Titanosaurs, the largest land animals

Titanosaurs were long-necked sauropods that came to dominate the Cretaceous on Gondwana's fragments and spread to most continents. Argentinosaurus huinculensis, from the Huincul Formation of Patagonia about 96 to 94 million years ago, was described in 1993 by Jose Bonaparte and Rodolfo Coria. It is known from partial bones, and estimates of 30 to 35 m in length and tens of tonnes make it a candidate for the largest land animal ever. Patagotitan mayorum, from Chubut and described in 2017, is about 100 million years old and was estimated at about 37 m long.

As the southern continents split, titanosaurs diversified in isolated land masses and reached Africa, India, Asia, Europe, Australia and the Americas. Many carried bony armor plates under the skin. At Auca Mahuevo in Argentina, a nesting colony dating to about 80 million years ago contains thousands of eggs, some with embryos preserved with skin, found in the 1990s. Titanosaurs survived until the asteroid at the end of the Cretaceous, and were the last of the great sauropods.