The K-Pg extinction event wiped out more than 75 percent of all species on Earth, but its impact on flowering plants has been unclear.
The experts have discovered that, despite losing some species, major flowering plant lineages miraculously survived.
“At least five major mass extinction events have punctuated the history of life and have profoundly shaped the diversity and distribution of entire groups of organisms,” wrote the study authors.
“The most recent of these events was the Cretaceous–Paleogene mass extinction (K-Pg) that occurred approximately 66 million years ago (Mya) and is associated with the Chicxulub Impact Event. This event led to the demise of non-avian dinosaurs and high extinction rates of vertebrate species.”
“High-resolution fossil records suggest that, despite initial regional massive extinction of angiosperm species, most of their major extant lineages (i.e. orders, families) originated during the Cretaceous, survived the K-Pg event, and eventually recovered in diversity during the Paleocene.”
The fossil record is lacking when it comes to plants, as they do not have skeletons like animals. This makes it challenging to trace the timeline of their evolution.
To investigate, Dr. Jamie Thompson of the Milner Centre for Evolution and Dr. Santiago Ramírez-Barahona of Universidad Nacional Autónoma de México turned to MEGA phylogenetics.
“Assessing macroevolutionary dynamics of angiosperms using phylogenetic evidence could provide key insights into the impacts of K-Pg and how this event triggered the restructuring of all terrestrial biomes and the emergence of modern-day ecosystems,” wrote the researchers.
The team analyzed evolutionary trees constructed from the DNA sequences of up to 73,000 living species of flowering plants. They used statistical models to estimate the rates of extinction throughout geological time.
The phylogenetic evidence revealed that the major flowering plant lineages were resilient to the K-Pg event. While some species disappeared, their larger families survived and eventually became dominant. Flowering plants make up about 300,000 of 400,000 modern plant species.
According to the study, the vast majority of flowering plant families that we are living today existed before the K-Pg event. These families – including the ancestors of orchids, magnolia, and mint – all shared Earth with the dinosaurs.
“After most of Earth’s species became extinct at K-Pg, angiosperms took the advantage, similar to the way in which mammals took over after the dinosaurs, and now pretty much all life on Earth depends on flowering plants ecologically,” said Dr. Thompson.
It is incredible to consider that flowering plants were tough enough to survive such a devastating event despite being immobile and relying on the sun for energy.
“Flowering plants have a remarkable ability to adapt: they use a variety of seed-dispersal and pollination mechanisms, some have duplicated their entire genomes and others have evolved new ways to photosynthesize,” said Dr. Ramírez-Barahona. “This ‘flower power’ is what makes them nature’s true survivors.”
Around 66 million years ago, Earth faced one of the most devastating events in its history — the Cretaceous–Palaeogene (K-Pg) mass extinction.
This catastrophe extinguished nearly 75% of Earth’s species, including the iconic non-avian dinosaurs. The extinction marked a pivotal shift in Earth’s biological diversity, paving the way for mammals to rise as dominant terrestrial animals.
Researchers point to two primary culprits — a massive asteroid impact and prolonged volcanic activity.
Evidence suggests a 10-kilometer-wide asteroid struck what is now the Yucatán Peninsula in Mexico, creating the Chicxulub crater. This impact unleashed an enormous amount of energy, equivalent to billions of nuclear bombs. It set forests ablaze, triggered tsunamis, and threw tons of debris into the atmosphere.
This debris blocked sunlight, leading to a phenomenon called “impact winter.” With reduced sunlight, photosynthesis slowed, disrupting food chains and ecosystems.
Concurrently, in what is now India, the Deccan Traps underwent extensive volcanic activity. These eruptions spewed vast quantities of lava and also released gases like sulfur dioxide and carbon dioxide.
These gases, when in the atmosphere, can contribute to both cooling (sulfur dioxide) and warming (carbon dioxide). Such dramatic shifts in temperature and atmospheric composition further stressed global ecosystems.
The K-Pg event’s impact on life was profound. Ocean ecosystems underwent a significant overhaul as many marine reptiles, like plesiosaurs and mosasaurs, vanished. The skies saw the disappearance of pterosaurs. On land, the non-avian dinosaurs, which had ruled for over 150 million years, came to an end.
However, with the demise of these giants, opportunities arose for other creatures. Mammals, which had previously lived in the shadows of the mighty dinosaurs, began to diversify and expand into niches left vacant. Birds, descendants of theropod dinosaurs, took to the skies in a more diverse array.
In summary, the Cretaceous–Paleogene mass extinction serves as a testament to the planet’s dynamic nature. It reminds us of the fragility of life and the interconnectedness of all living organisms.
While the event ended the reign of many species, it also provided opportunities for others to flourish. Today, as we look back at this crucial juncture in Earth’s history, we gain insights into the ever-evolving story of life on our planet.
The study is published in the journal Biology Letters.
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