The Aguja Formation is a geological formation in North America, exposed in Texas, United States and Chihuahua and Coahuila in Mexico, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.[1]
The ages of the Aguja Formation and its primary fossil-bearing unit, the Upper Shale, are not well understood. Due to the presence of the ammonite Baculites mclearni, which only occurs from 80.67 - 80.21 Ma, in the underlying Rattlesnake Mountain Sandstone and the Terlingua Creek Sandstone, it is likely that the Upper Shale was younger than 80.2 Ma.[2] A radiometric date of 76.9 Ma was recovered in the Upper Shale, making it likely the formation wasn't younger than 76.9 Ma.[2] The contact with the overlying Javelina Formation has been estimated at about 70 Ma ago[3] but also as recently as 68.5 million years ago.[4] This is unlikely, however, due to the presence of Bravoceratops, more primitive than an unnamed chasmosaurine from the De-na-zin Member of the Kirtland Formation, in the lowermost section of the formation.[5] The age of the Basal Sandstone is constrained by the presence of Scaphites hippocrepis III in the overlying Pen Formation which has been dated as old as 81.53 Ma.[2][6]
Considered by paleontologists Lucas, Sullivan, and Hunt to be distinct enough from the Chasmosaurus type species, C. belli to warrant being split off to a new genus, Agujaceratops.[9]
Indeterminate ornithomimid remains are known from the Upper Aguja Formation.[26] Indeterminate tyrannosaurid fossils are known from the Upper Aguja Formation of Texas and Mexico.[27]
^Woodward, H. N. (2005). Bone histology of the sauropod dinosaur Alamosaurus sanjuanensis from the Javelina Formation, Big Bend National Park, Texas.
^Sankey, J. (2010). Faunal composition and significance of high–diversity, mixed bonebeds containing Agujaceratops mariscalensis and other dinosaurs, Aguja Formation (Upper Cretaceous), Big Bend, Texas. In New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium (pp. 520-537).
^ abcde"Abstract," Lucas, Sullivan, and Hunt (2006)
^ abLongrich, N. R.; Sankey, J.; Tanke, D. (2010). "Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA". Cretaceous Research. 31 (2): 274. doi:10.1016/j.cretres.2009.12.002.
^Lehman, T.M.; Wick, S.L.; Barnes, K.R. (2016). "New specimens of horned dinosaurs from the Aguja Formation of West Texas, and a revision of Agujaceratops". Journal of Systematic Palaeontology. Online edition. doi:10.1080/14772019.2016.1210683.
^Listed as ?Gryposaurus sp. in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
^Prieto-Márquez, A. (2013). "Skeletal morphology of Kritosaurus navajovius (Dinosauria:Hadrosauridae) from the Late Cretaceous of the North American south-west, with an evaluation of the phylogenetic systematics and biogeography of Kritosaurini." Journal of Systematic Palaeontology, (advance online publication) doi:10.1080/14772019.2013.770417
^"Dinosaur distribution (Late Cretaceous; North America; Chihuahua)." Weishampel, et al. (2004). Page 588.
^ abc"Abstract," Longrich, Sankey, and Tanke (2010).
^Rivera-Sylva, H.E.; Frey, E.; Stinnesbeck, W.; Guzman-Gutirrez, J.R.; Gonzalez-Gonzalez (2017). "Mexican ceratopsids: Considerations on their diversity and evolution". Journal of South American Earth Sciences. doi:10.1016/j.jsames.2017.01.008.
^ abListed as cf. Dromaeosaurus sp. in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
^Longrich, N. R.; Barnes, K.; Clark, S.; Millar, L. (2013). "Caenagnathidae from the Upper Campanian Aguja Formation of West Texas, and a Revision of the Caenagnathinae". Bulletin of the Peabody Museum of Natural History 54: 23. doi:10.3374/014.054.0102. edit
^ abcd"Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 581.
^Listed as R. cf. gilmorei in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 581.
^Listed as Saurornitholestes cf. langstoni in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
^ abListed as cf. Troodon sp. in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
Longrich, N.R., Sankey, J., and Tanke, D. (2010) Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA. Cretaceous Research. doi:10.1016/j.cretres.2009.12.002.
Spencer G. Lucas, Robert M. Sullivan and Adrian P. Hunt: Re-evaluation of Pentaceratops and Chasmosaurus (Ornithischia: Ceratopsidae) in the Upper Cretaceous of the Western Interior. In: New Mexico Museum of Natural History and Science Bulletin 35 (2006), S. 367-370.PDF[permanent dead link]
Wagner, Jonathan R.; Lehman, Thomas M. (2009). "An Enigmatic New Lambeosaurine Hadrosaur (Reptilia: Dinosauria) from the Upper Shale Member of the Campanian Aguja Formation of Trans-Pecos Texas". Journal of Vertebrate Paleontology. 29 (2): 605–611. doi:10.1671/039.029.0208. S2CID128555861.