Xiaotingia zhengi

| 33 Comments

A lovely new dinosaur fossil from China is described in Nature today: it's named Xiaotingia zhengi, and it was a small chicken-sized, feathered, Archaeopteryx-like beast that lived about 155 million years ago. It shares some features with Archaeopteryx, and also with some other feathered dinosaurs.

xiaotingia.jpeg
(Click for larger image)

a, b, Photograph (a) and line drawing (b). Integumentary structures in b are coloured grey. cav, caudal vertebra; cv, cervical vertebra; dv, dorsal vertebra; fu, furcula; lc, left coracoid; lfe, left femur; lh, left humerus; li, left ilium; lis, left ischium; lm, left manus; lp, left pes; lpu, left pubis; lr, left radius; ls, left scapula; lu, left ulna; md, mandible; rfe, right femur; rfi, right fibula; rh, right humerus; ri, right ilium; rm, right manus; rr, right radius; rt, right tibiotarsus; ru, right ulna; sk, skull; ss, synsacrum.

Now here's why this particular fossil has some paleontologists in a dither. Systematics uses a set of objective, computer-based tools to objectively build phylogenetic trees: you plug a set of character parameters for a set of organisms into it, and it analyzes them and determines the most likely or most parsimonious tree to describe their relationships. Plugging in data from modern birds, Archaeopteryx, and dromeosaurs, for instance, generates trees in which Archaeopteryx clusters with the birds, and not the dromeosaurs. Archaeopteryx was not a direct ancestor of modern birds, but was thought to be related to the basal avians — so it was a kind of close cousin.

When Xiaotingia's data is tossed into the calculation, though, the results change. Xiaotingia doesn't cluster so tightly with birds; it's a more distant relative. However, Archaeopteryx shares enough significant features with Xiaotingia that they now cluster together, pulling Archaeopteryx out of the basal Aves and into a new classification. It says that Archaeopteryx is now a kind of second cousin, a little less closely related to the birds than previously thought.

bird_phylo.jpeg
(Click for larger image)

Archaeopteryx has historically been regarded as the most basal bird (avialan), but the discovery of the closely related Xiaotingia led Xu et al.1 to pull these archaeopterygids out of avialans (birds) and into deinonychosaurs along with dromaeosaurids and troodontids. This new grouping better accounts for the evolution of feeding strategies among bird-like dinosaurs. Previous research suggested that herbivory was common among this group, as reflected in the tall, boxy skulls of oviraptorosaurs and basal avialans such as Epidexipteryx. The triangular, sharp-toothed skull of Archaeopteryx was incongruous among basal avialans, but fits better among the carnivorous dromaeosaurids and troodontids.

I have to say that I think it's extremely cool that we have a new fossil from down around the roots of the bird family tree, and it does sharpen our knowledge of what was going on down there in the middle and late Jurassic. There was a whole assortment of delicate-boned, feathered, bipedal dinosaurs that were flourishing and diversifying in that window of time, and we've now got enough data that we can distinguish details in the family tree, which is absolutely fabulous.

However, a lot of the fuss over the specimen as somehow radically changing the importance of Archaeopteryx is a bit overblown. The relative status of Archaeopteryx and Xiaotingia is a bit of taxonomic detail — important details in working out the specific history of life — but it's the equivalent of deciding that a fossil belongs in one pigeonhole rather than the pigeonhole next to it. Its shift in status means that there's a bigger gap in the early history of the true birds than we thought, and it also means that there was a greater diversity of bird-like forms than we expected in the Jurassic. One other suggestion is that removing the carnivorous Archaeopteryx from the base of the bird family tree opens up the possibility that modern birds might have descended from the vegetarian side of the family — if the last common ancestor of birds was an herbivore, that has interesting implications for the paths evolution took.

But don't worry, Archaeopteryx still represents a beautiful example of a transitional form. This new fossil is just another transitional form discovered. Creationists cannot take any consolation from it: Archaeopteryx isn't suddenly gone, it's become a part of a richer picture of bird evolution.


Xu X, You H, Du K Han F (2011) An Archaeopteryx-like theropod from China and the origin of Avialae. Nature 475, 465-470.

33 Comments

OMFG! More gaps! Science id doomed.

In other words, prep yourselves for mountains of new, even more specious, arguments that prove Evilution can’t be true.

PS:

…This new fossil is just another transitional form discovered. Creationists cannot take any consolation from it…

You’re kidding, right?

cwjolley said:

PS:

…This new fossil is just another transitional form discovered. Creationists cannot take any consolation from it…

You’re kidding, right?

Perhaps the words should have read “Creationists cannot honestly take any consolation from it…”

Not that something like honesty ever stopped many of them.

Let’a all remember the Duane Gish Memorial Law of the propagation of gaps in the fossil record:

“For every n ancestral forms in a fossil lineage, there are n-1 gaps in the fossil record. As the number of different forms increases, so do the number of gaps. Therefore, the better known and more complete that any lineage or phylogenetic treemay be, the greater the opportunity of fooling the gullible with all of the gaps”

That specimen looks better than most roadkill I’ve seen. I find it amazing that this fossil is so well preserved. Cue dumb creationist argument in 3, 2, 1, .…

Roadkill? If it’s roadkill that means it coexisted with humans!!111!!!eleven!!!!!

Henry J said: Roadkill? If it’s roadkill that means it coexisted with humans!!111!!!eleven!!!!!

It wuz run down by Fred Flintstone. “YABBA DABBA DOO!”

This comment has been moved to The Bathroom Wall.

Been to UD where ‘NEWS’ aka O’Leary has put up this further evidence of the inability of science to have an idea and just darn well stick to it. Scordova laughs at the gullibility of the NCSE, and defends the barmy Dr Wells: ‘bornagain’ pitches in as the brains of the operation with the necessary hard research. An all round devastating reposte.

My wife and I were discussing this yesterday and I brought up a few of the (fallacious) reasons creationists are crowing (pun intended) about this. She, ever the poignant one, asked, “I don’t understand why they think moving Archeopteryx further from birds and closer to dinosaurs is such a score against science and/or evolution. Don’t they know that taxonomy is just our convenient way of representing nature’s relationships? Closer or farther, it’s still related right?” Exactly right. Funny that’s so obvious to some and not others.

She also quickly caught on to the issue of the scarcity of fossils and, more importantly, the ecological bias of fossilization. And she’s not exactly been all that exposed to science, though she was exposed to thinking. Those kind of concepts are no-brainers to her, but completely fly over the head of the creationist crowd.

Robin said:

My wife and I were discussing this yesterday and I brought up a few of the (fallacious) reasons creationists are crowing (pun intended) about this. She, ever the poignant one, asked, “I don’t understand why they think moving Archeopteryx further from birds and closer to dinosaurs is such a score against science and/or evolution. Don’t they know that taxonomy is just our convenient way of representing nature’s relationships? Closer or farther, it’s still related right?” Exactly right. Funny that’s so obvious to some and not others.

She also quickly caught on to the issue of the scarcity of fossils and, more importantly, the ecological bias of fossilization. And she’s not exactly been all that exposed to science, though she was exposed to thinking. Those kind of concepts are no-brainers to her, but completely fly over the head of the creationist crowd.

A similar story was related in Your Inner Fish. Dr. Shubin took a cast of Tiktaalik to his child’s pre-school (4 and 5-year-olds) and asked them what they thought it might be. One kid said a crocodile and why, another kid said a fish and why, then another kid said, ‘maybe it’s both’.

It’s obvious even to pre-schoolers. It is obvious to creationists, they just can’t admit it.

Geez these people do this stuff for a living, let them interpret the results or at least approve the ones doing the interpretations. Modern media wants to engulf everything that moves and market the “news” (which orgs like Yahoo have decided includes arcane scientific discovery and minutiae) with controversey and inflammatory interpretations. The public has come to think scientific inquiry is just another spin on politics. Or something. Jeez! Dummy up, America, vote Republican, they will interpret the world for you in convincing tones.

I disagree with the idea that moving Archaeopteryx is not imporant and interesting. Yes, it is like moving a fossil from one pigeon hole to another, but over the last several years of research, the big discovery in early “bird” evolution is that there are more pigeon holes than expected. Specifically, almost all of the obvious bird-related features that we think of when we look at birds are not unique to birds and are not about being a bird. There is a diverse category of dinosaur that used these features that we see today as fine-tuned for flight (and a few other features) in functionally overlapping but distinctly non-bird-like ways.

This may be a pattern with unravel ling ancient phylogeny in general. That which makes a deer a deer is a set of features fine tuned to be all deery and stuff but all/most of which evolved in a non-deer like group for other reasons, are not novel to (derived in) deer, but are quintessential do deer. Substitute “primate” for “deer” and that previous sentence (probably) works.

This latest find does not bring all this to light suddenly and without prior knowledge but it is an important step especially because some of the key cladistic/taxonomic features of the head have been nailed down.

And of course, as you point out, when we move fossils around we also move around the gaps, which requires god to move as well, I assume. What is really interesting, though, is how much taxonomic gaps are like Time Lord Technology: When you look at them, you can usually assume that they are bigger on the inside than they are on the outside.

Greg Laden said: I disagree with the idea that moving Archaeopteryx is not imporant and interesting.

Oh sure, plenty interesting in itself; but not fodder for claiming: “DEM SCIENTISTS WUZ WRONG ALL ALONG! Dem bozos such DUMMIES!”

We have an “intermediate form”: some features of earlier forms, some features of later forms. But not a “missing link”.

cwjolley said:

OMFG! More gaps! Science id doomed.

In other words, prep yourselves for mountains of new, even more specious, arguments that prove Evilution can’t be true.

Ah well, science has found an even better transitional form. Hence evolution is wrong.

bigdakine said:

cwjolley said:

OMFG! More gaps! Science id doomed.

In other words, prep yourselves for mountains of new, even more specious, arguments that prove Evilution can’t be true.

Ah well, science has found an even better transitional form. Hence evolution is wrong.

One might as well claim that the Bible never existed specifically because I can hold it in my hands.

Greg Laden said: That which makes a deer a deer is a set of features fine tuned to be all deery and stuff but all/most of which evolved in a non-deer like group for other reasons, are not novel to (derived in) deer, but are quintessential do deer.

Say this 5 times fast.

bigdakine said:

cwjolley said:

OMFG! More gaps! Science id doomed.

In other words, prep yourselves for mountains of new, even more specious, arguments that prove Evilution can’t be true.

Ah well, science has found an even better transitional form. Hence evolution is wrong.

And the mathematicians have an even more serious problem. There are an infinite number of gaps between the integers.

When filling the gaps with “rational” numbers didn’t work, they resorted to something down right irrational.

Then they started running wild with imaginary numbers, and all semblance of order went out the window.

That’s the problem with the entire fossil industry. People make these fossils have no idea how to make them consistent with the already existing frauds. That’s the only reason Piltdown Man was revealed as a fraud. It’s like Star Trek; all of the episodes can’t be put together to make a self-consistent narrative and it drives the fanboys apopleptic! I think when my dog and cat die I will dry out their bones and string them together with the dog’s head and the cat’s body. I’ll then send it to NatGeo and later see how PZ classifies it.

Mike Elzinga said:

bigdakine said:

cwjolley said:

OMFG! More gaps! Science id doomed.

In other words, prep yourselves for mountains of new, even more specious, arguments that prove Evilution can’t be true.

Ah well, science has found an even better transitional form. Hence evolution is wrong.

And the mathematicians have an even more serious problem. There are an infinite number of gaps between the integers.

When filling the gaps with “rational” numbers didn’t work, they resorted to something down right irrational.

Then they started running wild with imaginary numbers, and all semblance of order went out the window.

Oh, God, and he must be an Australian. There are times when I cringe, I really do.

Mike Elzinga said:

bigdakine said:

cwjolley said:

OMFG! More gaps! Science id doomed.

In other words, prep yourselves for mountains of new, even more specious, arguments that prove Evilution can’t be true.

Ah well, science has found an even better transitional form. Hence evolution is wrong.

And the mathematicians have an even more serious problem. There are an infinite number of gaps between the integers.

When filling the gaps with “rational” numbers didn’t work, they resorted to something down right irrational.

Then they started running wild with imaginary numbers, and all semblance of order went out the window.

And then all of that complex conjugatuion in public. Shameful!

Not to mention that some of those imaginary numbers are irreducibly complex!

The Jumbuck said: That’s the only reason Piltdown Man was revealed as a fraud.

Oh, still fussing that somebody debunked Piltdown man sometime ago in the last century? Why?

Creationists have always been and continue to be debunked, and they haven’t worried about it at all. They just ignore it and keep recycling the same old stories.

Dave Luckett said:

Oh, God, and he must be an Australian. There are times when I cringe, I really do.

A sheep from Queensland, do you suspect?

Dave Luckett said:

Oh, God, and he must be an Australian. There are times when I cringe, I really do.

I sympathize with you matey, but on the other hand it is (admittedly not very) comforting to know creationism isn’t strictly a Yankie delusion.

And compared to Ken Ham, the embarrassment factor in this is slight.

bigdakine said:

Mike Elzinga said:

bigdakine said:

cwjolley said:

OMFG! More gaps! Science id doomed.

In other words, prep yourselves for mountains of new, even more specious, arguments that prove Evilution can’t be true.

Ah well, science has found an even better transitional form. Hence evolution is wrong.

And the mathematicians have an even more serious problem. There are an infinite number of gaps between the integers.

When filling the gaps with “rational” numbers didn’t work, they resorted to something down right irrational.

Then they started running wild with imaginary numbers, and all semblance of order went out the window.

And then all of that complex conjugatuion in public. Shameful!

And then they demand conformity no matter where they go.

Mike Elzinga said: And then they demand conformity no matter where they go.

Enough. Sounds like an argument between Poles and Zeroes.

mrg said:

Mike Elzinga said: And then they demand conformity no matter where they go.

Enough. Sounds like an argument between Poles and Zeroes.

Poland attacked Japan?

I shall address him in our own language:

Look, sport, it’s pretty clear you’re two bricks short of a load. Either you’re taking the piss or you wooden know if someone was up yer with an armful of chairs. You’re down on the tintanks, but I’ll take Sydney to a brick you’ve never been closer to Baghdad than Dubbo. And you wooden know a fossil if it reared up and bit you. Go play trains somewhere else.

Mike Elzinga said: Poland attacked Japan?

It was an unstable situation.

“Down on the tintanks” … I can’t even find that one in Aussie slang dictionaries online. I do like “go play trains somewhere else.”

“Tintanks” = Yanks, rhyming slang. “Down on” or “dirty on” = having a negative attitude towards.

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This page contains a single entry by PZ Myers published on July 28, 2011 1:15 PM.

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