http://en.wikipedia.org/wiki/Presbyornithidae
Presbyornithidae were a family of waterbirds with an apparently global distribution that lived until the Earliest Oligocene, but are now extinct. Initially, they were believed to present a mix of characters shown by waterbirds, shorebirds and flamingos and were used to argue for an evolutionary relationship between these groups (Feduccia 1976), but they are now generally accepted to be "wading ducks", the sister taxon [actually ancestor] of the Anatidae, and thus essentially modern waterbirds. They were generally long-legged, long-necked birds, standing around one meter high, with the body of a duck, feet similar to a wader but webbed, and a flat duck-like bill adapted for filter feeding. Apparently, at least some species were very social birds that lived in large flocks and nested in colonies.
Sister taxon does not mean ancestor, it means most closely related taxon to another taxon. Pan (chimpanzees and bonobos) is generally accepted to be the sister taxon of hominina, which contains all hominins more closely to Homo Sapiens than Pan troglodytes. This doesn't mean that we're descended from chimpanzees, it just means that we're more closely related to chimpanzees than a lot of other things.
ReplyDeleteI should have said "actually ancestor". (I will change the post.)
ReplyDeleteWhat I am getting at, is that even though the wikipedia quote says "sister taxon" the actual relationship is "ancestor".
So how long ago did ducks (example muscovy and mallard) today share a common a ancestor?
ReplyDeleteAnonymous can you elaborate on what you mean please?
ReplyDeleteSpecifically, I read on a hatchery site that muscovies and mallards have been genetically separate for over 50 million years. This seems to be a long time, especially since the two still can produce (infertile) young. So when did the muscovy and the mallard share a common ancestor? And when did swans, geese, and ducks share a common ancestor? Does anyone know? I think H. sapien shared a common ancestor with lemurs 50 million years ago, that is why it doesn't seem to make sense that mallards and muscovies could be genetically isolated from each other and still be compatible (even if the result is a mule).
ReplyDeleteAnonymous, I am having a hard time relating what you are saying to what I have said.
ReplyDeleteI am suggesting that ducks, geese and swans EVOLVED from Presbyornithidae.
I am not talking about the cladistic idea of UNSPECIFIED last common ancestor.
I am happy to work with you, but you do not seem to have grasped the fundamental idea I am talking about.
Whoever "anonymous" is did grasp the point, if muscovies and mallards diverged 50 million years ago, then their common ancestor would have been a contemporary of presbyornithids. Also, the wikipedia post says sister taxon, because that is the actual relationship. It seems to me that you think of evolution as a linear progression where taxon A evolves into taxon B which evolves into taxon C with no branches and polytomies. You don't seem to understand that cladogenesis and adaptive radiations happen (alot), and that this would have happened in the past as well. Darwin's first drawing of a phylogenetic tree was branching! Also, you don't seem to understand that not everything fossilizes, and even if it does, there are so many ways that it could get destroyed. If you've ever seen any organism decaying, or erosion, you should realize that things get destroyed.
ReplyDelete"I am not talking about the cladistic idea of UNSPECIFIED last common ancestor."
please explain
"Whoever "anonymous" is did grasp the point, if muscovies and mallards diverged 50 million years ago, then their common ancestor would have been a contemporary of presbyornithids."
ReplyDeleteIf you accept the idea that it would have been a contemporary, what stops you from going the next step and thinking it could actually be the common ancestor?
In other words, those duck lines branched off from the presbyornithids line.
WOW. I was just asking a question. My initial question was when did the muscovy duck share a common ancestor with the mallard. I asked because the title of this discussion is "the ancestor of ducks, geese and swans". I was just wondering if you, or anyone, knew when ducks, geese or swans shared a common ancestor? Time IS an element of evolution. For example, H sapien shared a common ancestor with chimps about 6 million years ago. Or, if we were discussing whales and dolphins, the dolphins we see today shared a common ancestor about 10 million years ago. Then, I read on a hatchery site that the muscovy and mallard have been genetically isolated for 50 million years. I thought that seemed like a long time since the muscovy and mallard can produce young when mated (although the young are sterile). I would have to guesstimate that the ancestor to ducks, swans, and geese was about 50 million years ago, so the ancestor to ducks would be much less. I guess no one knows since an internet search turned up nothing.
ReplyDelete"If you accept the idea that it would have been a contemporary, what stops you from going the next step and thinking it could actually be the common ancestor?"
ReplyDeleteEvidence does, you can't just arbitrarily say that something was ancestral to something else, because they look similar and lived around the same point in time, you would first need to find some transitional presbyornithids, and then you would still probably have a crown group presbyornithidae separate of anatidae. Also, I think you meant "ancestor", not "common ancestor" that would mean something along the lines of "presbyornithidae begat presbyornithidae and anatidae" which doesn't really make sense. Also what about vegavis? It's from the late cretaceous, and it's about as close to anatidae as presbyornithidae is. Also, screamers show up in the miocene, but vegavis and presbyornithidae are closer to anatidae than it.
Here is the problem. Both django and anonymous are tying to shoehorn what I am saying into their cladistic box. And it does not fit.
ReplyDeleteCladistics is simply misguided.
If you really want to understand what I am saying you need to look at the whole idea of this entire site.
It might be helpful to look at the post from Dec 17, 2010 entitled "The Basic Picture".
I am delighted to discuss the ideas I am presenting with anyone. But the different paradigm must be understood.
What I am saying is closer to "Evolutionary Systematics".
Django you were right about this;
ReplyDelete"Also, I think you meant "ancestor", not "common ancestor."
I should have said "ancestor".
But I did say:
"In other words, those duck lines branched off from the presbyornithids line."
I thought that would clarify what I meant.
Anonymous you guestimated that the ancestor to ducks, swans, and geese was about 50 million years ago.
ReplyDeleteWhat I am saying is consistent with that, since I am saying that Presbyornithidae was the ancestor and according to wikipedia, Presbyornithidae stems from the late Cretaceous.
http://en.wikipedia.org/wiki/Presbyornithidae
"Cladistics is simply misguided."
ReplyDeleteHow? Please explain. Cladistic analyses determine how closely related things are by how many characteristics they have in common. Seems pretty reasonable, doesn't it? how is that misguided? Also, you post lots of cladograms on your blog, and you only seem to disagree with them when they don't conform to your "theory".
Anonymous; "Time IS an element of evolution", yes it is, but there are also plenty of ghost lineages. I'm not sure if I correctly interpreted what you wrote though.
"For example, H sapien shared a common ancestor with chimps about 6 million years ago."
It's Homo sapiens, not sapien, sapiens is a latin adjective that means wise, and, as with adjectives in english, there is no plural or singular for adjectives. I know it's not that big of a deal, but it's a pet peeve of mine.
Explaining the problems with cladistics is a big topic. Acquaint yourself with evolutionary systematics.
ReplyDeleteWhat I have proposed is based on an evolutionary systematics basis.
If you want to work with me, then that is the basis to work on.
Not really, evolutionary systematics differs from cladistics in many ways, but they still both use actual characteristics, and you said the anatidae arose from presbyornithidae without saying anything to back it up other than that they were around at the right time. I wouldn't be that surprised if what you said was true, but you would need to back up your claims.
ReplyDeleteYes, cladistics has its issues, but so does evolutionary systematics, any classification system is bound to, but they also have their merits.
If you think that anatidae may have arisen from presbyornithidae, please indicate why you might think that.
ReplyDeleteI don't think it, I just wouldn't be very surprised if it were true
ReplyDeleteWhy would you not be surprised?
ReplyDeleteWhat can be said on behalf of that possibility, such that you would not be surprised?
I wouldn't be surprised, but I just don't think it's all that likely, as there are only 3 widely accepted genera in presbyornithidae, and they're all more similar to each other than they are to anatids.
ReplyDelete