[pjvandehaar]

I agree that a stacked bar graph would be nice, since the focus is on the per-species total across all 8 tooth types.

Could you explain why a line graph is bad for a discrete but ordered variable, like [Molars - Premolars - Canines - Incisors]?

[benchaney]

In this case a line graph is bad because the line doesn't mean anything. It implies an extrapolation that doesn't actually exist.