The 13-million-year-old fossils of an extinct crocodylian, named ‘the storyteller,’ suggest that South American and Indian species evolved separately to acquire protruding, ‘telescoped’ eyes for river-dwelling, according by Rodolfo Salas-Gismondi from the University de Montpellier, France, and colleagues.
The gavialoids are a diversified group of mostly extinct long-snouted crocodylian species. Many of the evolutionary relationships between these species remain unclear; fossils of extinct gavialoids from South America and the extant Indian gharial gavialoid have similar telescoped eyes, but it was not known how these features evolved.
The authors of the present study examined Peruvian fossils from a 13-million-year-old South American species, the oldest known gavialoid crocodylian from the Amazon, which they named Gryposuchus pachakamue after Pachakamue, a pre-Hispanic South American ‘storyteller’ god thought to have knowledge about the origins of South American life. The fossils were dated as Middle Miocene and came from the Pebas Formation, which was likely made up of swampy waterways, suggesting that the crocodylian had a river-dwelling lifestyle. It had only slightly telescoped eyes. The researchers conducted phylogenetic and morphometric analysis to assess the likely evolutionary development of the protruding telescoped eyes of Indian and South American species.
CREDIT : Salas-Gismondi et al.
Although further research is needed, thibs study may further our understanding of both the ‘storyteller’ crocodylian and the evolution of all gavialoid crocodylians.
Access to the freely available paper: http://dx.