Monumento natural Bosques Petrificados, Prehistoric petrified forest park in Deseado Department, Argentina.

The Monumento natural Bosques Petrificados is a sprawling nature park in the Patagonian steppe containing scattered petrified tree trunks from ancient times. The fossilized remains vary in their mineral composition and preservation, creating a landscape of different-colored stone logs across the terrain.

The area was a dense forest landscape around 150 million years ago during the Jurassic period, gradually transformed into stone through volcanic activity. This mineralization process preserved the tree structures intact until today.

The name Jaramillo, added to the surrounding national park, honours the Jaramillo family, whose estancia El Cuadro was bought by the national parks administration in 1997. The fossil forest is dominated by Araucaria mirabilis, an extinct conifer identified from its cones; fossil fungi, ferns, Bennettitales and cycads, and primitive frogs, have also been found. The park is the core zone of a combined protected area of 78,543 ha.

The site is remote and requires a vehicle capable of handling unpaved roads to reach the park. Visitors should bring plenty of water and supplies, as there are no facilities or services available on-site.

The fossil trunks reach up to 30 m in length and 2 m in diameter, and the primitive forest included Araucaria mirabilis, identified from its cones, along with ferns, Bennettitales and Cycadidae. Fossils of primitive anurans have also been found in the deposit.