Paleontology in Arkansas
Terrestrial conditions continued into the Triassic, but during the Jurassic, another sea encroached into the state's southern half.
[3] During the Cenozoic the state's seas were inhabited by marine invertebrates and sharks, although the waters were gradually shrinking away.
Local grasslands and forests spread that were inhabited by creatures such as mammoths, mastodons, and giant ground sloths.
Remains of life from this period fossilized in the East Lafferty Creek and Cushman areas of Independence County.
[4] During the Early Cretaceous, the region of Arkansas southeast of the Ouachita Mountains was submerged by the Gulf of Mexico.
[4] During the Cretaceous, Arkansas was home to Belemnitella, Exogyra, Ostrea, Turritella, and other marine invertebrates in the Arkadelphia area of Clark County.
[9] During the Late Cretaceous the region now occupied by the Quachita Mountains of Arkansas may have attracted long necked plesiosaurs from hundreds of miles away as a source of gastroliths.
[4] During the Eocene epoch, Arkansas was home to a marine invertebrate fauna that included echinoderms, Ostrea, and Turritella.
[8] In 1973 the fossils Friday discovered were being cleaned and compared to related by dinosaurs by University of Arkansas professor James Harrison Quinn.
In the course of his research, Quinn made hypothetical clay models of the missing bones in the animal's foot and duplicated the actual fossils with plaster cast in latex molds.
Some areas of the quarry were rough due to what appeared to be large potholes, which frustrated the drivers of the excavation equipment.
After he visited the Purgatoire tracksite in Colorado he noticed that the local sauropod tracks resembled the "potholes" seen at the Briar site in Arkansas.
[15] Pittman later performed an aerial survey and found evidence for 10 parallel sauropod trackways on a rock surface that had also been extensively "trampled".
In 1989 Pittman successfully dated the dinosaur tracks of the Briar quarry as equal in age to the lower Glen Rose Formation's megatracksites, which are more than 200 miles away.
[16] In the fall of 1995 senior paleontologist of the Utah Geological Survey (then with Dinamation International), James Kirkland, examined the Arkansaurus foot and found it to be larger but otherwise nearly identical to a new species found two years prior in Utah rocks of Early Cretaceous age.
