The coyotes we have here in central Alabama are considerably larger than a fox. In fact, some of them are way more than 40 pounds. I have a feeling that they are cross breeding with wolf hybrids that people let loose. We shot one last year that was 70 pounds. It was definitely a coyote. They reek havoc with livestock. I've got two Great Danes to watch after me when I'm outside doing chores.
It is quite possible that they are some kind of hybrid, or perhaps coyotes just grow larger than I have assumed. But my old college biology professor has also described coming suddenly on a coyote while walking (it was catching grasshoppers), and if he considered himself in any danger he didn't indicate it.