice question

Molecular clocks calibrated with fossils, cryptospore fossils and early macrofossils place earliest embryophytes in mid Ordovician to early Silurian, approximately 470 million years ago, long after Cyanobacteria origin. Evidence includes tetrahedral cryptospore tetrads and dyads with sporopollenin walls from Oman, Argentina and China deposits, plus liverwort-like cuticle fragments and thalloid compressions. Vascular plants appeared later near 430 million years ago. This timeframe predates Devonian forests and far exceeds 100 million years which corresponds to angiosperm radiation. Three point two billion and one billion correspond to prokaryotic and early eukaryotic algal evolution.