Researchers say they've identified the oldest known Tyrannosaurus, shaking up the ongoing debate over how and when the dinosaurs arrived in North America.

Are we in a surge? How would we know? Is winter now "COVID season?" And what do you do if your whole family got the coronavirus over the holidays? We tackle readers' coronavirus questions.

Researchers found roughly 240,000 detectable plastic fragments in a typical liter of bottled water. Most of them were nanoplastics — particles less than 1 micrometer in size.

Neptune has long been depicted as a deeper, darker blue than its fellow ice giant Uranus, but a new study shows that both are a similar shade of light greenish blue.

The Guinness World Record folks would have us believe in a 19th century snowflake more than a foot wide, but some scientists are skeptical.

A new study has examined the potential ramifications of declining an invitation for a social outing, and found that people tend to overestimate just how much it matters.

A new study showed that cats fetched objects instinctively, in the absence of overt training. Fetching is defined as when the animal retrieves an object that's thrown.

An experimental technology that might someday allow infertile couples, as well as gay and trans couples, to have genetically related children stirs hope. So far, the technique has worked in mice.

More scientific evidence has surfaced to show that while Mittens may be your sweet angel, letting her roam outside is also a big threat to biodiversity.

Zebra finches who did not sing every day quickly lose their vocal prowess, a new study finds. The results could potentially shed light on vocal rehabilitation for humans, too.

A new study shows male zebra finches must sing every day to keep their vocal muscles in shape. Females prefer the songs of males that did their daily vocal workout.

The wild honeyguide responds to distinct calls from local honey foragers. Says one researcher: The bird basically seems to be saying, "Hey, I'm here and I know where there's some honey, so follow me."

The Food and Drug Administration approved two genetic treatments for sickle cell disease, including one that uses gene-editing. The approvals offer hope for patients and signal a new medical era.

A newly discovered pathway between the heart and brain can cause fainting, at least in mice.

A small study found that electrically stimulating an area deep in the brain allowed people with severe traumatic brain injuries to complete a cognitive test more quickly.