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 ~8 ~16 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 ~8 ~8

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 ~8 ~4 42 Caudal Vertebrae Caudal -- -- 43 Caudal Vertebrae Caudal -- -- 44 Caudal Vertebrae Caudal -- -- 45 Caudal Vertebrae Caudal -- -- 46 Caudal Vertebrae Caudal -- -- 47* Caudal Vertebrae Caudal ~10 ~4 48* Caudal Vertebrae Caudal ~42 ~4 49 Chevrons Caudal -- -- 50* Chevrons Caudal ~8 ~2 51 Chevrons Caudal -- -- 52 Chevrons Caudal -- -- 53 Chevrons Caudal -- -- 54 Chevrons Caudal -- -- 55 Chevrons Caudal -- -- 56 Chevrons Caudal -- -- 57 Chevrons Caudal -- -- 58 Chevrons Caudal -- -- 59 Chevrons Caudal -- -- 60* Chevrons Caudal ~6 ~3 61 Chevrons Caudal -- -- 62 Chevrons Caudal -- -- 63 Chevrons Caudal -- -- 63 Chevrons Caudal -- -- 65 Chevrons Caudal -- -- 66 Chevrons Caudal -- -- 67 Chevrons Caudal -- -- 68 Chevrons Caudal -- -- 69 Chevrons Caudal -- -- 70 Chevrons Caudal -- -- 71 Chevrons Caudal -- -- 72 Chevrons Caudal -- -- 73 Chevrons Caudal -- -- 74 Chevrons Caudal -- -- 75* Chevrons Caudal ~2 ~3.5

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) Other bone fossils and some rock deposits. 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) Given their closeness, it is possible that A was attached to the central skeleton. It is possible, that they were attached to the caudal vertebrae as calcified tendons holding spikes or resembling fans. But it seems unlikely that the two are members of the same organism. 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) A gastrolith is a small stone that helps animals digest food. A lot of herbivores had it to help them digest the greenery they had as a part of their diet. 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) Coprolites are dinosaur traces preserved in fossil form. These fossils are probably well preserved, which means that oxygen did not reach them. Since the minerals did not immediately evaporate into the environment, enabling the fossil to develop, an environment with a lot of sand is the most likely.