Salamander named after Quetzalcoatl: an ancient relative of the axolotl has been described in Mexico

The fossils were found in the state of Hidalgo, about 100 kilometres north of Mexico City. In the Pliocene, several million years ago, there was an ancient lake called Santa Maria Amahac. It was in its sediments that complete and articulated salamander skeletons were preserved - a rare feat for such fragile animals. The study is published in Palaeontologia Electronica.

Details

The modern Mexican axolotl is known for an unusual feature: it can remain a "cub" as an adult. That is, it does not undergo a complete transition to a terrestrial form, retains an aquatic lifestyle and the external features of a larva.

The new fossil species was also neotenic. Simply put, the adult animal retained juvenile features, like the modern axolotl. But the skull structure of the specimens found was unusual enough to separate them into a separate species.

Scientists studied several specimens from the Sanctorum locality in the Santa Maria Amahac region. The specimens were compared to modern Mexican Ambystoma species using prepared skeletons and computed tomography data. This approach allowed them to see details of the bone structure and to verify that the species in front of them was not an already known species, but a new fossil form.

Most importantly, these fossils were preserved almost intact. Salamanders have thin and brittle bones, so complete articulated fossil skeletons are rare. For Mexico, this is also the first formally described fossil salamander species, and the oldest known member of the Ambystoma genus in the country.

Why it's important

The find helps us better understand how the group of salamanders to which the modern axolotl belongs evolved. Today, Mexico is one of the centres of diversity for Ambystoma salamanders, but their ancient history in the region was less well known.

Ambystoma quetzalcoatli shows that this lineage existed in Mexico as early as the Pliocene. The study authors believe the new species was close to modern species from the central Trans-Mexican Volcanic Belt and possibly related to the tiger salamander group.

Background

The axolotl became famous for more than just its appearance. The modern Mexican axolotl can regenerate limbs, tail and some other tissues, so it is actively studied by biologists. But the new discovery does not speak directly about the regeneration of the ancient species: on the fossils can not confidently judge how well he regenerated tissues.

But from the bones we can understand other things: where such animals lived, what their environment looked like and how long ago this group was represented in Mexico. Judging by the data from Santa Maria Amahac, there was an intermountain lake there in the late Pliocene with a rich flora and fauna.

The name quetzalcoatli links the find to the cultural context of Mexico. Quetzalcoatl is not just a beautiful mythological image, but an important symbol of the region. Therefore, the name of the new species emphasises the place where the find was made.

Source

Jorge A. Herrera-Flores, María Patricia Velasco-de León, "Ambystoma quetzalcoatli sp. nov., a new species of fossil axolotl (Caudata: Ambystomatidae) from the Pliocene of Santa María Amajac, Hidalgo, Mexico", Palaeontologia Electronica, 2026.