Aguja Formation

Aguja Formation Stratigraphic range: Campanian-Maastrichtian, 80.5–72 Ma PreЄ Є O S D C P T J K Pg N
Type	Geological formation
Unit of	Tornillo Group
Sub-units	Upper Shale Member Terlingua Creek Sandstone Member McKinney Springs Marine Tongue Rattlesnake Mt. Sandstone Member Lower Shale Member Basal Sandstone Member
Underlies	Javelina Formation
Overlies	Pen Formation
Location
Region	Texas  Chihuahua
Country	USA  Mexico

The Aguja Formation is a geological formation in North America, exposed in Texas, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.

The ages of the Aguja Formation and its primary fossil-bearing unit, the Upper Shale, are not well understood. Two radiometric dates have been taken from different sections of the upper shale, yielding ages of 72.6 Ma +/- 1.5 Ma old, and 76.9 Ma +/- 1.2 Ma old, respectively. The contact with the overlying Javelina Formation has been estimated at about 70 Ma ago but also as recently as 68.5 million years ago. The base of the entire Aguja Formation has been estimated at about 80.5 million years old.

Baculites

B. mclearni

Hoplitoplacenticeras

H. plasticum

Pachydiscus

P. paulsoni

Deinosuchus

D. riograndensis

Phobosuchus

P. riograndensis

Reclassified as a Deinosuchus species.

Agujaceratops

A. mariscalensis

The type species, A. mariscalensis, was formerly considered a species of Chasmosaurus.

Angulomastacator

A. daviesi

Chasmosaurus

C. mariscalensis

"[Twelve] disarticulated skull (sic), postcrania, juvenile."

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.

Indeterminate

Edmontonia

Unnamed species

cf. Euoplocephalus

Unnamed species

Unnamed genus and species

Formerly referred to Kritosaurus and Gryposaurus, appears to be an unnamed species related to Secernosaurus.

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