[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: T.rex needs a diet!



I should clarify - I think the mass estimates based on bone scaling
are incorrect (I am biased towards volumetric reconstructions,
though). But the fact that the bone scaling studies do seem to be
underestimate mass is interesting in itself - i.e., rather than the
thinner/weaker bones (from whatever indicator they were using. Cortex
area?) of dinosaurs suggesting they were a lot lighter, it might
instead be that they had, well, thinner, weaker bones. Or very
different bone loading, as you said. Volumetric mass estimates gives
you a more-or-less independent variable to analyse the differences in
the mass vs. bone geometry relationship, so with enough volumetric
estimates you could go back and make a dinosaur curve to compare to
the mammalian one. Be a good study!

Viv

On 15 October 2011 18:49, Heinrich Mallison
<heinrich.mallison@googlemail.com> wrote:
>> The disagreement between volumetric estimates of mass and estimates
>> based on scaling of bone dimensions is interesting, though.
>
> To me, it is not. Two reasons:
> 1) scaling is either done by using mostly mammal data. Dinosaurs are
> fundamentally different in their body architecture from mammals. Their
> locomotion, accordingly, must have been quite un-mammalian, with
> forces differently created and distributed. Scaling on this basis = No
> go!
> 2) or scaling is done based on monitors, birds and one or two other
> values from crocs, then extrapolating to the fare thee well. Birds are
> fundamentally different in body shape from non-Avialae, and crocs are
> non-endotherm and non-cursorial. The other critters in the database
> are between one and three orders of magnitude smaller than your
> average large theropod or sauropod. This is not going to work either.
>
> What we need to do is volumetric models, with the soft tissues modeled
> according to extant animals (see, e.g., Allen et al 2009). Anything
> else, well - apples and pears. Sadly, we are in very short supply of
> very large, terrestrial, cursorial, tailed animals.
>
> H
> ___________________________________
> Dr. Heinrich Mallison
> Abteilung Forschung
> Museum für Naturkunde - Leibniz-Institut
> für Evolutions- und Biodiversitätsforschung
> an der Humboldt-Universität zu Berlin
> Invalidenstrasse 43
> 10115 Berlin
> Office phone: +49 (0)30 2093 8764
> Email: heinrich.mallison@gmail.com
> _____________________________________
> Fere libenter homines id quod volunt credunt.
> Gaius Julius Caeser
>
>
>
>
> On Sat, Oct 15, 2011 at 5:52 PM, Vivian Allen
> <mrvivianallen@googlemail.com> wrote:
>> Oh well, that's what happens when these so-called "scientists" apply
>> the so-called "scientific method" to "develop and test" such so-called
>> "hypotheses"...
>>
>> The disagreement between volumetric estimates of mass and estimates
>> based on scaling of bone dimensions is interesting, though. The most
>> straightforward synthesis, assuming both datasets are accurate (and I
>> have no reason to suspect otherwise), is that dinosaurs may have had
>> lower safety factors than mammals of equivalent size.
>>
>> On 15 October 2011 17:40,  <MKIRKALDY@aol.com> wrote:
>>> Only two years ago, dinosaurs were smaller than "scientists"  thought:
>>>
>>> http://www.sciencedaily.com/releases/2009/06/090621195620.htm
>>>
>>> Mary
>>> ----------
>>>
>>> In a message dated 10/13/2011 1:28:21 P.M. Eastern  Daylight Time,
>>> birdbooker@zipcon.net writes:
>>> HI  ALL:
>>> FYI:
>>>
>>> http://www.livescience.com/16524-rex-dinosaur-weighed.html
>>>
>>> sincerely
>>>
>>> Ian  Paulsen
>>> Bainbridge Island, WA, USA
>>> Visit my BIRDBOOKER REPORT blog  here:
>>> http://birdbookerreport.blogspot.com/
>>> --
>>>
>>>
>>
>