Important discovery of paleontologist Robert De Palma: the impact of the meteorite that triggered the mass extinction of the dinosaurs occurred in the spring
When we talk about the great extinction of the dinosaurs, we refer to a complex series of events that, about 66 million years ago, profoundly changed the appearance of the planet and the forms of life on Earth.
The great Cretaceous-Paleocene mass extinction wiped 75% of the then-living species from the face of the Earth, starting with a colossal event: the asteroid impact with our planet, at the small town Chicxulub, Mexico.
The K-T event
The asteroid impact was “only” the trigger of a long series of events that led to the great mass extinction: tsunamis, powerful volcanic eruptions and climatic upheavals are the basis of the complex series of events that caused the Cretaceous-Paleocene extinction.
This event led to the disappearance of 75% of Cretaceous animal and plant species, including non-avian dinosaurs and almost all reptiles, of which only the smaller species of turtles and crocodiles survived.
The hypothesis of the meteorite emerged in 1979, when the Nobel Prize winner for Physics Luis Álvarez, in the famous excavations of the Bottaccione gorge near Gubbio, identified the unusual presence of iridium, a common element in meteorites and very rare on Earth.
This hypothesis was accredited by numerous subsequent studies, including that of 2013 of paleontologist Robert De Palma, of the University of Berkeley, who discovered on the hills of Hell Creek, in North Dakota, the traces of a huge tsunami occurred as a result of the impact of Chicxulub.
The same De Palma, who is a true paleontology star, is leading the research team that recently published in Scientific Reports a study that appears to have identified another important feature of that series of events that began with the so-called K-T event and ended with the great Cretaceous-Paleocene mass extinction.
The impact occurred in the spring
The new study takes its cue from the analysis of the Tanis fossil site, within the Hell Creek Formation in North Dakota, to which Prof. De Palma himself gave his name.
“The data collected in the field, after a lot of hard work, have given us incredibly precise new details,” says De Palma, “not only about what happened at the Cretaceous-Paleocene boundary, but also exactly when the event happened.”
According to histological and histo-isotopic analyses of fish fossils “assembled following the impact,” the meteorite’s impact with Earth occurred during the warm season in the northern hemisphere.
The impact that caused the great mass extinction occurred between spring and summer, just after the breeding season of most species then living, including fish.
As De Palma reminds us, “the season plays an important role in many biological functions such as reproduction, food-gathering strategies, host-parasite interactions,” and the patterns adopted for raising young.
The season in which the tremendous impact that caused – followed by other disastrous events – the great dinosaur extinction occurred may have had an important impact on the harsh effects of the K-T event on terrestrial life. So defining the season in which the Chicxulub event occurred has been a critical issue in paleontology for years.
“The beauty of any great discovery like this,” says De Palma, “is the ability to give it back to the scientific community and the world at large.”