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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  True to form, Martin uses outdated dinosaur references.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)?  Every TWG version has oviraptorosaurian Caudipteryx.

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

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.

Mickey Mortimer

> Date: Thu, 5 Jan 2012 19:01:01 -0800
> From: bscreisler@yahoo.com
> To: dinosaur@usc.edu
> Subject: Re: Caudipteryx suffered from osteoarthritis
> >From Ben Creisler
> bscreisler@yahoo.com
> 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)?
> 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.
> ...........
> 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.