Angiosperms, or flowering plants, arose around 130 million years ago. Luckily, there’s no need to watch Jurassic Park to imagine what these plant species were like. Angiosperms are all around us even today, providing our vegetables, fruits, grains, and textiles like cotton, and account for about 80% of all living plants on Earth, critically maintaining our climate and atmosphere.
A major factor contributing to their terrestrial domination over these past millions of years is the characteristic angiosperm leaf. The veins of angiosperm leaves form complex networks that branch out across the leaf surface, efficiently transporting the water and nutrients needed to support photosynthesis within the entire plant. Despite being such a defining characteristic, the origin of angiosperm leaf venation has largely remained a mystery. It’s hard to answer questions like these with the few fossils we have of prehistoric plant life, and past studies have simply relied on comparison and contrast by eye to supplement educated guesses on species relation.
Recently, paleontologists at the University of Vienna studied the fossilized leaves of a plant called Furcula granulifer, the oldest fossil found to display a branching vein network similar to modern angiosperms, and thus thought to be an early member of the angiosperm lineage. Using microscopy and computerized analysis methods, they compared vein organization and cellular structure on the fossilized Furcula leaf to existing angiosperms. They observed key differences in vein density and surface pore shape which suggested Furcula wasn’t an angiosperm at all, but actually a kind of seed fern which developed a complex vein network over time in parallel with early angiosperm species, despite being unrelated. They concluded that Furcula’s extinction showed exactly what specific leaf vein traits made angiosperms so robust, allowing them to survive till this day.
As living organisms, we wouldn’t be here without the successes and failures of those that came before us, and that’s what evolution is all about. By looking more closely at these fossilized leaves, scientists can almost literally look into the past. Seeing where one extinct species failed clues us into the unseen advantages that make surviving species so successful. If we examine more fossils with these modern techniques, we could begin to trace the trials and errors of other plant groups, creating a map of the evolutionary changes that gave rise to the diverse flora of the world we see today.
These findings were unearthed by researchers in the Department of Palaeontology at the University of Vienna, led by postdoctoral fellow Mario Coiro.
Managing Correspondent: Maati McKinney
Press Article: Seed ferns experimented with complex leaf vein networks 201 million years ago, paleontologists find (Phys.org)
Original Journal Article: Parallel evolution of angiosperm-like venation in Peltaspermales: a reinvestigation of Furcula (New Phytologist)
Image Credit: Pixabay/Goumbik