Myth Agent by L.A. MacFadden

In 1910, science professor Ruttledge Rosenbaugh is shocked by the mysterious appearance of a feisty five-year-old girl in his secret university laboratory, claiming to be a forty-year-old woman from 1945, with no apparent knowledge of how she got there. When she suddenly disappears just as quickly, in a horrifying cocoon-like web, Ruttledge finds himself haunted by the sight he witnessed for many years to come.
Convinced that the girl is a time traveler, Rutt reminisces about his archaeological exploits with his mentor, and of the time machine his friend built. The machine’s technology is based on studies of a mysterious, ancient, fossilized bone he once discovered, with terrifying “evil” powers for anyone scratched or otherwise injured by it.