Logan is a name with Irish origins. The meaning of the name Logan is from the hollow. Common nicknames for Logan include Loag and Lo. Famous Loganâs include athletes Logan Bailly, Logan Coutre, Logan Kensing, and Logan Mankins.
During the Cambrian explosion, the atmospheric oxygen levels increased by up to 10 percent, and prior to that time the living creatures roaming the Earth were typically small, simple and often single-celled.
They cite a nearly 80-percent increase in oxygen levels where oxygen constituted about 14 percent of the atmosphere during the Darriwilian Stage (Middle Ordovician 460-465 million years ago) and increased to as high as 24 percent of the atmosphere by the mid-Katian (Late Ordovician 450-455 million years ago).