Blooming of March Spring. The Saga of the Jurassic. Earliest mammals

The first mammals evolved near the end of the Triassic Period from the nearly extinct Therapsids. Scientists have some difficulty in distinguishing where exactly the dividing line between Therapsids and early mammals should be drawn. Early mammals of the late Triassic and early Jurassic were very small, rarely more than a few inches in length. They were mainly herbivores or insectivores and therefore were not in direct competition with the Archosaurs or later dinosaurs. Many of them were probably at least partially arboreal and nocturnal as well. Most, such as the shrew-like Eozostrodon, were egg layers although they clearly had fur and suckled their young. They had three ear bones like modern mammals and a jaw with both mammalian and reptilian characteristics.