The National SAFEKIDS Campaign recommends that no child under the age of 12 be left at home alone. However, consider a child's age and maturity level. For example, if a child is extremely impulsive, it might be best to wait until he or she is older than 12.
Did people and dinosaurs live at the same time? No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs.
The Jurassic and Cretaceous (150 million years) was the age of the Dinosaurs, a long reign as a dominant animal group. The Tertiary, however, has been and still is the age of mammals. During the 2nd half of the Eocene (12 million years) the Oligocene (23 million years) and the Miocene (18 million years) the mammals have been dominant.