Vocabulary
This term describes how populations change over many generations.
What is evolution?
Scientists compare body structures in fossils mainly to determine this.
What is relatedness?
This process explains how one species becomes two over time.
What is speciation?
According to the calendar analogy, humans appear on Earth at this time.
What is very late in the year?
In an evolutionary tree, the most closely related species split from a common ancestor most ________.
What is recently?
This is a population from which multiple species evolved.
What is a common ancestor population?
Humans and blue whales share similar forelimb bones, which suggests this.
What is that they share a common ancestor?
Speciation often begins when populations are separated into different ________.
What are environments?
Wolves and whales are very different today mainly because of this.
What is evolving in different environments over long periods of time?
A structure shared by only two species (not a third) helps scientists determine this.
What is which species are more closely related?
This diagram shows evolutionary relationships based on shared ancestry.
What is an evolutionary tree?
Two species share a structure when it has the same bones in the same ________.
What are relative positions?
This process causes helpful traits to become more common in a population.
What is natural selection?
True or False: Small changes over short time periods create big differences.
What is false?
When making a scientific claim, this is more important than opinion.
What is strong evidence?
This type of structure is shared by only two species and helps determine relatedness.
What is a diagnostic structure?
This evidence helped scientists rule out the claim that the Mystery Fossil was related to crocodiles.
What is live birth?
Small changes can lead to large differences when they occur over this.
What is many generations or a long period of time?
This concept explains why species can look very different but still be related.
What is common ancestry plus evolutionary time?
Scientists use this type of structure to decide where the Mystery Fossil belongs on an evolutionary tree.
What is a diagnostic structure?
A trait that helps an organism survive and reproduce in its environment is called this.
What is an adaptive trait?
Sharing similar bone structures is stronger evidence of common ancestry than sharing this...
What is environment, diet, or location?
This is why bat wings, whale flippers, and wolf legs have the same basic bones but different shapes and functions.
What is adaptation to different environments?
In the calendar-year model of Earth’s history, this group appears shortly before humans.
What are mammals?
On an evolutionary tree, this point represents a common ancestor where one lineage splits into two.
What is a branch point (or node)?