What fossils did Charles Darwin find in Argentina?

During his voyage on the HMS Beagle, Charles Darwin conducted extensive fossil excavations at cliffs in Bahía Blanca and Port St. Julian, Argentina. His discoveries included a variety of large, extinct mammals, which he initially assumed were related to rhinoceroses, mastodons, cow-sized armadillos, and giant ground sloths such as Megatherium.1

Additionally, Darwin collected specimens of Toxodon, an extinct genus of mammal that resembled a short rhinoceros. He also unearthed a horse-sized mammal with a long face similar to an anteater. These findings were significant because they demonstrated that South American fossil mammals differed from those found in Europe, providing crucial evidence that later influenced debates regarding the theory of evolution.21