What you need to do is respond to what was actually said. Evolutionists have and continue to determine relatedness according to similarities in form.Nope. Relatedness isn't determined by vague similarity. If it were, people might have considered sea horses more related to horses or perhaps snakes.
That they do not do so according to your "vague similarities" is not a contradiction of what Jabin said.
:doh:Closely related? No, not very. How can we tell? But, But, they're similar in appearance! We can examine their skeletons and see major differences hidden in the similar shapes.
Similarities are similarities whether they be external or skeletal.
Only if you are sold out to the evolutionary mindset.Examining only the bones can tell us one is a mammal while the other is more closely related to lizards.
Just as there was lots of writing about phrenology.In the field of Systematics (classification), relatedness is character based and characters must be selected carefully. And there are entire textbooks devoted to the basics of doing this.