Although the scientific debate about its causes remains open (the impact of a meteorite in Chicxulub remains among the most feasible), there is more than enough fossil evidence about the so-called Cretaceous-Paleogene (K–Pg) mass extinction, which occurred a few years ago. 66 million years ago, which killed three-quarters of the plant and animal species on Earth, including the dinosaurs.
But, as is also known, some groups of small animals (including some mammals that were the ancestors of current humans) and plants survived the catastrophe and took evolutionary advantage of the situation. Understanding this process is not easy, if we take into account, for example, that one of the factors of the extinction of the dinosaurs was the long period of lack of light and its effects on the plants (food source) that is associated with this period now technically known as K-Pg.
A new study published in Biology Letters by researchers Jamie B. Thompson, from the University of Bath (United Kingdom), and Santiago Ramírez-Barahona, from the National Autonomous University of Mexico (Mexico), now shows some of the keys to understanding why angiosperm plants (the currently most abundant group of plants that produce flowers and fruits) escaped relatively unscathed from the mass extinction at the end of the Cretaceous. Some of these plants did not flower again but others became dominant in the plant kingdom.
The authors recall that there have been several mass extinctions in Earth’s history, the most famous being caused by the impact of an asteroid 66 million years ago, which profoundly changed the course of life on Earth. The Cretaceous-Paleogene (K-Pg) extinction eradicated at least 75% of all species on Earth, including dinosaurs, but until now it was unclear what kind of impact it had on flowering plants, Thompson and Ramírez say. -Barahona.
Plants do not have skeletons or exoskeletons like most animals, which means that fossils are relatively rare (difficult to find and study) compared to animals, making it difficult to understand the timeline of evolution based solely on of fossil evidence.
The authors of the new scientific research analyzed evolutionary or phylogenetic trees (a scheme that facilitates the understanding of evolutionary relationships between species) built from mutations in the DNA sequences of up to 73,000 living species of flowering plants (angiosperms).
In the study now presented, the authors used complex statistical methods, fitting “birth-death” models to estimate extinction rates over geological time.
While the fossil record shows that many of the species in this group disappeared, the lineages to which they belong, such as families and orders, survived long enough to flourish and then dominate numerous habitats.
Molecular clock evidence suggests that the vast majority of angiosperm families that exist today existed before the K-Pg event: species including the ancestors of orchids, magnolia, and mint shared the Earth with the dinosaurs.
Professor Thompson explained that, “after most species on Earth became extinct in K-Pg, angiosperms took advantage, similar to the way mammals took over after the dinosaurs, and “Now virtually all life on Earth is ecologically dependent on flowering plants.”
So what made them tough enough to survive despite being immobile and relying on the sun for energy?
Professor Ramírez-Barahona, for his part, highlights that “flowering plants have a remarkable capacity for adaptation: they use a variety of pollination and seed dispersal mechanisms, some have duplicated their complete genomes and others have developed new forms of photosynthesis “This ‘flower power’ is what makes them true survivors of the wild.”
