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Re: Drusilasaura, new titanosaur from Argentina



Well, its pretty incomplete so a size estimate will be tentative at best 
(especially since a table of measurements of the elements is missing, as 
usual!). Generally, go by the measurements listed in the text, and not the 
scale bars as these are mostly wrong.

As for a tentative size estimate, I've done a skeletal restoration of 
Malawisaurus in dorsal and lateral aspects and did a GDI volume estimate, and 
got a resulting mass of about 2.5 tonnes and about 11 meters long (see here: 
http://palaeozoologist.deviantart.com/art/Malawisaurus-2-view-skeletal-192706258).
 Unfortunately, Malawisaurus is not known from a scapula. However, 
Phuwiangosaurus does have a scapula preserved for it. The humerus in 
Malawisaurus is about 72 cm, and the humerus in Phuwiangosaurus (in one 
specimen, at least) is 95 cm. The scapula in this same specimen of 
Phuwiangosaurus is 100 cm long. So, if we do some extrapolation from comparable 
elements Phuwiangosaurus is 95/72=1.319 times as large as Malawisaurus in 
linear dimensions and (assuming they scale isometrically, which is probably 
wrong) therefore 1.319^3 times as heavy, or about 2.294*2.5=5.73 tonnes and 
14.5 meters long. Since the scapula in Drusilasaura is 143 cm, and the scapula
 in Phuwiangosaurus is 100 cm long, then Drusilasaura is 1.43 times as large as 
Phuwiangosaurus in linear dimensions (again, presuming they scale roughly 
isometrically) or about 2.924 times as heavy as Phuwiangosaurus, or about 16.75 
tonnes and about 20.7 meters long. 

There is, of course, a caveat to these rough estimates. Scaling from 
appendicular elements isn't a very good metric to use since they widely vary in 
proportions across the Sauropoda (and even in the Titanosauria). To give you an 
example, in Euhelopus the scapular blade is 120 cm long, but was probably 
smaller than Malawisaurus in mass and length and had a femur of 95.5 cm. The 
scapula in Daxiatitan (which appears to be a close relative of Euhelopus) is 
only 101 cm long, but its femur is 177 cm long. Also, the cervical vertebrae 
are easily 3 times bigger in linear dimensions than the cervicals of Euhelopus. 
So scaling from appendicular material is problematic at best. The best way to 
get an idea of size is from dorsal vertebrae, since sauropods carry the 
majority of their mass in their torso. However, no measurements are listed for 
the dorsal vertebrae of Drusilasaurua, and as you mentioned, scale bars are 
rarely correct, so it is impossible to get a
 better idea of its size without these dimensions.



----- Original Message -----
> From: Brad McFeeters <archosauromorph2@hotmail.com>
> To: dinosaur@usc.edu
> Cc: 
> Sent: Saturday, May 7, 2011 2:42 AM
> Subject: RE: Drusilasaura, new titanosaur from Argentina
> 
> 
> Anyone want to take a crack at a size estimate?  Most of the elements only 
> have 
> scale bars to go on, but the scale bar for the scapula (fig. 7) is nowhere 
> near 
> correct: the length is mentioned in the text as 143 cm, but the scale bar in 
> the 
> figure makes it look over 240 cm long!  
> 
> ----------------------------------------
>>  Date: Sat, 7 May 2011 01:10:52 -0400
>>  From: bh480@scn.org
>>  To: dinosaur@usc.edu
>>  Subject: Drusilasaura, new titanosaur from Argentina
>> 
>>  From: Ben Creisler
>>  bh480@scn.org
>> 
>> 
>>  In new issue of Revista Brasileira de Paleontologia:
>> 
>>  César Navarrete, Gabriel Casal & Rubén Martínez (2011)
>>  Drusilasaura deseadensis gen. et sp. nov., a new titanosaur
>>  (Dinosauria-Sauropoda), of the Bajo Barreal Formation, Upper Cretaceous of
>>  north of Santa Cruz, Argentina.
>>  Revista Brasileira de Paleontologia 14(1):1-14, Janeiro/Abril 2011
>>  doi:10.4072/rbp.2011.1.01
>> 
>>  free pdf at:
>> 
> http://www.sbpbrasil.org/revista/edicoes/14_1/Artigo%201%20-%20Navarret%20et
>>  %20al.pdf
>> 
>>  A new titanosaurid from Patagonia, Argentina, is here described,
>>  Drusilasaura deseadensis gen. et sp. nov., the materials include four
>>  dorsal vertebrae, one sacral vertebra, six caudal vertebrae, left scapula,
>>  dorsal rib fragments, two haemapophyses and indeterminate fragments. The
>>  material comes from the Upper Member of the Bajo Barreal
>>  Formation(Cenomanian-Turonian), exposed in the María Aike Ranch, Santa Cruz
>>  Province, Patagonia, Argentina. The taxon showsthe following character
>>  association: (i) presence in the anterior dorsal vertebrae, of two robust
>>  spinodiapophyseal laminae, one anterior and other posterior, which delimit
>>  an elongate and deep supradiapophyseal ca
esence in the
>>  anterior dorsal vertebra of a small circumneural lamina surrounding the
>>  neural canal in posterior view; (iii) the last sacral vertebra with
>>  postspinal lamina expanded toward the neural spine apex; (iv) prespinal
>>  laminae, at least until 5º? caudal vertebra, expanded toward the neural
>>  spine apex; (v) existence in the anterior caudal vertebrae of
>>  tuberopostzygapophyseal laminae; (vi) presence of ventral foramina, at
>>  least until the 4º? caudal vertebrae; and (vii) prezygapophyseal tuberosity
>>  jointed theprespinal lamina until the 4º? caudal vertebrae. The presence of
>>  a synapomorfic character of the clade Lognkosauria suggests the probable
>>  inclusion of the Drusilasaura deseadensis gen. et sp. nov. within the
>>  clade, in tandem with Mendozasaurus neguyelap, Futalognkosaurus dukei and
>>  probably Puertasaurus reuili.
>> 
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>