Aguja Formation | |
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Stratigraphic range: Lower to Middle Campanian ~ | |
Type | Geological formation |
Unit of | Tornillo Group |
Sub-units | Upper Shale, Terlingua Creek Sandstone, Rattlesnake Mt. Sandstone, Lower Shale & Basal Sandstone Members |
Underlies | Javelina Formation |
Overlies | Pen Formation |
Lithology | |
Primary | Sandstone, conglomerate, claystone |
Other | Mudstone, shale, limestone |
Location | |
Coordinates | 29°18′N103°30′W / 29.3°N 103.5°W |
Approximate paleocoordinates | 35°48′N77°00′W / 35.8°N 77.0°W |
Region | Texas Chihuahua Coahuila |
Country | USA Mexico |
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 Upper 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 Upper 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 Basal 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]
2 fragmentary caudal vertebrae of indeterminate reptiles are known from the Rattlesnake Mountain sandstone member. [8]
Crurotarsans of the Aguja Formation | ||||||
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Genus | Species | Location | Member | Material | Notes | Images |
Crocodilia | Indeterminate | Ten Bits Ranch, west Texas. [8] | Rattlesnake Mountain sandstone member. [8] | Teeth. [8] | A crocodilian. | |
Deinosuchus [9] | D. riograndensis | Texas, [9] Chihuahua, and Coahuila [10] | Osteoderm and mandible fragment | A giant alligatoroid. | ||
cf. D. sp. | West Texas [11] | Lower Shale [11] | Cervical osteoderm (TMM 44068-2). [11] | An alligatoroid. | ||
Goniopholididae | New genus & species | West Texas [11] | Lower Shale [11] | Partial skull & skeleton along with isolated osteoderms & teeth. [11] | May pertain to Denazinosuchus or a related taxon. | |
Phobosuchus [9] | P. riograndensis [9] | Texas, [9] Chihuahua, and Coahuila | Reclassified as a Deinosuchus species | |||
Ornithischians of the Aguja Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Member | Material | Notes | Images |
Agujaceratops | A. mariscalensis | Texas [12] | Low Upper Shale [13] | Formerly considered a species of Chasmosaurus [12] | ||
A. mavericus | West Texas [14] | A chasmosaurine. | ||||
Angulomastacator | A. daviesi | Texas [15] | Upper Shale [15] | A left maxilla. [15] | A lambeosaurine. | |
Ankylosauridae | Indeterminate | Texas [16] | Osteoderms, vertebrae & limb elements. [16] | Remains of an ankylosaurid, possibly represents Euoplocephalus sp. [16] | ||
Aquilarhinus [17] | A. palimentus | Texas [18] | Lower Shale [18] | Formerly referred to Kritosaurus and Gryposaurus. [19] | ||
Ceratopsidae genus & species indeterminate | Indeterminate | West Texas [11] | Lower Shale [11] | Ilia, sacral vertebra & sacral ribs. [11] | May represent Agujaceratops , but undiagnostic. | |
Chasmosaurus [20] | C. mariscalensis [21] | Texas [21] | [Twelve] disarticulated skull (sic), postcrania, juvenile." [22] | 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. [12] | ||
Edmontonia | E. sp [23] | Texas [16] | Osteoderm (TVP 45866-2) & skull (AMNH 3076). [16] | A nodosaurid. | ||
cf. Euoplocephalus [21] | E. sp [21] | Texas [16] | Upper Shale [16] | Osteoderms, sacrum & vertebra (TL-05-14). [16] | An ankylosaurid. | |
Kritosaurus [20] | Indeterminate [20] | Chihuahua [24] | ||||
Malefica | M. deckerti | Texas [25] | Upper Shale [25] | A partial left maxilla. [25] | Formerly referred to Kritosaurus. [25] | |
Nodosauridae genus & species indeterminate | Indeterminate | West Texas [11] | Lower Shale [11] | Isolated & associated osteoderms. [11] | Very similar to osteoderms of Invictarx . | |
Panoplosaurus | P. mirus | Texas [16] | Osteoderm (TMM 45605-4). [16] | A nodosaurid. | ||
Texacephale | T. langstoni | Texas [13] | Low Upper Shale [13] | Two frontoparietal domes. [13] | A pachycephalosaur. | |
Yehuecauhceratops | Y. mudei [26] | Coahuila [27] | A centrosaurine. | |||
Indeterminate ornithomimid remains are known from the Upper Aguja Formation. [28] Indeterminate tyrannosaurid fossils are known from the Upper Aguja Formation of Texas and Mexico. [29]
Theropods of the Aguja Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Member | Material | Notes | Images |
Avialae incertae sedis | West Texas [30] | Lower Shale [30] | 4 teeth (TMM 45947-349, 350, 351). [30] | A bird. | ||
Chirostenotes | C. sp. | Texas [31] | Femur & manual ungual. [31] | A caenagnathid | ||
Dromaeosauridae genus & species indeterminate | Indeterminate | West Texas [11] | Lower Shale [11] | Pedal phalanges (TMM 45909-2, TMM 44066-4). [11] | A dromaeosaur. | |
cf. Dromaeosaurus [32] | Indeterminate [32] | Texas [21] | ||||
Leptorhynchos | L. gaddisi | Texas [31] | Dentaries, caudal vertebra & limb elements. [31] | A caenagnathid | ||
Ornithomimidae | New genus & species | West Texas [11] | Lower Shale [11] | Vertebrae, ischium & limb elements. [11] | An unnamed species referred to informally as the 'Aguja ornithomimid'. | |
cf. Paronychodon | West Texas [30] | Lower Shale [30] | 2 incomplete teeth (TMM 45947-362). [30] | A maniraptoran. | ||
Richardoestesia | R. cf. gilmorei | Texas [33] | Low Upper Shale [33] | Fragment of a small tooth. [33] | A coelurosaur. | |
R. isosceles | Big Bend National Park, Texas [33] | Low Upper Shale [33] | Teeth. [33] | A coelurosaur. | ||
Saurornitholestes | S. cf. langstoni | Texas [30] [33] | Low Upper Shale & Lower Shale [30] [33] | Teeth. [30] [33] | A dromaeosaur. | |
Theropoda incertae sedis | Morphotype A | West Texas [30] | Lower Shale [30] | 8 teeth. [30] | Unserrated, recurved teeth. | |
Morphotype B | West Texas [30] | Lower Shale [30] | 5 tooth crowns. [30] | Bi-serrated teeth. | ||
Morphotype C | West Texas [30] | Lower Shale [30] | 7 teeth. [30] | Finely serrated, distal plication only. | ||
Morphotype D | West Texas [30] | Lower Shale [30] | 5 teeth. [30] | Short, coarsely serrated distal plication. | ||
Morphotype E | West Texas [30] | Lower Shale [30] | A tooth. [30] | Strongly recurved, serrated distal plication. | ||
Morphotype F | West Texas [30] | Lower Shale [30] | 2 tooth fragments. [30] | Medium size, finely serrated plications. | ||
cf. Troodon [34] | Indeterminate [34] | Texas [21] | ||||
Tyrannosauridae | Indeterminate | West Texas [30] [35] | Upper Shale [35] & Lower Shale [11] [30] | Isolated teeth & a handful of non-dental specimens. [30] [35] | A relatively small & gracile tyrannosaurid. [35] | |
Lepidosaurs of the Aguja Formation | ||||||
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Genus | Species | Location | Member | Material | Notes | Images |
Anguidae | Gen. et. sp. indet. | Texas. [36] | Isolated osteoderms & partial right frontal. [36] | An anguid. | ||
Apsgnathus | A. triptodon | Brewster County, Texas. [36] | Jaw elements. [36] | A scincomorph. | ||
Catactegenys | C. solaster | Brewster County, Texas. [36] | Jaw elements & teeth. [36] | A night lizard. | ||
Dryadissector | D. shilleri | West Texas. [30] | Lower Shale. [30] | Numerous isolated teeth. [30] | A varanoid. | |
Mosasauridae | Indeterminate | Ten Bits Ranch. [8] | Rattlesnake Mountain sandstone member. [8] | 1 partial vetebra. [8] | A mosasaur. | |
Odaxosaurus | O. piger | Brewster County, Texas. [36] | Jaw elements. [36] | An anguid. | ||
cf. Parasaniwa | cf. P. wyomingensis | Texas. [36] | Jaw fragments. [36] | A platynotan. | ||
Platynota | Gen. et. sp. indet. | Texas. [36] | Dorsal vertebra (TMM 43057-332). [36] | A platynotan. | ||
?Scincidae | Gen. et. sp. indet. | Brewster County, Texas. [36] | Jaw elements. [36] | A possible skink. | ||
cf. Scincomorpha | Gen. et. sp. indet. | Brewster County, Texas. [36] | Jaw elements. [36] | A scincomorph. | ||
Serpentes | Gen. et. sp. indet. | Texas. [36] | Partial left dentary & right maxilla. [36] | A snake. | ||
cf. Xenosauridae | Texas. [36] | Osteoderms & maxillae. [36] | A knob-scaled lizard. | |||
Testudines of the Aguja Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Member | Material | Notes | Images |
Adocus | A. sp. | Big Bend National Park, Texas. [37] | Upper Shale [37] | Shell fragments. [37] | An adocid. | |
Baenidae | Big Bend National Park, Texas. [37] | Upper Shale [37] | Shell fragments. [37] | 2 morphotypes present (A & B). | ||
Basilemys | B. sp. | Big Bend National Park, Texas. [37] | Upper Shale & Lower Shale [11] [37] | Shell fragments, partial plastron & leg scutes. [11] [37] | A nanhsiungchelyid. | |
Bothremydidae genus & species indeterminate | Indeterminate | West Texas [11] | Lower Shale [11] | Isolated peripheral bones (TMM 44068-1, 42452-8); costal bones (TMM 44064-6). [11] | A bothremydid, compatible with Chupacabrachelys . | |
Chupacabrachelys | C. complexus | Big Bend, Texas. [38] | Base of the Upper Shale [38] | A complete skull, and a nearly complete skeleton. [38] | A bothremydid. | |
cf. Denazinemys | cf. D. sp. | West Texas [11] | Lower Shale [11] | Shell elements. [11] | A baenid. | |
cf. Helopanoplia | Big Bend National Park, Texas. [37] | Upper Shale [37] | Shell fragments. [37] | A softshell turtle. | ||
cf. Hoplochelys | Big Bend National Park, Texas. [37] | Upper Shale [37] | Shell fragments. [37] | A kinosternoid. | ||
Terlinguachelys | T. fischbecki | Big Bend National Park, Texas [39] | Rattlesnake Mountain Sandstone [39] | A large, incomplete specimen. [39] | A protostegid. | |
Testudines indeterminate [8] | Morphotype 1 [8] | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | A shell fragment. | ||
Morphotype 2 [8] | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | A shell fragment. | |||
Morphotype 3 [8] | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | A shell fragment. | |||
Morphotype 4 [8] | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | A shell fragment. | |||
Trionychidae | Gen. et. sp. indet. | Big Bend National Park, Texas. [37] | Upper Shale & Lower Shale [11] [37] | Costal bone (TMM 44068-4) & shell fragments. [37] | A softshell turtle. | |
Approximately 75 whole and broken fragments of coprolites are known from the Rattlesnake Mountain sandstone member, presumably from bony fish. [8]
Bony fish of the Aguja Formation | ||||||
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Genus | Species | Location | Member | Material | Notes | Images |
Albula | A. sp. | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | Over 390 complete and fragmentary teeth. [40] | A bonefish. | |
?Enchodus | ?E. sp. | Ten Bits ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 2 abraded teeth. [40] | An aulopiform. | |
Eotexachara | E. malateres | West Texas [41] | Dentaries. [41] | A characiform. | ||
Lepidotes | ?L. sp. | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | Approximately 109 complete and fragmentary teeth. [40] | A lepidotid. | |
Melvius | M. sp. | West Texas [11] | Lower Shale [11] | Vertebrae. [11] | An amiid. | |
Osteichthyes | Indeterminate species A | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | 11 complete teeth. | ||
Indeterminate species B | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | 8 complete and fragmentary teeth. | |||
Indeterminate species C | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | 1 complete tooth. | |||
Indeterminate species D | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | 1 complete and 1 partial tooth. | |||
Indeterminate | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | Approximately 475 complete and fragmentary teleost centra. [40] | |||
Paralbula | P. casei | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | Approximately 900 complete and fragmentary teeth and tooth caps. [40] | ||
Primuluchara | P. laramidensis | West Texas [41] | Dentaries. [41] | A characiform. | ||
Stephanodus | ?S. sp. | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 21 whole and fragmentary specimens. [40] | A pycnodont. | |
Cartilaginous fish of the Aguja Formation | ||||||
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Genus | Species | Location | Member | Material | Notes | Images |
Brachyrhyzodus | B. wichitaensis | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 11 complete teeth. [40] | ||
Cantioscyllium | C. aff. meyeri | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 1 anterior tooth and 5 lateral teeth. [8] | A nurse shark. | |
Chiloscyllium | C. aff. greeni | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] | Approximately 90 abraded and fragmentary teeth. [40] | A bamboo shark. | |
Chondrichthyes [8] | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | 23 placoid scales and 69 dermal scales. | 4 morphotypes of placoid scales (A to D) present. | ||
Columbusia | C. sp. | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 20 complete & fragmentary teeth. [40] | A wobbegong. | |
Cretalamna | C. appendiculata | Ten Bits Ranch, west Texas. [8] | Rattlesnake Mountain sandstone member. [8] | 3 fragmentary teeth. [8] | Reassigned to C. cf. C. sarcoportheta. [40] | |
C. cf. C. sarcoportheta | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 3 incomplete teeth & fragments of additional teeth. [40] | Originally reported as C. appendiculata. | ||
Cretorectolobus [8] | C. olsoni | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | "20 complete and fragmentary teeth". | A carpet shark. | |
Hybodontidae genus & species indeterminate | Indeterminate | West Texas [11] | Lower Shale [11] | Fragment of a dorsal fin spine (TMM 42536-10). [11] | A hybodont. | |
Hybodus [8] | H. sp. | Ten Bits Ranch. | Rattlesnake Mountain sandstone member. [8] | 2 specimens, one complete and one partial tooth. | A hybodont. | |
Igdabatis | I. indicus? | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | A single incomplete tooth. [8] [40] | A myliobatid. | |
Ischyrhiza | I. cf. avonicola | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 5 complete and fragmentary rostral teeth. [40] | A sawskate. | |
I. mira | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 11 fragmentary rostral teeth and 230 whole and fragmentary oral teeth. [40] | A sawskate. | ||
Lonchidion | L. selachos | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 4 complete and 5 fragmentary teeth. [8] [40] | A hybodont. | |
Meristodon | M. sp. | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 2 teeth. [40] | A hybodont. | |
Myliobatiformes | Incertae sedis | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 3 complete specimens. [40] | ||
Protoplatyrhina | P. renae | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] | 70 complete and fragmentary teeth. [40] | A hypsobatid. | |
Ptychotrygon | P. agujaensis | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | Over 690 complete and fragmentary teeth. [40] | A sawskate. | |
P. triangularis | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | Over 170 complete and fragmentary teeth. [40] | A sawskate. | ||
P. aff. cuspidata | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | 7 whole and fragmentary teeth. [40] | A sawskate. | ||
P. sp. | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | One complete tooth (TMM 46018-71). [40] | A sawskate. | ||
Rhinobatos | R. casieri | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | "14 complete and fragmentary specimens". | A guitarfish. | |
R. sp. | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 18 complete & fragmentary specimens. [40] | A guitarfish. | ||
Rhombodus | R. levis | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | Over 22 complete and fragmentary teeth. [40] | A rajiforme. | |
Scapanorhynchus | S. texanus | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | Over 800 complete and fragmentary teeth. [40] | A mitsukurinid. | |
Sclerorhynchidae | Morphotype 1 | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [8] | One fragmentary rostral spine (TMM 46018-59). [40] | A sawskate. | |
Morphotype 2 | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [8] | One fragmentary rostral spine (TMM 46018-60). [40] | A sawskate. | ||
Morphotype 3 | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [8] | 3 fragmentary rostral teeth. [40] | A sawskate. | ||
Morphotype 4 | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [8] | 27 fragmentary rostral spines. [40] | A sawskate. | ||
Serratolamna | S. cf. S. caraibaea | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | About 34 teeth. [40] | A mackerel shark. | |
Squalicorax | S. kaupi | Ten Bits Ranch, west Texas. [8] [40] | Rattlesnake Mountain sandstone member. [8] [40] | "26 complete and fragmentary anterior and lateral teeth". | An anacoracid. | |
S. aff. S. lindstromi | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 4 specimens. [40] | An anacoracid. | ||
S. pristodontus | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | 2 specimens. | An anacoracid. | ||
S. aff. S. yangaensis | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 4 complete & several fragmentary teeth. [40] | An anacoracid. | ||
Squatina | S. hassei | Ten Bits Ranch, west Texas. [8] | Rattlesnake Mountain sandstone member. [8] | A single complete specimen. | An angelshark. | |
S. sp. | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | A complete tooth & 2 fragmentary teeth. [40] | An angelshark. | ||
Texatrygon | T. cf. T. copei | Ten Bits Ranch, west Texas. [40] | Rattlesnake Mountain sandstone member. [40] | 4 complete & fragmentary teeth. [40] | A sawskate formerly reported as T. hooveri. | |
T. hooveri | Ten Bits Ranch, west Texas. | Rattlesnake Mountain sandstone member. [8] | 4 complete and fragmentary specimens. [8] | Reassigned to T. cf. T. copei. |
Ammonites of the Aguja Formation | ||||||
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Genus | Species | Location | Member | Abundance | Notes | Images |
Baculites | B. mclearni |
| ||||
Hoplitoplacenticeras | H. plasticum | Rattlesnake Mountain Sandstone | ||||
Pachydiscus | P. paulsoni | Rattlesnake Mountain Sandstone | ||||
Color key
| Notes Uncertain or tentative taxa are in small text; |
Pachycephalosauria is a clade of ornithischian dinosaurs. Along with Ceratopsia, it makes up the clade Marginocephalia. With the exception of two species, most pachycephalosaurs lived during the Late Cretaceous Period, dating between about 85.8 and 66 million years ago. They are exclusive to the Northern Hemisphere, all of them being found in North America and Asia. They were all bipedal, herbivorous/omnivorous animals with thick skulls. Skulls can be domed, flat, or wedge-shaped depending on the species, and are all heavily ossified. The domes were often surrounded by nodes and/or spikes. Partial skeletons have been found of several pachycephalosaur species, but to date no complete skeletons have been discovered. Often isolated skull fragments are the only bones that are found.
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".
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 83.5 ± 0.7 Ma and 70.6 ± 3.4 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 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 Wapiti Formation is a geological formation of the Western Canada Sedimentary Basin in northwestern Alberta, and northeastern British Columbia, Canada. Its deposition spanned the time interval from the lower Campanian through to the upper Maastrichtian, between approximately 80 and 68 Ma. It was named by G.M. Dawson in 1881, presumably for exposures along the lower part of the Wapiti River and downstream along the Smoky River in Alberta.
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 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 El Picacho Formation is a geological formation in Texas, United States, whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation. The paleosols found here are rich in clay, calcite, and rhizoliths which show that during the Cretaceous period, this fossil formation, just like the neighboring Javelina Formation and Aguja Formation, was a fluvial flood plain.
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.
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.
Yehuecauhceratops is a genus of horned centrosaurine ceratopsid dinosaur from the Late Cretaceous of Coahuila, Mexico. It contains a single species, Y. mudei, described from two partial specimens by Rivera-Sylva et al. in 2016 and formally named by Rivera-Sylva et al. in 2017. It was a small centrosaurine with a body length of 3 metres (9.8 ft), making it smaller than Agujaceratops and Coahuilaceratops, the other two ceratopsids in its environment; the three may have been ecologically segregated. A ridge bearing a single roughened projection near the bottom of the squamosal bone, which probably supported a small horn, allows Yehuecauhceratops to be distinguished from other centrosaurines. Its affinities to nasutoceratopsin centrosaurines, such as Avaceratops and Nasutoceratops, are supported by various morphological similarities to the former.
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.