Question about Diploporita

[mbarco]

I was watching an online seminar: Pal(a)eoPercs - Sarah Sheffield 

https://youtu.be/rohOQbEirAQ

When, about at 11.54, she says that some Diploporitans lack diplopore (i.e. Amphoracystis) and some non-diploporitan echinoderms have diplopores (i.e. some edrioasteroid). 

So, which are the Diploporita distinctive features ? In order to tell: "Alright, this specimen belongs to the Diploporita class"

 

[Tidgy's Dad]

You can't. 

The Diploporita is almost certainly polyphyletic, back in the day any stemmed echinoderm with diplopores was lumped in here and the group has never been properly revised. 

It seems that diplopores evolved separately several times in early echinoderms. 

Edited December 17, 2022 by Tidgy's Dad

[mbarco]

Ok, now  I understand, thanks a lot