Datasheet unclear on the dimensions of the 16 pin SMD part
It's "surface mount DIP" - i.e. it's a DIP where the legs have been bent outwards rather than left straight.

That end section gives you the shape of the legs, and all the other 'plan' (top down) drawings are the same for both SM and TH versions.

It's very common on opto-isolators, and also 'dip-switches'.