You discover fossils of the 50 million-year old ancestors of modern-day whales,

Question

You discover fossils of the 50 million-year old ancestors of modern-day whales, which walked on land. Based on what you know about animal form and function, what would you expect to be true of these ancestral mammals relative to whales today?

Question 5 options:

their bodies demanded more total energy than modern day whales

they were smaller, with a higher surface area-to-volume ratio relative to modern-day whales

they used lungs for respiration whereas modern-day whales use gills

they had a 3 chambered heart whereas modern-day whales have a 4 chambered heart

their lungs exhibited a larger surface area than modern-day whales

their bodies demanded more total energy than modern day whales

they were smaller, with a higher surface area-to-volume ratio relative to modern-day whales

they used lungs for respiration whereas modern-day whales use gills

they had a 3 chambered heart whereas modern-day whales have a 4 chambered heart

their lungs exhibited a larger surface area than modern-day whales

Explanation / Answer

Modern whales have descended from ancient cetaceans which comprise of terrestrial mammals. Pakicetus, is the oldest cetacean, and the first known archaeocete lived 50 million years ago. The body of Pakicetus is smaller than modern whales. The limbs were useful to walk on terrestrial lands and they used swim in shallow waters rather deep in oceans. Option 2 is correct.

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