BS. The ar has been around since 1947.
No, technically the sentence is correct. Eugene Stoner first developed the select fire AR-10 in .308 in the mid 1950s to compete against the M14, but got no major military contracts.
He later shrunk down the AR-10 to the AR-15 chambered in .223 Remington as a select fire weapon in 1959. When the U.S. Air Force first adopted the Armalite AR-15, it was then designated as "Rifle, Caliber 5.56 mm, M16."
Only later, after Colt purchased all of the rights to the AR-15, did they come out with a semiautomatic version for civilian use.
So technically the AR-15 as we know it today was derived from the select fire AR-15 that the military designated M16.
Interesting aside, when I went through USAF Basic Training in 1977, our rifle marksmanship training was done using rifles that were marked "COLT AR-15" in fancy engraving, then a smaller stamped "M16" in a different font. They also had no forward assist.
Thanks for clarifying Yo-Yo.