A new study published in the journal ‘Historical Biology’ describes the remains of a crocodyliform excavated in the middle of the last century in Pallars Jussà. Their analysis reveals that this specimen, dating back about 70 million years, belonged to a different species than those already known from nearby contemporary sites.

The research provides new evidence of the diversity of vertebrate faunas, beyond dinosaurs, in Europe during the Late Cretaceous, shortly before the mass extinction of 66 million years ago. The remains were found, at the end of the 1950s, by a coal mine worker in Suterranya, in the municipality of Tremp (Lleida).

Josep Montané worked in the mine, where he collected several fossils, including a fragment of a skull similar to a crocodile. The fossil remained forgotten until 2023. This specimen (which is now part of the collection of the Museo de la Conca Dellà de Isona), was finally studied by Riccardo Rocchi (University of Bologna) and Bernat Vila (Institut Català de Paleontologia Miquel Crusafont and Conca Dellàà Museum).

After analyzing the skull, the researchers have determined that this skull fragment belonged to a specimen of the allodaposuchid family, a group of now extinct crocodilians that were very abundant during the Late Cretaceous of Europe. Crocodiles encompass several groups of “crocodiles”, the current forms and also their ancestors.

Although a species of allodaposuchid (Allodaposuchus palustris) was already described in 2015, in nearby and contemporary sites of Fumanya (Berguedà), the specimen recently described in Suterranya-Mina de lignite does not seem to belong to this species but rather shares more similarities with Allodaposuchus subjuniperus, a species known only from older sites in the Aragonese Pyrenees. Specifically, the fossil studied and that species share some characteristics of the region between the orbits.

Inhabited with rich biodiversity

From an unpublished document that has now come to light, researchers have discovered that Josep Montané also found some teeth associated with the skull and that they were attributed to the species Allodaposuchus subjuniperus.

Despite all this evidence, the fragmentary nature of the remains does not allow them to be conclusively attributed to Allodaposuchus subjuniperus, but it can be stated that it undoubtedly does not belong to the other known species, Allodaposuchus palustris.

This finding opens a scenario where at least two different species of allodaposuchids possibly coexisted in the same Late Cretaceous coastal ecosystem, reinforcing the interpretation that these areas represented a habitat with remarkably rich biodiversity, including crocodilians, dinosaurs, turtles, fish, plants and many other organisms that formed a complex ecological network a few million years before the great mass extinction that marked the extinction of all non-avian dinosaurs and, with them, the end of the Mesozoic.

The Suterranya-Lignite Mine deposit was formed 70 million years ago in a brackish coastal environment, which was part of the coasts of the Ibero-Armorican island of the archipelago that corresponds to today’s Europe.

The paleoenvironment where these crocodiles lived was a lagoon near the sea, with a confluence of marine waters and others that came from the continent, with abundant vegetation that would later favor the production of charcoal (lignite).