Plant carbon balance, evolutionary innovation and extinction in land plants

Summary The plant fossil record was reviewed to highlight how consideration of plant carbon balance strengthens our understanding of various evolutionary innovation and extinction events. Following a brief physiological primer to carbon acquisition and allocation in C3‐plants, specific evolutionary events are discussed in connection with postulated carbon‐based mechanisms. Primary topics include: (i) the evolution of plants with the C4‐photosynthetic pathway; (ii) the surprising lack of plant extinctions during the Pleistocene (1.6 million years ago, Ma); (iii) the trend toward declining plant diversity and increasing rates of herbivory across the Palaeocene/Eocene transition (57–52 Ma); and (iv) megaherbivore extinctions at the end of the Pleistocene (10 thousand years ago, Ka). A framework is presented for testing hypotheses on the cause–effect relationships between global carbon cycling, plant carbon dynamics and the evolution of terrestrial ecosystems.