A NEWLY DISCOVERED TRICERATOPS AND IT’S USE FOR TAPHONOMIC AND ALLOMETRIC INTERPRETATIONS

Skeletal elements of a Triceratops (GRNG-20) have been recovered during the summer field seasons of 2020-22 from the Grand River National Grasslands of South Dakota. This discovery allows the opportunity to experiment with techniques in the construction of a quarry map and learn more about the biology of the specimen. This study uses quarry maps to learn more about the post-mortem history of the Triceratops as well as assist in the prediction of future excavations. Furthermore, recovered elements will be used allometrically to provide estimates of femoral bone strength, mass, and overall body length of GRNG-20. In 2020, excavation began to the east of the quarry and progressed west over the last two field seasons. Quarry maps were created for each field season and demonstrate a highly disarticulated skeleton with the skull to the east of the quarry, and post-cranial material increasing in concentration to the west. Newly recovered skeletal elements appear to be trending more to the south according to the 2022 field seasons data. Therefore, future excavations will focus efforts to the south of the quarry. The orientation of long bones does not exhibit preferred orientations that would be expected of stream deposition. This study proposes that disarticulation occurred by predation or scavenging before burial on a floodplain. Approximately 49 skeletal elements have been recovered from the quarry and include predominantly cranial, thoracic, and appendicular material. Femoral bone scaling and proportions were used to calculate biological dimensions of specimen GRNG-20. Using the femoral bone strength, estimations of body mass and volume were calculated as 6,892.5 kg and 7.7 m³, respectively. The overall body length is estimated 7.6 m. Future excavations will be focused to the south of the quarry, as newly recovered skeletal elements and continued research will provide further insight into allometric relationships of GRNG-20.