South American canids
Up to 16 extinct canids (Wang et al. 2004), depending on the criteria
used for phylogenetic studies, inhabited South America since around 3
Mya. Canids originated in North America and spread first to Eurasia upon
the formation of the Bering Strait in the late Miocene (7-8 Mya), where
they radiated into multiple lineages. Later, at 3,5 Mya they also spread
to South America, in the Great American Biotic Interchange (GABI), which
however may have started as early as 20 Mya (see Bacon et al. 2015,
O’Dea et al. 2016, and Jaramillo et al. 2017). The GABI led to the
evolution of new canid species, of which at least 7 were hypercarnivores
(Prevosti & Forasiepi 2018). Hypercarnivores are those species with a
diet composed of at least 70% meat (Holliday & Steppan 2004), and so
have unique ecological characteristics and requirements, distinct from
other species of the group. Particularly in Canidae, hypercarnivores are
large in size due to energetic constraints (Wang et al. 2004) and thus
also very likely to be obligatory cooperative group hunters (Sheldon
1992). The South American ancient hypercarnivores came from 4 genera,Theriodictis , Protocyon , Speothos, and Canis, the latter having three species, C. gezi, C.
nehringi, and C. dirus (the dire wolf, also found in North America, although it has been recently included by Perri et al. (2021) in the genus Aenocyon, according to molecular data)
(Wang et al. 2004; Prevosti 2010). Members of these genera all went
extinct at the end of the Pleistocene, except the bush dog
(Speothos venaticus) which is a small, short-legged group-hunting
carnivorous canid living near water in the tropics. The
hypercarnivorous Pleistocene species, distributed as far south as
Argentina (Prevosti 2018), would most likely have hunted megafauna. Protocyon troglodytes, a group-living cursorial predator, as well
as the non-hypercarnivorous canids Dusicyon spp in Uruguay hunted
camelids, giant sloths, and other large and medium sized prey (Prevosti
et al. 2009). Dusicyon spp. went extinct much later than the
hypercarnivores (see below).
The 13 contemporary South American canids are divided into two lineages
(Perini et al. 2010), one of species similar to Old World foxes (genera Lycalopex, Atelocynus, and Cerdocyon ), and the
other of species similar to Old World wolves (Chrysocyon and Speothos ). Although it is unclear, some authors (see Austin et
al. 2013; Slater et al. 2009) consider this last lineage to be related
to the extinct genus Dusicyon mentioned previously.