Lab5_Excavation Stage I

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Texas A&M University *

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207

Subject

Geology

Date

Apr 3, 2024

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pdf

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5

Uploaded by ConstableFrog4162

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 Hindlimb 72 10 Long thick bone with two bones connecting 2* Tibia Hindlimb 73 10 Thick bone running below Femur 3 Fibula Hindlimb -- -- Thinner bone running below Femur 4* Tarsals Hindlimb 53 10 Foot running off of fibula/tibia 5 Distal Hindlimb -- -- 6 Medial Cuneiform Hindlimb -- -- 7 Metatarsal Hindlimb -- -- 8 Phalanges Hindlimb -- -- 9 Distal Phalanx Hindlimb -- -- 10 Distal Phalanx Hindlimb -- -- 11 Intermediate Cuneiform Hindlimb -- -- 12 Metatarsal Hindlimb -- -- 13 Phalanges Hindlimb -- -- 15 Lateral Cuneiform Hindlimb -- -- 16 Proximal Phalanges Hindlimb -- -- 17 Terminal Phalanx Hindlimb -- -- 18 Pubis Pelvis -- -- 19 Ischium Pelvis -- -- 20 Wing of Ilium Pelvis -- -- 21 Tibial Tubercle Hindlimb -- -- 22 Tibial Tubercle Hindlimb -- --
3) Interpreting the Skeleton (7 pts) a) Having identified the bones present in your specimen, list the order of the hindlimb bones starting with the bones that are most proximal (closest) to the pelvic girdle. (2 pts) Terms to use: tibia and fibula; tarsometatarsus; phalanges; astragalus and calcaneum; femur; ungual a. Femur b. Tibia and Fibula c. Astragalus and calcaneum d. Tarsometatarsus e. Phalanges f. Ungual (claw bone) b) Considering the bones that are present in these regions in the living animal, how complete is this specimen? (1 pt) I would argue that considering all the bones that are present in these regions in the living animal that the specimen is mostly complete. The hindlimb is very well represented by looking at the skeletal remains. c) Bones 21 and 22 of our organism represent the ankle bones. What type of ankle configuration does our organism have? (Appropriate terms could be “ crurotarsal ankle” like in the left figure or “ mesotarsal ankle” like in the right figure. The red line in each is the plane of the ankle hinge). (1 pt) Based upon the figure I would argue our organism has a “mesotarsal ankle” as displayed in the image to the right. d) What features are present in this portion of the skeleton that make you confident this fossil is a dinosaur? Consider the shared derived characters that are unique to Dinosauria and are not present in other groups. (1 pt) The features that are present in this portion of the skeleton that make me confident this fossil is a dinosaur is the three toed food. The presence of the femur, the limb proportions (longer limbs held more vertically beneath the body) and the ankle joint that allows for efficient movement and weight- bearing. e) Examine the hip and the orientation of the pubis. What type of hip is present in this specimen? (1pt) The type of hip that is present in this specimen is the saurischian hip.
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