Sullivant was a pen-and-ink artist, working during a time when penwork with meticulously
cross-hatched shading, like that of
Charles Dana Gibson, was particularly flourishing. While working technically within the rerstaints of such classical drawing, Sullivant and others like
A. B. Frost and
E. W. Kemble, sought out new, playful means of expression. Sullivant played with distorting anatomy,
perspective and animation. A striking feature was the greatly enlarged heads on hs figures, which, throughout the 1890s, became more and more exaggerated, an innovation pioneered by Frost that was widely imitated by his peers. Sullivant was noted largely for his animal caricatures and his character types—ethnic types like Irishmen, Jews and Negroes familiar in the American melting pot, as well as farmers, tramps and the suburban families which were emerging at the time. His "grotesque yet believable" animals were remarkably detailed and anatomically accurate, despite their gross exaggeration, and expressive in the moods, emotions and attitudes they displayed. The anatomical accuracy of his work was greatly helped by
Eadweard Muybridge's photographic studies of human and animal movement. It was the visuals and the action in his cartoons that were most often the "gag"—frequently the caption added little to the enjoyment of the cartoon. Sullivant had a penchant for using razor blades in his quest for perfection in his work, but not for the shading effects a razor can produce that many other cartoonists used it for. He used it to erase by scratching out work he was dissatisfied with, so he could draw on the paper again, saving only the parts of the drawing he could not part with.
Happy Hooligan's
Frederick Burr Opper commented on Sullivant's frequent razor blade use saying, "If Tom Sullivant scratched his head as much as his paper, he'd draw better cartoons!" His work became looser, more simplified and more exaggerated as Sullivant got older. According to animator
Nancy Beiman, his later work, in his sixties, was the best of his career. ==Legacy==