Horned Armadillos and Rafting Monkeys

Walking back along the sandy path I could feel the refreshing cool air on my bare shoulders. The sun was starting to make its way down the horizon, turning the sky to fire. Rustling in the branches in the overhanging trees makes me stop. A little tuff-eared marmoset monkey sits confidently watching me. Then I spot another. More rustling and another appears. This well trodden sand path is the only way to one of the most beautiful beaches on Ilha Grande. These monkeys know it. Apple cores, biscuit remains and other food debris are evidence of countless tourists feeding these cute looking miniature monkeys. Suddenly, they scarper: as fast as they came, they vanish. A deep low growl rumbles in the trees behind. I knew there were jaguars in Brazil, but I hadn’t heard that jaguars had made it to the island. I wasn’t going to wait around to find out.

A gorgeous little Brazillian Common marmoset monkey. (

A gorgeous little Brazilian Common marmoset monkey. (Photo by Carmen Busko. Public Domain)

Brazil, and South America in general, has truly incredible wildlife. From Darwin’s Rhea to the wonderfully fun tapirs, this is a haven of wonderful creatures. It has an incredibly rich and unique fauna which has lived there over the last 65 million years. Why was it so special? What the heck is litoptern or a sabre toothed metatherian? To answer these questions, and more about the ancient mammals of South America, I was lucky enough to be offered a chance to review Horned Armadillos and Rafting Monkeys.

Such a concise, detailed book could only have been written by Darin Croft, at Case Western Reserve University. An expert in fossil mammals from South America, this is Croft’s magnum opus on his life’s passion. He wanted to put this book together to show off the incredible and weird animals that used to live there, most of which, he notes, people have never heard of.

South America is unique. Until about 3 million years ago, it was alone, drifting. After the break up of the mega-continent, Gondwana, the South American landmass split off from Antarctica. And here, for around 30 million years, it floated. Animals were pretty much isolated from the rest of the world, and evolved into their own unique forms. Croft takes the reader to meet these distinctive beasts from the very beginning of the Paleocene all the way up to the Quaternary.

The two major landmasses Laurasia in the north, and Gondwana in the South, around 200 years ago. (Image from here.)

The two major landmasses Laurasia in the north, and Gondwana in the South, around 200 million years ago. (Image Public Domain.)

Honestly, I wasn’t too sure when I first flicked through and saw the layout. First impression was that it looked like another textbook. As we all know, first impressions can be deceiving. As I began to read it, the layout made sense. It worked for the story Croft was crafting: the mammals that lived in South America over time.

Each chapter focuses on one palaeontology site looking at some of the key fossils found there. Each site is a unique piece used to create a detailed picture of the diverse animals in the past. From Bolivia to Argentina, we travel across the continent where digging the dirt allows us to read the pages in geological time. Something struck me as I read: by talking about the context the fossils were found in we go right back to the very roots of how we know what we know, and how there is still so much to learn. I liked this a lot! Looking at fossil sites (with some wonderful photos) reminds us that discoveries, either by serendipity or well planned, funded palaeontology digs, are the result of a lot of hard work. This is where the unglamorous real work begins out in remote places with determined, dedicated teams of people meticulously looking through the sediment for fossils. Often they return empty handed, or at best, with a few fragmentary fossils; tantalising hints of what could be.

Each site is well introduced with their place in the story of South America. It is clearly written for a general audience and although jam packed full of facts, Croft is gentle on the jargon. If you are wanting a personal touch, a little something to bring the author alive, you won’t find it past the prologue. But that actually doesn’t matter too much. You will find yourself lost in the incredible creatures filling the pages of this book. From giant carnivorous armadillos to tiny weird horse-like litopterns, this is a feast for the palaeo-naturalist.

A horned armadillo (Peltephilus ferox) carefully scouts around the entrance to its burrow before embarking on a search for food. Illustration by Velizar Simeonovski and provided courtesy of Darin Croft and Indiana University Press.

A horned armadillo (Peltephilus ferox) carefully scouts around the entrance to its burrow before embarking on a search for food. (Illustration by Velizar Simeonovski and provided courtesy of Darin Croft and Indiana University Press.)

Key species found at each site are listed, with some nice information about what it was and what the environment was like. Lovely artwork by Velizar Simeonovski means there is a visual connection with the extinct beasts and not just an unreadable Latin name on the page. For me the real gem of this book is the photographs of the fossils of each creature written about. Like the fossil sites mentioned above, this brings it all back to how we know what we know, and the hard work of the palaeontologists.

There are dozens of incredible creatures highlighted in this book. Our giant swimming sloth makes an appearance, as do several other Twilight Beasts. With nearly 30 million years of isolation, South America really was a unique ecosystem. Armadillos and sloths evolved there, and it is later in the Pliocene and Pleistocene where we see their giant forms. There was a very familiar looking sabre toothed relative of the marsupials, Thylacosmilus atrox which superficially looked like a cat, but was not even slightly related (the sabre toothed metatherian I mentioned earlier).

Later towards the end of the Pliocene, around 3 million years ago, North America and South America are joined by the Isthmus of Panama. South America was alone no more. This connection had an enormous impact on the ecosystems: lots of animals from both continents were able to migrate to new ecosystems in what is known as the Great American Biotic Interchange (GABI).

Those South American animals that migrate north were not as successful as the northern species that moved south. The giant sloths and glyptodonts only made it into lower north America because the environment was much drier than they were used to. The newcomers to the south, however, thrived in the tropical environments. Tapirs, animals almost symbolic of the Amazon, originated in North America. Rabbits, pikas, bears, weasels, and deer (including the smallest deer species, the gorgeous Pudu) are all animals that made their way south, and adapted so well they are well and truly at home. The only northern Order which didnt survive until today were the Proboscidea, the Gompotheres that made it south became extinct around 10,000 years ago.

The Great American Interchange showing the creatures that moved to explore new lands.

The Great American Biotic Interchange showing the creatures that moved to explore new lands. The green animals were South American beasts that travelled north. The blue animals are North American beasts that moved south. (Image Public Domain)

It may be my geeky side coming out, but I enjoyed it. It has a lot of information, which can be pretty heavy going at times, but I know I will be going back to this book again and again. It also answered my ponderings about cats and monkeys. Cats too made it into South America after the Great American Biotic Interchange. Monkeys arrived in South America way before the cats arrived: between 37-40 million years ago, some African monkeys came adrift in the Atlantic ocean and landed in South America (this probably happened several times, with many rafting monkeys not surviving).

Hop into a time machine, and land around South America between 65 million years ago and today, and this book would be your guide.

Written by: Jan Freedman (@JanFreedman)

Further Reading:

Croft, D. A. (2017). ‘Horned armadillos and Rafting Monkeys: The fascinating fossil mammals of South America.’ Indiana University Press. [Book]

Read more about the wonderful Gomphotheres here.

Love the Giant Armadillo, find out more here.

Charles Darwin’s lost giant ground sloth – here.

More about the enormous giant ground sloth, Megatherium – here.

Did you know giant ground sloths dug burrows? Here you are.

The worlds smallest deer – here.

This entry was posted in Giant Ground Sloth, Gompothere, Ground Sloth, Macrauchenia, Pudu, Thalassocnus. Bookmark the permalink.

2 Responses to Horned Armadillos and Rafting Monkeys

  1. Entelodon says:

    A wonderful book! Pikas in South America?

  2. BrianL says:

    Yes, it is a lovely book in terms of subject matter and in being very readable at that. The photos if the original fossils are great. Yet, I really wouldn’t say the artwork is uniformly great; some are, most are good or okay and there are some I found positively ugly. This is partly due to me disliking digital paintings in general. They often end up somewhere in the uncanny valley to me. Some elements were also repetitive. Did you notice, for example, that those same egrets showed up at least three times?
    In general: good book, but I really don’t think it deserves all the praise for the art work it seems to get.

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