No menu items!

COSTA RICA'S LEADING ENGLISH LANGUAGE NEWSPAPER

HomeTopicsEnvironment and WildlifeFrom Dinosaurs to Treetops: The Extraordinary Evolution of Sloths

From Dinosaurs to Treetops: The Extraordinary Evolution of Sloths

Did you know that sloths used to be one of the most biodiverse groups of mammals to ever live in South America before the formation of the isthmus? Yeah, maybe it’s not my best pickup line, but an excellent topic of conversation, nonetheless.

Sloths are some of the coolest and cutest creatures to exist in the 21st century, but their story really started 65 million years ago. Sloths are Xenarthrans, a group of animals that includes the armored armadillos and the fierce anteaters. Their evolution starts long before most any other mammal.

Xenarthrans as we now know them started to evolve at a time when non-avian dinosaurs still roamed the Earth! Cool, right? This group was particularly adept at what they did due to various specializations relating to digging, such as specialized joints. They also had extra points of attachment between the vertebrae in the back. Because of this they were able to branch out into the variety of forms we see today.

Armadillo in Costa Rica
Photo via Toucan Rescue Ranch.
Costa Rica Anteater
Photo via Toucan Rescue Ranch.

Sloths as we know them appeared on Earth roughly 46 to 33 million years ago, in what is known as the Oligocene epoch. The last common ancestor between two- and three-fingered sloths diverged almost 40 million years ago, making two-fingered and three-fingered sloths as related to each other as house cats and hyenas!

Two-fingered sloths and three-fingered sloths are as closely related to each other as cats and hyenas.
Photo by Charles J Sharp, via Creative Commons.

Sloths quickly diversified into lots of different forms, from the gigantic 6-meter tall Megatherium, to the marine sloths like Thalassocnus and even some of the weirder species like the digging Lestodon, the rock climbing Diabolotherium and the armored Glossotherium.

Sloths used to be everywhere – from mountain cliffs to oceans!

Marine sloth
Photo by Michael B. H. / Creative Commons.

Nowadays, however, sloth diversity has been highly reduced. After the Americas collided with each other and the Great American Biotic interchange occurred, there wasn’t a lot of space for the mighty sloth. Experts believe that overhunting by early humans may have lead to the decline of this mighty creature, and the reduced families that we have now are also facing this problem.

Today, we only have six different species of sloths, four of them three-fingered sloths and two of them two-fingered sloths. All living sloths are arboreal creatures and all of them are facing problems due to poaching and human interaction.

Twix the sloth in Costa Rica
Via Toucan Rescue Ranch.

That is why it is important that we have rescue centers like the Toucan Rescue Ranch! Its mission is to ensure that one of the most wonderful and, once mightiest, groups of mammals to ever exist doesn’t go extinct.

— Andrés Sáenz Bräutigam is a Veterinary Assistant & Tour Guide at Toucan Rescue Ranch. 

This article was produced by The Toucan Rescue Ranch. The Toucan Rescue Ranch specializes in helping wild animals recover so that they can be reintroduced into the wild.

Trending Now

Canadian Tourism to Costa Rica Drops Amid Rising Crime Concerns

Canadian visits to Costa Rica have started to drop in 2025, with crime playing a big part in the shift. Data from the Costa...

Costa Rica Rescues Endangered Amphibians and Turtles in Store Bust

The Judicial Investigation Agency (OIJ), through its Specialized Section Against Environmental Crimes, carried out an operation at a store in Vázquez de Coronado, San...

Costa Rica Police Uncover Second Cyanide-Laced Mining Operation in Crucitas

The environmental crisis in Crucitas persists. Police discovered and dismantled an artisanal mining material processing plant in a wooded area of Tatú Hill in Crucitas,...

Salvadoran Lawyers Fight for Rights of Trump-Deported Migrants in Secretive Prison

A small group of overstretched and outmatched lawyers is fighting for the rights of men deported by the Trump administration and held in a...

Costa Rica’s Religious Culture Through the Eyes of a Non-Religious Expat

Costa Rica is the only country in the Americas that has an official religion—Catholicism—enshrined in its constitution. While the Constitution recognizes freedom of worship,...

Costa Rican Economists Raise Alarm Over U.S. Cash Transfer Tax

In 2026, the U.S. government will impose a 1% tax on cash remittances sent from the United States to Latin America. Electronic transfers will...
spot_img
Costa Rica Tours
Costa Rica Coffee Maker Chorreador
Costa Rica Coffee Maker Chorreador
Costa Rica Travel Insurance
Costa Rica Rocking Chait
Costa Rica Travel

Latest News from Costa Rica