page_title: Timeline of the evolutionary history of life
section_title: Historical extinctions
hierarchical_section_title: Timeline of the evolutionary history of life / Detailed timeline / Phanerozoic Eon / Cenozoic Era / Historical extinctions
caption_attribution_description: Captive Caribbean monk seal, Monachus tropicalis, of unknown sex at the New York Aquarium in ca. 1910. Specimen originally captured from either Arrecife´s Tria´ngulos (Campeche) or Arrecife Alacra´n (Yucatan) in Mexico (Townsend 1909).
context_page_description: This timeline of the evolutionary history of life represents the current scientific theory outlining the major events during the development of life on planet Earth. In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization, from kingdoms to species, and individual organisms and molecules, such as DNA and proteins. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species, living and extinct, have diverged through the process of evolution. More than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. However, a May 2016 scientific report estimates that 1 trillion species are currently on Earth, with only one-thousandth of one percent described.
caption: Caribbean monk seal
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS3 Windows", "Image DateTime": "2015:12:05 09:35:28", "Image ExifOffset": "164", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "302", "Thumbnail JPEGInterchangeFormatLength": "6534", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "950", "EXIF ExifImageLength": "495"}