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Description

Using the cover of darkness, a pack of “Saurornitholestes major” (3.5 m) harass a herd of Hadrosaurus foulkii (8 m) and try to separate a juvenile from its mother, North Carolina, 78 million years ago.

Compared to Laramidia and its ludicrously bountiful Late Cretaceous fossil record, the eastern continent of Appalachia has given us very little to clue us in on its saurian fauna during the final days of the dinosaurs. But still, several formations like Tar Heel, Mooreville Chalk, Donoho Creek and Demopolis Chalk have offered us some vital insights into this lost ecosystem.

All of these sites date to the early Campanian (82-77 mya) and like in the west, some of the most common large land animals found there are hadrosaurs like Hypsibema and the type genus of the whole family, Hadrosaurus itself, and they reached similar sizes to their western contemporaries. A top predator of this ecosystem was the tyrannosaur Appalachiosaurus, similar in size and shape to Laramidia’s albertosaurines, and although previously identified as a species of Albertosaurus, it is now recognized as representing a distinct lineage of tyrannosaurs, not closely related to those found in Laramidia.

This is unsurprising, as the great Western Interior Seaway spliced North America into two once it reached its full form around 100 million years ago, separating the dinosaur populations and resulting in independent evolution. The only taxa found on both sides of the sea are animals that could either fly, like Pteranodon, or swim, like Deinosuchus.

Fossils of small dinosaurs are even scanter than those of larger ones, but teeth identified as belonging to dromaeosaurs have been found across Appalachia. Many of them are of standard, coyote-sized raptors and thanks to wastebasket taxonomy, many of the raptor teeth were referred to the well-known genus Saurornitholestes, found at the Dinosaur Park, Oldman, Two Medicine and Kirtland Formation. While this genus did live at the same time as the Appalachian dromaeosaurs, the simple fact that the great inland sea formed tens of millions of years before Saurornitholestes emerged makes it quite obvious that the eastern raptors weren’t members of this genus or any other western genus for that matter.

The most interesting find, discovered at Tar Heel, are the teeth of large dromaeosaur similar in size to Deinonychus, described in 2015 and given the informal name of “Saurornitholestes major”. It’s a remarkable find, as it shows that large-sized raptors were native on both sides of the Western Interior Seaway. While Laramidia had taxa like Dakotaraptor and Dineobellator, Appalachia had its own cast of large predatory stem-birds, and we can only hope that better material of these eastern raptors turns up in the future.

Description

Using the cover of darkness, a pack of “Saurornitholestes major” (3.5 m) harass a herd of Hadrosaurus foulkii (8 m) and try to separate a juvenile from its mother, North Carolina, 78 million years ago.

Compared to Laramidia and its ludicrously bountiful Late Cretaceous fossil record, the eastern continent of Appalachia has given us very little to clue us in on its saurian fauna during the final days of the dinosaurs. But still, several formations like Tar Heel, Mooreville Chalk, Donoho Creek and Demopolis Chalk have offered us some vital insights into this lost ecosystem.

All of these sites date to the early Campanian (82-77 mya) and like in the west, some of the most common large land animals found there are hadrosaurs like Hypsibema and the type genus of the whole family, Hadrosaurus itself, and they reached similar sizes to their western contemporaries. A top predator of this ecosystem was the tyrannosaur Appalachiosaurus, similar in size and shape to Laramidia’s albertosaurines, and although previously identified as a species of Albertosaurus, it is now recognized as representing a distinct lineage of tyrannosaurs, not closely related to those found in Laramidia.

This is unsurprising, as the great Western Interior Seaway spliced North America into two once it reached its full form around 100 million years ago, separating the dinosaur populations and resulting in independent evolution. The only taxa found on both sides of the sea are animals that could either fly, like Pteranodon, or swim, like Deinosuchus.

Fossils of small dinosaurs are even scanter than those of larger ones, but teeth identified as belonging to dromaeosaurs have been found across Appalachia. Many of them are of standard, coyote-sized raptors and thanks to wastebasket taxonomy, many of the raptor teeth were referred to the well-known genus Saurornitholestes, found at the Dinosaur Park, Oldman, Two Medicine and Kirtland Formation. While this genus did live at the same time as the Appalachian dromaeosaurs, the simple fact that the great inland sea formed tens of millions of years before Saurornitholestes emerged makes it quite obvious that the eastern raptors weren’t members of this genus or any other western genus for that matter.

The most interesting find, discovered at Tar Heel, are the teeth of large dromaeosaur similar in size to Deinonychus, described in 2015 and given the informal name of “Saurornitholestes major”. It’s a remarkable find, as it shows that large-sized raptors were native on both sides of the Western Interior Seaway. While Laramidia had taxa like Dakotaraptor and Dineobellator, Appalachia had its own cast of large predatory stem-birds, and we can only hope that better material of these eastern raptors turns up in the future.