Los Alamitos Formation

Secernosaurus (meaning "severed lizard") is a genus of herbivorous hadrosaurid dinosaur that lived during the Late Cretaceous of what is now Argentina. This genus and its close relatives lived in South America, unlike most hadrosaurids, which lived in the Laurasian continents of Eurasia and North America. It has been suggested that the ancestors of Secernosaurus crossed into South America when a land bridge temporarily formed between North and South America during the Late Cretaceous and allowed biotic interchange between the two continents.

Ferugliotherium is a genus of fossil mammals in the family Ferugliotheriidae from the Campanian and/or Maastrichtian period (Late Cretaceous; around 70 million years ago) of Argentina. It contains a single species, Ferugliotherium windhauseni, which was first described in 1986. Although originally interpreted on the basis of a single brachydont (low-crowned) molar as a member of Multituberculata, an extinct group of small, rodent-like mammals, it was recognized as related to the hypsodont (high-crowned) Sudamericidae following the discovery of additional material in the early 1990s. After a ja

Huallasaurus (meaning "duck lizard") is an extinct genus of saurolophine hadrosaur from the Late Cretaceous Los Alamitos Formation of Patagonia in Argentina. The type and only species is H. australis. Originally named as a species of Kritosaurus in 1984, it was long considered a synonym of Secernosaurus before being recognized as its own distinct genus in a 2022 study, different from other members of Kritosaurini.

Groebertherium is a genus of dryolestoid mammal from the Late Cretaceous Los Alamitos and Allen Formations of Argentina. It is not closely related to other contemporary dryolestoids, all of which are part of the clade Meridiolestida.

Reigitherium was a mammal that lived during the Late Cretaceous (Late Campanian-Maastrichtian). Its fossils have been found in the Los Alamitos and the La Colonia Formations of Argentina.

Gondwanatherium is a genus of stem-mammal from the extinct suborder Gondwanatheria that lived in Patagonia, South America during the "Age of Dinosaurs", specifically during the Late Cretaceous (Campanian to Maastrichtian epochs).

Austrotriconodon is a mammal genus from the Campanian and Maastrichtian of South America. It currently contains only the type species, A. mckennai. Originally assumed to be a eutriconodont, more recent studies have recovered it as a meridiolestidan dryolestoid.

Leonardus is an extinct mammal genus from the Late Cretaceous (Late Santonian to Maastrichtian) of South America. It is a meridiolestidan, closely related to the also Late Cretaceous Cronopio and the Miocene Necrolestes.

geological formation in Argentina