everything below the <hr> is from SCO's web page, originally at http://www.sco.com/scosource/unixtree/unixhistory01.html
Scroll down to see a second version of the 1969-1973 (leftmost) frame, which contains the Legend.
There is an intersting change: the first (top) version labels the green-dot line "Linux" whereas the second (lower) version labels the green-dot line "SCO Linux Heritage".
This second version was found at http://www.caldera.com/darlmcbride/unixtree/unixhistory01.html
In all other aspects the two timelines are identical.
Click HERE to go to single-page chart.
Click on a page icon here to change page view below. Use scroll bar to scroll up and down.
Original UNIX history chart created by Eric Levenez. Copyright © 1996-2003, Eric Levenez. January 2, 2003. Used with permission.