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] Fossil palms have also been unearthed here.[2]
The ages of the Aguja Formation and its primary fossil-bearing unit, the Alto 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.[3] A radiometric date of 76.9 Ma was recovered in the Alto Shale, making it likely the formation wasn't younger than 76.9 Ma.[3] The contact with the overlying Javelina Formation has been estimated at about 70 Ma ago[4] but also as recently as 68.5 million years ago.[5] 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.[6] The age of the La Basa 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.[3][7]
Paleofauna
A duckbilled dinosaur (Hadrosauridae) caudal vertebra from the Aguja Formation
Reptiles
2 fragmentary caudal vertebrae of indeterminate reptiles are known from the Rattlesnake Mountain sandstone member.[8]
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.[10]
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]
A tribosphenidan; "cannot be confidently allied with either marsupials or eutherians".[43]
Bony fish
A diversity of bony fish, comprising both marine (Ten Bits/Rattlesnake Mountain locality) and freshwater (Lowerverse/Lower Shale locality) taxa, is known.[44] Approximately 75 whole and broken fragments of coprolites are known from the Rattlesnake Mountain sandstone member, presumably from bony fish.[8]
A palm. The seeds are indistinguishable from those of EoceneS. bracknellense, and so were assigned to that species. However, it is likely these Aguja palms would be found to represent distinct species if other parts of the plants were available for comparison.[2]
Gryposaurus was a genus of duckbilled dinosaur that lived about 80 to 75 million years ago, in the Late Cretaceous of North America. Named species of Gryposaurus are known from the Dinosaur Park Formation in Alberta, Canada, and two formations in the United States: the Lower Two Medicine Formation in Montana and the Kaiparowits Formation of Utah. A possible additional species from the Javelina Formation in Texas may extend the temporal range of the genus to 66 million years ago.
Kritosaurus is an incompletely known genus of hadrosaurid (duck-billed) dinosaur. It lived about 74.5-66 million years ago, in the Late Cretaceous of North America. The name means "separated lizard", but is often mistranslated as "noble lizard" in reference to the presumed "Roman nose".
Alamosaurus is a genus of titanosaurian sauropod dinosaurs containing a single known species, Alamosaurus sanjuanensis, from the Maastrichtian age of the Late Cretaceous period in what is now southwestern North America. It is the only known titanosaur to have inhabited North America after the nearly 30-million year absence of sauropods from the North American fossil record and probably represents an immigrant from South America.
The Lance (Creek) Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas. The Lance Formation is Late Maastrichtian in age, and shares much fauna with the Hell Creek Formation of Montana and North Dakota, the Frenchman Formation of southwest Saskatchewan, and the lower part of the Scollard Formation of Alberta.
The Two Medicine Formation is a geological formation, or rock body, in northwestern Montana and southern Alberta that was deposited between 82.4 Ma and 74.4 Ma, during Campanian time. It crops out to the east of the Rocky Mountain Overthrust Belt, and the western portion of this formation is folded and faulted while the eastern part, which thins out into the Sweetgrass Arch, is mostly undeformed plains. Below the formation are the nearshore deposits of the Virgelle Sandstone, and above it is the marine Bearpaw Shale. Throughout the Campanian, the Two Medicine Formation was deposited between the western shoreline of the Late Cretaceous Interior Seaway and the eastward advancing margin of the Cordilleran Overthrust Belt. The Two Medicine Formation is mostly sandstone, deposited by rivers and deltas.
The Kirtland Formation is a sedimentary geological formation.
Agujaceratops is a genus of horned dinosaur from the Late Cretaceous (Campanian) of west Texas. It is a chasmosaurine (long-frilled) ceratopsian. Two species are known, Agujaceratops mariscalensis, and A. mavericus.
The Judith River Formation is a fossil-bearing geologic formation in Montana, and is part of the Judith River Group. It dates to the Late Cretaceous, between 79 and 75.3 million years ago, corresponding to the "Judithian" land vertebrate age. It was laid down during the same time period as portions of the Two Medicine Formation of Montana and the Oldman Formation of Alberta. It is an historically important formation, explored by early American paleontologists such as Edward Drinker Cope, who named several dinosaurs from scrappy remains found here on his 1876 expedition. Modern work has found nearly complete skeletons of the hadrosaurid Brachylophosaurus.
The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.
The Fruitland Formation is a geologic formation found in the San Juan Basin in the states of New Mexico and Colorado, in the United States of America. It contains fossils dating it to the Campanian age of the late Cretaceous.
The Moreno Hill Formation is a geological formation in western New Mexico whose strata were deposited in the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. The age of the formation is dated between approximately 90.9 to 88.6 million years ago based on detrital zircons.
The Javelina Formation is a geological formation in Texas. Dating has shown that the strata date to the Maastrichtian stage of the Late Cretaceous, approximately 70 to 66.5 million years old. The middle part of the formation has been dated to about 69 million years ago plus or minus 1 million years and the top situated near the Cretaceous–Paleogene boundary, dated to 66 Ma ago. Dinosaur remains are among the fossils that have been recovered from the formation.
The Almond Formation is a geological formation of Late Cretaceous age in Wyoming. It was deposited in marsh, deltaic, lagoonal, estuarine, and shallow marine environments along the western shore of the Western Interior Seaway. It consists primarily of fine- to medium-grained sandstone, siltstone, shale, and coal. Fossils from the Almond Formation include remains of dinosaurs and plants.
Angulomastacator is a genus of duck-billed dinosaur from the Campanian-age Aguja Formation of Big Bend National Park, Texas. It is known from a single specimen, TMM 43681–1, a partial left maxilla. This bone is curved down approximately 45° at its anterior end, with the tooth row bent to fit, unlike any other hadrosaur. The unusual characteristics of the maxilla, which have not been reported from elsewhere, supports the hypothesis that the dinosaurs of the Aguja Formation were endemic forms. It was discovered in the upper shale member of the Aguja Formation, among plant, bone, and clam fragments in a bed interpreted as the deposits of a small tributary channel. This bed is just below rocks of the overlying Javelina Formation. Volcanic rocks at about the same level have been dated to 76.9 ± 1.2 million years ago.
Texacephale is a possibly dubious genus of pachycephalosaurid dinosaur from the Campanian stage of the Late Cretaceous. Its fossils come from the Aguja Formation of Big Bend National Park, in Texas, and were described in 2010 by Longrich, Sankey and Tanke. The generic name means Texas + "head" in reference to its place of discovery, and the specific name langstoni honors Wann Langston. It may be a synonym of Stegoceras.
Chupacabrachelys is an extinct genus of bothremydid turtle which existed in western Texas, United States during the late Cretaceous period. Its fossils were discovered in Aguja Formation in the Big Bend region, and its type example is one of the most complete bothremydid specimens known. It was first named by Thomas M. Lehman and Steven L. Wick in 2010 and the type species is Chupacabrachelys complexus. Chupacabrachelys was named after the cryptid of the same name from Mexican folklore.
Bravoceratops is a genus of large chasmosaurine ceratopsid dinosaur that lived approximately 70 million years ago, and is known from the Late Cretaceous Javelina Formation in what is now Texas, United States.
Leptorhynchos is an extinct genus of caenagnathid theropod from the Late Cretaceous of what is now the US state of Texas, although it has been suggested to also exist in Alberta and South Dakota. The type species is L. gaddisi, and it is currently the only widely accepted valid species. The generic name of Leptorhynchos comes from the Greek "leptos" meaning "small" and "rhynchos" meaning "beak". The specific epithet is in honor of the Gaddis family, who owned the land on which the holotype was discovered.
Menefeeceratops is a genus of ceratopsid dinosaur from the Menefee Formation in New Mexico, United States. It is potentially the oldest known member of the ceratopsids, as well as the centrosaurine subfamily, related to animals including Yehuecauhceratops and Crittendenceratops. The type and only species is Menefeeceratops sealeyi, known from a partial, non-articulated skeleton.
References
↑ Weishampel et al., 2004, "Dinosaur distribution (Late Cretaceous, North America).", pp.574-588
1 2 3 4 Manchester, Steven R.; Lehman, Thomas M.; Wheeler, Elisabeth A. (July 2010). "Fossil Palms (Arecaceae, Coryphoideae) Associated with Juvenile Herbivorous Dinosaurs in the Upper Cretaceous Aguja Formation, Big Bend National Park, Texas". International Journal of Plant Sciences. 171 (6): 679–689. doi:10.1086/653688. ISSN1058-5893. S2CID84762968.
↑ 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).
1 2 Longrich, 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. Bibcode:2010CrRes..31..274L. doi:10.1016/j.cretres.2009.12.002.
↑ 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.
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