In addition to creating legendary comics like Little Nemo in Slumberland, Winsor McCay was a pioneer of animation. His Gertie (1914) was the first American masterpiece of animated film. Two versions are known to have existed: the original in which McCay appeared on the vaudeville stage with an animated dinosaur named Gertie projected on screen, and a later one that contained a live-action prologue and epilogue filmed and distributed by William Fox’s Box Office Attractions Company. The Fox version is still extant as original nitrate prints, but McCay’s vaudeville version was lost. However, an examination of 334 of McCay’s original drawings reveals that near the end of the vaudeville version there was a ‘Curtain Call’ sequence not included in the Fox version. Fifteen drawings from the lost segment allowed its reconstruction by the Gertie Project applying digital technology. The authors have dated Gertie’s vaudeville chronology more precisely and have demonstrated McCay’s animation techniques, including his ‘split system’, by decoding his original annotations. The authors examine the filmmaker’s claim that he had made 10,000 drawings for Gertie. The resulting historic analysis of a milestone in silent film animation discusses the artistic mastery of Winsor McCay, issues of historical authenticity, and the archival implications of digital reconstruction.