In the 40s and 50s, they "doubted" that coyotes were encroaching...
For what it's worth, in the 40s and 50s, officials were quick to deny that coyotes were moving into the Northeast, and claimed that deer-kills and sightings were "packs of wild dogs".
There was a lengthy and fairly thoughtful article in Yankee Magazine (OK, so not the journal of record on biology, but still) a number of years back about the progression from "wild dogs" to the identification of the Eastern Coyote as a distinct subspecies.
I remember distinctly the first time I saw one in very-suburban Hingham, MA about 10 years ago. I was out walking our rescued greyhound when a big, burly, handsome fellow strolled out in front of us about 30 feet away. I commented aloud to Dale the Greyhound that, "if I didn't know better, I would swear that was a coyote..." Dale had no thoughts on the matter, but about a week later, there was an article in the local paper about coyotes on Boston's South Shore. The coyotes became a regular feature in the 'hood, and had become a bit of a problem by last summer, when several neighborhood cats went missing.
I don't have much trouble buying that mountain lions are staging a slow come-back in the reforested lands of New England.