Taphonomy of Late Jurassic (Tithonian) Morrison Formation Apatosaurus Sp. Vertebrae Found Associated with Teeth from Allosaurus Sp

Taphonomy of Late Jurassic (Tithonian) Morrison Formation Apatosaurus Sp. Vertebrae Found Associated with Teeth from Allosaurus Sp

Utah State University DigitalCommons@USU All Graduate Plan B and other Reports Graduate Studies 5-2021 Taphonomy of Late Jurassic (Tithonian) Morrison Formation Apatosaurus sp. Vertebrae Found Associated with Teeth from Allosaurus sp. and Ceratosaurus sp., and Body Size Extrapolation from the Associated Theropod Teeth. Greg C. Agyan Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/gradreports Part of the Behavior and Ethology Commons, Geology Commons, Other Ecology and Evolutionary Biology Commons, Paleobiology Commons, Paleontology Commons, Sedimentology Commons, and the Stratigraphy Commons Recommended Citation Agyan, Greg C., "Taphonomy of Late Jurassic (Tithonian) Morrison Formation Apatosaurus sp. Vertebrae Found Associated with Teeth from Allosaurus sp. and Ceratosaurus sp., and Body Size Extrapolation from the Associated Theropod Teeth." (2021). All Graduate Plan B and other Reports. 1541. https://digitalcommons.usu.edu/gradreports/1541 This Report is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Plan B and other Reports by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Taphonomy of Late Jurassic (Tithonian) Morrison Formation Apatosaurus sp. vertebrae found associated with teeth from Allosaurus sp. and Ceratosaurus sp., and body size extrapolation from the associated theropod teeth. _______________ A Thesis Presented to the Faculty of the Department of Geological Sciences Utah State University _________________ In Partial Fulfillment of the requirements for the Degree of Masters of Science In Applied Environmental Geoscience ________________ By Gregory Christian Agyan Spring 2021 _______________ Dr. Benjamin Burger Advisor Table of Contents General Audience Abstract ........................................................................................................................ 3 Abstract ..................................................................................................................................................... 3-5 1. Introduction ....................................................................................................................................... 5-6 2. Purpose of Study ................................................................................................................................... 6 3. Materials and Methods ................................................................................................................... 7-12 3.1 Taphonomy Analysis Methods ...................................................................................................... 7 3.2 Theropod Size Estimation Methods ........................................................................................ 7-12 3.2.1 Allosaurus Size Estimation ................................................................................................ 9-11 3.2.1.1 DNM-15 Allo 1 ......................................................................................................... 9-10 3.2.1.2 DNM-15 Allo 2 ....................................................................................................... 10-11 3.2.2 Ceratosaurus Size Estimation .......................................................................................... 11-12 3.2.2.1 DNM-15 Cerato ........................................................................................................... 12 4. Geologic/ Regional Setting ............................................................................................................ 12-14 4.1 Paleoclimatology of the Morrison Formation ....................................................................... 12-14 4.2 Geology of Dinosaur National Monument’s Carnegie Quarry ................................................ 14 5. Results of the Sauropod Locality Analysis .................................................................................. 15-19 5.1 Field Observations of the Locality ......................................................................................... 15-16 5.2 Thin Section Analysis .............................................................................................................. 16-18 5.2.1 Composition of the Locality Thin Sections ....................................................................... 16-17 5.2.2 Comparison of Locality Thin Sections to the Carnegie Quarry ....................................... 17-18 5.3 Interpretation of the Environment of Deposition ................................................................. 18-19 6. Taphonomy of Locality DNM-15 ................................................................................................. 19-24 6.1 Sauropod Taphonomy ............................................................................................................. 19-21 6.1.1 Apatosaurus Bone Orientation .......................................................................................... 19-21 6.1.2 Possible Cause of Apatosaurus Death............................................................................... 21-22 6.2 Theropod Tooth Taphonomy ................................................................................................. 22-23 6.2.1 Transportability of the Teeth ............................................................................................. 22-23 6.2.2 Possible Cause of Tooth Shedding and Preservation ....................................................... 23-24 7. Size Estimation Results From Shed Allosaurus Teeth ............................................................... 25-26 7.1 DNM-15 Allo 1 Results ................................................................................................................. 25 Page | 1 7.2 DNM-15 Allo 2 Results ............................................................................................................ 25-26 8. Size Estimation Results From Shed Ceratosaurus Tooth .......................................................... 26-27 9. Discussion ....................................................................................................................................... 27-29 9.1 Allosaurus Size Estimation Assumptions ............................................................................... 28-29 9.2 Allosaurus Size Estimation Limitations ..................................................................................... 29 9.3 Ceratosaurus Size Estimation Assumptions ......................................................................... 29-30 9.4 Ceratosaurus Size Estimation Limitations ................................................................................. 30 10. Conclusions .................................................................................................................................... 30-32 Acknowledgements .............................................................................................................................. 32-33 Figures and Tables ............................................................................................................................... 33-58 References ............................................................................................................................................. 59-61 Appendix (Measurements) ................................................................................................................. 61-66 Page | 2 General Audience Abstract A row of tail vertebrae from the long-necked dinosaur Apatosaurus was discovered from within Dinosaur National Monument in 1985. Buried within the tail vertebrae were three teeth from carnivorous dinosaurs. Two of the teeth were identified from Allosaurus and the third was from a carnivore with a distinctive nasal crest called Ceratosaurus. This study sought to determine how the Apatosaurus bones and carnivore teeth became associated, and to decipher the probable cause of the long-necked herbivore’s death. The bones and teeth were shown to have been preserved in a river channel deposit, but were unlikely to have been transported any great distance before burial. Dinosaur National Monument was likely prone to drought conditions during the Late Jurassic, and the Apatosaurus would have likely died as a result of the adverse conditions combined with its possible old age. The results of this study imply that the teeth were present among the Apatosaurus bones as a result of scavenging. The three teeth were shed during feeding, as they lack roots. The skull and body lengths of these individual carnivorous dinosaurs were estimated using mathematical formulas determined from skull and skeletal measurements of known specimens in museums. Based on the size of the Allosaurus teeth, these scavenging dinosaurs had an average skull length of about 80 cm and body length of 7 meters, while the Ceratosaurus tooth indicated a very large carnivorous dinosaur with an average skull length of about 1 meter and a body length of about 8.7 meters. Abstract An Apatosaurus sp. locality from Dinosaur National Monument designated DNM-15 was excavated in 1985, and associated with two Allosaurus teeth and one Ceratosaurus tooth that were near one of the caudal vertebrae. The Ceratosaurus tooth was buried between an overlying Page | 3 rib and that same caudal vertebra. The caudal vertebrae of the DNM-15 Apatosaurus were intact and articulated,

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