Lab 6 Payton Rodgers
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School
Texas A&M University *
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Course
207
Subject
Geology
Date
Apr 3, 2024
Type
Pages
4
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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 40cm 20cm 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 20cm 23cm 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 15cm 22cm 42 Caudal Vertebrae caudal -- -- 43 Caudal Vertebrae caudal -- -- 44 Caudal Vertebrae caudal -- -- 45 Caudal Vertebrae caudal -- -- 46 Caudal Vertebrae caudal -- -- 47* Caudal Vertebrae caudal 7cm 19cm 48* Caudal Vertebrae caudal 100cm 18cm Ends the tail 49 Chevron caudal -- -- 50* Chevron caudal 4cm 30cm 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 15cm 5cm 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 8 cm 8cm
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 determine the length. (1 pt)
The approximate total length of the tail is about 650 cm. b)
Describe how the size of the caudal vertebrae changes from the proximal to the distal end of the skeletal remains? (1 pt)
The size of the caudal vertebrae changes from the proximal to the distal end of the skeletal remains by decreasing. c)
Is the tail flexible or not? State you claim, provide your evidence, and explain your reasoning. (2pts)
I believe that the tail is flexible because of the number of vertebrae that allow it to move in different directions, except for the distal end. d)
Describe how the size and shape of the chevrons from anterior to posterior of the organism? (1 pt)
The chevrons from the anterior to the posterior of the organism increase in size, and the shape turns into a triangle. 3)
Evaluate your evidence to reach a preliminary identification (10pts)
a)
Given your observations of the caudal region, which major group(s) could this specimen belong to? State your claim (the clades), list your evidence, and explain your reasoning. (5 pts) I believe that this specimen belongs to the Titanosaur clade. This is because they have very similar caudal vertebrae and their structures are very similar based on what was presented in the mini assignment earlier and the research I did on each clade. b)
Are there any dinosaur groups that your evidence can rule out? State you claim (“This could not be the Clade X…”), list your evidence, and explain your reasoning. (5 pts) I believe that this species cannot belong to either the Ankylosaur or Spinosaur clade. The Spinosaur has long and mostly consistently sized chevrons, and this fossil does not. The ankylosaur cannot be it either because of the feature on the anterior part of the caudal region.
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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)
The fossils presented in Assemblage A are miscellaneous bone fossils and what appear to be rock deposits. 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)
I believe that there is a chance that they could have been connected to the main skeleton, because of how close they were found compared to the other fossils, but it’s highly unlikely. They could be connected to the caudal vertebrae if they were related but they don’t appear to be. 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 are stones that were swallowed by dinosaurs, specifically herbivores, to help with the digestion of the food (greenery) they are eating. 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)
I believe that the coprolites found in Assemblage B are trace fossils of the dinosaur, which implies that the fossils were preserved very well in a place without oxygen or weathering and erosion.