Appalachia (landmass)

For other uses, see Appalachia (disambiguation).

Map of North America during the Campanian

During most of the Late Cretaceous (100.5 to 66 million years ago) the eastern half of North America formed Appalachia (named for the Appalachian Mountains), an island land mass separated from Laramidia to the west by the Western Interior Seaway. This seaway had split North America into two massive landmasses due to a multitude of factors such as tectonism and sea-level fluctuations for nearly 40 million years.[1][2] The seaway eventually expanded, divided across the Dakotas, and by the end of the Cretaceous,[3] it retreated towards the Gulf of Mexico and the Hudson Bay.

This left the island masses joined in the continent of North America as the Rocky Mountains rose.[4] From the Cenomanian to the end of the Campanian ages of the Late Cretaceous, Appalachia was separated from the rest of North America. As the Western Interior Seaway retreated in the Maastrichtian, Laramidia and Appalachia eventually connected.[5] Because of this, its fauna was isolated, and developed very differently from the tyrannosaur, ceratopsian, hadrosaurid, pachycephalosaur and ankylosaurid dominated fauna of the western part of North America, known as "Laramidia".[6]

Due to high sea levels, subsequent erosion,[7] and the lack of orogenic input of sediment into the Western Interior Seaway unlike the east coast of Laramidia, no terrestrially formed deposits have survived, with most dinosaur remains originating from seaborne carcasses that were transported into marine environments. This same lack of terrestrial sediments is also present on the western coast of Laramidia. Some sediments in the northern part of the range have been removed by glacial erosion of the Laurentide Ice Sheet during Quaternary glaciations,[8] but it is difficult to ascertain how much sediment has been removed, or whether these sediments would have been any more productive than those that remain. Thus relatively little is known about Appalachia in comparison to Laramidia, with the exception of plant life, marine life and the insects trapped in amber from New Jersey.

In addition, due to a lack of interest in Appalachia, many fossils that have been found in Appalachia lie unstudied and remain in the inaccurate genera to which they were assigned in the days of E. D. Cope and O. C. Marsh. Only a few fossils of the terrestrial creatures that were found in this region have given us a brief glimpse into what life was like here during the Cretaceous period. However, the area has seen a bit of a resurgence of interest due to several discoveries made in the past few years.[9][10][11][12][13] As mentioned earlier, not much is known about Appalachia, but some fossil sites, such as the Woodbine Formation, Navesink Formation,[14] Ellisdale Fossil Site,[15] Mooreville Chalk Formation, Demopolis Chalk Formation, Black Creek Group and the Niobrara Formation,[16] together with ongoing research in the area,[17] have given us a better look into this forgotten world of paleontology.

  1. ^ Nielsen, Karsten Schjødt; Schröder-Adams, Claudia J.; Leckie, Dale A.; Haggart, James W.; Elberdak, Khalifa (December 2008). "Turonian to Santonian paleoenvironmental changes in the Cretaceous Western Interior Sea: The Carlile and Niobrara formations in southern Alberta and southwestern Saskatchewan, Canada". Palaeogeography, Palaeoclimatology, Palaeoecology. 270 (1–2): 64–91. Bibcode:2008PPP...270...64N. doi:10.1016/j.palaeo.2008.08.018.
  2. ^ Bertog, Janet (2010). "Stratigraphy of the Lower Pierre Shale (Campanian): Implications for the Tectonic and Eustatic Controls on Facies Distributions". Journal of Geological Research. 2010: 1–15. doi:10.1155/2010/910243.
  3. ^ Erickson, J. Mark (December 1999). "The Dakota Isthmus – Closing the Late Cretaceous Western Interior Seaway". North Dakota Academy of Science Proceedings. 53: 124–129. Retrieved 15 June 2019.
  4. ^ Weishampel, David B.; Young, Luther (1996). Dinosaurs of the East Coast. Baltimore, MD.: Johns Hopkins University Press. ISBN 9780801852169.
  5. ^ Stanley, Steven M. (1999). Earth System History. New York: W.H. Freeman and Company. pp. 487–489. ISBN 978-0-7167-2882-5.
  6. ^ Brownstein, Chase D. (February 2018). "The biogeography and ecology of the Cretaceous non-avian dinosaurs of Appalachia". Palaeontologia Electronica. 21 (1.5A): 1–56. doi:10.26879/801.
  7. ^ Liu, Lijun (15 June 2014). "Rejuvenation of Appalachian topography caused by subsidence-induced differential erosion". Nature Geoscience. 7 (7): 518–523. Bibcode:2014NatGe...7..518L. doi:10.1038/ngeo2187. ISSN 1752-0894.
  8. ^ Braun, Duane D. (September 1989). "Glacial and periglacial erosion of the Appalachians". Geomorphology. 2 (1–3): 233–256. Bibcode:1989Geomo...2..233B. doi:10.1016/0169-555X(89)90014-7.
  9. ^ Uren, Adam. "Dinosaurs in Minnesota: Fossil claw found in Iron Range has scientists excited". Bring Me the News. Retrieved 10 October 2015.
  10. ^ Sawyer, Liz. "Fossil adds to evidence of dinosaurs in Minnesota". Star Tribune. Retrieved 8 October 2015.
  11. ^ "Fossil finds behind N.J. strip mall causing excitement". CBS Evening News. 16 November 2014. Retrieved 16 November 2014.
  12. ^ Anonymous. "Rare fossil of a horned dinosaur found from 'lost continent'". University of Bath News. University of Bath. Retrieved 30 November 2015.
  13. ^ Anderson, Natali (26 January 2016). "Eotrachodon orientalis: New Duck-Billed Dinosaur Species Discovered". Science News.com. Science News. Retrieved 26 January 2016.
  14. ^ Kennedy, William J.; Landman, Neil H.; Cobban, William Aubrey; Johnson, R.O. (13 December 2000). "Additions to the ammonite fauna of the Upper Cretaceous Navesink Formation of New Jersey". American Museum Novitates: 31. hdl:2246/2008.
  15. ^ Gallagher, W.B. (1997). When Dinosaurs Roamed New Jersey. New Brunswick, NJ: Rutgers University Press. ISBN 9780813523484.
  16. ^ "Oceans of Kansas".
  17. ^ Brownstein, Chase (17 January 2018). "The biogeography and ecology of the Cretaceous non-avian dinosaurs of Appalachia". Palaeontologia Electronica. 21 (1.5a): 1–56. doi:10.26879/801.