The world’s trees are in critical danger, with a staggering number of tree species teetering on the brink of extinction, according to a new global analysis released Monday. The decade-long ...

Mesonychids were part of an extinct group of mammals closely related to living hoofed mammals like horses, deer and cows. While mesonychids have been found in California and the Midwest, ...

The John Day mesonychid was initially mis-identified as Hemipsaladon grandis, another large predator that would have shared a range with the mesonychid. NPS Mesonychid are an extinct branch of ...

But it occurred in groups that have either gone extinct, such as a group of hoofed carnivores called the mesonychids, or which now have few species, such as the sloths.