Do mammals have toothless lightweight Jaws?

Most mammals do not have toothless lightweight jaws; instead, they typically possess jaws equipped with teeth that vary in shape and size depending on their diet. However, some mammals, like certain species of anteaters and some whales, have evolved to have reduced or absent teeth, relying on specialized feeding mechanisms instead. In these cases, their jaws may be adapted for their specific dietary needs, but they are generally not considered lightweight in the same way that reptilian jaws can be.