didnt frank say some weres that those werent really teeth but were more of a bonegrosse gurke said:Serrasalmus do, it is one of the things that differentiate them from pygocentrus. They are palatine teeth.
out of here for anyone who wants moreThese ectopterygoid teeth while useful for identification of species, can be worn with age and sometimes non-existent in older specimens like S. rhombeus. The lower jaw is actually two pieces held together at the center by tissue which acts like a glue. Only the genera Pygocentrus and Pygopristis lack these ectopterygoid teeth at all ages. The characins are the most heterodont fish group, that is, a group with very different teeth from one taxon to the other.