User:Abyssal/Portal:Ordovician/DYK/1

...that fossil Thelodont fish (depiction pictured) surprised scientists by showing that stomachs evolved before jaws?
... that Aegirocassis is the earliest example of massive filter-feeder animals discovered?
... that members of the extinct bivalve genus Hemiconcavodonta are unique in the subfamily Concavodontinae in that their teeth point in two directions?
... that the extinct Argentinian bivalve Cuyopsis symmetricus was named for the symmetry of its rectangular shells?
... that the extinct bivalve subfamily Praenuculinae can be told apart from its sister subfamily by looking at teeth?