Lab5_Excavation Stage I (2)

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Texas A&M University *

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Course

207

Subject

Geology

Date

Apr 3, 2024

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pdf

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5

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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* 2* 3 -- -- 4* 5 -- -- 6 -- -- 7 -- -- 8 -- -- 9 -- -- 10 -- -- 11 -- -- 12 -- -- 13 -- -- 15 -- -- 16 -- -- 17 -- -- 18 -- -- 19 -- -- 20 -- -- 21 -- -- 22 -- -- Hindlimb 80 20 Femur 70 10 Hindlimb Tibia Two separate balls at the end of bone that are classified as two separate bones Fibula Hindlimb Skinnier bone of the hindlimb Tarsometataursus Hindlimb 50 10 Biggest bone with the phalanges The largest bone of the three longer ones Dewclaw Hindlimb Smallest claw separated from other claws Phalange Hindlimb Pelvic Pelvic Pelvic Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Hindlimb Ungual Ungual Phalange Phalange Phalange Phalange Phalange Phalange Phalange Phalange Astragalus Calcaneum Pubis Ischium Ilium Longer and straight edged Posterior orientation- Saurischian Has a serrated edge along the bottom
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. b. c. d. e. f. b) Considering the bones that are present in these regions in the living animal, how complete is this specimen? (1 pt) 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) 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) e) Examine the hip and the orientation of the pubis. What type of hip is present in this specimen? (1pt) f) How many functional digits are there on the foot? (1pt) Femur Tibia and Fibula Phalanges Tarsometatarsus Ungual Astragalus and Calacaneum This is a mesotarsal ankle since the bone reflects the configuration shown in the right figure. All the bones that make up the hindlimb and pelvis are present, therefore it could be infered that the specimen is complete. The regions presented are in fact complete The shape of the phalanges, presence of claws, and the proof of the specimen being "lizard hipped" make me confident that the fossil is a dinosaur. The pelvis is lizard-hipped so that would make the specimen part of the Saurischian orientation. There are 4 functional digits on the foot presented.
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