The distinctive shape of the frill with the hornlets on its edges (epoccipitals) make it possible to recognize species from incomplete or fragmentary remains.

[citation needed] Chasmosaurinae is defined officially in the PhyloCode by Daniel Madzia and colleagues in 2021 as "the largest clade containing Chasmosaurus belli and Triceratops horridus, but not Centrosaurus apertus".

[2] Kosmoceratops richardsoni Vagaceratops irvinensis Spiclypeus shipporum Pentaceratops sternbergii Utahceratops gettyi Agujaceratops mariscalensis Mojoceratops perifania Chasmosaurus belli Chasmosaurus russelli Coahuilaceratops magnacuerna Anchiceratops ornatus Regaliceratops peterhewsi Arrhinoceratops brachyops Ojoceratops fowleri Titanoceratops ouranos Nedoceratops hatcheri Torosaurus latus "Torosaurus" utahensis Triceratops prorsus Triceratops horridus The findings of a phylogenetic study done by Fowler and Freedman in 2020 are given below.

To improve resolution, certain species based on partial or immature remains (Bravoceratops and Agujaceratops) were excluded, as in the Mallon et al. study above.

[3] Chasmosaurus russelli Chasmosaurus belli Vagaceratops irvinensis Kosmoceratops richardsoni Utahceratops gettyi Pentaceratops sternbergii Coahuilaceratops magnacuerna Navajoceratops sullivani Terminocavus sealeyi Anchiceratops ornatus Arrhinoceratops brachyops Triceratopsini Triceratopsini was named by Nicholas R. Longrich in 2011 for the description of Titanoceratops, which he defined as "all species closer to Triceratops horridus than to Anchiceratops ornatus or Arrhinoceratops brachyops".