GEOL 207- Lab6_Excavation Stage II

Dinosaur Excavation Stage II Part I: Excavation Stage II – Caudal Region Below is “site map” image of the excavation site(s). These images, and others you will need to complete this assignment, are available at: https://sites.google.com/tamu.edu/geol- 207-dinosaur-world-ex2/home . An arrow is labeled in the top right corner of your image indicating the direction of North. On your site map image, each bone has been numerically labeled. 1) Identify and Catalog the Bones: Use Table 2 below to catalog the bones recovered during the excavation. For each numbered bone, you should identify the type of bone and the region of the body the bone is from (in this lab, all bones are from the caudal region). Under notes, provide any features present that are important sharded derived characters that could help you in your identification. You should also provide an approximate measurement for each bone marked with a * using the scale bars on the zoom- in photos available at : https://sites.google.com/tamu.edu/geol-207-dinosaur-world-ex2/home Table 2. Bone catalog for Excavation Stage II. (10 pts) Bone Number Bone Identification Skeletal Region Measurements Other Notes Length (cm) Width (cm) 22* Caudal Vertebrae caudal 40 cm 20 cm 23 Caudal Vertebrae Caudal -- -- 24 Caudal Vertebrae Caudal -- -- 25 Caudal Vertebrae Caudal -- -- 26 Caudal Vertebrae Caudal -- -- 27 Caudal Vertebrae Caudal -- -- 28 Caudal Vertebrae Caudal -- -- 29 Caudal Vertebrae Caudal -- -- 30 Caudal Vertebrae Caudal -- -- 31 Caudal Vertebrae Caudal -- -- 32 Caudal Vertebrae Caudal -- -- 33 Caudal Vertebrae Caudal -- -- 34* Caudal Vertebrae Caudal 20 cm 24 cm 35 Caudal Vertebrae caudal -- -- 36 Caudal Vertebrae caudal -- -- 37 Caudal Vertebrae caudal -- -- 38 Caudal Vertebrae caudal -- -- 39 Caudal Vertebrae caudal -- -- 40 Caudal Vertebrae caudal -- --

41* Caudal Vertebrae caudal 15 cm 20 cm 42 Caudal Vertebrae caudal -- -- 43 Caudal Vertebrae caudal -- -- 44 Caudal Vertebrae caudal -- -- 45 Caudal Vertebrae caudal -- -- 46 Caudal Vertebrae caudal -- -- 47* Caudal Vertebrae caudal 6 cm 19 cm 48* Caudal Vertebrae caudal 100 cm 18 cm End of tail 49 Chevron caudal -- -- 50* Chevron caudal 4 cm 30 cm 51 Chevron caudal -- -- 52 Chevron caudal -- -- 53 Chevron caudal -- -- 54 Chevron caudal -- -- 55 Chevron caudal -- -- 56 Chevron caudal -- -- 57 Chevron caudal -- -- 58 Chevron caudal -- -- 59 Chevron caudal -- -- 60* Chevron caudal 13 cm 9 cm 61 Chevron caudal -- -- 62 Chevron caudal -- -- 63 Chevron caudal -- -- 63 Chevron caudal -- -- 65 Chevron caudal -- -- 66 Chevron caudal -- -- 67 Chevron caudal -- -- 68 Chevron caudal -- -- 69 Chevron caudal -- -- 70 Chevron caudal -- -- 71 Chevron caudal -- -- 72 Chevron caudal -- -- 73 Chevron caudal -- -- 74 Chevron caudal -- -- 75* Chevron caudal 8 cm 8 cm 2) Interpret the Skeleton (5 pts) a) What is the approximate total length of the tail? Be sure to use the scale bars in the images determine the length. (1 pt) - The total length of the tail is approximately 3.5 meters.

b) Are there any dinosaur groups that your evidence can rule out? State you claim (“This could not be the Clade X…”), list your evidence, and explain your reasoning. (5 pts) - They cannot be part of the Ankylosaur clade because it has club-like features whereas this fossil does not. It also cannot be part of the Spinosaurus clade because the Spinosaur has consistent size of chevrons and this fossil doesn’t.

4) Interpret the Paleoecology and Environment (5 pts) To place a fossil skeleton in the a paleoecological and environmental context, we often look for the nearby remains of other organisms as well as biogenic sedimentary structures are called trace fossils . Trace fossils, or ichnofossils , are traces of living organisms ( such as burrows, trackways, root marks, etc .) that have been preserved in the substrate and provide evidence for the organism’s behaviors. Certain trace fossils can only be preserved in a specific type of depositional environment, thus they can also be used in paleoenvironmental interpretation. There are two sets of trace fossils were preserved near the caudal region of this skeleton. a. Examine Assemblage A on the dorsal side of the caudal region. What type of fossils are presented in this assemblage? (1 pt) - There seem to be other bone fragments and some stones in this assemblage. b. Do you think the fossils in Assemblage A are part of the same individual as the main skeleton? Make your claim, describe your evidence, and explain your reasoning. (2 pts) - Its possible assemblage A could have been part of the of the main skeleton due to the being found near the site. Possibly connected to the caudal vertebrae, but due to the spikey appearance of the fossils I would say it’s more unlikely than likely to be part of the main skeleton. c. The small rounded stones in Assemblage A are gastroliths. What is the function of gastroliths to an organism? Which groups of dinosaurs would you expect to have gastroliths? (1 pt) - The function of gastroliths is to aid in digestion of the organism’s food. The group of dinosaurs you would expect to have gastroliths would be herbivores to help them digest the plants they were eating. d. Assemblage B near the distal end of the caudal region contains coprolites. What does the preservation of coprolites imply about the environment in which these fossils were preserved? (1 pt) - The environment which the fossils were preserved would imply that it lacked oxygen as displayed by the well-preserved fossils and coprolites so possibly an arid environment.