Here are the Chicago Cubs, from the July 11, 1908, Chicago Examiner. But that is not a modern-style, costumed mascot posing with a team 103 years ago. It’s actually “The Friendly Bear,” a character in the traveling production of The Top o’ th’ World, a Broadway musical set in “Xmas Land” at the North Pole.
The actor frolicking in that polar bear costume, Arthur Hill, was best known for playing the Cowardly Lion in the original stage play version of The Wizard of Oz (1902) - which, by the way, premiered in Chicago.
It’s worth pointing out that this was almost certainly the Friendly Bear’s last appearance with the Cubs - and that these Cubs were the last to win the World Series. Coincidence?