Comments on: On the Path Towards Leviathan

By: H2O

H2O — Wed, 22 Oct 2008 23:29:39 +0000

Invigilator : Just because the animal went into the water to escape a predator doesn’t mean it would stay in the water. Just because a seal goes on land occaisionally (escaping an orca for example), doesn’t mean it will evolve legs and go hunting for food on land.

By: Invigilator

Invigilator — Fri, 29 Feb 2008 15:18:48 +0000

“Why would a land mammal leave the land, and go for a dip?”

Probably to get some food, or escape a predator.

Does this have to be repeated endlessly?

By: Carl Zimmer

Carl Zimmer — Sun, 24 Feb 2008 22:51:13 +0000

Mats [8]: No, questioning that whales evolved is not religious. However, it’s necessary to consider all the evidence. If you look at the evolutionary tree of whales, based on fossils discovered so far, you will see that the body plan of living whales did not evolve “at the same time.” Different parts of the body adapted at different times. Hindlegs, for example, did not entirely disappear even after whales had become entirely adapted to life in the water. As for the ability to be aquatic and still able to survive on land–you only need to consider living mammals to see how that could have happened. The water chevrotain, for example, is a small deer that dives regularly in rivers. Seals, on the other hand, can spend weeks at sea but can come back on land to reproduce.

This particular article did not address these issues because they took place millions of years *before* baleen whales evolved. But I’ve written many posts here, and an entire book (At the Water’s Edge), on that subject. So your criticism is unfounded.

By: Mats

Mats — Sun, 24 Feb 2008 20:24:21 +0000

The article, however, failed to explain why would a land mammal leave the land, and go for a dip.

It didn’t explain either how did all the land mammal’s land-adapted characteristicis evolved at the same time, in order to make the “would be whale” become more and more aquatic, but still able to survive on land while he is not totally aquatic.

But…questioning that whales evolved is religious.

By: Hume's Ghost

Hume's Ghost — Sun, 17 Feb 2008 04:31:40 +0000

Heh. A scan of google turns up hits for people saying that baleen is irreducibly complex.

By: Jason

Jason — Fri, 15 Feb 2008 01:52:07 +0000

As having very recent terrestrial ancestors, the ancient whale would have eaten at the surface. During its transformation into a below surface diner, I would imagine that proto-baleen would be an effective way to remove large amounts of water from the mouth, thus mitigating ingestion of saltwater and increasing the efficiency of finding, catching, and eating prey.

Proto-baleen would have been more about removing water than about straining small animals, thus we see the sharp teeth as well.

If the size of the tongue could be determined somehow (bone attachments) we could predict its effective use as a piston, forcing water out of the mouth to allow for below-surface ingestion.

Only later, when toothed whales would develop more effective means of removing salt water from its system would the baleen slowly become less necessary and disappear altogether.

Thoughts?

By: Bill

Bill — Thu, 14 Feb 2008 16:38:39 +0000

Is there any precedent for evolution of baleen-like structures in fish or other organisms?

By: Mrs Tilton

Mrs Tilton — Tue, 12 Feb 2008 12:08:31 +0000

Yay Carl! (Both of them!)

By: Jim Lemire

Jim Lemire — Tue, 12 Feb 2008 04:04:32 +0000

so should I continue to read “At Water’s Edge” or should I put it down now and wait for the next edition?

By: simea mirans

simea mirans — Tue, 12 Feb 2008 04:02:22 +0000

Paging Dr. Simmons...