Asteroid impact theory challenged

Approximately 66 million years ago, an asteroid 15 kilometers wide struck the Yucatán peninsula in Mexico, triggering a global catastrophe that led to the extinction of approximately 75 percent of all species on the planet, including all non-avian dinosaurs. Recent research suggests the asteroid may not have traveled to Earth alone.

New crater discovered off Africa

A study published in Science Advances in 2022 identified a potential crater nearly 8.5 kilometers wide off the coast of West Africa, named Nadir. The crater, which may have been formed by a space rock at least 400 meters wide, is believed to have been created around the same time as the Chicxulub crater in Mexico.

Impact could have worsened the catastrophe

The study's author, Veronica Bray, a planetary scientist at the University of Arizona, suggested that the impact of the object that created Nadir, while smaller than Chicxulub, could have worsened the global catastrophe that marked the end of the Cretaceous period. The object that created Nadir may have come from a single parent body that fractured into two before entering Earth's atmosphere and striking the ground 5,500 kilometers apart.

Crater found through seismic data

The potential crater was discovered accidentally by geologist Uisdean Nicholson from Heriot-Watt University in Edinburgh, who was studying the separation of South America from Africa. Using seismic data, Nicholson identified a structure that resembles an impact crater, with a depression surrounded by a rim and a prominent peak in the center.

Impact energy compared to modern estimates

Modeling suggests the crater was formed by a space rock about 400 meters wide traveling at nearly 70,000 kilometers per hour, releasing energy equivalent to 5,000 megatons of TNT. Researchers estimate the Nadir crater dates back to about 66 million years ago, similar to the Chicxulub impact.

Study may help understand future impacts

The study of the Nadir event could help understand the effects of future impacts on Earth. The size of the rock that would have crashed into Nadir is comparable to the asteroid Bennu, which has a 1 in 1,750 chance of hitting Earth over the next three centuries.

Nadir's role in the extinction remains unclear

The implications of the Nadir impact for the extinction of the dinosaurs remain uncertain. The energy released by the Nadir impact would have been overshadowed by the collision of the Chicxulub asteroid. However, it could have "added insult to injury" in an already devastated ecosystem, according to Bray.

Other impact clusters documented

Groups of comet or asteroid fragment impacts have been documented on Earth and other planets. For example, near where Jennifer Anderson lives in the American Midwest, a trio of craters dating back about 460 million years is associated with a potential collision in the asteroid belt that sent meteorites toward Earth.

Funding requested for further study

According to estimates, an impact the size of Nadir occurs approximately every 100,000 years. The authors of the study have requested emergency funding to drill into the Nadir formation and collect samples of the shocked, melted, and mixed rock of the crater, as well as the sediment layers above it.

Experts urge caution before conclusions

Gareth Collins, a planetary scientist specializing in impact craters at Imperial College London, noted that conclusions about the discovery cannot yet be drawn and that direct samples will be needed to determine the origin of the "crater" and more precise dates for the potential impact it would have caused.