Space dust in Chicxulub crater confirms that asteroid killed off dinosaurs

ScientiFix, our weekly feature, offers you a summary of the top global science stories of the week, with links to their sources.

Representational image of a dinosaur | Photo: Pxhere

Iridium in Chicxulub crater shows link between asteroid impact, dinosaur extinction

Scientists have found space dust in Chicxulub crater, which provides evidence that the asteroid impact and dinosaur extinction are “indisputably linked”.

Some 66 million years ago, dinosaurs on Earth were wiped out, and a growing body of researchers supports the theory that the main culprit was an asteroid impact in what is  present-day Mexico as against the theory that volcanism in Deccan traps wiped out life.

Researchers found a spike in concentrations of iridium in the layers atop the Chicxulub crater, which correspond to the time of the dinosaurs’ demise and similar deposits around the world.

Iridium is a metal that occurs in higher concentrations in meteorites, but only in low concentrations in Earth’s crust.

Though this space dust is present in low quantities all over Earth, the researchers found it is four times more concentrated in the Chicxulub impact crater than in the surrounding area. 

The findings, combined with the spike in worldwide iridium deposits at the time of the dinosaurs’ demise, constitutes indisputable evidence that the suspected dinosaur-killing asteroid that created the Chicxulub crater was indeed the culprit.

Teen T-rex may have outcompeted other dinosaurs 

Teenage Tyrannosaurus rex may have given other dinosaurs of the era a tough time, fundamentally re-shaping the diversity of the prehistoric predators.

The study demonstrated that the offspring of enormous carnivorous dinosaurs may have outcompeted smaller rival species.

Dinosaurs like T-rex were small at birth — about the size of a house cat — because they were born from eggs. This meant as they grew to the size of a city bus, they would have changed their hunting patterns and prey items. 

Paleontologists have always suspected that giant carnivorous dinosaurs would change behaviour as they grew. But how that affected the world around them remained largely unknown.

The researchers say that dinosaurs had surprisingly low diversity. 

On collecting data from well-known fossil localities from around the globe, including over 550 dinosaur species, what researchers found was a gap in communities that had ‘megatheropods’ — dinosaurs over 4,000 kg in weight, and 10 meters in length — and that very few carnivorous dinosaurs between 100-1,000 kg existed.

This research is important because it explains why dinosaur diversity was lower than expected based on other fossil groups. 

It also explains why there are many more very large species of dinosaurs than small, which is the opposite of what would be expected.

But most importantly, it demonstrates the results of growth from very small infants to very large adults in an ecosystem.

Elusive neutron star from 1987 supernova found

Back in 1987, a star exploded just outside our galaxy. But researchers have been searching for the squashed stellar core that should have been left behind — which had so far been obscured by the debris of the explosion.

NASA’s X-ray telescopes have now found clues to a neutron star, which formed after the supernova. 

When a star explodes, it collapses onto itself before the outer layers are blasted into space. What is left is a very dense remnant, which is a compact object that is either a black hole or a white dwarf of a neutron star. 

When the compressed remnant is an extraordinarily dense object, with the mass of the Sun squeezed into an object only about 10 miles across, it forms a neutron star. These are called so because they are made nearly exclusively of densely packed neutrons. They are laboratories of extreme physics that cannot be duplicated on Earth.

As the first supernova visible to the naked eye in about 400 years, Supernova 1987A (or SN 1987A for short) sparked great excitement among scientists and soon became one of the most studied objects in the sky. 

The supernova is located in the Large Magellanic Cloud, a small companion galaxy to our own Milky Way, only about 170,000 light-years from Earth.

Data from NASA’s Chandra X-ray Observatory and previously unpublished data from NASA’s Nuclear Spectroscopic Telescope Array, in combination with data from the ground-based Atacama Large Millimeter Array reported last year, now present an intriguing collection of evidence for the presence of the neutron star at the center of SN 1987A.

The researchers now predict that over the next few years the debris will clear, revealing the existence of the neutron star.

Lunar samples from NASA Apollo missions reveals the moon’s past 

Volcanic rock samples collected during NASA’s Apollo missions have the signature of key events in the early evolution of the moon.

By analysing these samples, researchers will be able to learn about how the Moon’s iron core formed, and what happened to the sea of molten rock that was believed to have covered the moon for around 100 million years after it formed.

The analysis used a technique called secondary ion mass spectrometry to study volcanic glasses returned from the Apollo 15 and 17 missions, which are thought to represent some of the most primitive volcanic material on the moon. 

This study looked at 67 individual volcanic glass samples and their melt inclusions, which are tiny blobs of molten lava trapped within crystals inside the glass. 

Melt inclusions capture the lava before sulphur and other volatile elements are released as gas during eruption. They offer a pristine picture of what the original source lava was like. 

In a way, these are like little time capsules capturing the lunar past.

Red light boosts sexual activity in moths

Dim red light boosts sexual activity in yellow peach moths — which is a model organism or one that is studied extensively.

It turns out that a genetic pathway in the antennae ultimately makes males more sensitive to the odor of the female sex pheromone in red light and thus more motivated to mate.

The researchers speculate that the relatively long wavelength of red light enables it to enter tissues and cells, and stimulates the expression of certain genes.

The scientists propose that this finding could potentially help to boost reproduction in at-risk species, or species that are economically important.