Twin Mountains Formation

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Twin Mountains Formation
Stratigraphic range: Early Cretaceous
Type Geological formation
Unit of Trinity Group
Underlies Glen Rose Formation
Thickness 150 ft (46 m)
Region North America

The Twin Mountains Formation, also known as the Twin Mountain Formation, is a sedimentary rock formation, within the Trinity Group, found in Texas of the United States of America. It is a terrestrial formation of Aptian age (Lower Cretaceous), and is notable for its dinosaur fossils. Dinosaurs from this formation include the large theropod Acrocanthosaurus, the sauropod Sauroposeidon, and the ornithopod Tenontosaurus.[1] [2] It is the lowermost unit of the lower Cretaceous, lying unconformably on Carboniferous strata. It is overlain by the Glen Rose Formation. It is the lateral equivalent of the lower part of the Antlers Formation.[3]



  1. ^ Weishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loueff, Jean; Xu Xing; Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth M.P.; Noto, Christopher N. (2004). "Dinosaur distribution". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka. The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 517–606. ISBN 0-520-24209-2. 
  2. ^ Rose, Peter J. (2007). "A new titanosauriform sauropod (Dinosauria: Saurischia) from the Early Cretaceous of central Texas and its phylogenetic relationships" (web pages). Palaeontologia Electronica. 10 (2). 
  3. ^ "Geologic Unit: Twin Mountains". National Geologic Map Database. USGS. Retrieved 31 May 2014. 
  4. ^ a b c d e f g h Weishampel, David B; et al. (2004). "Dinosaur distribution (Early Cretaceous, North America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 553-556. ISBN 0-520-24209-2.
  5. ^ "Table 19.1," in Weishampel, et al. (2004). Page 414.