Researchers Unearth Previously Unknown Ancient Alligator Species

A recent publication in Scientific Reports unveils the remarkable discovery of an previously unknown ancient alligator species in Thailand, closely linked in evolutionary terms to the Chinese alligator (Alligator sinensis). The research, conducted by a team led by Gustavo Darlim, Márton Rabi, Kantapon Suraprasit, and Pannipa Tian, centered on the analysis of an almost fully preserved fossilized skull, dating back to less than 230,000 years ago, unearthed in Ban Si Liam, Thailand. This newfound species has been christened “Alligator munensis,” a nod to its geographic proximity to the Mun River.

The study delved into the examination of the remains and the exploration of the evolutionary connections between A. munensis and other alligator species. To accomplish this, the researchers compared the findings with those of 19 specimens from four extinct alligator species, along with the presently living American alligator (Alligator mississippiensis), Chinese alligator, and spectacled caiman (Caiman crocodilus). Furthermore, the team scrutinized previously published research on the skeletal traits and evolutionary affiliations among various alligator species.

Distinctive skull characteristics unique to A. munensis were identified, including a broad and short snout, a tall skull structure, a reduced number of tooth sockets, and nostrils positioned far from the snout’s tip. Moreover, striking similarities were observed between the skulls of A. munensis and the Chinese alligator, such as the presence of a small opening in the roof of the mouth, a ridge on the skull’s top, and an elevated ridge behind the nostrils.

The researchers posit that these two species share a close genetic lineage and may have diverged from a common ancestor in the lowlands of the Yangtze-Xi and Mekong-Chao Phraya river systems. They speculate that geological changes, specifically the elevation of the southeastern Tibetan Plateau between 23 and five million years ago, may have been responsible for the isolation of distinct populations and the evolution of two distinct species.

Notably, the scientists observed that A. munensis possessed large tooth sockets toward the rear of its mouth, indicative of the potential for large teeth capable of crushing shells. Consequently, it is suggested that A. munensis may have been a consumer of hard-shelled prey, including snails, in addition to other animals.

This research significantly enhances our understanding of the evolutionary history of Asian alligators and is documented in the article titled “An extinct deep-snouted Alligator species from the Quaternary of Thailand and comments on the evolution of crushing dentition in alligatorids” by Gustavo Darlim, Kantapon Suraprasit, Yaowalak Chaimanee, Pannipa Tian, Chotima Yamee, Mana Rugbumrung, Adulwit Kaweera, and Márton Rabi, published on July 13, 2023, in Scientific Reports (DOI: 10.1038/s41598-023-36559-6).

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