Could it be Wendigo's Child, by Thomas F. Monteleone...? This short story was included in the book, Monster Tales: Vampires, Werewolves & ThingsMonster Tales: Vampires, Werewolves & Things, published in 1973.
Set in Corona, Arizona, we follow young Marty Alvarez as he sets out to explore an Indian burial ground recently uncovered just a short bike ride's distance from home. Hoping to discover arrowheads or other artifacts, Marty instead finds buried a small mummy that appears to be part human, part bird.
Convinced he's made an important archeological find, he wraps the thing in his shirt and takes it home in the basket of his bike. Along the way, Marty stops by an Indian friend, Charlie Longhand, in hopes of learning more about his find.
After asking Charlie a vague question about Indian mummies, we learn of an old Indian legend of the "Wendigo", a fearful god that was part man, part reptile and part bird. It was said that when a child died, its buried body would sometimes transform into a child of Wendigo to protect the graves from harm.
Once home, Marty stashes the mummy in his cellar overnight. But the creature's presence has disturbed his dog, Digger, who is now howling endlessly in the backyard. Hoping to assure Digger there is nothing to be afraid of, Marty leads the dog into the dark cellar, armed only with a flashlight. But the Wendigo is missing! Or is it?