13-million-year-old 'storyteller' crocodylian fossils show evidence for parallel evolution
|Gryposuchus pachakamue mandible in the field |
[Credit: D. De Francesci; CCAL]
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.
Their analysis suggested that the 'storyteller' crocodylian with slightly telescoped eyes represents the ancestral condition from which the South American lineage evolved telescoped eyes.
The eyes therefore evolved in parallel in South American and Indian lineages, at first showing partial telescoping as in the 'storyteller' crocodylian, and eventually becoming fully telescoped as seen in later-evolving species.
Both South American and Indian species adopted a river-dwelling lifestyle, and it is likely that telescoped eyes were adaptive, helping them to catch fish in these habitats.
Although further research is needed, thibs study may further our understanding of both the 'storyteller' crocodylian and the evolution of all gavialoid crocodylians.
Source: PLOS [April 20, 2016]