Open Paleo

Plesiolophus

McFeeters et al., 2026

From Ancient Greek 'plesios' (near) and 'lophos' (crest); in reference to this taxon's phylogenetic proximity to Parasaurolophus while retaining more plesiomorphic cranial anatomy.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Plesiolophus is an extinct genus of lambeosaurine hadrosaurid dinosaur known from the Late Cretaceous (Campanian age) Oldman Formation of Canada. The genus contains a single species, Plesiolophus warnerensis, known from a partial skull. It belongs to the clade Parasaurolophini, where it exhibits more primitive cranial characters than its relatives.

Diagnosis

  1. Adult frontal platform does not overhang the remainder of the frontals or the parietal posteriorly
  2. Postorbital process of the laterosphenoid projects anterolaterodorsally
  3. Dorsal surface of the parietal between the interfrontal process and the sagittal crest is down-warped, forming a well-developed triangular plateau separating the two
  4. Basipterygoid processes of the parabasisphenoid stout, with a complex lateral topography of an anterior swelling and a posterior depression
  5. Alar process of the basisphenoid is pendent, robust, and subrectangular in shape
  6. Frontal platform is steeply inclined, and a sagittal crest is present on the posterior part of the parietal

Species

Plesiolophus warnerensis McFeeters et al., 2026

Type species

Named for Warner, Alberta, where the holotype was discovered.

Holotype
TMP 2016.023.0039 , Royal Tyrrell Museum of Paleontology
Material
Articulated posterior skull roof and braincase: partial prefrontals, complete fused frontals, parietal, partial postorbitals, left squamosal fragment, and nearly complete neurocranium
Horizon
middle Oldman Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Milk River Ridge Reservoir, Alberta, Canada

References

  1. McFeeters, B. D.; Evans, D. C.; Ryan, M. J.; Maddin, H. C. (2026). A new parasaurolophin dinosaur (Hadrosauridae: Lambeosaurinae) from the Oldman Formation of southern Alberta. Canadian Journal of Earth Sciences 63: 1-23. doi:10.1139/cjes-2026-0013 mcfeeters2026a