What caused the decline of the Eugeneodontids - (Buzz saw sharks)

[Joseph Fossil]

I've been fascinated with the Eugeneodontids (the buzz-saw chondrichthyans) and how they managed to practically become the apex predators of most oceanic environments from the Carboniferous to the Permian with famous members like Edestus and Helicoprion. Two genus of this extraordinary group even survived the Permian-Triassic Extinction 252 Million Years ago - Fadenia and Caseodus!

 

http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34456

 

http://www.fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=34451

 

But by the Olenekian stage of the Triassic, the group disappeared. I can understand why the more specialized members of the group like Helicoprion went extinct (ecological specialists and top predators don't do well in events like the Permian-Traissic Extinction event), but what caused the extinction of Fadenia and Caseodus? What occurred in the Triassic that ended the reign of the Eugeneodontids? 

[Tidgy's Dad]

Don't know much about sharks, but maybe Fadenia and Caseodus were just 'dead clades walking'. 

After an extinction event, there is a burst of evolutionary activity, so perhaps other creatures evolved that were better suited to these ecological niches and outcompeted the last of the eugeneodontids, or new predators evolved to finish them off.

Edited October 11, 2022 by Tidgy's Dad

[siteseer]

It's possible the surviving eugeneodontids had become rare or restricted enough geographically to be vulnerable to changes in the environment that were not a big problem for more numerous and more widely distributed competitors.  As Tidgy's Dad noted, they might have been outcompeted by groups that were radiating at the time.  Sometimes, that doesn't mean other groups were faster, more efficient hunters.  They might have just been faster reproducing.