Following the impact of a meteorite onto Earth’s surface 66 million years ago, the extinction of dinosaurs and other animals caused a diversity crisis that saw the reorganization ecosystems according to the species that survived. The result was that the Iberian Peninsula’s northwestern portion was covered by tropical forests, where a variety of turtles and crocodiles emerged 20 million years later in the Eocene period. The oldest deposits found in this area are actually remnants of ecosystems that were dominated by crocodiles, which are closely related to the Nile crocodiles. That’s right, Spain had distant cousins to Egypt’s crocodiles.

This is thanks to the fossil remains of the “Collection of Fossil Vertebrates From the Duero Basin-Room of the Turtles”, University of Salamanca. These remains were found at different locations with remains from the Eocene Period in the Castilian–Leonese provinces of Zamora, Salamanca, and Soria. Although their analysis has been slowing down over the past decades, a new project has provided updated geological and paleontological information that will help them to improve their research. Professor Francisco Ortega led the work in collaboration with other members of UNED Evolutionary Biology Group, researchers from the University of Salamanca, and the Autonomous University of Madrid. It was published in the journal Historical Biology.

These primitive animals lived on the peninsula up to the Eocene period (34 million years ago), when there was strong competition. Two of the crocodile groups studied were terrestrial predators since the Eocene had yet seen the main carnivorous mammal groups, such as felines. Santiago Martin de Jesus, the scientific curator of the “Collection of Fossil Vertebrates of the Duero Basin- Sala of the Turtles”, states that this type of crocodile will disappear from the Iberian Peninsula after a few millions years.

Geological diagram of Duero Basin, showing the Eocene levels shown in orange. Below are some turtle shells and crocodile specimens taken from the Eocene at the Duero Basin. University of Salamanca

This project’s main interest lies in its ability to “allow us to understand how the Earth recovered following a process that saw mass extinction, how different animals emerged in the ecological void left by dinosaurs, and how they were destroyed by more competitive faunas.” These models provide a snapshot of the past and help us to understand what’s happening now and in the future, if certain environmental conditions are met. It provides information about how life has been and can be continued,” says Francisco Ortega, a paleontologist from the UNED.

The specialist adds that it is also very distinctive because the environment conditions at the time in history caused the animals who emerged from the Ebro Basin experience changes that were not seen in any animals from other parts of the world. world”.

Crocodiles of the Eocene at the Duero Basin. University of Salamanca

The ‘Collection of fossil vertebrates from Duero Basin- Turtle Room’ currently has 23,000 specimens. However, there are still between 5, 000 and 8, 000 that are not yet inventoried. Emiliano Jimenez, a professor at the University of Salamanca who died in 1990, began his research in the 1970s. The researchers are attempting to carry on his legacy. Martin de Jesus says that Castilla y Leon is a superior paleontological community to others in Spain. “Castilla y Leon can provide a lot more information for human knowledge than other Spanish communities.”