How asteroids can shape evolution

Like many of us, the Earth bears traces of ancient times. Our planet’s crust contains a collection of ancient craters that formed about 465 million years ago. Canals were created at a time when animals in the seas were taking on a wide range of new forms, building complex ecosystems from plankton to jawless fish to… Looks like a spaceship Filter feeders. At that time, these strange invertebrates may have been able to look up through shallow water at night and see the glow of Earth’s ring itself, which may have resembled Saturn’s ring.

Spotting the Milky Way on a clear night is amazing enough. I can’t help but feel jealous of the early fish and old crabs who may have seen the temporary land strip of spinning debris. This band, which Monash University planetary scientist Andrew Tomkins and colleagues argue exists in a new paper, may be the result of an asteroid passing by. Just close enough To our prehistoric planet, to be shattered into countless pieces. (Unlike Saturn’s ring, it wasn’t made up of much ice.) The small, iron-rich rocks remained in their orbit for a while, but — as my favorite new technical term put it — they “got out of their orbit” around the year 465. Millions of years ago, Some of them hit the ground. Although the ancient crater cluster is the only physical evidence that such a ring ever existed, it is likely that life on Earth recorded the geological marvel as well.

The new hypothesis of the existence of such an episode is still in its early stages, and not every episode remains proposed in our scientific vision of the past. Geologists previously suggested that Earth had a ring during the Eocene epoch 35.5 million years agoBut the idea was more about searching for a possible cause for ancient climate changes than about hard evidence from the rock record. Ordovician craters in Earth’s rocky record were likely created by another astronomical phenomenon, such as asteroid debris forming a miniature moon and then collapsing. Whatever happened, we know that an unusual event rained chunks of rock across the surface of our planet about 465 million years ago, and a bit of space made its way to Earth.

Assume that the source of those rocks was a ring, and follow the consequences of this debris field: When Earth bounced a ring around its center, this could have affected how sunlight reached the planet’s surface. The ring likely would have shaded the hemisphere that experiences winter, while slightly warming the summer in the other hemisphere, Tomkins and co-authors suggest. Huge amounts of dust from the asteroid and the impacts of smaller pieces may have affected sunlight and global climate as well, and may help explain why Earth turned into an ice house between 444 and 463 million years ago. As we know well from our current habit of converting an igloo climate into a greenhouse climate, a changing climate is having a major impact on life on our planet.

During the time when Earth may have gained and lost its ring, life was going through an amazing evolutionary phase. Paleontologists know this as the Great Ordovician Biodiversity Event. Think of it as a sequel to the more famous and earlier Cambrian explosion, which saw the rapid origin of many different types of animal bodies and groups of organisms in the seas. GOBE was an expansion of the period following those previous themes, as everything from algae to early shellfish and fish evolved into new forms and created ecosystems similar to what we see in today’s oceans. It was a gathering of what we would consider modern ocean ecosystems, a rich plankton base that allowed many other life forms to flourish.

Knowing the cause of GOBE is difficult if not impossible, since it is not Sim Earth We cannot simply re-run different scenarios to see what fits our hypothesis best. However, the Earth Ring and its climate consequences may have had a major impact on Earth life, and it was the sudden global shift that prompted life to evolve in different ways. Whether it was a ring, a mini-moon, or some other scenario, the sprinkling of our planet with space rocks may have created the conditions that formed what we consider “modern” oceans.

Half a century ago, such ideas were received by the scientific community as speculative at best and fanciful at worst. Evolution was usually seen as referring to terrestrial processes. (This is still the case, in most cases.) But today, we can think about how an impending asteroid and a possible orbit around the Earth might have affected life in the distant past because we know that space debris had a profound impact on life at another time. Long after the GOBE, about 66 million years ago, when Earth’s ecosystems were filled with organisms as diverse as the seas, a 6-mile-wide asteroid struck Earth at a place we now call Chicxulub, on the Yucatan Peninsula. The heat pulse from the impact’s falling debris wiped out virtually all non-avian dinosaurs on the planet within a day, and soot and dust filled with solar-reflecting compounds created a global winter that lasted at least three years. Not only did the world lose almost all of its dinosaurs; Flying pterosaurs, marine mosasaurs, and reef-building clams the size of a toilet seat were also lost, in addition to the mass extinction of mammals, lizards, birds, and even plankton. Only this yearPlanetary scientists have identified the asteroid as a carbonaceous chondrite, an iron-heavy chunk of rock left over from the formation of our solar system that was pulled onto a collision course with Earth in the most catastrophic million-to-one shot ever seen.

For all the devastation the space rock has caused, it has paved the way for a lot of other life forms. Without this asteroid, we would not be here or learn about the planet we now call home.

Primates were already present at the time the asteroid struck, in the northern hemisphere spring 66 million years ago. When they emerged from hiding in the wake of the first day and searched for food in the dark years that followed, the world changed radically. Angiosperms, or flowering plants, again grew faster and more densely than their previously ubiquitous conifer relatives had. The iron from the massive asteroid was distributed in dusty debris and fertilized soil across the planet, allowing Earth to host the asteroid. The first rainforests In the tropics. Without large dinosaurs to till plants and keep forests relatively open, plants grew densely into multi-level habitats that served as a crucible for mammal evolution. Here our ancestors, among many other life forms, found themselves in a world of dense, new habitats. Dinosaurs were out of the way, but competition for space and food between these tiny creatures pushed the remaining species into new forms. Had the asteroid missed or even struck a different place on the planet, the world would still have been covered in forests of monkey puzzle trees and resinous ginkgo trees, and a place where dinosaurs of all shapes and sizes spread. While mammals flourished Only in small size.

The evolution of life on Earth and what happens on our planet are often discussed. Life adapts to cooperation, competition, climate change and human impact. But Earth exists as part of the solar system, the galaxy and the universe too, and sometimes other parts of the universe come to visit us. The Earth is not an isolated terrarium, and life on it has been affected as much by shocks and near misses as by continental drift. We can’t answer why birds are the only dinosaurs still alive, or perhaps even how our oceans built their complex ecosystems, without talking about asteroids and their consequences. Speeding rocks have changed the course of life so unpredictably that it is often easier to write them off as a rare and unusual part of the story. We are beginning to see evidence otherwise. We owe our existence to an asteroid. Our story is tied more than 9 billion miles away to the outskirts of our solar system. It’s bittersweet, even the prospect of my existence due to a cold piece of rock that took away the dinosaurs I was hoping to see alive.