Dinosaurs like Tyrannosaurus rex have a lot of holes in their skull. How many temporal fenestrae does a Tyrannosaurus have?

Question

BlackTom AI · Accepted Answer

Diapsid skulls have two temporal fenestrae, so Tyrannosaurus rex — a diapsid dinosaur — is described as having two temporal fenestrae (one upper and one lower behind each eye).

1. Relevant knowledge points and concepts
- Temporal fenestrae are openings in the skull behind the orbit (eye socket) that lighten the skull and provide space for muscle attachment.  
- Amniote skull types: anapsid (0 fenestrae), synapsid (1 fenestra on each side), diapsid (2 fenestrae on each side).  
- Dinosaurs, including theropods like T. rex, belong to the diapsid lineage of reptiles.

2. Step-by-step reasoning
- Identify T. rex’s larger group: it is a theropod dinosaur within Archosauria, which are diapsid reptiles.  
- Apply the diapsid definition: diapsids possess two temporal openings behind the orbit on each side of the skull (an upper/supratemporal and a lower/infratemporal fenestra).  
- Conclude that T. rex has the diapsid condition: two temporal fenestrae (per side; commonly referred to simply as "two" when classifying skull type).

3. Intermediate details and clarification
- On one side of a diapsid skull you find two fenestrae; since skull descriptions often name the condition (anapsid/synapsid/diapsid) by the number of fenestrae per side, “two” denotes the diapsid condition. (If someone counts every opening on both sides, that yields four openings total.)

4. Why the correct answer is correct
- Because T. rex is a diapsid, it exhibits the characteristic two temporal fenestrae behind each eye — this is the defining trait used to classify its skull type.

5. Why other possible answers are incorrect
- “Zero” would describe anapsid skulls (e.g., some early turtles historically thought to be anapsid), which T. rex is not.  
- “One” would indicate a synapsid (mammal-line) condition, not true for dinosaurs.  
- “Four” can be a source of confusion: there are two on each side (total four), but skull-type classification uses the count per side, so “two” is the correct standard answer.

6. Conclusion
- Therefore, using the standard diapsid classification, the correct answer is Two, matching the provided answer.

Dinosaurs like Tyrannosaurus rex have a lot of holes in their skull. How many temporal fenestrae does a Tyrannosaurus have?单项选择题

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