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Re: Caudipteryx suffered from osteoarthritis



 Ha. True to form, Martin uses outdated dinosaur references. Why
 Hwang et al. (2002), and not something more recent that used more
 oviraptorosaurs and birds like Senter (2007)?

Because, like all BANDits, he has no *ucking idea that those more recent papers even exist. He has never tried to find out whether they exist, because he doesn't care about the nonavian dinosaur literature, not being interested in nonavian dinosaurs and all. I don't follow the muscicapid literature either.

This lack of information is what allows a BANDit to be a BANDit without having to lie to himself*. Maintaining this lack of information, however, is intellectual dishonesty -- willful ignorance. There's a _reason_ why I don't pontificate about muscicapid intra- or interrelationships!

* Was about to write "themself", but are there any women in the BAND other than the first author of the 1997 Science blurb on sea snake collagen?

 And sprawling Microraptor with a geocentric tarsal joint?!
 Hilarious.

Geocentric? What do you mean?

 Finally, maybe I'm just biased, but if I had a huge sample of
 Caudipteryx, I would use it to solve the problem of whether C. dongi
 is valid and how/why the Zhou et al. (2000) specimens seem to differ
 cranially from the paratype.

Now that we know those specimens exist, I hope someone will get around to doing that work...

> Here are a few passages from the Discussion section of the
> article:
>
> Our study shows that Early Cretaceous birds from the Liaoning fauna
> in China (with the exception of Caudipteryx) seldom manifest
> osteoarthritis (Table 1). The rarity of osteoarthritis in Early
> Cretaceous birds mirrors that in Cretaceous dinosaurs. The
> frequency in the oviraptosaur Caudipteryx is significantly greater.
> In modern birds, osteoarthritis shows a species specific variability
> in prevalence (Rothschild and Panza, 2005, 2006). There is also an
> inverse relationship to body mass in recent birds (Rothschild and
> Panza, 2008). In contrast, the Mesozoic sample shows a positive
> correlation with body size (Table 1) with the highest incident in
> the comparatively large Caudipteryx. Caudipteryx is classified as an
> oviraptorsaur (Lü et al., 2002), but were oviraptorsaurs feathered
> dinosaurs or birds (Dyke and Norell, 2005; Hwang et al., 2002)?

"Oviraptosaurs" once, "oviraptorsaurs" twice. Boo. Display of utter carelessness on the parts of authors and reviewers alike.

> The next largest form, Microraptor, with its feathered feet, is
> unlikely to have been a ground bird (Alexander et al., 2010). It is
> not surprising that it avoided osteoarthritis (less than 1%).
> Landing on tree trunks apparently did not overstress its ankle
> joint, and an inherent sprawling posture distributed the stresses,
> in spite of the geocentric nature of the ankle. A geocentric joint
> rotates as well as flexes and extends and is subject to greater
> stresses than a hinge joint.

They can look at a hinge and declare it not a hinge? Wow.

A sprawling posture, impossible as it would be without *ucking taking the femoral heads completely out of the hip joints, wouldn't "distribute the stresses" much. It would focus them on the pubis. Ouch.

> Why then isn’t Caudipteryx as well protected from osteoarthritis as
> are the modern ratites that it resembles? Its reduced wing
> parallels that seen in flightless birds and suggests that
> Caudipteryx also had a flighted ancestor, at least as capable as the
> gliding dromaeosaur Microraptor (Alexander et al., 2010). This
> means that the adaptation for terrestrial locomotion seen in
> Caudipteryx developed de novo in that genus and may not have been
> perfected to a point that prevented development of osteoarthritis.
> We have not yet had an opportunit rs including forms that are more
> cursorially adapted, but such a study might help illuminate the
> reasons for osteoarthritis in these animals.

They probably think that's an argument for considering it a bird, LOL.