Around 90 million years ago, eastern and western North America were isolated from each other by a salty sea, creating two landmasses: Appalachia and Laramidia. The ancestors of Triceratops and Tyrannosaurus strutted about on the latter in what would one day become Utah and Alberta, leaving plentiful bones behind. A lack of fossils from eastern North America, however, has obscured Appalachia, leading to it being called a ‘lost landmass.’ Now, new research is broadening our knowledge of the dinosaurs that lived and died near the major metropolises of the eastern United States and Canada.
Dinosaurs from eastern North America have always been regarded as rather strange by scientists.
One relative of Tyrannosaurus rex from New Jersey has gigantic hands tipped with giant claws, a far cry from the notoriously puny arms of its western cousin. Giant duck-billed dinosaurs, more than 35 feet long from beak to tail, left their remains in the sediments of North Carolina.
All named eastern North American dinosaurs are known only from incomplete or fragmentary skeletons. Unlike the world-class fossil deposits of the American West, eastern North American sediments usually produce only the stray bone shard or tooth.
Unfortunately, this lack of fossils from eastern North America has hindered attempts at better understanding the distribution and evolution of dinosaurs during a period known as the Cretaceous, which lasted from about 140-65 million years ago.
The paleontologist tallied up reports of dinosaurs from across the eastern part of the continent as presented in publications spanning over 150 years of scientific inquiry.
“This is, to my knowledge, the most complete review of eastern North American dinosaurs out there,” he said.
Additionally, Brownstein compared the compiled Appalachian dinosaur faunas to each other and to those from the American West to understand how the former changed from the latter during the 30 million year period of their separation.
The results suggest that eastern North American dinosaur faunas were not only distinct from those of the west, but also that the former were by-and-large composed of species rather more ‘primitive’ than their relatives from western North America and Asia, a hypothesis that has been gaining ground in recent years.
Additionally, the new research may show that the dinosaur wildlife from different parts of Appalachia differed from that of other areas of the landmass.
“A phenomenon known as faunal provincialism, in which different regions of a larger area have distinct assortments of species, may have occurred on Laramidia, and only recently has it been proposed for Appalachian dinosaurs,” Brownstein said.
“The new data does seem to indicate limited provincialism may have occurred among Appalachian dinosaur faunas, but future research will be needed to better substantiate this hypothesis.”
This research was published in the journal Palaeontologia Electronica.
Chase D. Brownstein. 2018. The biogeography and ecology of the Cretaceous non-avian dinosaurs of Appalachia. Palaeontologia Electronica 21.1.5A: 1-56; doi: 10.26879/801