Paleontologists have examined the fossilized lower jaws of Brasilodon quadrangularis, a mouse-sized creature that lived in Brazil during the Late Triassic epoch, some 225 million years ago. The analysis of the different growth stages showing tooth development in each of the Brasilodon fossils provided evidence that these were the remains of a mammal. Previously, the earliest accepted record in geological time of mammals was 205 million years ago. Brasilodon...
