In 2004, paleontologists discovered fossils of a previously unknown dinosaur species in Argentina. The creature's unique skeletal structure suggested ...

Sentence Structure

• Sentence 1:
  • In 2004, paleontologists discovered fossils of a previously unknown dinosaur species in Argentina.

• Sentence 2:
  • The creature's unique skeletal structure suggested it lived both on land and in water.

• Sentence 3:
  • This discovery prompted researchers to investigate a fundamental question: Why [did/(?)] this species [develop/(?) amphibious characteristics [?/.]

Understanding the Meaning

Let's read through the passage to understand what's happening:

The first sentence tells us:

• In 2004, paleontologists discovered fossils of a previously unknown dinosaur species in Argentina.
  • This sets up the context - a dinosaur discovery.

The second sentence adds detail:

• The creature's unique skeletal structure suggested it lived both on land and in water.
  • This explains what was special about this dinosaur - it appeared to be amphibious.

Now the third sentence:

• This discovery prompted researchers to investigate a fundamental question:

This is where we have the blank. Let's look at the choices:

• Choice A: did this species develop amphibious characteristics.
• Choice B: this species developed amphibious characteristics?
• Choice C: did this species develop amphibious characteristics?
• Choice D: this species developed amphibious characteristics.

So we're deciding between:

• Word order: "did this species develop" vs. "this species developed"
• Ending punctuation: question mark vs. period

To see what works here, let's understand what this sentence structure is doing:

The sentence says researchers investigated "a fundamental question:" and then uses a colon. What do we notice about this?

• The colon is introducing and presenting the actual question itself
  • It's like saying "Here's the question they investigated: [the question]"

• What comes after that colon should BE that question - stated directly

Now here's the key: When we state a question directly (not embedded in a sentence), we need two things:

1. Question word order (inverted):
   • "Why did this species develop..."
   • NOT "Why this species developed..." (this would be for an indirect question, like "They wondered why this species developed...")

2. Question mark punctuation:
   • Because it's an actual question being stated

So we need: "Why did this species develop amphibious characteristics?"

The correct answer is Choice C.

GRAMMAR CONCEPT APPLIED

Presenting Direct Questions vs. Indirect Questions

When you introduce and state an actual question directly (called a direct question in grammar terms), you need both proper question word order and question mark punctuation:

Direct Question Format:

• Setup: The question is:
• Question: Why did the population decline?
• Inverted word order: "did the population decline" (auxiliary verb "did" comes before subject "population")
• Question mark at the end

Indirect Question Format:

• Setup: Scientists wondered
• Embedded question: why the population declined.
• Statement word order: "the population declined" (subject before verb)
• Period at the end (no question mark)
• The question is embedded within a larger statement

How this applies to our question:

The sentence says "investigate a fundamental question:" with a colon. That colon signals that what follows is the direct question itself being presented. Therefore, we need:

• Inverted question word order: "did this species develop"
• Question mark: "?"
• Complete format: "Why did this species develop amphibious characteristics?"

Key signal: When you see text like "the question is:" or "a question:" with a colon, what follows should be formatted as a direct question with both inverted word order and a question mark.