Salas-Gismondi R. auteur aut IRD Flynn J. J. auteur aut IRD Baby Patrice auteur aut IRD Tejada-Lara J. V. auteur aut IRD Wesselingh F. P. auteur aut IRD Antoine P. O. auteur aut IRD text journalArticle eng text/pdf born digital access Amazonia contains one of the world's richest biotas, but origins of this diversity remain obscure. Onset of the Amazon River drainage at approximately 10.5 Ma represented a major shift in Neotropical ecosystems, and proto-Amazonian biotas just prior to this pivotal episode are integral to understanding origins of Amazonian biodiversity, yet vertebrate fossil evidence is extraordinarily rare. Two new species-rich bonebeds from late Middle Miocene proto-Amazonian deposits of northeastern Peru document the same hyper-diverse assemblage of seven co-occurring crocodylian species. Besides the large-bodied Purussaurus and Mourasuchus, all other crocodylians are new taxa, including a stem caiman-Gnatusuchus pebasensis-bearing a massive shovel-shaped mandible, procumbent anterior and globular posterior teeth, and a mammal-like diastema. This unusual species is an extreme exemplar of a radiation of small caimans with crushing dentitions recording peculiar feeding strategies correlated with a peak in proto-Amazonian molluscan diversity and abundance. These faunas evolved within dysoxic marshes and swamps of the long-lived Pebas Mega-Wetland System and declined with inception of the transcontinental Amazon drainage, favouring diversification of longirostrine crocodylians and more modern generalist-feeding caimans. The rise and demise of distinctive, highly productive aquatic ecosystems substantially influenced evolution of Amazonian biodiversity hotspots of crocodylians and other organisms throughout the Neogene. specialized Miocene caimanine crocodylians proto-Amazonia Pebas System molluscs durophagy PEROU AMAZONIE 036 082 021 064 282 1804 art. 20142490 [10 p.] 2015 0962-8452 https://www.documentation.ird.fr/hor/fdi:010064020 10.1098/rspb.2014.2490 0962-8452 [F B010064020] https://www.documentation.ird.fr/hor/fdi:010064020 https://www.documentation.ird.fr/intranet/publi/2015/04/010064020.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2015-05-04 2017-08-23 fdi:010064020 fre