Paleozoic Herbaceous Lycopsids and the Beginnings of Extant Lycopodium Sens Lat. And Selaginella Sens. Lat.

High precision U–Pb zircon geochronology for Cenomanian Dakota Formation floras in Utah

“…We assign the specimen to Selaginella because it shows no vegetative characters that may be used to distinguish it from this extant genus. Precedent exists for the presence of this genus in the mid-Cretaceous; numerous examples have been found of Mesozoic and Paleozoic age on multiple continents (Watson, 1969;Ash, 1972;Thomas, 1992;Banks, 2009). Though many fossil species have been named in the genus, we do not attempt further identification, since only one sterile stem has thus far been recovered from the Westwater locality.…”

Evolution of Lycopodiaceae (Lycopsida): Estimating Divergence Times from rbcL Gene Sequences by Use of Nonparametric Rate Smoothing

“…Reviewing the fossil record of herbaceous lycopsids, Thomas (1992) suggested a crown group origin of extant Lycopodiaceae in the Late Carboniferous, but, counterintuitively, Skog and Hill (1992) concluded that much modern species diversity was of more recent origin (Late Jurassic-Cretaceous). This hypothesis is important because it suggests that extant species diversity has evolved in parallel with that in modern families of angiosperms and ferns (Skog and Hill, 1992).…”

Megaspore morphology in the Selaginellaceae in a phylogenetic context: A study of the megaspore surface and wall structure using scanning electron microscopy

“…Lycopods were, in spite of the low diversity seen today, an important part of the Carboniferous flora (Thomas, 1992(Thomas, , 1997, with the oldest fossil unequivocally assigned to the Selaginellaceae from the Visean epoch (333-350 million years ago; Rowe, 1988). The extant plants in the Selaginellaceae are herbaceous and found throughout the world, predominantly in the tropics, and have creeping to erect main stems.…”