A scientific team has found in Colorado (USA) a collection of fossils that describe how after the great extinction that exterminated the dinosaurs, life recovered on Earth and the rise of mammals began, according to an article published in the journal Science.
"66 million years ago the course of life on Earth changed fundamentally," said Ian Miller, a paleo-botanist at Denver Nature and Science Museum (USA), who collaborated in the research with paleontologist Tyler Lyson.
A killer asteroid
A massive asteroid collided with Earth and destroyed ecosystems across the planet. "The collision caused the extinction of three out of four types of living organisms," Miller added. "While that was a really bad period for life on Earth, some ways survived, including some of our earliest ancestors."
All modern mammals, including humans, can trace their origins in those first survivors of the impact and "now we have fossils of animals and plants, we have an impressive record of the first million years after the extinction of dinosaurs, "Lyson said.
Change in research methods
For more than 100 years scientists have traveled the Corral cliffs in the central region of Colorado without finding too many fossils dating from the late Cretaceous and early tertiary periods, around the supposed impact of the asteroid. The discoveries that Science details today – and that are a matter of documentary "Rise of the Mammals" produced by NOVA-, resulted from a change in the method of paleontological research and research.
Traditionally, the paleontologists they have left in search of bones or bone fragments that are visible or can be extracted from the excavations, but in 2016 Lyson participated in an expedition in South Africa and saw the attention that scientists give to concretions.
The surprising result
In geology one concretion is the accumulation within a porous rock of substances transported in solution by the water that precipitate forming a mass in the substrate, normally of rounded forms. The core of a concretion can be organic matter, and "sometimes that organic core can be a bone," Lyson explained.
The breaking of these concretions found in the Colorado cliffs He showed an immense wealth of fossils of both animals and plants that present a detailed picture of the first millions of years of recovery, both of the environment and species, and of the dynamic relationship between plants, animals and the climate.
"We knew virtually nothing about this interval," said Lyson, "and suddenly, we found all these amazing fossils that correspond right to the center of this interval. "Since 2016, paleontologists have documented nearly 1,000 vertebrate fossils in the area, more than 6,000 plants and counted more than 37,000 pollen grains as part of this study.
. (tagsToTranslate) Science (t) United States