How was the vertebrate/arthropod LCA segmented

post from Pharyngula on 07 May 2012 02:12:59 PM. © Pharyngula

Vertebrates are modified segmented worms; that is, their body plan is made up of sequentially repeated units, most apparent in skeletal structures like the vertebrae.

Arthropods are also modified segmented worms. Look at a larval fly, for instance, and you can see they are made up of rings stacked together.

So here's a simple and obvious question: can we infer that the last common ancestor of vertebrates and arthropods was also a segmented worm? That is, is segmentation a common ancestral trait, or did arthropods and vertebrates invent it independently? At first thought, you might assume they are: it's a complex trait shared by two taxa, so the simplest assumption is that both groups inherited it from their common ancestor (making it a synapomorphy), but there are also substantial differences in the mechanism of segmentation, so it's possible that this trait wasn't present in the common ancestor (making it a homoplasy).

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Singularity Hub Membership Update: Your New Body
is On Order (Please Allow 6-8 Decades for Delivery)

post from Singularity Hub on 07 May 2012 01:15:42 PM. © Singularity Hub

Have you considered which kind of futuristic body you’d like to pilot in the years ahead? The Singularity Hub Membership [...]

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Astronomers find a galactic nursery 12.7 billion
light years away

post from Bad Astronomy on 07 May 2012 12:33:10 PM. © Bad Astronomy

You know why astronomy is cool? Because of things like this: Galaxy clusters are collections of galaxies held together by their own gravity. We see clusters all over the place, and they’re among the largest structures in the Universe. We can find[...]

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Unholy Haleakal!

post from Supernova Condensate on 07 May 2012 12:31:33 PM. © Supernova Condensate

I managed to miss an absolute gem over the weekend. A comic about the Supermoon -- featuring a zombie Phil Plait!

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Sauropod farts warmed the planet

post from New Scientist - Environment on 07 May 2012 12:00:00 PM. © New Scientist - Environment

Modern cows are a major source of methane, a greenhouse gas. Just think what must have come out of the biggest plant eating dinosaurs?

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Exergy, existentialism and the environment

post from Sciencebase Science Blog on 07 May 2012 11:57:59 AM. © Sciencebase Science Blog

Exergy is perhaps an unfamiliar concept. Energy we can fairly easily get to grips with, it’s a measure of the ability of a system to do work. Work is what causes a system to change its energy state?hmm…first law of thermodynamics. But, what is exergy and where does it fit into the energy equation? By [...]

Exergy, existentialism and the environment is a post from: Sciencebase Science Blog

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Do You Know What I Really Love About Spring
(Washers)

post from CR4 - Recent Blog Entries on 07 May 2012 11:05:07 AM. © CR4 - Recent Blog Entries

Do you know I really love about spring? Besides baseball. And the weather. And the sundresses. ...via Voices From RussiaIt's spring cleaning!I know, that probably sounds absurd, but I love the chance to get the winter dust out and get some fresh air circulating in my home.But, do you know

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xkcd is the very model of a modern major science
grad

post from Bad Astronomy on 07 May 2012 11:00:01 AM. © Bad Astronomy

Hmmmm? the astronomer in today’s xkcd comic looks familiar, even as a stick figure.At least he didn’t draw me as a zombie. But I’m no Feynman.And hey, together with SMBC I think this makes me king of the four-letter comics. I mean, um.[...]

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TED: Michael Tilson Thomas: Music and emotion
through time - Michael Tilson Thomas (2012)

In this epic overview, Michael Tilson Thomas traces the development of classical music through the development of written notation, the record, and the re-mix.

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Jaguar Debuts XJ Sport and Speed Nürburgring
Taxi

From Autoblog: Those looking to get around the Nürburgring with a quickness will soon be able to hop into a Jaguar XJ. The luxury automaker has announced it will bolster its fleet at the infamous German track with the addition of an XJ Supersport. The-510 horsepower sedan will feature a

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