New Pliocene Axolotl from Mexico and Three Miocene Hyaenodonts from Pakistan Enrich Ancient Amphibian and Carnivorous Mammal Records

Two major 2026 discoveries have dramatically expanded our knowledge of ancient vertebrates on opposite sides of the globe.

In Hidalgo, Mexico, paleontologists described Ambystoma quetzalcoatli, the first named fossil salamander species from the country and the oldest record of the genus Ambystoma in Mexico. The complete, articulated skeletons from the Pliocene (~4.2 Ma) Santa María Amajac site preserve the classic neotenic traits of modern axolotls—retaining larval features like external gills into adulthood—while showing a distinctive skull that sets it apart. These are the first fully articulated fossil axolotl relatives ever found in Mexico, proving the lineage was already established in the Trans-Mexican Volcanic Belt millions of years ago.

Meanwhile, in Pakistan’s Siwalik deposits (Middle to Late Miocene, ~14–9.5 Ma), researchers identified three hyaenodont species, including the new Metapterodon anari. One mᴀssive form, possibly referable to Megistotherium or Hyainailouros, may have reached 500 kg—polar-bear size—while the new species adds to the group’s final Asian radiation. These fossils confirm hyaenodonts dispersed from Africa into South Asia and survived as top predators until the late Miocene.

Together, the discoveries highlight unexpected longevity and diversity: neotenic amphibians thriving in ancient Mexican lakes and hypercarnivorous mammals dominating Asian ecosystems long after their African heyday. Both underscore how under-explored regions continue to rewrite the deep-time history of vertebrates.