measurement standards (was: Re: Spinosaurus aegyptiacus holotype)

["Jordan Mallon" <j_mallon@hotmail.com>]

All this talk about taking inaccurate measurements brings up a point that 
has special interest to me right now, as I am in the midst of measuring some 
chasmosaur bones for my BSc thesis.  I had never really thought about it 
until recently, but if I am trying find, say, the maximum length of a 
certain element, what is the "right" way to go about it?  For example, if 
I'm interested in measuring the maximum height of a vertebra, would I keep 
the vertebra level so that the base of the centrum is parallel to the ground 
and measure to the top of the neural spine from there (somewhat akin to its 
position in the living animal), or would I simply manoeuver the vertebra so 
that I get the maximum length from the base of the centrum to the top of the 
neural spine in my calipers (whichever orientation that might be)?  Are 
there standard ways of taking measurements from different elements, I guess 
is what I'm asking.  My understanding is that the answer is pretty much no 
and that so long as I'm consistent with my measurements, all is well.  But 
I'd very much appreciate the input of someone who has done a lot of this 
type of thing before.  For what it's worth, I'm taking a lot of the same 
measurements Lehman did in his initial description of Chasmosaurus 
mariscalensis.
Thanks,

Jordan Mallon

Undergraduate Student, Carleton University
Vertebrate Paleontology & Paleoecology

Paleoart website: http://www.geocities.com/paleoportfolio/
AIM: jslice mallon

> From: "Tim Williams" <twilliams_alpha@hotmail.com>
> Reply-To: twilliams_alpha@hotmail.com
> To: dinosaur@usc.edu
> Subject: Re: Spinosaurus aegyptiacus holotype
> Date: Thu, 19 Feb 2004 12:13:57 -0600
>
> Mickey Mortimer wrote:
>
> > The dorsal neural arches are not fused to the centra.  I don't see why
> > people ignore Spinosaurus' size, or claim it's uncertain that it was 
> > larger
> > than Tyrannosaurus.
>
>
> Can we be certain that Stromer's measurements were accurate?  The type 
> material was obliterated (*sob*), so the dimensions of individual elements 
> are based on Stromer's descriptions alone.
>
> This same issue applies to the type material for _Amphicoelias 
> fragillimus_: Cope's measurements of the type vertebra suggests a truly 
> enormous sauropod.  Although it may seem unlikely that someone could get 
> something as simple as linear measurements wrong (how hard is it to use a 
> tape measure?), I seem to recall that this is what happened with the 
> scapula referred to _Ultrasaurus_.  A second look at this scapula showed 
> that the original length given for this bone was exaggerated, and that the 
> scapula was no larger than one previously referred to _Brachiosaurus_.
>
>
> Tim
>
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