Most of the North American dinosaurs are known from Laramidia - the sub-continent western to the Western Interior Sea. From Appalachia, far less dinosaurs are known. However, looking at maps, Appalachia was bigger in area while Laramidia was a relatively narrow band stretching from Alaska to south Mexico.

Map from Wikipedia

Why there are more dinosaurs known from Laramidia and not from Appalachia?

I can think of several reasons:

  1. Laramidia had richer dinosaur fauna indeed. Then I ask: why?
  2. Discovery bias - West America has better sites for digging fossils: wide open badlands without obstructions such as forests and vast construction, which prevent digging.
  3. Preservation bias - Laramidia had better conditions for preserving fossils.
  • $\begingroup$ I'm no expert, but I think from my readings (possibly from reading Mark Jaffe's The Gilded Dinosaur) it's #2 almost entirely. $\endgroup$
    – bob1
    Commented Feb 14 at 21:52

1 Answer 1


Its not, there are just more trees over Appalachia.

its easier to find fossil in dry climates which have more exposed bedrock and sedimentary rock. We find plenty of fossils in Appalachia just mostly in mines and other large scale excavation. Any place with little to no vegetation is best.

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If you want to know why arid climates are better for finding fossils, there is an existing question about that.



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