70 Ma nonmarine diatoms from northern Mexico

Biomineralization and Evolutionary History

“…Uncertainty plagues Rothpletz' (1896) report of diatoms in Middle Jurassic rocks, but unambiguous frustules occur in Lower Cretaceous marine rocks from many localities (Harwood and Nikolaev 1995). By late in the Cretaceous Period the group had both radiated in the oceans (Harwood and Nikolaev 1995) and colonized non-marine environments (Chacón-Baca et al 2002). The fossil record suggests that diatom diversity has continued to expand up to the present (Barron 1993).…”

Life cycle of 70 Ma-old non-marine pennate diatoms

“…The chert is present within a thin (<150 m) sedimentary deposit of the volcano-sedimentary Tarahumara Formation, which has an overall NNWeSSE configuration across east-central Sonora (Gonzalez-Leon et al, 2011). The age of this locality has not been dated directly but is thought to be 70 ± 2 Ma (Chacon-Baca et al, 2002), based on its biostratigraphic correlation with the isotopically-dated Cerro El Obispo (McDowell et al, 2001), located to the South of the Huepac Chert.…”

Rutilariaceae redefined: a review of fossil bipolar diatom genera with centrally positioned linking structures, with implications for the origin of pennate diatoms

“…Strelnikova, 1974;Hajo´s & Stradner, 1975;Chaco´n-Baca et al, 2002;Beraldi-Campesi et al, 2004;Sims et al, 2006;Witkowski et al, 2011a), complemented by molecular data (Sorhannus, 2007), show that a substantial diversity of pennate diatoms was present in both marine and non-marine habitats as early as the Late Cretaceous (Figs 74-82). At present, the oldest reliably dated occurrence of pennates is reported from Arctic Canada (Witkowski et al, 2011a), with a minimum age of 76 myr.…”