Arundel Formation Explained

Arundel Formation
Type:Geological Formation
Period:Aptian
Prilithology:Clay
Otherlithology:Siderite nodules
Namedfor:Anne Arundel County, Maryland
Namedby:W. B. Clark, 1897[1]
Region:, Washington D. C.
Country:United States
Unitof:Potomac Group
Underlies:Patapsco Formation (Unconformity)
Overlies:Patuxent Formation
Thickness:up to 125feet

The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland[2] of the United States of America. It is of Aptian age (Lower Cretaceous). This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It consists of clay lenses within depressions in the upper part of the Patuxent Formation that may represent oxbow swamp facies.[3] It is named for Anne Arundel County, Maryland.[4]

Vertebrate paleofauna

Dinosaurs

Dinosaurs present include cf. Acrocanthosaurus,[5] [6] the possible ornithischian Magulodon,[5] the poorly known theropods "Allosaurus" medius, "Creosaurus" potens, and "Coelurus" gracilis, the ornithomimosaurian "Dryosaurus" grandis,[7] as well as another indeterminate ornithomimosaurian (though it most likely is Nedcolbertia),[8] the sauropod Astrodon, the nodosaurid Priconodon,[9] a possible basal ceratopsian,[10] and potentially the ornithopod Tenontosaurus.[3] Other vertebrates are not as well known from the formation, but include a freshwater shark, a lungfish,[11] at least three genera of turtles, and at least one crocodilian.[3]

Dinosaurs reported from the Arundel Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Acrocanthosaurus[12] A. cf. atokensis
  • Maryland
"Teeth", "incomplete skeleton"A large carcharodontosaurid theropod. Presence long suspected but uncertain, but confirmed in 2024 following the discovery of more complete remains.
Allosaurus[13] "A." medius
  • Maryland
"Tooth."[14] An indeterminate theropod tooth.
Astrodon[15] A. johnstoni
  • Maryland
  • Washington D.C.[16]
"Tooth."[17]
"Capitalsaurus"[18] "C." potens
  • Washington D.C.
"Vertebra."A neotheropod possibly synonymous with Acrocanthosaurus.[19]
Coelurus"C." gracilis"Manual ungual and teeth."A dromaeosaurid synonymous with Deinonychus.
Creosaurus"C." potensReclassified as "Capitalsaurus" potens
cf. DeinonychusIndeterminate
  • Maryland
A dromaeosaurid
Dryosaurus"D." grandis
  • Maryland
"Limb elements."[20] An indeterminate member of Ornithomimosauria.
Magulodon[21] M. muirkirkensis
  • Maryland
"Tooth"Likely an ornithischian, this genus is a nomen nudum that has not been formally published.
Neoceratopsia indet.Indeterminate
  • Maryland
"Teeth"An indeterminate member of Neoceratopsia. Initially believed to have belonged to an indeterminate member of Dryosauridae or the genus Tenontosaurus.
Ornithomimus"O." affinisJunior synonym of "Dryosaurus" grandis
PleurocoelusP. altus
  • Maryland
"Tibia [and] fibula."[22] Possibly synonymous with Astrodon.
P. nanus
  • Maryland
Possibly synonymous with Astrodon.
PriconodonP. crassus
  • Maryland
"Teeth, tibia."[23] A large nodosaurid.
cf. Tenontosaurus[24] Indeterminate
  • Maryland

Pterosaurs

Unassigned pteradactyloid tracks.[25]

Other fossils

William Bullock Clark (1897) described lignitized trunks of trees often found in upright positions with their roots still intact.[1]

G. J. Brenner (1963) described spores and pollen within the formation.[26]

See also

References

Notes and References

  1. Clark, W.B., 1897, Outline of present knowledge of the physical features of Maryland: Maryland Geological Survey Volume Series, v. 1, pt. 3, p. 172-188. https://openlibrary.org/works/OL1557440W/Outline_of_present_knowledge_of_the_physical_features_of_Maryland
  2. Web site: Geologic Map Legends. Coastal Plain Rocks and Sediments. Maryland Geological Survey. 27 June 2011. https://web.archive.org/web/20110526061259/http://www.mgs.md.gov/esic/geo/lgcp.html. 26 May 2011 . live.
  3. Book: Kranz, Peter M. . 1998 . Mostly dinosaurs: a review of the vertebrates of the Potomac Group (Aptian Arundel Formation), USA . Lucas, Spencer G. . Spencer G. Lucas . Kirkland, James I. . James Kirkland (paleontologist) . Estep, J.W. . Lower and Middle Cretaceous Terrestrial Ecosystems . New Mexico Museum of Natural History and Science Bulletin 14 . 235–238 .
  4. Web site: Geologic Unit: Arundel . National Geologic Map Database . USGS.
  5. Book: Harris, Jerald D. . 1998 . Large, Early Cretaceous theropods in North America . Lucas, Spencer G. . Spencer G. Lucas . Kirkland, James I. . James Kirkland (paleontologist) . Estep, J.W. . Lower and Middle Cretaceous Terrestrial Ecosystems . New Mexico Museum of Natural History and Science Bulletin 14 . 225–228.
  6. Book: Lipka, Thomas R. . 1998 . The affinities of the enigmatic theropods of the Arundel Clay facies (Aptian), Potomac Formation, Atlantic Coastal Plain of Maryland . Lucas, Spencer G. . Spencer G. Lucas . Kirkland, James I. . James Kirkland (paleontologist) . Estep, J.W. . Lower and Middle Cretaceous Terrestrial Ecosystems . New Mexico Museum of Natural History and Science Bulletin 14 . 229–234 .
  7. Brownstein. Chase D.. Redescription of Arundel formation Ornithomimosaur material and a reinterpretation of Nedcolbertia justinhofmanni as an "Ostrich Dinosaur": Biogeographic implications. PeerJ Preprints. e2308v1.
  8. Gilmore. Charles W.. An Ornithomimid Dinosaur in the Potomac of Maryland. Science. 24 October 1919. 50. 1295. 394–395. 10.1126/science.50.1295.394. 17830121. 1919Sci....50..394G.
  9. Book: Weishampel, David B. . David B. Weishampel . Barrett, Paul M.. Coria, Rodolfo A.. Le Loueff, Jean. Xu Xing. Zhao Xijin. Sahni, Ashok. Gomani, Elizabeth M.P.. Noto, Christopher N. . Weishampel, David B. . Dodson, Peter . Osmólska, Halszka . The Dinosauria . limited . 2nd . 2004. University of California Press . Berkeley . 978-0-520-24209-8 . 517–606 . Dinosaur distribution .
  10. Web site: Chinnery. Brenda J.. Lipka. Thomas R.. Kirkland. James I.. Parrish. Michael J.. Brett-Surman. Michael K.. Neoceratopsian teeth from the Lower to Middle Cretaceous of North America. terpconnect.umd.edu/. Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin No. 14. 297-302 pp. . 1998 . March 13, 2019.
  11. Frederickson, J. A., Lipka, T. R., & Cifelli, R. L. (2016). A new species of the lungfish Ceratodus (Dipnoi) from the Early Cretaceous of the eastern USA. Journal of Vertebrate Paleontology, e1136316.
  12. Carrano . Matthew T. . 2024-05-01 . First definitive record of Acrocanthosaurus (Theropoda: Carcharodontosauridae) in the Lower Cretaceous of eastern North America . Cretaceous Research . 157 . 105814 . 10.1016/j.cretres.2023.105814 . 0195-6671.
  13. "3.25 Maryland, United States; 1. Arundel Clay," in Weishampel, et al. (2004). Page 556.
  14. "Table 4.1," in Weishampel, et al. (2004). Page 78.
  15. "3.25 Maryland, United States; 1. Arundel Clay" and "3.34 Washington D. C., United States; 1. Arundel Clay," in Weishampel, et al. (2004). Page 556.
  16. "3.34 Washington D. C., United States; 1. Arundel Clay," in Weishampel, et al. (2004). Page 556.
  17. "Table 13.1," in Weishampel, et al. (2004). Page 270.
  18. Kranz, D. 1998. Mostly Dinosaurs: A Review of the Vertebrates of the Potomac Group (Aptian Arundel Formation), USA, in Lucas, Kirkland and Estep, eds., 1998: 235-238.
  19. Brownstein. Chase D.. 2018. The biogeography and ecology of the Cretaceous non-avian dinosaurs of Appalachia. Palaeontologia Electronica. 1–56. 10.26879/801. free.
  20. "Table 6.1," in Weishampel, et al. (2004). Page 139.
  21. Kranz, P. (1996). Notes on the sedimentary iron ores of Maryland and their dinosaurian faunas. Maryland Geological Survey Special Publications 3:87–115.
  22. "Table 13.1," in Weishampel, et al. (2004). Page 266.
  23. "Table 17.1," in Weishampel, et al. (2004). Page 368.
  24. Listed as "?Tenontosaurus sp." in "3.25 Maryland, United States; 1. Arundel Clay," in Weishampel, et al. (2004). Page 556.
  25. Lockley, M.; Harris, J.D.; and Mitchell, L. 2008. "A global overview of pterosaur ichnology: tracksite distribution in space andtime." Zitteliana. B28. p. 187-198. .
  26. Brenner, Gilbert J., 1963, The spores and pollen of the Potomac Group of Maryland: Maryland Geological Survey Bulletin, no. 27, 215 p. https://www.science.org/doi/abs/10.1126/science.143.3608.795.c

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