A pycnodont premaxilla bearing a large incisiform tooth with an unusual crown morphology is described from the Palaeocene (Thanetian) phosphate deposits of Morocco. This peculiar tooth shows a broad, fan-shaped multicuspid crown with nine cusps, well adapted for benthic macroalgal scraping. This morph, assigned to a new species of Pycnodus (P. multicuspidatus sp. nov.), emphasizes the phenotypic plasticity of the group and documents an additional trophic specialization among Palaeogene pycnodontiform fishes. In the post-K/Pg boundary marine ecosystem of the Ouled Abdoun Basin, P. multicuspidatus sp. nov. may have opportunistically replaced Maastrichtian fish taxa with a similar front dentition and feeding behaviour, such as the putative specialized pycnodontiforms Stephanodus and Hadrodus.

Criticisms by Kriwet regarding recent work on pycnodont phylogeny are based on the use of additive characters. Therefore, applying transformation series in phylogenetic reconstruction is justified in theory and in practice, and an example of additional ontogenetic evidence supporting character ordering in pycnodonts is provided. Moreover, comments on some pycnodont genera are included, and the accurate taxonomic use of the genera Coelodus and Ocloedus is emphasised.