12. how long ago did basilosaurus live?

13. what is the nasal opening on basilosaurus?

14. list 2 ways we know maiacetus was a whale.

15. maiacetus is called a ____________.

16. dna contains ____________.

17. the closest living dna match to whales is ____________.

18. about how long did the whale/hippo common ancestor live?

19. whales and hippos share what characteristics?

20. bird wings are modified ____________.

Question

12. how long ago did basilosaurus live?

13. what is the nasal opening on basilosaurus?

14. list 2 ways we know maiacetus was a whale.

15. maiacetus is called a ____________.

16. dna contains ____________.

17. the closest living dna match to whales is ____________.

18. about how long did the whale/hippo common ancestor live?

19. whales and hippos share what characteristics?

20. bird wings are modified ____________.

Accepted Answer

To answer these questions, we'll draw from knowledge in the field of Biology (specifically paleontology, evolutionary biology, and anatomy) and provide brief explanations for each:

### Question 12: How long ago did Basilosaurus live?
# Brief Explanations:
Basilosaurus lived during the late Eocene epoch, approximately 40 to 34 million years ago. Fossil records and geological dating methods (e.g., radiometric dating of rock layers) confirm this timeframe.
# Answer:
Basilosaurus lived approximately 40–34 million years ago (late Eocene epoch).

### Question 13: What is the nasal opening on Basilosaurus?
# Brief Explanations:
Basilosaurus had a **blowhole** (or nasal opening) positioned further back on its skull compared to modern whales, but still adapted for an aquatic lifestyle. This feature is a key anatomical trait linking it to whale evolution (showing a transition from terrestrial to marine respiration).
# Answer:
The nasal opening on Basilosaurus was a blowhole (or a posteriorly positioned nasal aperture) adapted for breathing at the water’s surface, reflecting its aquatic lifestyle.

### Question 14: List 2 ways we know Maiacetus was a whale.
# Brief Explanations:
1. **Anatomical Adaptations**: Maiacetus had whale - like features such as a streamlined body, limb adaptations (e.g., reduced hind limbs) suited for aquatic locomotion, and a skull structure (e.g., ear bones) characteristic of cetaceans.
2. **Fossil Context and Evolutionary Linkage**: Its fossil record places it in the evolutionary lineage of whales (archaeocetes), showing transitional traits between terrestrial ancestors and fully marine whales (e.g., adaptations for both land and water).
# Answer:
1. Anatomical traits: Streamlined body, whale - like ear bones, and reduced hind limbs for aquatic life.
2. Evolutionary placement: Fossil record confirms it is part of the cetacean (whale) evolutionary lineage (archaeocete).

### Question 15: Maiacetus is called a ________.
# Brief Explanations:
Maiacetus is called a **transitional whale (or archaeocete)**. It is a key transitional fossil, showing adaptations for both terrestrial (e.g., functional hind limbs for walking) and aquatic (e.g., streamlined body) life, bridging the gap between land - dwelling ancestors and fully marine whales.
# Answer:
transitional whale (or archaeocete, or “walking whale” due to its semi - aquatic adaptations)

### Question 16: DNA contains ________.
# Brief Explanations:
DNA (deoxyribonucleic acid) contains the **genetic instructions (or genetic code)** for the development, function, growth, and reproduction of all known organisms. Structurally, it contains nucleotides (adenine, thymine, cytosine, guanine) arranged in a double - helix, encoding genes (sequences of bases) that direct protein synthesis and cellular processes.
# Answer:
the genetic instructions (or “the code for life,” or more specifically, deoxyribonucleotides (A, T, C, G) that encode genes and regulate biological processes)

### Question 17: The closest living DNA match to whales is ________.
# Brief Explanations:
Genetic studies (DNA sequencing) show that the **hippopotamus** is the closest living relative to whales. Molecular evidence (e.g., shared DNA sequences, genetic mutations) and evolutionary phylogenetics confirm this close relationship, placing whales and hippos in the clade “Cetartiodactyla.”
# Answer:
the hippopotamus (hippo)

### Question 18: About how long did the whale/hippo common ancestor live?
# Brief Explanations:
The common ancestor of whales and hippos (a member of the artiodactyl group) lived approximately **50–60 million years ago** (during the Paleocene - Eocene transition). Fossil and molecular clock analyses (using DNA mutation rates) estimate this timeframe for the divergence of the cetacean (whale) and hippopotamid lineages.
# Answer:
The whale - hippo common ancestor lived approximately 50–60 million years ago.

### Question 19: Whales and hippos share what characteristics?
# Brief Explanations:
1. **Anatomical/Physiological**: Both are mammals (warm - blooded, nurse young, have hair/fur at some stage). They share similar skeletal features (e.g., artiodactyl - like ankle bones, a trait of their shared artiodactyl ancestry).
2. **Genetic/Molecular**: They share a close evolutionary relationship (Cetartiodactyla clade), with similar DNA sequences and genetic regulatory mechanisms.
3. **Ecological/Behavioral (to an extent)**: Both are semi - aquatic (hippos are fully aquatic in behavior, whales are fully marine; their common ancestor was likely semi - aquatic).
# Answer:
- Anatomical: Mammalian traits (warm - blooded, milk - producing), artiodactyl - like skeletal features (e.g., ankle bones).
- Genetic: Close DNA similarity (shared evolutionary lineage in Cetartiodactyla).
- Ecological: Semi - aquatic adaptations (ancestral trait; hippos are semi - aquatic, whales are fully marine).

### Question 20: Bird wings are modified ________.
# Brief Explanations:
Bird wings are modified **forelimbs**. Evolutionarily, bird wings evolved from the forelimbs of their reptilian (dinosaur) ancestors, with adaptations (e.g., feathers, hollow bones, modified muscles) for flight (or in some cases, gliding/non - flight functions like swimming in penguins).
# Answer:
forelimbs

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Question

Explanation:

Question 12: How long ago did Basilosaurus live?

Answer:

Question 13: What is the nasal opening on Basilosaurus?