Texas - US

The Aguja formation consists of alternating mudstones and sandstones interpreted as having been deposited by a prograding delta complex and to some extent more proximal fluvial facies and possess a rich dinosaur fauna. It records the last two major regressions of the Cretaceous epiric sea across the region, and the intervening transgression, and exhibits an intertonguing relationship with the marine Pen Formation. Marine fossils in the transgressive sand unit in the lower third of the formation suggest a \\\"middle\\\" Campanian age for the lower part of the section, and vertebrate biostratigraphy of the upper portion and the overlying Javelina Fm. suggest a Late Campanian to Early Maastrichtian (Judithian to Edmontonian) age for the upper part. This formation is considered partially equivalent to the nearby San Carlos Formation.

The dinosaurian fauna is similar in character to northern Judithian faunas, although strikingly less diverse. Different and unique species of hadrosaurs, ceratopsians, ankylosaurs and large sauropods are common to the Aguja Formation; many of the dinosaur associations found here do not occur anywhere else in North America. Additionally, associated plant remains are encountered in carbonaceous shales, lignites and sandstones of equivalent age throughout the park.

The upper Aguja Formation. sometimes looks alot like the lower Javelina Fm, just as apparently the top of the non-Naashoibito Kirtland Shale looks a lot like the Naashoibito Member in some areas. So there are fossils running around with tags that say \\\"Javelina\\\" but which should say \\\"Aguja.\\\" Vertebrate fossils are also rare in the Javelina Formation, and tend to be encrusted in especially unpleasant concretions.


Agujaceratops mariscalensis - Ceratopidae Chasmosaurinae - Cretaceous Late Campanian


Angulomastacator daviesi - Hadrosauridae Lambeosaurinae - Cretaceous Late Campanian


Chasmosaurus mariscalensis - Ceratopidae Chasmosaurinae - Cretaceous Late Maastrichtian


Edmontonia sp (2) - Ankylosauria Nodosauridae - Cretaceous Late Campanian Maastrichtian


Edmontonia cf. rugosidens - Ankylosauria Nodosauridae - Cretaceous Late Campanian


Palaeoscincus rugosidens - Ankylosauria Nodosauridae - Cretaceous Late Campanian


Ricardoestesia isosceles - Tetanurae Coelurosauria - Cretaceous Late Campanian


Texacephale langstoni - Pachycephalosauria Pachycephalosauridae - Cretaceous Late Campanian


Hadrosaurine indet. (=KRITOSAURUS cf. navajovius ?) - Ornithopoda Hadrosauridae - Cretaceous Late Campanian


?Gryposaurus sp. ( = Kritosaurus sp. ) - Ornithopoda Hadrosauridae - Cretaceous Late Campanian


Ceratopsid indet. - Ceratopia Ceratopidae - Cretaceous Late Campanian


Lambeosaurine indet. - Ornithopoda Hadrosauridae - Cretaceous Late Campanian


Nodosaurid indet. - Ankylosauria Nodosauridae - Cretaceous Late Campanian


Ornithomimid indet. - Theropoda - Cretaceous Late Campanian


Stegoceras sp. - Pachycephalosauria Pachycephalosauridae - Cretaceous Late Campanian


Tyrannosaurid indet. - Theropoda - Cretaceous Late Campanian


Theropod teeth - Theropoda - Cretaceous Late Campanian - (Torres-Rodriguez et al 2010)