ARACEAE FROM THE UPPER CRETACEOUS CERRO DEL PUEBLO FORMATION OF COAHUILA, MEXICO

Three new fossil aroids (family Araceae) from the Campanian aged Cerro del Pueblo Formation (72.5 Ma) of Coahuila, Mexico, illustrate the flourishing diversity, paleobiogeography, and paleoecology of monocotyledonous angiosperms in the Late Cretaceous of North America. Today, Araceae is the most diverse family within the order Alistmatales and is comprised of approximately 144 extant genera and 3,645 published species. Fossil calibrated molecular phylogenies place the origination of Araceae in the Early Cretaceous at approximately 105−128 Ma, likely in the tropics of northern Gondwana, with the first occurrences of fossil aroids known from several Aptian aged deposits. By the Campanian, aroid fossils are comparatively diverse and widespread, although the discovery of three species in the Cerro del Pueblo Formation is exceptional in the context of aroid diversity within a single Cretaceous formation.

The Cerro del Pueblo aroids, alongside other Late Cretaceous aroids from Europe, Asia, Africa, and northern North America indicate a rapid poleward migration of the Araceae during the Mid- and Late Cretaceous, potentially due to changes in global climate. Furthermore, there is evidence for niche partitioning in the Cerro del Pueblo aroids, which include both aquatic and terrestrial forms. Overall, the Cerro del Pueblo aroids described in this study contribute to the increasingly well-known diversity of the Cretaceous Araceae, the Cerro del Pueblo Formation flora, and represent the first fossil aroids described from the Mesozoic of Mexico.