As I was composing my previous three posts, I searched the paleobiology database for information regarding the geological layers in which the various primitive whales were found. As I recorded the chronology of these fossils, I happened to notice an interesting pattern regarding their biogeography that is consistent with the theory that whales descended from terrestrial mammals. I will illustrate this by re-listing the fossils in the order described in the previous posts, along with the recorded localities in which they’ve been discovered. In parentheses are the estimated time periods of the geological ranges they were found in millions of years before the present. Try to see if you notice the same pattern that I did.
1. Terrestrial to semi-aquatic species
Indohyus: India and Pakistan (55.8-40.4 Ma)
Pakicetus: India and Pakistan (55.8-40.4 Ma)
Ambulocetus: Pakistan (48.6-40.4 Ma)
Remingtonocetus: India and Pakistan (48.6-40.4 Ma)
2. Species with evidence of strongly aquatic adaptations, e.g., presence of tail flukes, early formation of blowholes
Rhodocetus: Pakistan (48.6-40.4 Ma)
Artiocetus: Pakistan (48.6-40.4 Ma)
Protocetus: Egypt (48.6-40.4 Ma)
Georgiacetus: Southeastern USA (48.6-37.2 Ma)
3. Fully aquatic species, e.g., vestigial hind limbs
Dorudon: Egypt, New Zealand, SE USA, Western Sahara (40.4-33.9 Ma)
Basilosaurus: Antarctica, Egypt, Jordan, Pakistan, UK, Southeastern USA, Western Sahara (40.4-33.9 Ma)
Simocetus: Oregon (33.9-28.4 Ma)
Waipatia: New Zealand (27.3-25.2 Ma)
Janjucetus: Australia (28.4-23.03 Ma)
Mammalodon: New Zealand, Australia (25.2-23.03 Ma)
Aetiocetus: Japan, Mexico, Oregon (33.9-23.03 Ma)
Eomysticetus: South Carolina (28.4-23.03 Ma)
What should be taken from this is that the earlier whale species, which were still terrestrial or only semi-aquatic, were all found in Pakistan and India. When whales started becoming more aquatic, as demonstrated by the presence of tail flukes and the early formation of blowholes, some of them were still found near Pakistan while others began to disperse to other locations. By the time fully aquatic whales appear, their distribution is circumglobal. From an evolutionary perspective, this makes sense –terrestrial mammals would have a more difficult time dispersing from Pakistan and India to other continents. But once certain key innovations evolved, particularly to facilitate a predominantly aquatic lifestyle, dispersal became much easier for these primitive whales.
Questions for Creationists
Why does it appear that the earliest whale-like mammals all lived in one location (Pakistan and India), whereas those that have more aquatic specializations are found in other parts of the world? If all mammals left Noah’s Ark, why did all of the primitive whale-like mammals head to Pakistan and India and not to other places in the world?