Asa Steele was unprepared for the incredible events that began to unfold when Rila Elliot, a long-lost love,stepped out of the past and his faithful dog Bowser started loping into it through time trails he'd discovered in his own backyard.
Rila's appearance was mere coincidence, but Bowser's retrieval of fresh dinosaur bones was as inexplicable as was the curious crater in Asa's backyard that seemed to have been made by a spaceship from the stars.
Soon Asa himself tripped in time, led into prehistoric eras by an enigmatic cat-faced alien. In short order, the time trails in the quiet town of Willow Bend became the focus of global attention and government scrutiny. Then time-traveling turned into big business and led to big trouble, when Asa and Rila uncovered an interstellar mystery from before recorded time!
aka "Catface", published by Magnum Books, August 1980
Not one of his best. I’d recommend it to readers who already know they like Simak or those looking for mainstream SF from the Seventies. Familiar are the magical friend, faithful dog, and plucky girlfriend, besides the familiar backdrop of aliens coming to a small town in Wisconsin (as in All Flesh is Grass and his well-known short story The Big Front Yard). Simak assumes that the finders of a time travel device would use it to make money and he has tart fun with shysters, hucksters, and PR liars.