It was formally described in 2010, though it appeared as an informal designation (nomen nudum) as early as 2008.[3]Coahuilaceratops was named by Mark A. Loewen, Scott D. Sampson, Eric K. Lund, Andrew A. Farke, Martha C. Aguillón Martínez, C.A. de León, R.A. Rodríguez de la Rosa, Michael A. Getty and David A. Eberth in 2010 and the type species is Coahuilaceratops magnacuerna.[2] Although based on incomplete remains, Coahuilaceratops is thought to possess among the largest horns of any dinosaur currently known, rivaling in absolute size those of larger chasmosaurines like Triceratops and Torosaurus. Its horns are estimated to have been up to 1.2 m (4 feet) long.[4][2] It was a medium-sized ceratopsian, reaching 4 metres (13 ft) in length and 1 metric ton (1.1 short tons) in body mass.[5]
Systematics
Coahuilaceratops is a member of the Chasmosaurinae. Below is a cladogram that represents the findings of Caleb Brown and Donald Henderson (2015), finding Coahuilaceratops to be the sister taxon to the Texan Bravoceratops.[6]
This pairing was replicated by Jordan Mallon et al. in 2016, although Bravoceratops had to be cut from the analysis to create meaningful results. [7] In 2021, Sierraceratops was described and found to clade with Coahuilaceratops and Bravoceratops, and its describers, Sebastian Dalman et al., suggest they all form a clade unique to southern Laramidia.[8]
^Barrera Guevara, Daniela, Belinda Espinosa Chávez, Claudia Inés Serrano Brañas, Claudio de León Dávila, Daniel Posada Martinez, Elizabeth Freedman Fowler, and Denver Fowler. 2024. "Stratigraphic Reassessment of the Mexican Chasmosaurine Coahuilaceratops magnacuerna as the First Diagnostic Dinosaur Remains from the Cerro Huerta Formation (Lower Maastrichtian) Supporting the Southern Origin of the Triceratopsini" Diversity 16, no. 7: 390. https://doi.org/10.3390/d16070390
^ abcLoewen, M.A., Sampson, S.D., Lund, E.K., Farke, A.A., Aguillón-Martínez, M.C., de Leon, C.A., Rodríguez-de la Rosa, R.A., Getty, M.A., Eberth, D.A., 2010, "Horned Dinosaurs (Ornithischia: Ceratopsidae) from the Upper Cretaceous (Campanian) Cerro del Pueblo Formation, Coahuila, Mexico", In: Michael J. Ryan, Brenda J. Chinnery-Allgeier, and David A. Eberth (eds), New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium, Indiana University Press, 656 pp.
^Dalman, Sebastian G.; Lucas, Spencer G.; Jasinski, Steven E.; Longrich, Nicholas R. (2021-09-29). "Sierraceratops turneri, a new chasmosaurine ceratopsid from the Hall Lake Formation (Upper Cretaceous) of south-central New Mexico". Cretaceous Research. 130: 105034. doi:10.1016/j.cretres.2021.105034. ISSN0195-6671. S2CID244210664.