Lab 7_Excavation Stage III

DINOSAUR EXCAVATION STAGE III Part I: Excavation Stage III - Vertebral Column 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-ex-3/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 3 on the next page 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, ap- propriate regions are “cervical”, “dorsal”, “sacral”). Under notes, provide any features present that are important sharded derived characters that could help you in your iden- tification. 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-ex3/home . Table 3. Bone catalog for Excavation Stage 3. (5 pts) Bone Number Bone Identification Skeletal Region Measurements Other Notes Length (cm) Width (cm) 76* sacral 77* sacral 78 cervical -- -- 79 cervical -- -- 80 cervical -- -- 81 dorsal -- -- 82 dorsal -- -- 83 dorsal -- -- 84 dorsal -- -- 85 dorsal -- -- 86 dorsal -- -- 87 dorsal -- -- 88 dorsal -- -- 89* dorsal 90* dorsal 91 dorsal -- -- 92 dorsal -- -- 93 dorsal -- -- 94 -- --

95 -- -- 96* 97 -- -- 98 -- -- 99 -- -- 100 -- -- 101 -- -- 102 -- -- 103 -- -- 104 -- -- 105 -- --

4) Taphonomic considerations (3 pts) a) Bones #98-105 are ribs that articulate from the spinal column. How many ribs would you expect to be present if the skeleton was complete? How does the completeness of the ribs compare with the completeness of the spinal column? Provide a well-reasoned explanation for the differences you observe. (3 pts) 5) Use the Stratigraphic Column to Interpret the Age of the Dinosaur. (7 pts) Fossils can be used to create stratigraphic ranges that allow scientists to track the species duration, or longevity of groups, from their origination to their extinction in an area. The oldest fossil of a species is its first appearance datum (FAD) and the youngest fossil of a species is the last appearance datum (LAD). It may be helpful to think of FADs as the origination date of the group whereas you could think of LADs as the group’s extinction date . Examine the stratigraphic column on the next page before answering the questions below. The species below were found in this stratigraphic record. Using the information from their FADs and LADs (First Appearance Datum and Last Appearance Datum, respectively) to constrain the age of the excavation site, denoted as a bone icon on the stratigraphic chart. Organism FAD Age (Ma) LAD Age (Ma) Aquilapollenites 81 65 Baculites asperformis 80 75 Crassostrea subtrigonalis 77 66 Wodehouseia spinata 69 66 Momopites 66 62 Caryapollenites 62 57 1. What is the potential age range, in millions on years (Ma) of the excavation site? (1 pt) 2. What geologic age is excavation site? List the Geologic Period and Geologic Age after consulting the international stratigraphic chart. (1 pt) Knowing the age of the excavation site should help you constrain the identity of the dinosaur. 3. Describe the changes in the environment of deposition starting from the oldest interval. For each stratigraphic interval, make a claim about the type of environment, state your evidence, and explain your reasoning. Be as specific as your evidence will allow. (5 pts) a. Lowermost stratigraphic interval (Oldest interval) b. Dinosaur-bearing Interval c. Uppermost stratigraphic interval (Youngest interval)