Study: First Flowering Plants Appeared in Jurassic Period or Even Earlier
Flowering plants (angiosperms) are the most diverse of all land plants, becoming abundant in the Cretaceous period (145 to 66 million years ago) and achieving dominance in the Cenozoic (66 million years ago-present). However, the exact timing of their origin remains a controversial topic. To resolve this discrepancy, a team of paleontologists from Europe and China estimated the ages of angiosperm families on the basis of the fossil record and their living diversity. Their results, published in the journal Nature Ecology & Evolution, support Charles Darwin’s hypothesis of a rapid Cretaceous diversification of angiosperms and indicate that several families originated in the Jurassic, strongly rejecting a Cretaceous origin for the group.
Ubiquitous across terrestrial and aquatic systems, angiosperms are the most diverse group of land plants on Earth today.
Fossil evidence indicates that angiosperms and their system group, gymnosperms, had already diverged by the Late Carboniferous epoch (306.2 million years ago).
The earliest-known fossil evidence of crown angiosperms dates to the Early Cretaceous epoch (135 million years ago), but the true time of their origin remains debated.
The sudden appearance of crown angiosperm fossils, apparently without forebears displaying evidence of the gradual assembly of the angiosperm body plan, was considered ‘an abominable mystery’ by Charles Darwin and his contemporaries.
“A diverse group of flowering plants had been living for a very long time shadowed by ferns and gymnosperms, which were dominating ancient ecosystems,” said Dr. Daniele Silvestro, a researcher at the University of Fribourg, the Swiss Institute of Bioinformatics, the University of Gothenburg, and the Gothenburg Global Biodiversity Centre.
“This reminds me of how modern mammals lived for a long time laying low in the age of dinosaurs, before becoming a dominant component of modern faunas.”
“While we do not expect our study to put an end to the debate about angiosperm origin, it does provide a strong motivation for what some consider a hunt for the snark — a Jurassic flowering plant,” added Professor Philip Donoghue, a researcher at the University of Bristol.
“Rather than a mythical artifact of genome-based analyses, Jurassic angiosperms are an expectation of our interpretation of the fossil record.”
The team’s conclusions are based on complex modeling using a large global database of fossil occurrences, which the team compiled from more than 700 publications.
These records, amounting to more than 15,000, included members of many groups of plants including representatives of palms, orchids, sunflowers, and peas.
“Scientific debate has long been polarized between paleontologists who estimate the antiquity of angiosperms based on the age of the oldest fossils, versus molecular biologists who use this information to calibrate molecular evolution to geologic time,” said Dr. Christine Bacon, a researcher at the University of Gothenburg and the Gothenburg Global Biodiversity Centre.
“Our study shows that these views are too simplistic; the fossil record has to be interpreted.”
“A literal reading of the fossil record cannot be used to estimate realistically the time of origin of a group. Instead, we had to develop new mathematical models and use computer simulations to solve this problem in a robust way.”
“Understanding when flowering plants went from being an insignificant group into becoming the cornerstone of most terrestrial ecosystems shows us that nature is dynamic,” said Professor Alexandre Antonelli, a researcher at the University of Gothenburg, the Gothenburg Global Biodiversity Centre, the Royal Botanic Gardens, Kew, and the University of Oxford.
“The devastating human impact on climate and biodiversity could mean that the successful species in the future will be very different to the ones we are accustomed to now.”
D. Silvestro et al. Fossil data support a pre-Cretaceous origin of flowering plants. Nat Ecol Evol, published online January 28, 2021; doi: 10.1038/s41559-020-01387-8