http://www.sciencemag.org/news/2018/07/america-s-first-dogs-lived-people-thousands-years-then-they-vanished

Where did America’s dogs come from—and why did they disappear?

When 19th century naturalists and explorers first encountered the dogs of Native Americans, they were shocked by the canines’ wolflike appearance. The animals were large and strong, and they didn’t bark—they howled. “If I was to meet with one of them in the woods,” remarked John James Audubon, “I should most assuredly kill it.”