Editing Monocotyledon (section)

==== Molecular clock estimates  ====

[[Kåre Bremer]], using [[RuBisCO large subunit|rbcL]] sequences and the [[Network science|mean path length method]] for estimating [[genetic divergence|divergence times]], estimated the age of the monocot crown group (i.e. the time at which the ancestor of today's ''Acorus'' diverged from the rest of the group) as 134 million years.{{sfn|Bremer|2000}}{{sfn|Bremer|2002}} Similarly, Wikström ''et al.'',{{sfn|Wikström|Savolainen|Chase|2001}} using Sanderson's [[Robust statistics|non-parametric rate smoothing approach]],{{sfn|Sanderson|1997}} obtained ages of 127–141 million years for the crown group of monocots.{{sfn|Sanderson et al|2004}} All these estimates have large error ranges (usually 15-20%), and Wikström ''et al.'' used only a single calibration point,{{sfn|Wikström|Savolainen|Chase|2001}} namely the split between [[Fagales]] and [[Cucurbitales]], which was set to 84&nbsp;Ma, in the late [[Santonian]] period. Early molecular clock studies using strict clock models had estimated the monocot crown age to 200 ± 20 million years ago{{sfn|Savard et al|1994}} or 160 ± 16 million years,{{sfn|Goremykin|Hansman|Martin|1997}} while studies using relaxed clocks have obtained 135-131 million years{{sfn|Leebens-Mack et al|2005}} or 133.8 to 124 million years.{{sfn|Moore et al|2007}} Bremer's estimate of 134 million years{{sfn|Bremer|2000}} has been used as a secondary calibration point in other analyses.{{sfn|Janssen|Bremer|2004}} Some estimates place the diversification of the monocots as far back as 150&nbsp;mya in the [[Jurassic]] period.{{sfn|Zeng et al|2014}}

The lineage that led to monocots (stem group) split from other plants about 136 million years ago{{sfn|Magallon|Gomez-Acevedo|Sanchez-Reyes|Tania Hernandez-Hernandez|2015}} or 165-170 million years ago.{{sfn|Zeng et al|2014}}