Fossil floral and fruit evidence for the evolution of unusual developmental characters in Fagales

Abstract

Flowers of many living Fagales exhibit unusual developmental characteristics. At anthesis, ovulate flowers have carpels bearing immature orthotropous ovules. After pollination, the ovules increase in size and become anatropous and the ovary enlarges. Simultaneously, the pollen tubes extend from the stigma to the ovules with several phases of growth and quiescence. Finally, after the first fertilization, the remaining ovules abort, resulting in a single‐seeded fruit. Three‐dimensionally preserved potentially fagaceous mesofossil flowers from the Campanian of Massachusetts, USA, provide evidence on the evolution of these characters. The fossils share putative synapomorphies with the Fagales (six tepals, mostly inferior, three‐carpellate ovary with each locule initially containing two pendant ovules, punctate‐rugulate, tricolporate pollen and fruit with a single seed). However, the fossil is bisexual and has nectaries, characters shared with the sister order Cucurbitales, and both lack the fagalean immature orthotropous developmental stage. The fossil shares synapomorphies of an inferior ovary and a single‐seeded indehiscent fruit with both living orders and appears to be transitional. Comparison of ontogenetic changes between the fossil and related fagalean taxa suggests independent stepwise changes in development in which some characters of the modern clades were in place at ∼ 75 Myr and others evolved more recently. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168, 353–376.

Phylogenetic investigation of the complex evolutionary history of dispersal mode and diversification rates across living and fossil Fagales

“…). The basal placement of the remaining Cretaceous mesofossils was consistent with a previously performed family‐level phylogenetic analysis that included one such mesofossil (Taylor et al ., ). The topology of the calibrated total‐evidence phylogeny was consistent with phylogeny of Li et al .…”

A late Cretaceous fagalean inflorescence preserved in amber from New Jersey

“…The perianth of Soepadmoa additionally suggests that this early fagalean clade may have been entomophilous, with a well‐developed perianth, which was either reduced or lost in the various anemophilous fagalean clades that later arose. Along with charcoalified flowers and inflorescences of fagaceous affinity from the same locality (Crepet et al., ; Nixon, Gandolfo, and Crepet, in progress) and other localities (Taylor et al., ) that appear to have more derived features within the family, this inflorescence is the oldest unequivocal fossil evidence of stem Fagales and possibly represents an ancestral type for Fagaceae. The fossil, because of its unusual combination of features, favors the interpretation that primitive Fagales bore simple bracteose dichasia with lamellate cupules.…”

“…(), and Archaefagacea Takahashi et al. () and unnamed flowers (Taylor et al., ) based on charcoalified fossils have been described as belonging to the Fagales.…”

A botanical Christmas stocking

“…For example, Pirie & Doyle () used fossils to date clades of Annonaceae, Edwards et al . () described a new group of Early Devonian dyad producing plants, Martínez, Artabe & Bodnar () described a new fossil cycad genus from Argentina, supporting the existence of a greater diversity of subfamily Encephalartoideae in South America during the Cretaceous, and Taylor, Hu & Tiffney () presented evidence from fossil flowers and fruits as the basis of some unusual developmental characters in Fagales. In this issue, Edwards, Axe & Honegger () revisit the Mid‐Palaeozoic Nematothallus W.H.Lang, on the basis of thallus reconstructions from new collections from the Welsh borders and Barral et al .…”