Mini-Assignment 6: Prepare for the next excavation lab (caudal bones and trace fossils)
To answer the questions below, read pages 226-231 about dinosaur trace fossils and see box 6.1 and page 341 for information about the skeletal regions you’ll seen
in lab this week.
1.
What trace fossil could serve as evidence that main dinosaur you are excavating was predated upon? (1 pt)
Teeth marks are the largest indicator that the dinosaur I am excavating was predated upon. If the bone where the tooth marks show signs of healing, the dinosaur was predated upon while it was still living. If the tooth marks show no signs of healing, it is likely that the dinosaur was scavenged.
2.
What evidence could you use to support that a given coprolite was made by a dinosaur? What might give you uncertainty about what animal made the coprolite? (2 pts)
The size of the coprolite may be a pretty good indicator on whether or not the coprolite was made by a dinosaur. If the coprolite is large enough, it may be safe to assume that the coprolite could have only belonged to a dinosaur. Moreover, fossil locality is important. If the coprolite is present where only dinosaur bones are found, then it may be likely that the fossil was the owner of the coprolite – especially if that dinosaur was carnivorous (the bones in their feces make fossilization happen more readily). 3.
The ventral bones beneath the skeleton are called chevrons. What are the functions of chevrons? (1 pt)
The chevrons are an arch-like structure that you can find beneath the centrum of the caudal vertebrae. These bones are there primarily to provide protection to the anatomy of the tail; the chevrons protect nerves and blood vessels in the tail. Additionally, the chevrons allow for better movement of the tail. This is because the chevrons are used as attachment sites for muscles and flexors. 4.
What are the two types of bones represented in the caudal region of the organism’s skeleton? (1pts)
The centrum and the neural arch are represented in the caudal region. Located at the top of the neural arch is a neural spine. Some organisms also have chevrons beneath their centrum. 5.
Examine the figures of these dinosaur tails. You may need to be logged in to the library using your NetID and password to view some images. Describe the differences you see among the taxa using at least 5 of the following terms
: centrum, neural arch, neural spine, transverse process, chevron, osteoderm, caudal, sacral (5 pts)
Ankylosaur:
https://journals.plos.org/plosone/article/figure/image?size=large&id=10.1371/journal.pone.0006738.g001
Titanosaur:
https://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fsrep06196/MediaObjects/
41598_2014_Article_BFsrep06196_Fig1_HTML.jpg?as=webp
Spinosaur:
https://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fs41586-020-2190-3/MediaObjects/
41586_2020_2190_Fig1_HTML.png?as=webp
In the images we can see the caudal vertebrae
of the spinosaurus, the ankylosaur, and the titanosaur. It is easy to see that the ankylosaur is a shield bearing dinosaur simply by its tail. The tail of the ankylosaur has osteoderm
in several spots – it makes a kind of tail club. With this in mind, the image portrays the ankylosaur having a shorter caudal vertebrae, labeled free caudal, in comparison to the titanosaur and the spinosaurus. Half of the ankylosaur’s tail consists of the “handle” and “knob.” The titanosaur and the spinosaurus does not have this osteoderm
nor do they have the tail club, handle, or knob. All of the dinosaurs have centra
, though all varying in length and numbers. What is interesting about the spinosaurus is the neural arches
and the neural spines
. They are incredibly long (or tall) in size which is a feature the titanosaur and ankylosaur do not possess. These long neural arches
and neural spines
give the appearance of a taller tail – not quite as tall as its back but taller than most other dinosaurs. The chevrons
in the titanosaur are
