10/21/2012 01:00 pm ET

Animal Photos Of The Week

In animal news this week, researchers announced that 25 primate species on three continents are "on the brink of extinction and need global action to protect them from increasing deforestation and illegal trafficking," reported the Associated Press. The report from the International Union for Conservation of Nature lists species of spider monkeys, lemurs, gorillas and other primates as severely threatened.

Some positive news came out of Colorado this week, when it was reported that "Stumpy," the three-legged tortoise was safely returned to his owner. Stumpy was "kidnapped" when "Wildman" Phil Rakoci's car was stolen from a Walmart parking lot in Englewood, Colorado. The tortoise, who uses a wheel to scoot around, "loves people," according to Rakoci. Stumpy, along with other creatures like a python and several tarantulas, are part of a traveling educational show for children.

A keeper at Sydney's Taronga Zoo was critically injured this week when an elephant calf crushed her against a fence post. AP reported that the woman was in "critical but stable" condition at Sydney hospital.

Scientists revealed this week that dolphins sleep with only half of their brains, while the other half remains alert and on the lookout for sharks. A marine biologist at the National Marine Mammal Foundation in San Diego told LiveScience, "Dolphins can continue to swim and think for days without rest or sleep, possibly indefinitely."

In case you missed International Sloth Day on October 20, check out some of the best videos of one of the cutest animals around.

Below, find some of our favorite animal photos taken in the past week:

Animal Photos Of The Week 10/21/12