Comment by yaakov34 | Hacker News Reader

Comment by yaakov34 | Hacker News Reader

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Here's the paper link (kudos to the journalists for at least giving us the title of the paper, if not a link we could follow; sometimes the article in the popular press looks nothing like what the scientists published). http://rsbl.royalsocietypublishing.org/content/roybiolett/13...

If I read this correctly, the discovery is not that the early whales were predators, but that filter-feeding evolved separately from their teeth; that is, the baleen - which is not homologous to teeth - is the first filter mechanism that the whales acquired, while previously, some people thought that the whales developed filter-feeding with their teeth before developing the baleen.

This is an exciting discovery, I suppose, for scientists studying whale evolution, but probably for nobody else. The popular press treatment turned it into "they discovered that whales were predators", which makes little sense, since a) everybody knew the whales did not have baleen when they were land-dwelling, I mean, how would that work; and b) all whales obviously had teeth at some point in their evolution, before the baleen whales lost them.

That just introduces more questions. What was the evolutionary advantage of baleen before it was used for filter feeding?

Edit: Three hypothesis outlined in the parent's linked PDF:

* Archaic mysticetes used their denticulate teeth to (suction) filter feed like living leopard and crabeater seals, thereby linking tooth function directly with the evolution of bulk feeding and baleen.

* A period of overlap, during which baleen and teeth would have functioned alongside each other.

* Archaic whales first turned from raptorial into suction feeders, which then triggered tooth loss and, eventually, facilitated the emergence of baleen.

> everybody knew the whales did not have baleen when they were land-dwelling, I mean, how would that work

And what if everybody were wrong? Perhaps some quirk led to development of baleen, which the proto-whales discovered was useful in the sea. So they stayed there.

Then we would expect all whales to be baleen whales, but they aren't. The fact that only one branch of cetaceans has baleen suggests that it came about after the cetaceans' common ancestor went in the water.

I see, thanks. I think that the type of classification that you are referring to is called Cladistics.

This also greatly simplifies thier evolution. If the teeth were used as a filter then they would have likely evolved into a better filter rather than a new structure developing. Ive never heard of such parralel development of different structures to acomplish the same task. One normally becomes dominant and that's the path. The eventual loss of unneeded teeth and the later development of baleen seems much easier.

> Ive never heard of such parralel development of different structures to acomplish the same task.

https://en.wikipedia.org/wiki/Queensland_lungfish#Breathing

The linked article discusses the lung fish which has gills for getting oxygen from water and a lung that can be used to extract oxygen from the air. It seems that this is an example of different structures used for the same purpose, extracting oxygen from the environment, but not the same task. One task extracts oxygen from water and the other from air.

The article also talks about "killer whales" and their teeth, but Orcas aren't whales. They're dolphins (or more specifically, they belong to the porpoise group of mammals).

While Orcas are members of dolphin family (Delphinidae), they are not members of the porpoise family (Phocoenidae) and the whole Orcas are not whales distinction is kind of silly anyway because they're all cetaceans.

Dolphins, whales, orcas, and porpoises all share a common ancestor before getting back to land animals, they are all cetaceans.

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