Javelina 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.^[1] 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 (in the overlying Black Peaks Formation^[1]), dated to 66 Ma ago.^[2] Dinosaur remains are among the fossils that have been recovered from the formation.^[3]

Javelina Formation
Stratigraphic range: Maastrichtian, 70–66.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Distinctive mauve and red beds of the Javelina Formation outcropping in Big Bend National Park, Texas
Type	Geological formation
Unit of	Tornillo Group
Underlies	Black Peaks Formation
Overlies	Aguja Formation
Lithology
Primary	Sandstone
Other	Claystone, mudstone, siltstone, conglomerate
Location
Coordinates	29.3°N 103.4°W / 29.3; -103.4
Approximate paleocoordinates	36.0°N 82.8°W / 36.0; -82.8
Region	Texas
Country	United States
Type section
Named for	Javelina
Javelina Formation (the United States) Show map of the United States Javelina Formation (Texas) Show map of Texas

Age

The typical age range of the Javelina Formation has been difficult to determine.^[4] Only one geological site in the Javelina Formation has thus far yielded the correct rock types for radiometric dating. The outcrop, situated in the middle strata of the formation about 90 meters below the K-Pg boundary and within the local range of Alamosaurus fossils and below two sites that have yielded Quetzalcoatlus fossils, was dated to 69.0 plus or minus 0.9 million years old in 2010.^[2] Indeterminate chasmosaurinae fossils have also been as well.^[5]

Fossil content

Vertebrate paleofauna

Vertebrates of the Javelina Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Alamosaurus	A. sanjuanensis				A titanosaurian sauropod, also from the Ojo Alamo Formation
Bravoceratops	B. polyphemus				A chasmosaurine ceratopsid known from the lowermost part of the Javelina Formation which dates back to the early Maastrichtian.[6]
Dasyatis[7]	Unknown				A ray
Gryposaurus?[8]	G.? alsatei[8]				A saurolophine hadrosaurid known from the Two Medicine Formation, the Dinosaur Park Formation, the Kaiparowits Formation, possible remains have also been unearthed in the El Picacho Formation.[9]
Kritosaurus[8][10][11][12]	K. cf. navajovius[8][13][12][11]				A saurolophine handrosaurid, also known from the Kirtland Formation, Aguja Formation, Ojo Alamo Formation and the El Picacho Formation. A possible second species of Kritosaurus might have lived in the Javelina Formation.[8][12] Fossils have also been unearthed in the Olmos Formation.[14]
Quetzalcoatlus	Q. northropi and Q. lawsoni[15]				An azhdarchid pterosaur
Rhombodus[7]	Unknown				A ray
Saurornitholestes[16]	S. cf. langstoni				A dromaeosaurid
Saurolophinae[8]	Indeterminate[8]				A saurolophine handrosaurid similar to the genus Saurolophus.
Torosaurus[17]	T. cf. utahensis[17]				A chasmosaurine ceratopsid whose remains have been found in the Frenchman Formation, Hell Creek Formation, North Horn Formation, McRae Formation, and Lance Formation.
Troodontidae	Indeterminate[18]				A troodontid
cf. Tyrannosaurus	Indeterminate[19]				A tyrannosaurid, originally identified from the Hell Creek Formation. Also found in the Denver, Ferris, Frenchman, Lance, Livingston, North Horn, Scollard, and Willow Creek Formations.[20]
Trionychidae	Indeterminate				Indeterminate turtle remains
Wellnhopterus[15]	W. brevirostris				An azhdarchid pterosaur.

Flora

Woody dicots and angiosperms have been unearthed in this formation.^[21][22] Plant fossils indicate that this area was a woodland habitat.^[23]

Flora of the Javelina Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Javelinoxylon[24]	J. multiporosum[25]				A dicotyledonous tree

See also

• List of dinosaur-bearing rock formations
• List of fossiliferous stratigraphic units in Texas
• Paleontology in Texas
• Cretaceous Texas
• Corsicana Marl
• El Picacho Formation
• Escondido Formation
• Kemp Clay
• Nacatoch Sand
• Neylandville Marl