Conventional paleontology, solely based on the body fossil record, had claimed - if not imposed - that the entire contemporary Mammal Class, from mice to whales, including primates from whom we stem, had evolved from a small group of shrew-like early mammals known as Morganucodonts, following the demise of the dinosaurs 65 million years ago. This theory had surmised that predatory dinosaurs, known as Theropods, had fed upon early mammals from the beginning of the Jurassic to the end of the Cretaceous, hereby keeping their size and numbers small, rare, nocturnal, and insectivores. And that the only ones that managed to survive this intense predation up until the demise of the dinosaurs were these very small and fossorial Morganucodonts.
This book describes the discovery made in the late 1990's in southeastern Utah that challenges, if not confirms, that early mammals had not only diversified by the very beginning of the Jurassic from very small prey animals to fairly large carnivorous species, but were, numerically speaking, the dominant terrestrial species from the Jurassic onward to modern times. This book further heralds the use of inter-disciplinary determinations to solve complex issues as the one posed by the dinosaurs-mammals relationship.