Appalachia (Mesozoic)

Dinosaurs

In Late Cretaceous North America, the dominant predators were the tyrannosaurs, huge predatory theropods with proportionately massive heads built for ripping flesh from their prey. Tyrannosaurs were the dominant predators in Appalachia too, but rather than the massive Tyrannosaurinae, like Gorgosaurus, Albertosaurus and Lythronax, which ironically evolved during the same time that the Western Interior Seaway had fully separated Laramida for Appalachia, the smaller dryptosaurs were the top predators of Appalachia. Rather than developing the huge heads and massive bodies of their kin, dryptosaurs had more in common with the basal tyrannosaurs like Dilong and Eotyrannus, having long arms with three fingers, a more lithe skull and body, and were not as large as the largest tyrannosaurids. Three genera of Appalachian tyrannosaurs are known, Dryptosaurus, Diplotomodon and Appalachiosaurus while other indeterminate fossils lie scattered throughout most of the southern United States like Georgia, North Carolina, and South Carolina. These fossiled teeth possibly belong to a species of Appalachiosaurs or an undescribed species of a new tyrannosaur. Various ornithomimid bones, such as Coelosaurus, have also been reported from Appalachia from Missouri, Mississippi, Alabama, Georgia and as far north in states like Maryland, New Jersey and Delaware, but it is now believed that some of these are the bones of juvenile dryptosaurs while others belong to various undescribed species of ornithomimids. The case of Arkansaurus is such an example of indeterminate fossils being discovered to be dating back to the Early Cretaceous. It should be noted the dryptosaurs weren't the only predatory dinosaurs in Appalachia. Indeterminate dromeaosaurine fossils and teeth, mostly matching those of Saurornitholestes, have also been unearthed in Appalachia as well; mostly in the southern states like Missouri, North Carolina, South Carolina, Alabama, Mississippi and Georgia. Interestingly, along with the dromaeosauridae remains, tyrannosauroidea and possible ornithomimid remains have been unearthed in Missouri as well.

Another common group, arguably the most wide spread species in the area, of Appalachian dinosaurs were the Hadrosauroidea, which is now considered to be their "ancestral homeland"; eventually making their way to Laramidia, Asia, Europe, South America and Antarctica where they diversified into the lambeosaurine and saurolophine dinosaurs, though some of the primative hadrosaurs were still present until the end of the Mesozoic. While the fossil record shows a staggering variety of hadrosaur forms in Laramidia, hadrosaur remains for Appalachia show less diversity due to the relative uncommon number of fossil beds. However, many hadrosaurs are known from Appalachia, such as Claosaurus, Eotrachodon, Lophorhothon, Hypsibema crassicauda, Hypsibema missouriensis, and Hadrosaurus. These hadrosaurs from Appalachia seem to be closely related to the crestless hadrosaurs of Laramidia like Gryposaurus and Edmontosaurus, despite the fact that they are not considered to be saurolophines. Claosaurus is known from a specimen which floated into the Interior Seaway and was found in Kansas, might also be from Appalachia, since it was found closer to the Appalachia side of the seaway and is unknown from Western North America. Hadrosaur remains have even been found in Iowa, though in fragmentary remains, Tennessee, most notably from the Coon Creek Formation. Hypsibema crassicauda, over fifty feet long, was one of the largest eastern hadrosaurs, outgrowing some of the more larger and more derived western hadrosaurs like Lambeosaurus and Saurolophus. The genus likely took the environmental niche occupied by large sauropods in other areas, possibly grown to colossal sizes to that of Magnapaulia and Shantungosaurus. Hypsibema missouriensis, was another large species of hadrosaur, but it grew up to 45 to 49 feet, which wasn't as large as Hypsibema crassicauda, interestingly enough, when it was first discovered in 1945, it was mistaken for a species of sauropod. It should also be noted that Hypsibema missouriensis, possibly even all of the other hadrosaurs living on Appalachia, had serrated teeth for chewing the vegetation in the area. Indeterminate lambeosaurinae remains, mostly similar to Corythosaurus, have been reported from New Jersey's Navesink Formation and Nova Scotia, Canada. It cannot yet be explained how lambeosaurines might have reached Appalachia though some have theorized that a land bridge must have formed some time during the Campanian.

The nodosaurids, a group of large, herbivorous armored dinosaurs resembling armadillos, are another testament to Appalachia's difference from Laramidia. During the early Cretaceous, the nodosaurids prospered and were one of the most wide spread dinosaurs through out North America. However, by the latest Cretaceous, nodosaurids were scarce in western North America, limited to forms like Edmontonia, Denversaurus and Panoplosaurus; perhaps due to competition from the ankylosauridae; though it should be noted they did thrive in isolation, most notably in Appalachia, as mentioned earlier and in the case of Struthiosaurus, Europe as well. Nodosaurid scutes have been commonly found in eastern North America, while fossil specimens are very rare. Often the findings are not diagnostic enough to identify the species, but the remains attest to a greater number of these armored dinosaurs in Appalachia. Multiple specimens have been unearthed in Kansas in the Niobrara Formation, Alabama in Ripley Formation, Mississippi, Delaware, Maryland and New Jersey, possibly belonging to a multitude of different species. Five possible and best known examples of Appalachian nodosaurids, from both the early and late Cretaceous period, include Priconodon, Propanoplosaurus, Niobrarasaurus, Silvisaurus and possibly Hierosaurus, though it should be noted that its validity is disputed. Just like the Claosaurus specimen, it is possible that the specimens of Niobrarasaurus, Silvisaurus and Hierosaurus floated into the Interior Seaway from the east, since these two species of nodosaurids were discovered in the famous chalk formations of Kansas and are not known from any location from Western North America. Kansas was also apart of Appalachia when the other parts were covered by oceans, which were a part of the Western Interior Seaway.

While remains of the advanced ceratopsians, most notably the centrosaurines and chasmosaurines which were very common in Laramidia during this timeperiod, where not found in Appalachia, the leptoceratopsids somehow managed to inhabit that location. A Campanian-era leptoceratopsid ceratopsian has been found in the Tar Heel Formation, marking the first discovery of a ceratopsian dinosaur in the Appalachian zone. This specimen bears a uniquely long, slender and downcurved upper jaw, suggesting that it was an animal with a specialised feeding strategy, yet another example of speciation on an island environment. Recently, a ceratopsian teeth were unearthed in Mississippi's Owl Creek Formation, which have been dated to be 67 million years old. While leptoceratopids remains, the few that have been discovered in recent years, have been unearthed in the southern part of Appalachia, they appear to be completely absent from the northern part of Appalachia, states like New Jersey, Delaware and Maryland. Suggesting the idea, proposed by paleontologist David R. Schwimmer, that there was a possible providence during the Late Cretaceous.

Several bird remains are known from Appalachian sites, most of them sea birds like Hesperornithes, Ichthyornis, Enantiornithes like Halimornis and Ornithuraes like Apatornis and Iaceornis. Of particular interest are possible lithornithid remains in New Jersey, arguably one of the best records for Cretaceous birds as some specimens were preserved in the greensands in the area, which would represent a clear example of palaeognath Neornithes in the Late Cretaceous. However, this issue is still under debate.

Non-dinosaur herpetofauna

Through the Ellisdale Fossil Site, a good picture of Appalachia's non-dinosaurian fauna is present. Amidst lissamphibians, there is evidence for sirenids (including the large Habrosaurus), the batrachosauroidid salamander Parrisia, hylids, possible representatives of Eopelobates and Discoglossus, showing close similarities to European faunas, but aside from Habrosaurus (which is also found on Laramidia) there is a high degree of endemism, suggesting no interchanges with other landmasses throughout the Late Cretaceous. There is also a high degree of endemism in regards for its reptilian fauna: among squamates, the teiid Prototeius is exclusive to the landmass, and native representatives of Iguanidae, Helodermatidae, and Necrosauridae. Amidst turtles, Adocus, Apalone, and Bothremys are well represented, the latter in particular more common in appalachian sites than laramidian ones. The five local crocodilian genera, Deinosuchus, Thoracosaurus, Eothoracosaurus,Leidyosuchus, Borealosuchus, are well established in Laramidia as well, probably indicative of their ocean crossing capacities. Deinosuchus, being one of the largest crocodilians of the fossil record, was an apex predator that did prey on the dinosaurs in the area, the same case applies for Laramidia as well, despite the fact that the majority of its diet consisted of turtles and sea turtles. Pterosaur fossils, mostly similar to Pteranodon and Nyctosaurus, have been unearthed in Georgia, Alabama and Delaware. On a similar note, azhdrachid remains have been reported in Tennessee. It should be noted that no fossilized remains of snakes have been discovered in Appalachia during the Cretaceous period, only being found in Laramidia.

Mammals

Several types of mammals are also present on Ellisdale and in the both of the Carolinas. The most common are ptilodontoidean multituberculates, such as Mesodma, Cimolodon and a massively sized species. The sheer diversity of species on the landmass, as well as the earlier appearance compared to other Late Cretaceous locales, suggests that ptilodontoideans evolved in Appalachia. Metatherian are also known, including an alphadontid, a stagodontid, and an herpetotheriid. Unlike ptilodontoideans, metatherians show a lesser degree of endemism, implying a degree of interchange with Laramidia and Europe.