Cyonasua

Cyonasua (meaning "dog-coati" in Greek) is an extinct genus of procyonid from the Late Miocene to Middle Pleistocene of South America. Fossils of "Cyonasua" have been found in Argentina (Ituzaingó, Epecuén, Huayquerías, Monte Hermoso, Chapadmalal, Maimará, Ensenada, La Playa, Chiquimil, Andalhuala, and Cerro Azul Formations), Bolivia (Tariquía Formation), Uruguay (Camacho Formation), and Venezuela (San Gregorio Formation). The oldest well-dated fossils of "Cyonasua" are approximately 7.3 million years old. Most fossils of "Cyonasua" are late Miocene to early late Pliocene (Huayquerian to Chapadmalalan SALMAs, 7.3-3 million years old) in age, but a single early Pleistocene specimen (the holotype and only known specimen of "Cyonasua meranii") indicates that members of this genus survived until at least 0.99 million years ago (the fossil layer where this specimen was collected dating to the Jaramillo Chron).
"Cyonasua" is the oldest terrestrial carnivoran known from South America, and represents the earliest undisputed southward mammalian migrants of the Great American Interchange. "Cyonasua" appears in the fossil record much earlier than other North American immigrant groups, most of which did not appear until 3 million years ago, including other carnivorans, many of which did not appear in South America until the early Pleistocene (about 1.2 million years ago). The next oldest remains of carnivorans in South America are rare specimens of "Lycalopex" and "Galictis" from the Barrancalobian (~2.9 million years old), nearly 4.4 million years after the first appearance of "Cyonasua" in South America. The ancestors of "Cyonasua" are thought to have arrived from Central America by island hopping before the formation of the Isthmus of Panama.
"Cyonasua" arrived in South America when ecosystems there were still dominated by metatherian carnivores, namely sparassodonts and carnivorous opossums. Unlike most sparassodonts, which were hypercarnivores, "Cyonasua" was an omnivore and it is thought that it did not directly compete with sparassodonts for food. This is thought to be one possible reason why "Cyonasua" and its close relatives were able to colonize South America many millions of years before other carnivorans. Because sparassodonts and other native predators like terror birds and teratorns were hypercarnivores, and other predators such as opossums were much smaller than most procyonids, the large, omnivorous "Cyonasua" could occupy an otherwise unoccupied niche in South American ecosystems.
"Cyonasua" was much larger than any extant procyond, weighing about 15–25 kg, about the same size as a medium-sized dog. However, it was much smaller than its later relative "Chapalmalania", which was the size of a small bear. "Chapalmalania" is thought to have been closely related to "Cyonasua", with the two genera frequently referred to as ""Cyonasua"-group procyonids". "Chapalmalania" is thought to have evolved from a species of "Cyonasua" in South America, with "Cyonasua" as traditionally defined potentially being paraphyletic.
Limb bones of "Cyonasua" suggest that this genus was a generalized terrestrial mammal with some capability to dig and climb, similar to raccoons ("Procyon") and coatis ("Nasua"). Fossils of "Cyonasua" have been found inside crotovines (fossil burrows), but these are thought to have been made by the large armadillo "Ringueletia" and later occupied by "Cyonasua". The teeth of "Cyonasua" suggest it was omnivorous, more carnivorous than most living procyonids, but less carnivorous than the modern ringtails ("Bassariscus" spp.)