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  • 21 Aug, 2019

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Aguja 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. Fossil palms have also been unearthed here.

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. 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. 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. 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.

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.

Ornithischians

Ornithischians of the Aguja Formation
Genus Species Location Member Material Notes Images
Agujaceratops A. mariscalensis Texas Lower Alto Shale Formerly considered a species of Chasmosaurus
A. mavericus West Texas Middle Alto Shale A chasmosaurine.
Angulomastacator A. daviesi Texas Middle Alto Shale A left maxilla. A lambeosaurine.
Ankylosauridae Indeterminate Texas Lower Alto Shale Osteoderms, vertebrae & limb elements. Remains of an ankylosaurid, possibly represents Euoplocephalus sp.
Aquilarhinus A. palimentus Texas Middle Abajo Shale Partial skeleton Formerly referred to Kritosaurus and Gryposaurus.
Ceratopsidae genus & species indeterminate Indeterminate West Texas Middle Abajo Shale Ilia, sacral vertebra & sacral ribs. May represent Agujaceratops, but undiagnostic.
Chasmosaurus C. mariscalensis Texas [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.
Edmontonia E. sp 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 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 Middle Alto Shale Frontal A pachycephalosaur, represents a new unnamed species
Texacephale T. langstoni Texas Lower Alto Shale Two frontoparietal domes. A pachycephalosaur.
Yehuecauhceratops Y. mudei Coahuila A centrosaurine.

Theropods

Indeterminate ornithomimid remains are known from the Upper Aguja Formation. Indeterminate tyrannosaurid fossils are known from the Upper Aguja Formation of Texas and Mexico.

Theropods of the Aguja Formation
Genus Species Location Member Material Notes Images
Avialae incertae sedis West Texas Middle Abajo Shale 4 teeth (TMM 45947-349, 350, 351). A bird.
Chirostenotes C. sp. Texas 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 Indeterminate Texas
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 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, Teeth can belong to different taxa.
S. langstoni Coahuila 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 Indeterminate Texas
Tyrannosauridae Indeterminate West Texas 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

Sauropods

Indeterminate titanosaurid remains are known from the Upper Aguja Formation of Mexico.

Sauropods of the Aguja Formation
Genus Species Location Member Material Notes Images
Titanosauridae Indeterminate Chihuahua Four partial posterior caudal vertebrae & dorsal or sacrocaudal vertebra A relatively massive titanosaurid.

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 D. riograndensis Texas, Chihuahua, and Coahuila Upper Shale Multiple partial skulls & skeletons accounting for nearly the entire skeleton minus the tail. A giant alligatoroid.
cf. D. sp. West Texas 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. 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. 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 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. 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 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. 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. 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 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.
Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

See also

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. doi:10.1086/653688. ISSN 1058-5893. S2CID 84762968.
  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. Bibcode:2017PLoSO..1288426F. doi:10.1371/journal.pone.0188426. ISSN 1932-6203. PMC 5699823. PMID 29166406.
  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. 8: e9251. doi:10.7717/peerj.9251. ISSN 2167-8359. PMC 7278894. PMID 32547873.
  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" (PDF). Journal of Systematic Palaeontology. 18 (6): 461–498. Bibcode:2020JSPal..18..461P. doi:10.1080/14772019.2019.1625078. ISSN 1477-2019. S2CID 202018197.
  8. ^ Schubert, Joseph (May 2013). Elasmobranch and osteichthyan fauna of the Rattlesnake Mountain Sandstone, Aguja Formation (Upper Cretaceous; Campanian), West Texas (Thesis thesis).
  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" (PDF). Geosphere. 20 (3): 825–879. doi:10.1130/ges02662.1. ISSN 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. 15 (8): 641–674. Bibcode:2017JSPal..15..641L. doi:10.1080/14772019.2016.1210683. ISSN 1477-2019. S2CID 88907183.
  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. 29 (2): 605–611. Bibcode:2009JVPal..29..605W. doi:10.1671/039.029.0208. ISSN 0272-4634. S2CID 128555861.
  13. ^ West, Bryanna (2020). Campanian-Maastrictian Ankylosaurs of West Texas (PDF) (Thesis). 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. 12 (2): 133–175. Bibcode:2014JSPal..12..133P. doi:10.1080/14772019.2013.770417. ISSN 1477-2019. S2CID 84942579.
  16. ^ 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. Bibcode:2019CrRes..99..291L. doi:10.1016/j.cretres.2019.02.028. ISSN 0195-6671. S2CID 135044927.
  17. ^ "Dinosaur distribution (Texas and Chihuahua)." Weishampel, et al. (2004). Page 582 and 588.
  18. ^ "Dinosaur distribution (Late Cretaceous; North America; Texas)." Weishampel, et al. (2004). Page 582.
  19. ^ "Table 23.1," in Weishampel, et al. (2004). Page 496.
  20. ^ Listed as Edmontonia cf. rugosidens in "Dinosaur distribution (Late Cretaceous; North America; Texas).", Weishampel et al., 2004, p.582
  21. ^ 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. 143: 105416. doi:10.1016/j.cretres.2022.105416. ISSN 0195-6671. S2CID 253470207.
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