Here's a sci-fi triple-treat: time travel, aliens, and dinosaurs!
This kool tale appeared in the HTF Ziff-Davis' anthology Weird Thrillers #2 (1951)!
Illustrated by Murphy Anderson, who was doing quite a bit of work for ZD including the second issue of Space Busters and both issues of Lars of Mars as well as various one-shots like this.
We don't know who wrote this tale, but it might be series editor Jerry (Superman) Siegel.