Complexity character scores for fossil and extant vascular plant reproductive structures

Morphological diversity and complexity are notable features of
multicellular life, although whether they evolve gradually or in early
bursts is unclear. Vascular plant reproductive structures, such as
flowers, are familiar examples of complicated morphology, and here we
analyze changes in complexity over time using a simple approach based on
the number of part types. We find that reproductive complexity increased
in two pulses separated by nearly 250 million years of stasis, including
an initial Devonian rise with the radiation of vascular plants and a
dramatic Late Cretaceous increase reflecting flowering plant
diversification. These pulses are associated with innovations that
increased functional diversity, suggesting that shifts in complexity are
linked to changes in function, regardless of whether they occur early or
late in the history of vascular plants.