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Fossil Finds - St. George Dinosaur Discovery Site at Johnson Farm
What Fossils Have Been Found?
Since the original discovery of several Eubrontes tracks in February, 2000, thousands of dinosaur tracks have been found on the now City of St. George properties and from localities directly across the road. A total of 25 track horizons (layers) have been identified to date, and without a doubt, more will turn up with further exploration in the future. Along with the dinosaur tracks is an incredible assortment of sedimentary structures including ripple marks, raindrop impressions, salt crystal casts, mud cracks, rill marks, load casts, tool marks, interference ripples, and flute casts.
During this Early Jurassic Period, the land in the St. George area was at or near sea level since the Rocky Mountains had not yet begun to form. The location was close to the equator and all of the continents of Earth were attached into the supercontinent of Pangaea. Streams and lakes once covered portions of southern Utah and northern Arizona depositing the many rocks we now see in the St. George area. An enormous freshwater lake called "Lake Dixie" once covered this area during the Early Jurassic period. The St. George Dinosaur Discover Site at Johnson Farm is contained within the Moenave Formation, which consists of sequences of sandstone, mudstone, siltstone, and shale. The Moenave overlies the Upper Triassic Chinle Formation and underlies the Lower Jurassic Kayenta Formation that forms the red cliffs above St. George.
A summary of the kinds of fossils thus far discovered at and near the St. George Dinosaur Tracksite at Johnson Farm follows:
Trace Fossils:
- Three types of identified theropod dinosaur (meat-eating dinosaur) tracks to date (Eubrontes, Grallator, and Gigandipus).
- Several as yet unidentified types of dinosaur tracks
- World's largest and best preserved collection of dinosaur swimtracks
- Dinosaur tail drags and a squatting Eubrontes trace
- Dinosaur skin impressions and scale scratch lines
- Abundant upright-walking crocodilian tracks called Batrachopus
- Several unidentified types of non-dinosaur vertebrate tracks
- Possible turtle swim trails
- Fish swimtracks
- Invertebrate trails, trackways, and burrows
- Root casts and rhizoconcretions
- Insect or beetle trails
- Cleft-footed clam trails (Protovirgularia)
Animal Fossils:
- Ostracods
- Conchostracans
- Bivalve molluscs (still to be determined)
- New freshwater fish fauna (semionotids, new species of Lissodus hybodont shark, new species of coelacanth fish, possible colobidontiform fish, many as-of-yet unidentified fish species)
- Terrestrial vertebrae remains (including two theropod dinosaur vertebra and 15 theropod teeth)
Plant Fossils:
- Horsetail (Equisetum) impressions
- Abundant conifer branches, cones, and seeds
- Fern-like Plants
- Possible cycad leaves
- Many unidentified seeds
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