The idea of dinosaurs often brings to mind vast western plains or exotic jungles, leading many to wonder what prehistoric creatures lived closer to home. Exploring Tennessee’s ancient past reveals a complex geological story that shaped its fossil record. Understanding the state’s conditions millions of years ago helps explain the unique nature of its fossils and the challenges paleontologists face in finding dinosaur traces.
Tennessee’s Ancient Landscape
Tennessee’s geological history during the Mesozoic Era, the age of dinosaurs, largely explains the scarcity of terrestrial dinosaur fossils. For much of the Triassic and Jurassic periods, vast portions of the state remained above sea level, experiencing significant erosion rather than the deposition of sediments that preserve fossils. This erosional environment means that rock layers from these periods are largely absent or very thin across the state, creating a gap in the fossil record.
During the Late Cretaceous period, approximately 75 million years ago, a substantial part of western Tennessee was submerged by a shallow marine environment. This sea, known as the Mississippi Embayment, was an extension of the ancient Gulf of Mexico. While this marine inundation led to abundant discoveries of sea creatures, it made the preservation of land-dwelling dinosaur remains in these areas highly improbable. In contrast, eastern Tennessee during the Cretaceous was dry land, forming part of an ancient landmass called Appalachia.
What the Fossil Record Reveals
The fossil record in Tennessee offers glimpses into its prehistoric life, though complete dinosaur skeletons are exceptionally rare, if not entirely absent. Evidence typically consists of fragmentary remains like isolated bone fragments or teeth. The only non-avian dinosaur bones positively identified from Tennessee belong to a type of hadrosaur, or duck-billed dinosaur, specifically Edmontosaurus.
These Edmontosaurus remains, dating to the Late Cretaceous period, around 75 million years ago, include tail vertebrae, leg bone fragments, and foot bones. These finds often indicate that dinosaur carcasses were washed out to sea, disarticulated, and buried in marine sediments. While land dinosaur fossils are scarce, Tennessee’s marine Cretaceous deposits are rich with other prehistoric life. These include numerous marine reptiles like mosasaurs and plesiosaurs, as well as abundant invertebrates such as clams, oysters, and snails. These marine creatures are frequently found in Tennessee’s fossil beds and are distinct from true dinosaurs.
The Tennessee State Dinosaur
Tennessee does not have an official state dinosaur. The state’s official fossil is Pterotrigonia thoracica, a bivalve clam that thrived in the shallow seas covering western Tennessee during the Cretaceous period. This ancient clam’s abundance in the fossil record made it a fitting choice to represent the state’s paleontological heritage.
Despite not holding an official title, the Edmontosaurus holds a significant place in Tennessee’s dinosaur story. Its fragmentary bones are the only non-avian dinosaur remains discovered within the state’s borders. Institutions like the McClung Museum at the University of Tennessee, Knoxville, display these hadrosaur bones, alongside a large bronze replica of an Edmontosaurus annectens.