Published on August 5th, 2014 | by David Marshall
Episode 32: Canids
We’re all familiar with canines (dogs, wolves, jackals, foxes, etc), but these are just only one of three sub-families of the larger canid family to survive to the present day. There were also the Hesperocyoninae and Borophaginae, but what did these other canids look like and why did they go extinct? The canid family also falls within the larger suborder Caniformia which includes skunks, bears and seals, but how are all these related?
We’ve therefore quite a lot of history of the group to cover before we eventually see Canis lupus familiaris become man’s best friend. To talk us through their evolution is Dr Xiaoming Wang of the Natural History Museum, Los Angeles.
Podcast: Download (Duration: 38:18 — 52.6MB)
The order Carnivora is divided into the suborders Feliformia and Caniformia. Within Caniformia, the Canidae occupy the most basal/primitive position of all the families. Relationships of modern representatives of the order Carnivora based on DNA hybridization data (Wayne et al. 1989). Time scale in millions of year before present (MYBP) is based on comparisons of DNA sequence divergence to first appearance times in the fossil record.
Canidae comprises three subfamilies, two extinct and one extant. Despite Hesperocyoninae and Borophaginae having a greater diversity through the Cenozoic, it was only the Caninae that persisted through to the modern day.
The canids first appeared in North America before spreading to Eurasia. Diagram illustrating the timings of major canid dispersals.
Tooth morphology is an important diagnostic characteristic for the canidae both on large and small scales. Dental evolution of representative canids as shown in upper cheek teeth.
Dentition is important for determining palaeoecology in canids. Iterative evolution of large hypercarnivores. Number (N) of hypocarnivorous (white), mesocarnivorous (grey), and large (20 kg) hypercarnivorous (black) species over time in each of the three subfamilies.For the Hesperocyoninae and Borophaginae, their stratigraphic ranges were broken into thirds; for the Caninae, four time divisions were used because of the large number of species appearing in the past 5 million years. Species were assigned to dietary categories and body mass was estimated on the basis of dental morphology as described in Van Valkenburgh (1991) and Wang et al. (1999).
An adult Hesperocyon gregarious, a canid species that could have been ancestral to all three major canid subfamilies, watches over her two pups in front of their den. The scene is set in western North America between 40 million and 34 million years ago, when early canids, like most other members of the order Carnivora, were still evolving in a forested environment. Illustration by Mauricio Antón.
Reconstruction of the borophagines Epicyon saevus (small individual, based on AMNH 8305) and Epicyon haydeni (large individual, composite figure, based on specimens from Jack Swayze Quarry). These two species co-occur extensively during the late Clarendonian and early Hemphillian of Western North America. Illustration by Mauricio Antón. (From Wang et al. 1999.)
Reconstruction of a savanna in western North America about 15 million years ago, a pack of Aelurodon ferox (Borophaginae) pursues a three-toed horse of the genus Neohipparion. In such an open landscape, both predator and prey were driven to evolve stamina and speed. Illustration by Mauricio Antón.
A solitary Borophagus diversidens defends its prey from a pack of Canis lepophagus. Such a confrontation, whose outcome could go either way, may have been common a few million years ago. A bone-crushing species, B. diversidens was the last of the borophagines, whereas the would-be robbers were members of the ascendant genus Canis, whose living examples are the coyote, gray wolf (including the domestic dog), red wolf, Ethiopian wolf, black-backed jackal, golden jackal, and side-striped jackal. Illustration by Mauricio Antón.
A young adult Eucyon davisi, about the size of a living coyote, approaches one of its parents in a submissive attitude. The large social groupings in several species of the subfamily Caninae may have arisen when such youngsters remained in their parents’ territory and helped raise pups. The genus Eucyon lived in North America from about 9 million to 5 million years ago. Illustration by Mauricio Antón.
A dire wolf (Canis dirus) calls for its pack as a herd of mammoths ambles past. The scene is based on fossils found in the Rancho La Brea tar pits, which trapped animals between 20,000 and 10,000 years ago. Illustration by Mauricio Antón.
Studies and reconstructions of the canines Canis dirus (dire wolf) and Canis lupus(grey wolf) from late Pleistocene Rancholebrea Tarpits, Los Angeles, California. Illustration by Pat Ortega.