Lab5_Excavation Stage I

DINOSAUR EXCAVATION STAGE I Part I: Excavation Stage I - Pelvic Girdle and Hindlimb A new fossil site has just been excavated and you are on the team that must identify what has been found. In the next 4 laboratory assignments you will examine different portions of the skeleton and use anatomical clues to narrow down the possible identity the fossil. After completing all 4 assignments, you will be placed in groups to compare your evidence and create a consensus report on your findings. 1) Find Your Bearings. 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-ex1/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.

2) Identify and Catalog the Bones: use the Table 1 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 (for this lab, “hindlimb” and “pelvis” are appropriate terms for skeletal 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-ex1/home . Table I. Bone catalog for Excavation Stage I. (5 pts) Bone Number Bone Identification Skeletal Region Measurements Other Notes Length (cm) Width (cm) 1* Femur Lower Leg 80 15 2* Tibia Lower Leg 80 15 3 Fibula Lower Leg 75 2-10 4* Tarsals Foot 50 10 5 Distal Foot 8 2 6 Medial Cuneiform Foot 10 3 7 Metatarsal Foot 8 3 8 Phalanges Foot 8 3 9 Distal Phalanx Foot 5 2 10 Distal Phalanx Foot 8 1 11 Intermediate Cuneiform Foot 10 4 12 Metatarsal Foot 10 3 13 Phalanges Foot 8 2 15 Distal Phalanx Foot 10 3 16 Lateral Foot 10 3 17 Terminal Phalanx Foot 7 2 18 Pubis Appendicula r skeleton 65 10-27 19 Ischium Appendicula r skeleton 50 5-25 20 Wing of Ilium Appendicula r skeleton 55 15-30 21 -- -- 22 -- --

4) Evaluate your evidence to reach a preliminary identification (10pts) Below is a phylogeny depicting the major groups of dinosaurs. The letters depict possible positions of shared derived characters on the phylogeny. Describe where the shared derived characters you came across when examining the pelvis and hindlimbs would fall on the phylogeny using the letters. [You should have at least 4 characters to place from #3.] (4 pts) F G H B Given the evidence you have so far, what clade of dinosaur do you have? State your claim (the clade), list your evidence, and explain your reasoning. (6 pts) Saurischians, this can be argued through the hip anatomy as well as the ankles.

5) Interpreting the Depositional Environment (8 pts) Sedimentary structures are geologic features of the substrate that were preserved and provide evidence for the environment of deposition ( e.g., streams, deserts, etc). Use supplementary table 1 to answer the following questions: 1. A few sedimentary structures discovered at the dig site are mud-cracks , ripple marks , and trackways. In what type of environment would we expect to see each of these sedimentary structures? (3 pts) a. Mudcracks: _______s tream or shallow water________ b. Ripple Marks: _______ shores ______ c. Trackways: _______ river, stream, or shallow water________ 2. Many different types of rocks are found within this field site, including siltstones, limestones, and evaporites. Given this evidence, make a claim about the depositional environment and provide your reasoning. (1 pt) This could range from ocean to deserts to caves because these are all sedimentary rocks and those are where they are typically found. 3. Some fossils can be used as an indicator of the depositional environment. Within the field site, you find a few fish fossils similar to the fish bones found at the Green River Formation. Given this evidence, make a claim about depositional environment and provide your reasoning. ( 1 pt) 4. Given all the geological evidence in #1-3, make a claim about the most likely depositional environment and provide a well-reasoned argument. ( 3 pts) The fossil was found in an arid desert, the great condition of the fossil is one way to tell this. Another way to tell this is the type of rocks found at the fossil site, as sedimentary rocks are found in the desert.