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. 2020 Jun 5;8:e9251. doi: 10.7717/peerj.9251

Figure 10. Stratigraphic positions of chasmosaurine taxa.

Figure 10

Morphospecies of Chasmosaurus (A–D) and Pentaceratops (E–J) clades which do not overlap stratigraphically. These are hypothesized to form two anagenetic lineages which resulted from a cladogenetic branching event prior to the middle Campanian. (A) “Chasmosaurus russelli”, lower Dinosaur Park Fm, ~76.8 Ma. (B) Chasmosaurus belli, middle Dinosaur Park Fm, ~76.5–76.3 Ma. (C) Vagaceratops irvinensis, upper Dinosaur Park Fm, ~76.1 Ma. (D) Kosmoceratops richardsoni, middle Kaiparowits Fm, ~76.0–75.9 Ma. (E) Utahceratops gettyi, middle Kaiparowits Fm, ~76.0–75.6 Ma. (F), c.f. Pentaceratops sternbergii, unknown occurrence within “Fruitland Formation” ~76.0–75.1 Ma. (G) Aff. Pentaceratops n. sp., uppermost Fossil Forest Mbr, Fruitland Fm, ~75.1 Ma. (H) Navajoceratops sullivani, lowermost Hunter Wash Mbr, Kirtland Fm, ~75.0 Ma. (I) Terminocavus sealeyi, middle Hunter Wash Mbr, Kirtland Fm, ~74.7 Ma. (F) Anchiceratops ornatus, Drumheller to Morrin Mbr, Horseshoe Canyon Fm, ~71.7–70.7 Ma. Stratigraphic positions and recalibrated radiometric dates from Supporting Information 1 and Fowler (Chapter 2). Timescale from Gradstein et al. (2012). Specimens not to scale. Images adapted from Lehman (1998); Holmes et al., 2001; Sampson et al. (2010); Maidment & Barrett (2011); and Longrich (2014).