Question

Scientists found a fossil in South Dakota. They reconstructed the fossil and believe it may be from an ancient animal called Hoplophoneus. To learn more about the fossil, scientists need to look for patterns in its body structure and compare it to other organisms. They compared the fossil to modern-day animals and other ancient animals to better understand its relationships.

Figure 1 - Badlands South Dakota



This is an image of the badlands of South Dakota where the Hoplophoneus fossil was found.

Figure 2 - Hoplophoneus Fossils



This is an image of the Hoplophoneus fossils found in the badlands of South Dakota reconstructed by scientists.

Table 1 - Bones of Organisms with Similar Body Structures

Hoplophoneus Mountain Lion Saber-tooth Cat


The Hoplophoneus jaw allowed for opening its mouth past 45 degrees, that is extremely wide! If the modern-day tiger or mountain lion opened its mouth past 45 degrees, this part of the jaw would pop the cat's eye out.
The saber-toothed cat's jaw has a smaller muscle attachment, which allows it to open its mouth past 45 degrees.



This table shows the skulls of other organisms that appear to have similar structures.



Figure 3 - Skeletal Structures



Hoplophoneus (ancient)



Mountain Lion (modern)



Saber tooth cat (ancient)

These images show the skeletal structures of the ancient Hoplophoneus, modern mountain lion, and ancient saber-tooth cat.

Your Task

Use the information provided to answer the following questions. You will use patterns in body structures from different organisms to infer relationships and construct an explanation about the Hoplophoneus fossil.

Question 1

Scientists reconstructed the fossil found in the Badlands of South Dakota, creating a complete skeleton shown in Figure 2. They used different strategies to figure out what kind of organism the fossil might belong to.

Instructions: Use the table below to decide if each strategy would be helpful (and realistic) for understanding what the organism is.

(1 point)
response - correct
Helpful NOT Helpful
Patterns from other fossils


Common body structures


Photographs of ancient organisms


Comparing to modern day organisms


How scattered the fossils were


Question 2
Use the table to answer the question.

Table 1 - Bones of Organisms with Similar Body Structures

Hoplophoneus Mountain Lion Saber-tooth Cat




The Hoplophoneus jaw allowed for opening its mouth past 45 degrees, that is extremely wide!



If the modern-day tiger or mountain lion opened its mouth past 45 degrees, this part of the jaw would pop the cat's eye out



The saber-toothed cat's jaw has a smaller muscle attachment, which allows it to open its mouth past 45 degrees.

This table shows the skulls of other organisms that appear to have similar structures.


Question 2

Look at the images of the skulls in Table 1. Identify traits for each skull and mark them on the table below.

(1 point)
Hoplophoneus Mountain Lion Saber-tooth Cat
Long sharp teeth in the front of the mouth (not incisors/fangs)



The jaw can open past 45 degrees



Thin, tall ridge on the top of the skull



Extra long incisor teeth (fang teeth)



Ridge behind the eye socket



Wider nasal passage (heart-shaped nose hole)



Question 3
Question 3

Use Table 1 to correctly complete the CER statment.

(2 points)
Claim: The Hoplophoneus skull looks more like the
skull.

Evidence: According to my answers to Question 2, they both have
,
, and
.

Reasoning: Because these two skulls are the most similar, they look more alike.

Question 4
This is a cladogram. It is a tool scientists use to show how different species are related. In this cladogram, the Hoplophoneus is placed as a common ancestor to both saber-toothed cats and modern cats, including mountain lions.

Question 4

Using what you have learned about the skull structures and evolutionary relationships drag and drop the saber-toothed cat and mountain lion into the positions where you think they belong on the cladogram.
Remember, species that are more closely related to each other will branch closer together.

(1 point)
Drop target 1
Drop target 2

Answers

GPT-4o mini
### Question 1

**Instructions**: Determine if each strategy would be helpful or not for understanding what the organism is.

| Strategy | Helpful | NOT Helpful |
|------------------------------------------|---------|-------------|
| Patterns from other fossils | ✔ | |
| Common body structures | ✔ | |
| Photographs of ancient organisms | | ✔ |
| Comparing to modern day organisms | ✔ | |
| How scattered the fossils were | | ✔ |

### Question 2

**Fill in the table based on traits from each skull shown in Table 1.**

| Trait | Hoplophoneus | Mountain Lion | Saber-tooth Cat |
|-----------------------------------------------|--------------|---------------|------------------|
| Long sharp teeth in the front of the mouth | ✔ | | ✔ |
| The jaw can open past 45 degrees | ✔ | | ✔ |
| Thin, tall ridge on the top of the skull | ✔ | | |
| Extra long incisor teeth (fang teeth) | | | ✔ |
| Ridge behind the eye socket | | ✔ | ✔ |
| Wider nasal passage (heart-shaped nose hole) | ✔ | | |

### Question 3

**Complete the CER statement.**

Claim: The Hoplophoneus skull looks more like the **saber-tooth cat** skull.

Evidence: According to my answers to Question 2, they both have **long sharp teeth in the front of the mouth**, **the jaw can open past 45 degrees**, and **a thin, tall ridge on the top of the skull.**

Reasoning: Because these two skulls are the most similar, they look more alike.

### Question 4

**Cladogram Placement**:

- **Drop target 1**: Saber-tooth Cat
- **Drop target 2**: Mountain Lion

In the cladogram, place the Saber-tooth Cat and Mountain Lion as follows:
- The Saber-tooth Cat should branch closer to the Hoplophoneus since they share more similar traits (e.g., jaw structure).
- The Mountain Lion, while still related, will be placed further down the clade since it diverges from the common ancestor after the Saber-tooth Cat.