Re: Dino reputation 'is exaggerated'

[don ohmes <d_ohmes@yahoo.com>]

Or pdf's are available through Ken Carpenter...

--- "E Schachner, Earth Sciences"
<es4772@bristol.ac.uk> wrote:

> 
> Phil actually discusses the nature of the keratin
> sheath in the paper - He 
> concludes that it's constructed of beta-keratin by
> using the Extant 
> Phylogenetic Bracket (Witmer, 1995). Mammalian
> keratin is made of alpha 
> kerotine, while reptiles and birds have the beta
> form. See excerpt below:
> 
> --> "The morphology of the fossil ungual claw cores
> of dromaeosaurs
> combined with rare soft tissue preservation (Clark
> et al. 1999)
> indicates that it would have been protected by a
> similar keratin
> sheath. Extant Phylogenetic Bracketing (EPB: Witmer
> 1995) can
> be used to reconstruct the structure and properties
> of the keratin
> claws possessed by non-avian dinosaurs. Mammal claws
> are
> composed of an a-keratin (helical), but bird and
> reptile claws are
> composed of b-keratins (pleated-sheet) (e.g. Fraser
> & MacRae
> 1980). Given that dinosaurs fall within the EPB of
> birds and
> crocodilians, it is likely that the claws of
> dinosaurs were composed
> of b-keratin. Experiments to determine the Young
> modulus of
> ostrich claw b-keratin indicated that they are
> mechanically aniso-
> tropic, a property arising from the orientation of
> the keratin fibrils
> (Bonser 2000)."
> 
> Also, the specifics on the robotic leg are in the
> paper too - They 
> calculated the force for a 2m tall 40kg animal, and
> attacked both pig and 
> crocodilian skin. They used both Velociraptor and
> Deinonychus as a model.
> 
> Its a good paper, here is the reference:  Manning,
> PL., Payne, D., 
> Pennicott, J., Barrett, PM., Ennos, RA. (2005).
> Dinonsaur killer claws or 
> climbing crampons? Biology Letters of the Royal
> Society. Published online
> 
> Emma
> 
> ----------------------
> E Schachner, Earth Sciences
> es4772@bristol.ac.uk
>