Data from: The evolutionary history of dogs in the Americas

Dogs were present in the Americas prior to the arrival of European
colonists, but the origin and fate of these pre-contact dogs are largely
unknown. We sequenced 71 mitochondrial and seven nuclear genomes from
ancient North American and Siberian dogs spanning ~9,000 years. Our
analysis indicates that American dogs were not domesticated from North
American wolves. Instead, American dogs form a monophyletic lineage that
likely originated in Siberia and dispersed into the Americas alongside
people. After the arrival of Europeans, native American dogs almost
completely disappeared, leaving a minimal genetic legacy in modern dog
populations. Remarkably, the closest detectable extant lineage to
pre-contact American dogs is the canine transmissible venereal tumor, a
contagious cancer clone derived from an individual dog that lived up to
8,000 years ago.