caption: Is Earth Unique The Right Time Atmosphere Mass extinctions
exif: {"Image DocumentName": "Is Earth Unique The Right Time Atmosphere Mass extinctions", "Image ImageDescription": "Earth\u2019s early atmosphere lacked oxygen. Primitive photosynthetic organisms added oxygen to the atmosphere 2.5 billion years ago. Mass extinctions. 65 million years ago, an asteroid struck Earth. Killed the non-avian dinosaurs. Allowed for mammals to become the dominant terrestrial organisms.", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}