Mega garra fauna

This assemblage of giants that inhabited South America until geologically recent times is the most spectacular mammalian fauna of the whole world and of all times. This unusual gathering of species of over a tonne of body mass was the Darwin’s first inspiration for his theory of evolution by natural selection.

The South American Pleistocene megafauna is peculiar in every respect, at its 10 or 12 giants living together.

This is the most diverse assemblage of very large mammals known and many of them have no living analogues. Among its members we find a terrifying sabretoothed felid, a large bear, a mastodont, the armoured glyptodonts, several species of ground sloths and the odd South American ungulates Toxodon and Macrauchenia.

Ground sloths were enlarged relatives of the present-day tree sloths, those strange mammals that live upside down on the branches of the highest Amazonian trees. Among many important differences, size is paramount: at their body masses measured in tonnes, they most certainly were unable to climb trees…

Glyptodonts are relatives to armadillos, only the size of a car and with typical patterns in their scutes.

The strangest of them all are those without modern relatives: Toxodon and Macrauchenia. Both are noteworthy by their strange anatomy, as well as by their size.

When did they live?

Those animals inhabited South America until 10,000 years ago in an epoch called Pleistocene. This is very recent when compared with the time in which dinosaurs lived, as they became extinct about 65 million resaltar en español years ago. And, since they are so recent, they lived along with humans when they arrive to the Americas.

How was the enviroment?

By the time in which those giant mammals lived, the climate in the region was drier and colder than nowadays. It was the “Ice Age”.

That cold climate had the consequence that the water, instead of filling the oceans, accumulated in the polar regions, forming extensive glaciers.

The lowering in the sea level made the coastline to be farther away than in the present, hence many localities, today submerged, were not near the coast.

Wich was their size?

¿Qué tamaño tenían?



Earth sloths were not that “slothful” as the present ones. They did not live hanging from trees.

You would have to picture a very strong tree to hold a 3.000 kg Lestodon!


Glyptodons could stand in two feet for reproduction, and for strengthening their tail blows.


The bones in macrauchenia’s hoofs were transversally more resistant, which allowed them to make sharp curves while running, and thus better escaping from predators.


One can tell a mammoth from a mastodon by looking at it’s defenses. If they are curved, it’s a mammoth. If they are straight, then it’s a mastodon.


Some researchers believe that the Toxodon had a horn, like those of a rhinoceros. That’s why you can find them that way in many reconstructions.


In the Pleistocene the llamas didn’t only live in the Andes, they also lived in Uruguay!

3 books to know more


Megafauna. Giant Beasts of Pleistocene South America. (más información)
by Richard A. Fariña, Sergio Vizcaíno and Gerry De Iuliis. 2013. Bloomington: Indiana University Press, 416 pp. ISBN: 978-0-253-00230-3.

Megafauna. (For children)
by Richard Fariña, Mariana Di Giacomo and Mauro Muyano. 2010. Montevideo: Fin de Siglo.

Hace sólo diez mil años. (more information)
by Richard Fariña and Sergio Vizcaíno. 2009. 6ª ed. (with DVD). Montevideo: Fin de Siglo.