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. 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 FormationWoodward, H. N. (2005). Bone histology of the sauropod dinosaur Alamosaurus sanjuanensis from the Javelina Formation, Big Bend National Park, Texas.), dated to 66 Ma ago. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 574-588. .

Age The typical age range of the Javelina Formation has been difficult to determine. In 2006, the middle portion of the Javenila Formation about below the K-Pg boundary was dated to million years ago by Lehman and colleagues. Using this date, in correlation with a measured age from the underlying Aguja Formation and the likely location of the K-Pg boundary in the overlying Black Peaks Formation, the authors argued that the Alamosaurus fauna seems to have lasted from about 70–66 million years ago, with the earliest records of Alamosaurus near the base of the Javelina Formation and the latest just below the K-Pg boundary in the Black Peaks Formation. However, Leslie et al. (2018) and Lehman et al. (2022) later corrected this age estimate, since the dinosaur fossils are actually known from the upper portion of the Javelina Formation. The K-Pg boundary of the Javelina Formation is known to be at the ~ level, and the youngest-known Alamosaurus fossil-bearing locality (TxVP 42426, incorrectly referred to TMM 41450 by Leslie et al. and subsequently corrected by Lehman et al.) is known from the top of the sandstone unit at ~ level, approximately ~ below the K-Pg boundary. With dating based on magnetostratigraphy constraining the maximum depositional age of the dinosaur fossil-bearing section at approximately 66.4 million years ago, the Alamosaurus fauna can be dated to the latest Maastrichtian age.

Fossil content

Vertebrate paleofauna Dinosaurs Ankylosaurs Vertebrates of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Ankylosauria indet. Indeterminate Upper Fragmentary remains of an unnamed ankylosaurNodosauridae Indet.IndeterminateAn undescribed nodosaurid.

Ceratopsians

Vertebrates of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Bravoceratops B. polyphemus A chasmosaurine ceratopsid known from the lowermost part of the Javelina Formation which dates back to the early Maastrichtian. Chasmosaurinae indet. Indeterminate Lower and Upper Dentary and horncore Multiple remains of indeterminate chasmosaurines. The horncore and dentary are stated as being similar in size to Triceratops. The horncore comes from the Lower Javelina Formation and the dentary comes from the Upper Javelina Formation. Torosaurus T. cf. utahensis A chasmosaurine ceratopsid whose remains have been found in the Frenchman Formation, Hell Creek Formation, North Horn Formation, McRae Formation, and Lance Formation. Ceratopsidae indet. IndeterminateUppermostSyncervicalA large indeterminate ceratopsid, only diagnostic to Ceratopsidae.

Hadrosaurs Hadrosaurs of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Gryposaurus? G.? alsatei Upper 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. Kritosaurus K. cf. navajovius A saurolophine hadrosaurid, 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. Fossils have also been unearthed in the Olmos Formation. Saurolophinae indet. Indeterminate A saurolophine handrosaurid similar to the genus Saurolophus.

Sauropods Sauropods of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Alamosaurus A. sanjuanensis Upper A titanosaurian sauropod, also from the Ojo Alamo Formation

Theropods Theropods of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Ornithomimidae indet. Indeterminate Upper Fragmentary remains of an unnamed ornithomimidhttps://www.researchgate.net/publication/234025996_Dinosaur_Distribution Saurornitholestes S. cf. langstoni A dromaeosaurid Troodontidae indet. Indeterminate A troodontid Tyrannosaurus Identified as either cf. T. sp. or T. rex Upper 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. Tyrannosauridae Indet.IndeterminateUpperHindlimb and metatarsal material. Estimated as 75% the size of Sue the T. rex. Possibly a sub-adult Tyrannosaurus or Small bodied taxon.

Pterosaurs Pterosaurs of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Quetzalcoatlus Q. northropi Upper An azhdarchid pterosaur Q. lawsoni Wellnhopterus W. brevirostris An azhdarchid pterosaur

Turtles Fish of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Trionychidae indet. Indeterminate Indeterminate turtle remains

Fish

Fish of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images Dasyatis Unknown A ray Rhombodus Unknown A ray

Flora Woody dicots and angiosperms have been unearthed in this formation. Plant fossils indicate that this area was a woodland habitat. Flora of the Javelina Formation Genus Species Location Stratigraphic position Material Notes Images JavelinoxylonJacobs, L. 1995. Lone Star Dinosaurs. Texas A&M University Press. p.102 J. multiporosum A dicotyledonous tree

Javelina Formation

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