Aguja Formation Explained

Aguja Formation
Type:	Geological formation
Age:	Lower to Middle Campanian ~
Period:	Campanian
Prilithology:	Sandstone, conglomerate, claystone
Otherlithology:	Mudstone, shale, limestone
Region:
Country:	Mexico
Coordinates:	29.3°N -103.5°W
Paleocoordinates:	35.8°N -77°W
Unitof:	Tornillo Group
Subunits:	La Basa Sandstone Member, Rattlesnake Mountain Sandstone Member, Terlingua Creek Sandstone Member, Abajo Shale Member, and Alto Shale Member
Underlies:	Javelina Formation
Overlies:	Pen Formation

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]

Age

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. 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.^[7]

Paleofauna

Reptiles

2 fragmentary caudal vertebrae of indeterminate reptiles are known from the Rattlesnake Mountain sandstone member.^[8]

Ornithischians

Ornithischians of the Aguja Formation
Genus	Species	Location	Member^[9]	Material	Notes	Images
Agujaceratops	A. mariscalensis	Texas^[10]	Lower Alto Shale		Formerly considered a species of Chasmosaurus
	A. mavericus	West Texas^[11]	Middle Alto Shale		A chasmosaurine.
Angulomastacator	A. daviesi	Texas^[12]	Middle Alto Shale	A left maxilla.	A lambeosaurine.
Ankylosauridae	Indeterminate	Texas^[13]	Lower Alto Shale	Osteoderms, vertebrae & limb elements.	Remains of an ankylosaurid, possibly represents Euoplocephalus sp.
Aquilarhinus^[14]	A. palimentus	Texas	Middle Abajo Shale	Partial skeleton	Formerly referred to Kritosaurus and Gryposaurus.^[15]
Ceratopsidae genus & species indeterminate	Indeterminate	West Texas	Middle Abajo Shale	Ilia, sacral vertebra & sacral ribs.	May represent Agujaceratops, but undiagnostic.
Chasmosaurus^[16]	C. mariscalensis	Texas		[Twelve] disarticulated skull (sic), postcrania, juvenile."^[17]	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.
Edmontonia	E. sp^[18]	Texas	Lower Alto Shale	Osteoderm (TVP 45866-2) & skull (AMNH 3076).	A nodosaurid.
cf. Euoplocephalus	E. sp	Texas	Lower Alto Shale	Osteoderms, sacrum & vertebra (TL-05-14).	An ankylosaurid.
aff. Kritosaurus	K. navajovius	Texas	Upper Alto Shale	Two dentary teeth	Tooth crown morphology matches with Kritosaurus
Malefica	M. deckerti	Texas^[19]	Middle Alto Shale	A partial left maxilla.	Formerly referred to Kritosaurus.
Nodosauridae genus & species indeterminate	Indeterminate	West Texas	Middle Abajo Shale	Isolated & associated osteoderms.	Very similar to osteoderms of Invictarx.
Panoplosaurus	P. mirus	Texas	Lower Alto Shale	Osteoderm (TMM 45605-4).	A nodosaurid.
Saurolophinae	Indeterminate	Texas	Alto Shale	Various cranial and appendicular elements	Material from several localities previously referred to Kritosaurus but do not have its diagnostic features.
Saurolophinae	Indeterminate	Texas	Alto Shale	Various manual elements and vertebrae representing two individuals	Included in phylogenetic analyses as the "Big Bend OTU", most recently considered a kritosaurin
Stegoceras	S. sp.	West Texas^[20]	Middle Alto Shale	Frontal	A pachycephalosaur, represents a new unnamed species
Texacephale	T. langstoni	Texas^[21]	Lower Alto Shale	Two frontoparietal domes.	A pachycephalosaur.
Yehuecauhceratops	Y. mudei^[22]	Coahuila^[23]			A centrosaurine.

Theropods

Indeterminate ornithomimid remains are known from the Upper Aguja Formation.^[24] Indeterminate tyrannosaurid fossils are known from the Upper Aguja Formation of Texas and Mexico.^[25]

Theropods of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Avialae incertae sedis		West Texas^[26]	Middle Abajo Shale	4 teeth (TMM 45947-349, 350, 351).	A bird.
Chirostenotes	C. sp.	Texas^[27]		Femur & manual ungual.	A caenagnathid
Dromaeosauridae genus & species indeterminate	Indeterminate	West Texas	Middle Abajo Shale	Pedal phalanges (TMM 45909-2, TMM 44066-4).	A dromaeosaur.
cf. Dromaeosaurus^[28]	Indeterminate	Texas^[29]
Leptorhynchos	L. gaddisi	Texas	Lower Alto Shale	Dentaries, caudal vertebra & limb elements.	A caenagnathid
Ornithomimidae	New genus & species	West Texas	Middle Abajo Shale	Vertebrae, ischium & limb elements.	An unnamed species referred to informally as the 'Aguja ornithomimid'.
cf. Paronychodon		West Texas	Middle Abajo Shale	2 incomplete teeth (TMM 45947-362).	A maniraptoran.
Richardoestesia	R. cf. gilmorei	Texas^[30]	Low Upper Shale	Fragment of a small tooth.	A coelurosaur.
	R. isosceles	Big Bend National Park, Texas	Low Upper Shale	Teeth.	A coelurosaur.
Saurornitholestes	S. cf. langstoni	Texas	Lower Alto Shale & Middle Abajo Shale	Teeth.	A dromaeosaur.
	S. langstoni	Coahuila ^[31]		Teeth
	Saurornitholestes sp.	Coahuila		Teeth
Theropoda incertae sedis	Morphotype A	West Texas	Alto Shale	8 teeth.	Unserrated, recurved teeth.
	Morphotype B	West Texas		5 tooth crowns.	Bi-serrated teeth.
	Morphotype C	West Texas		7 teeth.	Finely serrated, distal plication only.
	Morphotype D	West Texas		5 teeth.	Short, coarsely serrated distal plication.
	Morphotype E	West Texas		A tooth.	Strongly recurved, serrated distal plication.
	Morphotype F	West Texas		2 tooth fragments.	Medium size, finely serrated plications.
cf. Troodon^[32]	Indeterminate	Texas
Tyrannosauridae	Indeterminate	West Texas^[33]	Lower Alto Shale & Middle Abajo Shale	Isolated teeth & a handful of non-dental specimens.	Postcranial remains suggest a relatively small & gracile tyrannosaurid, considered a member of the Teratophoneini^[34]

Sauropods

Indeterminate titanosaurid remains are known from the Upper Aguja Formation of Mexico.^[35]

Crocodylomorphs

Crocodylomorphs of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Crocodilia	Indeterminate	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Teeth.	A crocodilian.
Deinosuchus^[36]	D. riograndensis	Texas, Chihuahua, and Coahuila^[37]	Upper Shale	Multiple partial skulls & skeletons accounting for nearly the entire skeleton minus the tail.	A giant alligatoroid.
	cf. D. sp.	West Texas^[38]	Middle Abajo Shale	Cervical osteoderm (TMM 44068-2).	An alligatoroid.
Goniopholididae	New genus & species	West Texas	Middle Abajo Shale	Partial skull & skeleton along with isolated osteoderms & teeth.	May pertain to Denazinosuchus or a related taxon.
Phobosuchus	P. riograndensis	Texas, Chihuahua, and Coahuila			Reclassified as a Deinosuchus species

Turtles

Testudines of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Adocus	A. sp.	Big Bend National Park, Texas.^[39]	Upper Shale	Shell fragments.	An adocid.
Baenidae		Big Bend National Park, Texas.	Upper Shale	Shell fragments.	2 morphotypes present (A & B).
Basilemys	B. sp.	Big Bend National Park, Texas.	Upper Shale & Lower Shale	Shell fragments, partial plastron & leg scutes.	A nanhsiungchelyid.
Bothremydidae genus & species indeterminate	Indeterminate	West Texas	Lower Shale	Isolated peripheral bones (TMM 44068-1, 42452-8); costal bones (TMM 44064-6).	A bothremydid, compatible with Chupacabrachelys.
Chupacabrachelys	C. complexus	Big Bend, Texas.^[40]	Base of the Upper Shale	A complete skull, and a nearly complete skeleton.	A bothremydid.
cf. Denazinemys	cf. D. sp.	West Texas	Lower Shale	Shell elements.	A baenid.
cf. Helopanoplia		Big Bend National Park, Texas.	Upper Shale	Shell fragments.	A softshell turtle.
cf. Hoplochelys		Big Bend National Park, Texas.	Upper Shale	Shell fragments.	A kinosternoid.
Terlinguachelys	T. fischbecki	Big Bend National Park, Texas^[41]	Rattlesnake Mountain Sandstone	A large, incomplete specimen.	A protostegid.
Testudines indeterminate	Morphotype 1	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	A shell fragment.
	Morphotype 2	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	A shell fragment.
	Morphotype 3	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	A shell fragment.
	Morphotype 4	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	A shell fragment.
Trionychidae	Gen. et. sp. indet.	Big Bend National Park, Texas.	Upper Shale & Lower Shale	Costal bone (TMM 44068-4) & shell fragments.	A softshell turtle.

Lepidosaurs

Lepidosaurs of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Anguidae	Gen. et. sp. indet.	Texas.^[42]		Isolated osteoderms & partial right frontal.	An anguid.
Apsgnathus	A. triptodon	Brewster County, Texas.		Jaw elements.	A scincomorph.
Catactegenys	C. solaster	Brewster County, Texas.		Jaw elements & teeth.	A night lizard.
Dryadissector	D. shilleri	West Texas.	Middle Abajo Shale	Numerous isolated teeth.	A varanoid.
Mosasauridae	Indeterminate	Ten Bits Ranch.	Rattlesnake Mountain sandstone member.	1 partial vertebra.	A mosasaur.
Odaxosaurus	O. piger	Brewster County, Texas.		Jaw elements.	An anguid.
cf. Parasaniwa	cf. P. wyomingensis	Texas.		Jaw fragments.	A platynotan.
Platynota	Gen. et. sp. indet.	Texas.		Dorsal vertebra (TMM 43057-332).	A platynotan.
?Scincidae	Gen. et. sp. indet.	Brewster County, Texas.		Jaw elements.	A possible skink.
cf. Scincomorpha	Gen. et. sp. indet.	Brewster County, Texas.		Jaw elements.	A scincomorph.
Serpentes	Gen. et. sp. indet.	Texas.		Partial left dentary & right maxilla.	A snake.
cf. Xenosauridae		Texas.		Osteoderms & maxillae.	A knob-scaled lizard.

Mammals

Mammals of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Alphadon^[43]	A. perexiguus	Brewster County, Texas	Upper Shale		A metatherian.
Paleomolops	P. langstoni	Brewster County, Texas	Upper Shale		A tribosphenidan; "cannot be confidently allied with either marsupials or eutherians".

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.

Bony fish of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Acanthomorpha indet.	family indet.genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	An acanthomorph.
Acanthopterygii indet.	order indet.family indet.genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	An acanthopterygian.
	Acanthopterygian fin spine morph 1			Fin spines
	Acanthopterygian fin spine morph 2
	Acanthopterygian fin spine morph 3
	Acanthopterygian fin spine morph 4
	Euacanthopterygian fin spine morph 1
	Euacanthopterygian fin spine morph 2
Albula	A. sp.	Ten Bits Ranch, west Texas.^[45]	Rattlesnake Mountain sandstone member.	Over 390 complete and fragmentary teeth.	A bonefish.
		Lowerverse, west Texas	Lower Shale
Amiidae indet.	genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	An amiid.
?Anomoeodus	?A. sp.	Lowerverse, west Texas	Lower Shale	Isolated tooth crown	A pycnodont. Likely transported out of a marine habitat.
Atractosteus	A. sp.	Lowerverse, west Texas	Lower Shale	Teeth, jaw fragments, vertebral centra, scales.	A gar.
Clupeiformes indet.	family indet.genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	A clupeiform.
cf. Cyclurus	cf. C. sp.	Lowerverse, west Texas	Lower Shale	5 fragmentary tooth plates with teeth.	An amiid.
Ellimmichthyiformes indet.	family indet.genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	An ellimmichthyiform.
Elopiformes indet.	family indet.genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra	An elopiform.
?Enchodus	?E. sp.	Ten Bits ranch, west Texas.	Rattlesnake Mountain sandstone member.	2 abraded teeth.	An aulopiform.
		Lowerverse, west Texas	Lower Shale	4 isolated teeth.
Eotexachara	E. malateres	Lowerverse, west Texas^[46]	Lower Shale	Dentaries.	A characiform.
?Gonorynchiformes indet.	family indet.genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Cranial bone, vertebral centrum, basibranchial.	A gonorynchiform.
Hiodontidae indet.	genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	A hiodontiform.
Lepidotes	?L. sp.	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Approximately 109 complete and fragmentary teeth.	A lepidotid.
cf. Melvius	cf. M. sp.	Lowerverse, west Texas	Lower Shale	Vertebrae, 13 isolated teeth.	An amiid.
Micropycnodon	M. sp.	Lowerverse, west Texas	Lower Shale	4 isolated teeth	A pycnodont. Likely transported out of a marine habitat.
Osteichthyes indet.	Indeterminate species A	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	11 complete teeth.	A bony fish.
	Indeterminate species B			8 complete and fragmentary teeth.
	Indeterminate species C			1 complete tooth.
	Indeterminate species D			1 complete and 1 partial tooth.
	Indeterminate			Approximately 475 complete and fragmentary teleost centra.
	Tooth morph 1	Lowerverse, west Texas	Lower Shale	Teeth
	Tooth morph 2
	Centrum morph 1			Vertebral centra.
	Centrum morph 2
	Centrum morph 3
	Centrum morph 4
Ostariophysi indet.	order indet.family indet.genus et sp. indet.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	An ostariophysian.
Paralbula	P. cf. casei	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Approximately 900 complete and fragmentary teeth and tooth caps.	A bonefish. Lowerverse specimens likely transported out of a marine habitat.
		Lowerverse, west Texas	Lower Shale
Primuluchara	P. laramidensis	Lowerverse, west Texas	Lower Shale	Dentaries.	A characiform.
Stephanodus	?S. sp.	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	21 whole and fragmentary specimens.	A pycnodont.
?Wilsonichthys	?W. sp.	Lowerverse, west Texas	Lower Shale	Vertebral centra.	An osteoglossiform.

Cartilaginous fish

Cartilaginous fish of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Brachyrhyzodus	B. wichitaensis	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	11 complete teeth.
Cantioscyllium	C. aff. meyeri	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	1 anterior tooth and 5 lateral teeth.	A nurse shark.
Chiloscyllium	C. aff. greeni	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Approximately 90 abraded and fragmentary teeth.	A bamboo shark.
Chondrichthyes		Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	23 placoid scales and 69 dermal scales.	4 morphotypes of placoid scales (A to D) present.
Columbusia	C. sp.	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	20 complete & fragmentary teeth.	A wobbegong.
Cretalamna	C. appendiculata	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	3 fragmentary teeth.	Reassigned to C. cf. C. sarcoportheta.
	C. cf. C. sarcoportheta	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	3 incomplete teeth & fragments of additional teeth.	Originally reported as C. appendiculata.
Cretorectolobus	C. olsoni	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	"20 complete and fragmentary teeth".	A carpet shark.
Hybodontidae genus & species indeterminate	Indeterminate	West Texas	Lower Shale	Fragment of a dorsal fin spine (TMM 42536-10).	A hybodont.
Hybodus	H. sp.	Ten Bits Ranch.	Rattlesnake Mountain sandstone member.	2 specimens, one complete and one partial tooth.	A hybodont.
Igdabatis	I. indicus?	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	A single incomplete tooth.	A myliobatid.
Ischyrhiza	I. cf. avonicola	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	5 complete and fragmentary rostral teeth.	A sawskate.
	I. mira	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	11 fragmentary rostral teeth and 230 whole and fragmentary oral teeth.	A sawskate.
Lonchidion	L. selachos	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	4 complete and 5 fragmentary teeth.	A hybodont.
Meristodon	M. sp.	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	2 teeth.	A hybodont.
Myliobatiformes	Incertae sedis	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	3 complete specimens.
Protoplatyrhina	P. renae	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	70 complete and fragmentary teeth.	A hypsobatid.
Ptychotrygon	P. agujaensis	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Over 690 complete and fragmentary teeth.	A sawskate.
	P. triangularis	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Over 170 complete and fragmentary teeth.	A sawskate.
	P. aff. cuspidata	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	7 whole and fragmentary teeth.	A sawskate.
	P. sp.	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	One complete tooth (TMM 46018-71).	A sawskate.
Rhinobatos	R. casieri	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	"14 complete and fragmentary specimens".	A guitarfish.
	R. sp.	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	18 complete & fragmentary specimens.	A guitarfish.
Rhombodus	R. levis	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Over 22 complete and fragmentary teeth.	A rajiforme.
Scapanorhynchus	S. texanus	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	Over 800 complete and fragmentary teeth.	A mitsukurinid.
Sclerorhynchidae	Morphotype 1	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	One fragmentary rostral spine (TMM 46018-59).	A sawskate.
	Morphotype 2	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	One fragmentary rostral spine (TMM 46018-60).	A sawskate.
	Morphotype 3	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	3 fragmentary rostral teeth.	A sawskate.
	Morphotype 4	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	27 fragmentary rostral spines.	A sawskate.
Serratolamna	S. cf. S. caraibaea	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	About 34 teeth.	A mackerel shark.
Squalicorax	S. kaupi	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	"26 complete and fragmentary anterior and lateral teeth".	An anacoracid.
	S. aff. S. lindstromi	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	4 specimens.	An anacoracid.
	S. pristodontus	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	2 specimens.	An anacoracid.
	S. aff. S. yangaensis	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	4 complete & several fragmentary teeth.	An anacoracid.
Squatina	S. hassei	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	A single complete specimen.	An angelshark.
	S. sp.	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	A complete tooth & 2 fragmentary teeth.	An angelshark.
Texatrygon	T. cf. T. copei	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	4 complete & fragmentary teeth.	A sawskate formerly reported as T. hooveri.
	T. hooveri	Ten Bits Ranch, west Texas.	Rattlesnake Mountain sandstone member.	4 complete and fragmentary specimens.	Reassigned to T. cf. T. copei.

Invertebrates

Ammonites

Ammonites of the Aguja Formation
Genus	Species	Location	Member	Abundance	Notes	Images
Baculites	B. mclearni		Rattlesnake Mountain Sandstone Terlingua Creek Sandstone
Hoplitoplacenticeras	H. plasticum		Rattlesnake Mountain Sandstone
Pachydiscus	P. paulsoni		Rattlesnake Mountain Sandstone

Plants

Plants of the Aguja Formation
Genus	Species	Location	Member	Material	Notes	Images
Sabal	S. bigbendense	Big Bend National Park, Texas.	Upper Shale	4 seeds.	A palm. It has the largest seeds of any fossil Sabal.
	S. bracknellense	Big Bend National Park, Texas.	Upper Shale	5 seeds.	A palm. The seeds are indistinguishable from those of Eocene S. 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.

See also

• List of dinosaur-bearing rock formations

References

Bibliography

• Sullivan, R.M., and Lucas, S.G. 2006. "The Kirtlandian land-vertebrate "age" – faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America." New Mexico Museum of Natural History and Science, Bulletin 35:7-29.

Notes and References

1. Weishampel et al., 2004, "Dinosaur distribution (Late Cretaceous, North America).", pp.574-588
2. 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 . 10.1086/653688 . 84762968 . 1058-5893.
3. Fowler. Denver Warwick. 2017-11-22. Revised geochronology, correlation, and dinosaur stratigraphic ranges of the Santonian-Maastrichtian (Late Cretaceous) formations of the Western Interior of North America. PLOS ONE. 12. 11. e0188426. 10.1371/journal.pone.0188426. 1932-6203. 5699823. 29166406. 2017PLoSO..1288426F. free.
4. Woodward, H. N. (2005). Bone histology of the sauropod dinosaur Alamosaurus sanjuanensis from the Javelina Formation, Big Bend National Park, Texas.
5. 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).
6. Fowler. Denver W.. Fowler. Elizabeth A. Freedman. 2020-06-05. Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs: evidence from the Campanian of New Mexico. PeerJ. en. 8. e9251. 10.7717/peerj.9251. 32547873. 7278894. 2167-8359 . free .
7. Prieto-Márquez. Albert. Wagner. Jonathan R.. Lehman. Thomas. 2020-03-18. An unusual 'shovel-billed' dinosaur with trophic specializations from the early Campanian of Trans-Pecos Texas, and the ancestral hadrosaurian crest. Journal of Systematic Palaeontology. 18. 6. 461–498. 10.1080/14772019.2019.1625078. 2020JSPal..18..461P . 202018197. 1477-2019.
8. Elasmobranch and osteichthyan fauna of the Rattlesnake Mountain Sandstone, Aguja Formation (Upper Cretaceous; Campanian), West Texas . May 2013 . Thesis . Joseph . Schubert.
9. Lehman . Thomas M. . Wick . Steven L. . (Charlie) Macon . Craig C. . Wagner . Jonathan R. . Waggoner . Karen J. . Brink . Alyson A. . Shiller . Thomas A. . 2024-03-20 . Stratigraphy and depositional history of the Aguja Formation (Upper Cretaceous, Campanian) of West Texas, southwestern USA . Geosphere . 20 . 3 . 825–879 . 10.1130/ges02662.1 . 1553-040X.
10. Lucas . Spencer G. . Sullivan . Robert M. . Hunt . Adrian P. . January 2006 . Re-evaluation of Pentaceratops and Chasmosaurus (Ornithischia: Ceratopsidae) in the Upper Cretaceous of the Western Interior . New Mexico Museum of Natural History and Science Bulletin . 35 . 367–370.
11. Lehman . Thomas M. . Wick . Steven L. . Barnes . Kenneth R. . 2017-08-03 . New specimens of horned dinosaurs from the Aguja Formation of West Texas, and a revision of Agujaceratops . Journal of Systematic Palaeontology . en . 15 . 8 . 641–674 . 10.1080/14772019.2016.1210683 . 2017JSPal..15..641L . 88907183 . 1477-2019.
12. Wagner . Jonathan R. . Lehman . Thomas M. . 2009-06-12 . 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 . en . 29 . 2 . 605–611 . 10.1671/039.029.0208 . 2009JVPal..29..605W . 128555861 . 0272-4634.
13. West . Bryanna . 2020 . Campanian-Maastrictian Ankylosaurs of West Texas . Texas Tech University .
14. Listed as ?Gryposaurus sp. in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
15. Prieto-Márquez . Albert . 2014-02-17 . 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 . en . 12 . 2 . 133–175 . 10.1080/14772019.2013.770417 . 2014JSPal..12..133P . 84942579 . 1477-2019.
16. "Dinosaur distribution (Texas and Chihuahua)." Weishampel, et al. (2004). Page 582 and 588.
17. "Table 23.1," in Weishampel, et al. (2004). Page 496.
18. Listed as Edmontonia cf. rugosidens in "Dinosaur distribution (Late Cretaceous; North America; Texas).", Weishampel et al., 2004, p.582
19. Prieto-Márquez . Albert . Wagner . Jonathan R. . 2022-11-10 . A new 'duck-billed' dinosaur (Ornithischia: Hadrosauridae) from the upper Campanian of Texas points to a greater diversity of early hadrosaurid offshoots . Cretaceous Research . en . 143 . 105416 . 10.1016/j.cretres.2022.105416 . 0195-6671 . 253470207.
20. Wick . Steven L. . Lehman . Thomas M. . 2024-09-19 . A rare ‘flat-headed’ pachycephalosaur (Dinosauria: Pachycephalosauridae) from West Texas, USA, with morphometric and heterochronic considerations . Geobios . 10.1016/j.geobios.2024.08.006 . 0016-6995.
21. 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 . 2010CrRes..31..274L . 10.1016/j.cretres.2009.12.002.
22. Rivera-Sylva . H.E. . Hendrick . B.P. . Dodson . P. . 2016 . A Centrosaurine (Dinosauria: Ceratopsia) from the Aguja Formation (Late Campanian) of Northern Coahuila, Mexico . PLOS ONE . 11 . 4 . e0150529 . 2016PLoSO..1150529R . 10.1371/journal.pone.0150529 . 4830452 . 27073969 . free.
23. 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 . 10.1016/j.jsames.2017.01.008 .
24. Sullivan, R.M., and Lucas, S.G. 2006. "The Kirtlandian land-vertebrate "age" – faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America." New Mexico Museum of Natural History and Science, Bulletin 35:7-29.
25. Web site: Mortimer. M. Tyrannosauroidea. The Theropod Database. 2004. 2007-08-21. https://web.archive.org/web/20130929074932/http://archosaur.us/theropoddatabase/Tyrannosauroidea.html#Tyrannosaurusrex. 2013-09-29. dead.
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27. Longrich . Nicholas R. . Barnes . Ken . Clark . Scott . Millar . Larry . April 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 . en . 54 . 1 . 23–49 . 10.3374/014.054.0102 . 128444961 . 0079-032X.
28. Listed as cf. Dromaeosaurus sp. in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
29. "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
30. Sankey . Julia T. . 2001 . Late Campanian Southern Dinosaurs, Aguja Formation, Big Bend, Texas . Journal of Paleontology . 75 . 1 . 208–215 . 10.1666/0022-3360(2001)075<0208:LCSDAF>2.0.CO;2 . 1306931 . 0022-3360.
31. Ramírez-Velasco & Hernández-Rivera . A.A & R. . 2015 . Diversity of late cretaceous dinosaurs from Mexico . Boletín Geológico y Minero . 126 . 1 . 63-108.
32. Listed as cf. Troodon sp. in "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
33. Lehman . Thomas M. . Wick . Steven L. . September 2012 . Tyrannosauroid dinosaurs from the Aguja Formation (Upper Cretaceous) of Big Bend National Park, Texas . Earth and Environmental Science Transactions of the Royal Society of Edinburgh . en . 103 . 3–4 . 471–485 . 10.1017/S1755691013000261 . 2012EESTR.103..471L . 129232391 . 1755-6910.
34. Rivera-Sylva . Héctor E. . Longrich . Nicholas R. . 2024 . A New Tyrant Dinosaur from the Late Campanian of Mexico Reveals a Tribe of Southern Tyrannosaurs . Fossil Studies . 2 . 4 . 245–272 . 10.3390/fossils2040012 . free.
35. Montellano-Ballesteros, M. 2003. "https://www.redalyc.org/pdf/572/57220207.pdf."
36. "Aguja Formation (Upper Shale Member), Big Bend Region, Texas," in Sullivan and Lucas (2006). Page 16.
37. Web site: The first mandible fragment of Deinosuchus (Eusuchia: Alligatoroidea) discovered in Coahuila, Mexico. ResearchGate. 2016-03-27.
38. Lehman . Thomas M. . Wick . Steven L. . Brink . Alyson A. . Shiller . Thomas A. . 2019 . Stratigraphy and vertebrate fauna of the lower shale member of the Aguja Formation (lower Campanian) in West Texas . Cretaceous Research . 99 . 291–314 . 10.1016/j.cretres.2019.02.028 . 2019CrRes..99..291L . 135044927 . 0195-6671.
39. Sankey . Julia . January 2006 . Turtles of the upper Aguja Formation (late Campanian), Big Bend National Park, Texas . New Mexico Museum of Natural History and Science Bulletin . 35 . 235–243.
40. Lehman . Thomas M. . Wick . Steven L. . 2010 . Chupacabrachelys complexus, N. Gen. N. Sp. (testudines: Botheremydidae), from the Aguja Formation (campanian) of West Texas . Journal of Vertebrate Paleontology . 30 . 6 . 1709–1725 . 10.1080/02724634.2010.520782 . 25790797 . 2010JVPal..30.1709L . 129303574 . 0272-4634.
41. Lehman . Thomas M. . Tomlinson . Susan L. . November 2004 . Terlinguachelys fischbecki, a new genus and species of sea turtle (Chelonioidea: Protostegidae) from the Upper Cretaceous of Texas . Journal of Paleontology . en . 78 . 6 . 1163–1178 . 10.1666/0022-3360(2004)078<1163:TFANGA>2.0.CO;2 . 2004JPal...78.1163L . 54755373 . 0022-3360.
42. Nydam . Randall L. . Rowe . Timothy B. . Cifelli . Richard L. . 2013 . Lizards and Snakes of the Terlingua Local Fauna (late Campanian), Aguja Formation, Texas, with Comments on the Distribution of Paracontemporaneous Squamates Throughout the Western Interior of North America . Journal of Vertebrate Paleontology . 33 . 5 . 1081–1099 . 10.1080/02724634.2013.760467 . 42568627 . 2013JVPal..33.1081N . 86519841 . 0272-4634.
43. Cifelli . Richard L. . December 1994 . Therian mammals of the Terlingua local fauna (Judithian), Aguja Formation, Big Bend of the Rio Grande, Texas . Contributions to Geology . University of Wyoming . 30 . 2 . 117–136.
44. Wick . Steven L. . Brink . Alyson A. . 2022-11-01 . A new non-marine osteichthyan fauna from the Upper Cretaceous (Campanian) of West Texas: Additional evidence for latitudinal segregation among bony fish in the Western Interior . Cretaceous Research . 139 . 105299 . 10.1016/j.cretres.2022.105299 . 2022CrRes.13905299W . 0195-6671.
45. Schubert . Joseph A. . Wick . Steven L. . Lehman . Thomas M. . January 2017 . An Upper Cretaceous (middle Campanian) marine chondrichthyan and osteichthyan fauna from the Rattlesnake Mountain sandstone member of the Aguja Formation in West Texas . Cretaceous Research . en . 69 . 6–33 . 2017CrRes..69....6S . 10.1016/j.cretres.2016.08.008 . 133098369.
46. Wick . Steven L. . 2021-12-01 . New early Campanian characiform fishes (Otophysi: Characiformes) from West Texas support a South American origin for known Late Cretaceous characiforms from North America . Cretaceous Research . en . 128 . 104993 . 10.1016/j.cretres.2021.104993 . 2021CrRes.12804993W . 0195-6671.