Ancestry & Descent
Structural Analysis
The Mystery Fossil Case
Mechanisms of Change
The Fossil Record
100

This is the specific term for a single population that splits into two or more groups, each evolving into a new species.

What is a Common Ancestor Population?

100

While a human arm and a bird wing look different, their "one-two-many" bone arrangement is evidence of this.

What is Evolutionary Relatedness?

100

This was the primary reason Claim 3 (Crocodiles) was eliminated early in the investigation.

What is Lays Eggs (Does not give live birth)?

100

This concept explains why a species' body structures might remain unchanged for millions of years.

What is Stability?

100

Scientists use this type of evidence to observe "transitional" forms between extinct and living species.

What is Evolutionary History?

200

If two species share a structure that a third species does not have, it suggests the first two share a more ______ common ancestor.

What is Recent?

200

These are specific shared structures that help scientists "diagnose" exactly where a branch occurs on an evolutionary tree.

What are Diagnostic Shared Structures?

200

To place the Mystery Fossil with whales, scientists had to identify a shared structure it has with whales that it does NOT share with this animal.

What is the Wolf?

200

Natural selection acts on these, which must be present in a population for evolution to occur.

What are Adaptive Traits (or Variations)?

200

These are the specific layers of the Earth where paleontologists find the oldest fossil evidence.

What are Bottom/Lower Layers?

300

This term describes the process where different species evolve similar traits independently, often making them look related when they aren't.

What is Convergent Evolution?

300

All mammals share this specific structure, which serves as a "shared structure" for the entire Cetacea and Carnivora groups.

What is the Backbone (Vertebral Column)?

300

This specific anatomical structure in the Mystery Fossil's skull provided a critical clue about its relationship to Pakicetus.

What is the Middle Ear Bone?

300

This is the necessary condition for a population to split into two descendant species (Speciation).

What is Separation (Geographic or Reproductive)?

300

This digital tool allows you to see how different species are connected by going back to a common node.

What is the Evolutionary History Simulation?

400

This phrase describes the "family tree" relationship where every living thing can be traced back to a single origin.

What is Common Ancestry?

400

In the "one-two-many" pattern, these are the two specific bones that make up the "two" section of the human forearm.

What are the Radius and Ulna?

400

This is the specific evolutionary claim that the Mystery Fossil is a transitional form between land mammals and modern whales.

What is Claim 1?

400

This is the primary driver that causes a population to adapt and change its body structures over many generations.

What is Environmental Change?

400

When comparing two observations, the one that is more ________ is considered stronger scientific evidence.

What is Precise?

500

This is the term for a structure that has lost its original function but remains in a descendant species (like tiny pelvic bones in whales).

What is a Vestigial Structure?

500

This describes the relationship between species A and B if they share a common ancestor that species C does not.

What is Closely Related?

500

If the Mystery Fossil had a blowhole, it would be a shared structure with whales; since it had nostrils, it suggests this about its habitat.

What is It Lived On Land (or was semi-aquatic)?

500

These are the three things that must stay consistent for a population to experience evolutionary stability.

What are Environment, resources, and Predators?

500

This is the term for the total collection of all fossils ever discovered and the information they provide.

What is the Fossil Record?