New bird records for the Late Pleistocene of the American continent recovered in Central México and their paleogeographic implications

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Late Pleistocene fossil birds from the Chapala-Zacoalco basins are reported for the first time in the American continent. Two coracoids (MPG-R-10134 and MPG-R-10153) were assigned to Tadornini (gen. and sp. indeterminate) and an ulna (MPG-R-10195) to Megaceryle torquata. The tadornine from the Chapala-Zacoalco basins is the first record of Tadornini in the locality, indicating a more austral distribution of the group in North America during the Late Pleistocene, covering the gap of tadornines distribution between North and South America before their full extinction in North America by the end of the Pleistocene. M. torquata is the oldest record of the species in México and the southernmost fossil record for the Pleistocene, although this species does not exist today in the locality. The fossil record of American tadornines suggests that this group dispersed from South to North America before the formation of the Isthmus of Panamá. Fossil and molecular evidence of Megaceryle suggest a nearctic colonization of the genus from southeast Asia in the Early Pleistocene and a southward dispersion by the Late Pleistocene, as shown by its record in the Chapala-Zacoalco basins. The dispersal hypothesis of Megaceryle contradicts the previous hypothesis of a south to north dispersal of the genus in the American continent. The exact causes that led to the disappearance of some Late Pleistocene avian taxa from the Chapala-Zacoalco in the recent requires further investigation.