The toads, which Tracy’s team calculated have been around since the time of the mammoths, were discovered in one small part of Nevada, a 760-acre oasis of hot springs in the Great Basin Desert.

An environmental group said Tuesday it had captured a "monster" toad the size of a small dog. IE 11 is not supported. For an optimal experience visit our site on another browser.

New research suggests Sonoran Desert toads went into steep decline after stories of their mind-bending chemical properties ...

A version of this article appears in print on , Section D, Page 2 of the New York edition with the headline: Small Leapers: This Toad Is So Tiny They Call It a Flea.