Surely it is the teacher's job to check anything (or design it) presented by volunteers? I would talk to the teacher. Say that she might not know but... And that it concerns you when your child comes home with things that are so inaccurate. It is possible the teacher will be offended but she might take the 'out' of letting you assume she had been too busy to notice.
If there are religous arguements there are many better examples of food chains anyway. Why use that one? Or were the actually trying to study pre-history?
