Lab6_Excavation Stage II_NicholasH

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 18cm 11cm Implied start of tail 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 12cm 10cm 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 6cm 11cm 42 Caudal Vertebrae Caudal -- -- 43 Caudal Vertebrae Caudal -- -- 44 Caudal Vertebrae Caudal -- -- 45 Caudal Vertebrae Caudal -- -- 46 Caudal Vertebrae Caudal -- -- 47* Caudal Vertebrae Caudal 5cm 10cm 48* Fused Vertebrae Caudal 7cm 60cm Very end tip of tail (composed of multiple stiff vertebrae with chevrons) 49 Chevron Caudal -- -- First chevron 50* Chevron Caudal 4cm 14cm 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 5cm 4cm First triangular chevron 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 6cm 5cm Last disconnected chevron 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 to determine the length. (1 pt) I believe the tail is around 335cm long. b) Describe how the size of the caudal vertebrae changes from the proximal to the distal end of the skeletal remains? (1 pt)

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) It seems to be other bone fossils from a different animal with sauropod gastroliths . 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) No, because there seem to be differently shaped vertebrae as well as what looks to be rib cage bones far too small to be associated with this fossil. Also, I have previously ruled out the sauropoda clade and the deposit including sauropod gastrolith would contradict my previous statement. 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) Gastroliths were commonly used by the sauropoda clade as a means to help stomach digestion. 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 coprolite still being intact means it must have been covered before the decomposition process could take effect. This means that the fossil was found in a dry desert.