Their similar skin did not come from a a “shared amphibious ancestor”:
A new study shows that the similarly smooth, nearly hairless skin of whales and hippopotamuses evolved independently. The work suggests that their last common ancestor was likely a land-dwelling mammal, uprooting current thinking that the skin came fine-tuned for life in the water from a shared amphibious ancestor. The study is published today in the journal Current Biology and was led by researchers at the American Museum of Natural History; University of California, Irvine; University of California, Riverside; Max Planck Institute of Molecular Cell Biology and Genetics; and the LOEWE-Centre for Translational Biodiversity Genomics (Germany).
“How mammals left terra firma and became fully aquatic is one of the most fascinating evolutionary stories, perhaps rivaled only by how animals traded water for land in the first place or by the evolution of flight,” said John Gatesy, a senior research scientist in the American Museum of Natural History’s Division of Vertebrate Zoology and a corresponding author on the study. “Our latest findings contradict the current dogma in the field—that relatives of the amphibious hippo might have been part of the transition as mammals re-entered life in the water.” …
“When you look at the molecular signatures, there is a striking and clear answer,” said study co-corresponding author and evolutionary genomicist Michael Hiller, from the Max Planck Institute of Molecular Cell Biology and Genetics and the LOEWE-Centre for Translational Biodiversity Genomics in Germany. “Our results strongly support the idea that ‘aquatic’ skin traits found in both hippos and cetaceans evolved independently. And not only that, we can see that the gene losses in the hippo lineage happened much later than in the cetacean lineage.”American Museum of Natural History, “Skin deep: Aquatic skin adaptations of whales and hippos evolved independently” at Phys.org
Out of curiosity, how much of the middle painting above — and its relationship to the other two — is fact and how much is conjecture?
In any event,
One less lectern …
One less lectern to pound, pound …
(To the tune of “One more river… ”)
The paper is open access.
See also: Evolution appears to converge on goals—but in Darwinian terms, is that possible?