The meteorite that caused the extinction of the dinosaurs 66 million years ago destroyed many more slow-growing evergreens than faster-growing deciduous trees.
This is the conclusion of a study from the University of Arizona, the results of which are published in the journal Plos Biology . Applying biomechanical formulas to a sample of thousands of fossil angiosperm leaves – plants that, except conifers, bear flowers – the team reconstructed the ecology of a diverse and prosperous plant community over a 2.2 million year period spanning the impact event that wiped out more than half of the botanical species living at that time.
According to the researchers, after the disaster, fast-growing deciduous angiosperms largely replaced their evergreen peers. Perennial angiosperms, such as holly and ivy, tend to prefer shade, do not grow much, and their leaves are dark in color.
” Today you don’t see many forests dominated by evergreen flowering plants . Most are deciduous species, plants that lose their leaves at some point in the year,” says the study’s lead author, Benjamin Blonder of the Department. of Ecology and Evolutionary Biology of the UA.
The study provides evidence that the impact that caused the extinction affected existing plant communities at the time . Although it was already known that the plant species that existed before the impact were different from those that came after, there was little data on whether the change in plant assemblages was just a random phenomenon or a direct result of the event.
For Blonder, “if you think of a mass extinction caused by a catastrophic event, such as a meteor hitting the Earth, it is possible to imagine that all species have the same probability of dying. The survival of the fittest does not apply , the Impact is like a reset button, however the alternative hypothesis is that some species have properties that allow them to survive.
Our study proves that there was a drastic change from slow versus fast growing plant species . This implies that the extinction was not random and that the way a plant acquires resources predicts how it can respond to a large disturbance, which is why modern forests are generally deciduous and not evergreen. “
