Los Alamitos Formation, Geological formation in Río Negro Province, Argentina
Los Alamitos Formation is a geological layer in Río Negro Province containing siltstone and sandstone beds that hold fossilized remains. These deposits reveal details about how the landscape and ecosystems developed in northern Patagonia during that remote period.
This layer formed about 85 to 66 million years ago during two geological epochs when dinosaurs and other animals inhabited the region. It marks the end of the Mesozoic Era and records life before the major extinction event.
Scientists have documented numerous fossils including Aeolosaurus rionegrinus, Huallasaurus australis, and multiple specimens that inform current paleontological research.
The site lies in a remote area of northern Patagonia and requires preparation and permits for access. Researchers use specialized equipment to excavate and document the fossils, meaning visits are typically connected to scientific expeditions.
The layer contains fossils of early birds and small mammal-like creatures that measured only a few centimeters long. These tiny animals lived alongside massive dinosaurs and reveal the diversity of life in that era.
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