Chancy History of a Supposedly Vanished South American Rodent, Lagostomus crassus, with Remarks on Recent Extinctions in Caviomorphs

Lagostomus crassus is a chinchillid rodent exclusively based in an isolated cranium exhumed near Cusco, Peru, by Jan Kalinowski. Although controversial from the very beginning, the validity of the species persisted for more than a century included in treatises and analyses of recent extinctions. Here, we support the hypothesis advanced in the 1960s by Angel Cabrera: L. crassus is a junior synonym of Lagostomus maximus and probably represents an animal taken to Peru. The case of L. crassus is used here as a trigger to discuss the extinction of caviomorphs that occurred in the South American mainland during the Late Holocene-Anthropocene. Biological extirpations differentially affected this group of rodents in contrast with the resilience of cricetids, the other diverse clade of the order inhabiting the continent. Cases and potential causes are reviewed and combined to explore how several caviomorphs went out in recent times.