Axios

A cataclysmic asteroid strike 66 million years ago off the Yucatán Peninsula changed tropical forests in distinct ways revealed in extensive new fossil evidence.

Why it matters: The new study may help to determine how the tropical forests of South America — contributors to the global climate, rich with species and a lifeline for tens of millions of people — emerged and how they may be shaped by the pressures of climate change today.

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America is in a race to vaccinate people before the country is overwhelmed by variants that are spurring a fourth wave of COVID-19.

Why it matters: Spring is here, and when cases were dropping, hope was rising for a more normal summer. But experts warn this will only happen if people keep social distancing, wearing masks and getting vaccinated as soon as they can.

Americans are worried about the rapid spread of COVID-19 variants, and are still willing to take safety precautions as a result, according to new Harris Poll data.

Why it matters: Despite the race to vaccinate as many people as possible, the variants are fueling another surge in cases across the U.S.

On the eve of the MLB regular season's start, Washington Nationals general manager Mike Rizzo announced a player has tested positive for COVID-19, and four teammates and a staffer are in quarantine.

Why it matters: Major League Baseball is still reeling from the impact of the coronavirus last season, when sponsor revenue plummeted by up to 60% and players' salary also fell, as the pandemic shortened the season.

Former Alaska Gov. Sarah Palin (R) urged Americans to "use common sense to avoid spreading" COVID-19, including wearing masks, as she told People Magazine Wednesday that she previously tested positive for the virus.

Why it matters: The influential conservative firebrand and 2008 Republican vice presidential nominee's comments come at a time when some GOP lawmakers have gone against health officials' guidance on face coverings and other suggested precautions.

Frog cells can gather together on their own to create tiny living moving robots.

The big picture: Researchers are trying to build soft robots, biodegradable ones and even living versions in hopes of using the machines in hard-to-access disaster zones, within the human body to deliver medicine and for environmental cleanup.