Miriam Gallegos and Angel Ray Montoya entered their pleas Friday.
Prosecutors say Montoya killed the child while Gallegos was at work then the couple conspired to cover the crime by disposing of the body in a ravine in September 2007.
The couple told authorities the girl was missing. Authorities say the child died of asphyxiation.
Montoya faces charges of first-degree murder and child abuse resulting in death, while Gallegos faces charges of accessory to a crime and child abuse resulting in death.
The Associated Press