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Re: Massive macronarians with missing measurements (long)



Measure Your Damned Dinosaur!
http://svpow.wordpress.com/2009/04/23/mydd/

Zach, I feel your pain.  I think we've all got used to the idea that
length limitations on printed-on-paper publications limit how much
useful information we can include, and that's made it acceptable for
descriptive papers to skimp on comprehensive measurements and (even
more) figures.  With the rise of no-limits journals like PLoS, that
time is happily drawing to a close: it's time we all raised our game
with the quality and quantity of figures and measurements in our work.

One point, though -- the apparent inconsistency between the
diapophyseal and parapophyseal widths in the Argentinosaurus dorsal
figure you cited.  Don't forget that when photographing or otherwise
illustrating large objects like sauropod vertebrae, perspective
becomes and important factor.  The depth of the element is almost
always a significant fraction of the camera distance, which means that
perspective distortion becomes a big deal.  That's why you need to be
careful when reading measurements off figures (although often that's
still the best you can do).

-- Mike.



On 5 July 2010 23:12, Zach Armstrong <zach.armstrong64@yahoo.com> wrote:
> (How do you like that for some alliteration? ;) )
>
> I was/am trying to work on a research paper dealing with the size of sauropod
> dinosaurs, and for that my plan was to restore the skeletons of multiple large
> titanosaurs in multiple-views for each genus (most of which have not been 
> given
> a rigorous skeletal treatment, to my knowledge).  However, upon getting the
> research papers that describe them, there is an apparent lack of measurements
> for many of our massive macronarian friends. Most frustrating is when a taxon 
> is
> known from fairly complete remains, and yet measurements of the material are
> almost completely lacking or are contradictory.
>
> A case in point is _Futalognkosaurus_, for which an apparently complete 
> skeleton
> is known, but for which measurements are lacking. The first paper in which it
> was described had an almost complete lack of measurements, with the exception 
> of
> a 137 cm length for the pubis. The second paper on _Futalognkosaurus_  had a 
> few
> more measurements, but still not enough to give a complete picture. For
> instance, in regards to dorsal vertebrae length, the latter paper says, and I
> quote:
>
> "The ten articulated dorsal vertebrae are partially prepared, all being
> opisthocoelous (Fig.14). The most anterior dorsal has an elongated centrum and
> the second is 2/3 the length of the first. The centrum length gradually 
> reduces
> in the more posterior elements of the sequence, with the first one being 43cm
> long and the last one 28cm (without considering the anterior ball)."
>
>
> Now, from the wording here it isn't clear if the first *posterior* dorsal  is 
> 43
> cm long or if the first dorsal vertebrae in the dorsal column is 43 cm long
> (which makes a big difference in regards to total torso length and because 
> there
> is sometimes a clear distinction between anterior and  posterior dorsals,
> evidently). The wording is not clear. Assuming it is the first dorsal, for the
> length of the second dorsal, why not just list the length, instead of saying 
> it
> is 2/3 the length? What does that mean? Is it 2/3 of the total length of the
> centrum of the first dorsal (including the anterior "ball"), or is it 2/3 of 
> the
> *functional* length of the first dorsal? Is this 2/3 in as exactly
> 66.66666......% of the length of the first dorsal or 2/3 as in 67% or 66%, or 
> as
> in "2/3 of the Senate majority" which is actually 60%? Assuming the former, 
> then
> the functional length of the 2nd dorsal is ~28.7 cm long, which means if 
> centrum
> length gradually reduces to 28 cm functional length for the 10th dorsal than 
> the
> total dorsal column length is just shy of being 300 cm long (my exact estimate
> is 298.4 cm, but I digress). To compare, the dorsal column of the HMN SII
> _Giraffatitan brancai_  is estimated by Greg Paul to be about 378 cm for its
> *12* dorsals, which means, that on average, the dorsal column of
> _Futalognkosaurus_ is about 79% of the length of _Giraffatitan_ and roughly 
> 95%
> of the length per individual vertebrae. So it is not immediately clear that
> _Futalognkosaurus_ was the 32-34 m in length as originally claimed, especially
> since HMN SII was only about 22.3 m long (if one goes off of Paul's 
> estimates).
>
> Further problematic, is that in the original paper, the scale bar was off in 
> the
> skeletal as noted by Matt Wedel and Mike Taylor on SV-POW! Now, one would hope
> this scale bar issue would be correct in the follow-up paper. But, no, in 
> fact,
> for the cervical vertebrae for which multiple views are given, one gets
> consistently inconsistent lengths! Going off the scalebars in Fig. 3, the 
> atlas
> is ~27 cm tall, but in Fig. 4, the scalebar indicates a height of ~20 cm tall.
> In Fig. 5, the scalebar indicates a total preserved length for the axis of ~35
> cm, but in Fig. 6 it appears to be ~32 cm long. In Fig. 7, the scalebar
> indicates a height of 26 cm, but in Fig. 8, ~32 cm tall. In Fig. 11, the
> photographed portion of the posterior cervical from base of the posterior
> portion of the centrum up is indicated to be ~101 cm tall, but in Fig. 12 it 
> is
> 80 cm tall (also odd is that the parapophysis visible in Fig. 11 disappears in
> Fig. 12). So what are the dimensions of these cervicals? I do not know. I made
> an attempt to contact Jorge Calvo as well as Bernardo Gonzalez Riga about 
> this,
> but neither have replied to my emails. My hope is that someone on the list has
> personal knowledge and is willing to contact me about this issue, but I'm not
> holding my breath. At any rate, _F. dukei_ is apparently far shorter in length
> than originally reported (maybe only 25 meters in length compared to 32-34
> meters as originally reported).
>
>
> However, Calvo et al. (2007) and Calvo et al. (2008) are not the only papers 
> in
> which this is a problem. Take the description of _Argentinosaurus_ for 
> instance
> and the figures therein. In the paper, the maximum width between the 
> diapophyses
> for the dorsal described as potentially the first dorsal vertebrae is 129 cm 
> and
> 77 cm from between the parapophyses. However, depending on which measurement 
> you
> "believe" the apparent width from the figures between the diapophyses is ~122 
> cm
> or the width between the parapophyses is ~80 cm. Similarly problematic, is 
> that
> measurements for the centrum lengths are only given for 2 of the 5 vertebrae 
> for
> which measurements could be given. In light of the apparent impreciseness of 
> the
> drawings, scaling from known measurements might be problematic. However the
> measurements I get are as follows:
>
> 2nd? dorsal (preserved portion)...~43 cm
> 3rd? dorsal...49 cm (given in paper)
> Fused posterior dorsals: anterior...46 cm
>                                    posterior (preserved proportion)...44 cm
> Posterior dorsal...50 cm (given in paper)
>
> (Note, however that Novas revised the sequence positions of these vertebrae 
> (but
> I forget the reference), so that the 2nd? is actually the 10th dorsal, the 
> 1st?
> is actually the 5th, the single posterior dorsal is the 4th, and the fused
> posterior dorsals are actually the 6th and 7th. The 3rd was still considered 
> the
> 3rd.)
>
> And again, vertebral measurements are missing for _Andesaurus_  in the 
> original
> description (although measurements are given for the appendicular 
> elements...),
> and only 3 of the preserved 31 vertebrae are figured, and only 2 of these have
> scalebars with a listed measurement for the scalebar. In view of the previous
> problems mentioned with scalebars, I am hesitant to take these scalebars at 
> face
> value. Although, if one did take them at face value, _Andesaurus_ was 
> apparently
> not as large as some have estimated. The posterior dorsal then is only about 
> 23
> cm long in functional length, which is about 82 % the length of the posterior
> dorsals of _Futalognkosaurus_ which suggests a length of 20-22 m for
> _Andesaurus_ or even less.
>
> Another case is Daxiatitan. Known from 22 vertebrae, measurements are only 
> given
> for 5 of the cervicals and none of the dorsals or caudals, also only 2 of the
> cervicals and 4 of the dorsals are figured. Quite similar to _Euhelopus_ in
> anatomy, and some of the elements of _Daxiatitan_  overlap with _Euhelopus_, 
>  in
> particular, the overlapping posterior cervicals and anterior dorsals of
> _Daxiatitan_ are 6.1 m compared to 2.06 m in _Euhelopus which may mean
> _Daxiatitan_ was ~3.03 times the length of Euhelopus. The tail of _Euhelopus_ 
> is
> unknown, but comparing from other sauropods the tail may have been about 3
> meters long, with the precaudal series about 6 meters long for a total length
> (excluding the skull) of 9 meters, meaning _Daxititan_ may have been over 27
> meters long. Unfortunately, the total width and height of the vertebrae are 
> not
> given so it is difficult to compare in the other dimensions. However, if it 
> was
> basically a _Euhelopus_ scaled up by 3.03 in each dimension, it may have 
> massed
> over 27 times that of _Euhelopus_, meaning if _Euhelopus_ massed 2800 kg,
> _Daxiatitan_ *might* mass over 75,600 kg! That is, it might be one of the
> largest sauropods. However, we can't be sure because the other dimensions of 
> the
> vertebrae are not given!
>
>
> Similarly, _Puertasaurus_ has a anterior dorsal vertebrae (considered to 
> likely
> be the 2nd dorsal) 106 cm tall and 168 cm wide. However, the centrum length is
> not given! Scaling off the illustrations, the centrum is ~41.6 cm long in 
> total,
> with a functional length excluding the anterior convexity of ~30.3 cm long.
> _Puertasaurus_ has some similarities with _Futalognkosaurus_ , and in Calvo et
> al. (2008) paper on _Futalognkosaurus_ anatomy, the anterior dorsals are
> described as being 100 cm wide between the transverse processes. This would 
> seem
> to indicate that _Puertasaurus_ is 68% wider than _Futalognkosaurus_. However,
> as I estimated above, the D2 in _Futalognkosaurus_ is around 28.7 cm long,
> meaning _Puertasaurus_ is only about 5.5% longer than _Futalognkosaurus_. So
> instead of being 1.68^3=4.74 times the mass of _Futalognkosaurus_,
> _Puertasaurus_ *might* only be 1.68*1.055*1.055=1.87 times the mass of
> _Futalognkosaurus_.
>
> This illustrates why, in the case of _Daxiatitan_, for instance, one needs
> multiple measurements of each vertebrae (total height, length and width). So
> while _Daxiatitan_ might be 3.03 times the length of _Euhelopus_,  maybe it 
> is a
> much gracile animal and only mass maybe 5 times the mass of _Euhelopus_ for a
> mass of maybe 14,000 kg versus 75,600 kg.
>
> In conclusion, all sauropod workers should have to recite to themselves when
> working on "their" specimen: "Measure my massive macronarian!" (from hereon,
> M^4. More alliteration--it's a mnemonic device, so use it). So please, if you
> are working on a large sauropod (or a small one, or any dinosaur or extinct or
> extant vertebrate), remember to measure your massive macronarian! It's 
> science,
> it ain't that hard people, and people such as myself will be able to do useful
> work and cite you for it!
>
>
> Hopefully I haven't hurt any one's feelings for criticizing their work, which
> was not my intention, but something has to be said! And if anyone has, or 
> knows
> where I can get, more reliable information on measurements, by all means send 
> it
> my way! And if you feel I have unfairly criticized your or someone else's 
> work,
> email me and we'll talk.
>
> Best regards,
>
> Zach
>
>
>
>
>
>