Scientists Find Missing Link in Bird Evolution 236
BlueCup writes "Dozens of fossils of an ancient loon-like creature that some say is the missing link in bird evolution have been discovered in northwest China. The remains of 40 of the nearly modern amphibious birds, so well-preserved that some even have their feathers, were found in Gansu province, researchers report in Friday's issue of the journal Science. Previously only a single leg of the creature, known as Gansus yumenensis, had been found."
Re:Regardless... (Score:1, Informative)
Re:Doubious Dating Techniques (Score:5, Informative)
Often proponents of creationism and intelligent design tend to choose the dating technique that fits the picture they have in their minds. For example, the poster above me stated a single, unrefined example of a dating technique being off in order to set a mindset that this technique is unreliable, and, unjustifiably, useless in all situations. He or she also states the half life of carbon-14, and a continued presence of it in fossils to understate the possible age of the fossil, conviently fitting into creationary mold set by the bible. How old is the world again? 6,000 years?
Re:Doubious Dating Techniques (Score:5, Informative)
After ~60k years, the level of C-14 in a sample can not be reliably seperated from the "background noise" of the C-14 that might just happen to be lingering around.
Potassium-argon dating can not be used on once-living things because radioactive Potassium-40 decays into Argon, a gas, which tends to escape into the environment -- unless it's in solid rock. Thus is is useful for dating lava flows. Also, the half-life of radioactive Potassium-40 is very long, about 1.3 million years (compare to C-14 at a mere 5730 years). Therefore K-Ar dating is only useful for dating "really old non-organic things" like... ancient lava flows.
It's simply a matter of using the right tool for the job.
=Smidge=
Re:"Missing link"? (Score:2, Informative)
Re:FSM Strikes Again! (Score:5, Informative)
I'm just an evolutionary biologist, so you'll have to take this with a grain of salt, but that's bullshit. What they did was note that most species of birds near that occur near the base of the evolutionary tree are aquatic. That's it: they described a pattern. I suppose you could be right, maybe they have some vested interest in early birds being aquatic. I can't imagine what possible motivation you might have for fabricating such an esoteric claim, but you're the one who (anonymously) claims to know so much more than us biologists.
Of course, you could very easily and objectively test this yourself. Look up the latest evolutionary tree for birds, figure out which ones the ecology is known for, and label your tree accordingly. Then look at the tree, and see if the species near the base of the tree are mostly aquatic. If they are, then the guys in the article are ok. I don't think this is pressing enough that I'm going to rush out and do it myself. But you can be sure that there are more than enough fanatical ornithologists in the world to check these things out.
If you really can't find an "evolutionist" who knows more about the subject than you do, you are looking in the wrong places.
yp.
Caveat Emptor (Score:3, Informative)
Re:Missing Link, eh? (Score:3, Informative)
Case in point: Some science journalist invents the "missing link" label, and the readers now believe that "transitional species" were not well-adapted specimens for their time, but were merely a waystation from one well-adapted species to another. This flawed description of how things work implies a directionality, and even an intent/goal of evolution. Which, it's perfectly logical for those readers to assume, implies an intelligence governing the process.
The problem is a lack of sound understanding of science at a very basic level, for which scientists and science journalists share some responsibility. It's not just fundies dumbing down our kids (although--don't get me wrong--they're doing a hell of a job).
Evolutionary Link (Score:3, Informative)
Evolutionary links are inferred from biological data. With living species this is done primarily with DNA, but for fossils you have to use morphological information. So the taxonomists would line up all the specimens they have and figure out morphological connections among them. You might find that one group of fossils all have a certain bone structure, so they get grouped together while another group with different bone structure is interpreted as being a different lineage. You might be lucky enough to find a specimen with an intermediate structure, linking the two groups. This is a very basic explanation - there are all kinds of variations for deciding which features to use to make your classification, what to do with features that produce conflicting results and how to interpret the differences, but you get the idea...
yp.
Re:How do they know this creature was amphibious?? (Score:3, Informative)
The exact wording, from the abstract [sciencemag.org] is
The anatomy of Gansus, like that of other non-neornithean (nonmodern) ornithuran birds, indicates specialization for an amphibious life-style, supporting the hypothesis that modern birds originated in aquatic or littoral niches.
Which can be summarized as 'if something looks like a duck, then it likely live, at least sometimes, in water'. Doesn't mean it does, but it is likely. Also note that the researchers admit that this is just a single data point, and no real conclusions can be drawn. Also of note is that other researchers are not convinced, as the development to modern birds, or all varieties, probably took many different paths, leading to birds occupying various niches, from tress to water.
I thing I notice is missing in the summary is that these fossil remains are not crushed. They are three dimensional, and of great detail.
Re:Doubious Dating Techniques (Score:5, Informative)
Uh, no; there doesn't have to be a reliable way to date something. There are a great many ways of dating old things. Usually, scientists consider a date determined by a single method to be preliminary and requiring verification. The verification usually happens by using several different methods. If they all come up with a similar date, that is considered good support for the date.
Most of the methods used by paleontlogists are based on various sorts of decay processes, mostly the decay of radioactive isotopes. Taken singly, each of these has ways that that the samples can be contaminated, giving a bad date. But different chemical elements or compounds have different kinds of contamination that produce different kinds of dating errors. If you use N different dating methods, it's unlikely that all would be contaminated in such a way as to produce the same error. So if all N (or N-1) give the same date, that implies that there's little or no contamination, and the date is reliable.
The first scientific papers dealing with a new discovery often have tentative dates due to the use of a single dating method. But with new fossil beds, once good fossils have been excavated, it's routine to apply several different dating methods to pin down the fossils' ages more precisely.
This whole topic is a serious scientific field in it own right. Explaining how it all works would take several years of intensive study.
Re:FSM Strikes Again! (Score:3, Informative)
And that's the main point that academics have been making - evolution (right or wrong) is a testable scientific theory, ID (right or wrong) is not. There's a lot of static from more emotion-laden people on both sides, but that's the view of almost all scientists.
some fossils that could be intermediary. to my knowledge, not a single one has been proven beyond a reasonable doubt, though
The Horse Series [wikipedia.org] is rather compelling.
some pro-evolutionists ... claim it is silly to think this bird is intermediary and outline why
It's sort of like trying to tell if Julius Ceasar was a direct ancestor of yours through genetic testing. You may be able to show that you're related, but with this many generations, it's possible that his brother was your ancestor, not Julius. That's what they're discussing.
did you ever wonder why we can't point to a living creature TODAY that is transitionary? ... a law that says all transitionary anmials have to go extinct?
We can't tell it something is transitionary until its gone - to be transitionary it has to turn into something else - meaning it's not here anymore.
the fossil record ISN'T what was predicted!
Whis is why evolutionary theory has been changed to correspond with new information. But you should know that the basics haven't changed (complex things have simpler ancestors, etc).
there are no land / water transitional ear fossils ... according to macroevolutionary theory, such a change should lead to reduced adaptibility over the tens of thousands/millions of years required to make the change
For this, I don't have any examples off the top of my head. But here's an idea: increased adaptation to land was more important than reduced adaptation to the water. The idea of trade offs (like faster metabolism or needing to eat less, having many weak offspring or fewer stronger ones) is a basic part of evolutionary theory.
where are all the pre-dinosaur fossil transitions that led to the dinosaurs
This [wikipedia.org] should get you started.
And for the big paragraph, I'll have to give short answers:
for example, why would an asexual reproductive system turn to the more complex sexual method?
Because it provides many benefits. That's why most things that normally reproduce asexually still swap genes on occation.
how would a centimeter stub of a limb on one creature be beneficial so as to give it time to end up as an arm with fingers?
Because even a stub is better than nothing for pulling a fish through mud. And a stub with toes that dig in is even better. And and stub with toes and an extra joint is even better. And ...
how did a life form spontaneously combust WITH REPRODUCTIVE ABILITIES
Most likely because the only thing the first life from did was reproduce. That was the defining point between being living and non-living.
how can an environement that can create life from death, if one even exists ... be compatible with an environment that can sustain that life?
Why would the "creation environment" be any different from the "sustaining environment"?
how does life come from death?
You might as well ask "how can beauty come from uglyness" and expect a scientific answer. In everyday life there's a clear difference between animals and plants, or life and death, but in the larger world things are much greyer. Just like we have bacteria that both eat and photosynthesize, there are lots of things that aren't clearly living or non-living - prions, self-replicating RNA strands, viruses, etc.
35-70 years (Score:3, Informative)
What sort of research have you seen? I remember from catholic religion classes, 70 years was considered about right. A survey of the scholarship at wikipedia [wikipedia.org] claims ranges of:
- Mark: c. 68-73
- Matthew: c. 70-100
- Luke: c. 80-100
- John: c. 90-110
(years A.D.). Jesus is thought to have died ~30 A.D.Given that the average life expectancy at that time was ~40 years, it would have taken ancient men of the time for the accounts to have been first-hand witnessings. Peter is said to have lived until 64 AD - I don't think we know when he was born but he probably lived at least into his fifties, so not everybody died at 40.