Geographic setting of the Merchantville dinosaur fauna: (a) map of North American during the Campanian stage of the Late Cretaceous epoch, showing the location of New Jersey and Delaware; (b) map of New Jersey and Delaware showing the locations from which the described specimens were recovered; (c) diagram showing preserved bones (in white) and relative sizes of (from left to right) the tyrannosaur and the hadrosaurid (adult, juvenile). Image credit: Chase Doran Brownstein, doi: 10.1098/rsos.210127.
SciNews has a post about two new dinosaurs from Allalachia during the Cretaceous Period. Back in the Cretaceous Period, North America was bisected by the Western Interior Seaway. In the west was Laramidia for which the fossil record is very rich. The land mass to the east is called Appalachia. Much less is know about Appalachian dinosaurs as conditions for fossil preservation weren't ideal. A paper in the journal Royal Society Open Science discusses that and introduces a tyranosaur from New Jersey, Drytosaurus, and a hadrosaur.
For most of the second half of the Cretaceous period, North America was divided into two land masses, Laramidia in the West and Appalachia in the East, with the Western Interior Seaway separating them.
While famous dinosaur species like Tyrannosaurus rex and Triceratops lived throughout Laramidia, much less is known about the animals that inhabited Appalachia.
“One reason is that Laramidia’s geographic conditions were more conducive to the formation of sediment-rich fossil beds than Appalachia’s,” said Brownstein, author of a paper published in the journal Royal Society Open Science.
The specimens he examined were collected in the 1970s from the Late Cretaceous Merchantville Formation in New Jersey and Delaware.
“These specimens illuminate certain mysteries in the fossil record of eastern North America and help us better understand how geographic isolation affected the evolution of dinosaurs,” Brownstein said.
