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Re: Largest Dinosaurs

Walt wrote-

> I found the articles on the web and was wondering if you knew anything
about the finds.

They were indeed in my sauropod file-

âFutalogknosaurusâ unpublished 2001
âF. dukeiâ unpublished 2004
Late Turonian-Early Coniacian, Late Cretaceous
Portezuelo Formation of Rio Neuquen Subgroup, Argentina
Material- (MUCPv 304) eight cervical vertebrae (1.02 m), partial dorsal
vertebra, sacrum, two caudal vertebrae (proximal 800 mm high), ilia, pubis
(1.37 m), ischium
Description- Titanosaurid characters include- no dorsal hyposphene-hypantra;
six sacrals; procoelous proximal caudals; anteriorly placed caudal neural
arches; open haemal arches; pubis longer than ischium. Diagnostic characters
include- very high dorsal(?) neural spines; sail-like in anterior view;
strong prespinal laminae on proximal caudal vertebrae; proximal caudal
neural spines laterally expanded at distal end.
References- Calvo, Porfiri, Veralli and Poblete, 2001. One of the largest
titanosaurid sauropods ever found, Upper Cretaceous, Neuquen, Patagonia,
Argentina. JVP 21(3) 37A.
Calvo, Porfiri, Veralli and Poblete, 2001. A giant Titanosauridae from the
Upper Cretaceous of Neuquen, Patagonia, Argentina. Jornadas Argentinas de
PaleontologÃa de Vertebrados, Esquel. Ameghiniana, 38 (4 Supl.): 5R.

undescribed sauropod (Munoz 2000)
Cenomanian-Early Turonian, Late Cretaceous
Rio Limay Subgroup, Argentina
Material- (Florentino Ameghino Museum coll.) two cervical vertebrae, femur
(2 m)
Reference- anonymous, 2000. Biggest dinosaur believed dug up in Argentina.
CNN news article, Jan 19.

Munoz's specimen has a femur 2 m long, compared to Argentinosaurus'
estimated 2.5 m long femur (Mazetta et al., 2004).  So it was probably
smaller, though the uncertainty of what kind of sauropod it is and what
other proportions it had makes definite statements impossible.
"Futalogknosaurus" is difficult to compare directly to Argentinosaurus,
since they only share sacral parts and a partial dorsal vertebra.  However,
using pubis/femur ratios from other titanosaurs (Argyrosaurus,
Epachthosaurus, Phuwiangosaurus) results in a femur only 1.4-2.3 m long in
"Futalogknosaurus".  So it was probably Antarctosaurus? giganteus sized at
most, and near certainly smaller than Bruhathkayosaurus.  Perhaps a more
exact size can be estimated once it's described, which seems to be in the
near future.

> Since the Rapetosaurus and Saltasaurus are significantly smaller animals,
is it just a matter of
> scaling to derive your length estimates basing on the fact  they will have
nearly identical body
> proportions?

Well, that's my method.  If I had enough data, I could increase the accuracy
by using known vertebral lengths, to account for possible proportional
differences (like I did for segnosaurs -
http://dml.cmnh.org/2002Aug/msg00433.html ).  Smith et al. (2001) performed
an allometric study of titanosaurs, which they used to estimate limb element
lengths more accurately.

> How is the age of the specimen determined?  When dealing with a find is it
possible to
> determine whether specimen was fully developed adults or juveniles?

Various methods, the most common being the amount of fusion between
vertebral centra and neural arches.  Then there's "juvenile bone texture",
the amount of LAG's in histological sections, and a lot of potential fusion
between elements.  There are a few studies that work towards understanding
how each of these trends correlate with growth and age, but not many.  This
area of paleontology needs a lot of work.

> Is a single Femur or vertebrae or tibia enough to do a valid size

Depends what you mean by "valid", and what you have to compare it with.  If
you have an allometric study of the species, a single measurement can lead
to quite accurate estimates of total size.  In addition, there are some
studies which attempt to use limb bone or vertebral centrum measurements to
estimate mass.  But if you don't know exactly what your specimen is related
to, or have no complete relatives, the estimate's going to be a lot less

> How much variation is there in body size, shape, bulkiness among the
various Titanosaurs?

Good question.  There have been general statements that some are more robust
than others (e.g. Neuquensaurus vs. Antarctosaurus), but no quantitative
study from what I know.

> Looking at your estimates on size and the descriptions of the dinosaurs,
could not Paralitian
> weighed in as heavy as Argentinosaurus.

There may have been Paralititan specimens larger than the holotype, but
according to unpublished data, the holotype's femur would be approximately 2
meters long, which is much shorter than Argentinosaurus' holotype.
Similarly, the estimates for Paralititan's mass based on limb element
diameters are significantly lower than those for Argentinosaurus' (~47% of
the latter's mass; also unpublished data).

> Isn't there some speculation that Amphicoelias vertebrae never existed and
was a hoax by
> Cope?

Speculation, yes.  Evidence, no.

> I know there was a recent find in Spain as well as another Titanosaur in
Argentina that may have topped the 100 ton mark but there hasn't been much
released on them, maybe you have heard more?

This one?

undescribed sauropod (Royo, 2004)
Tithonian-Barremian, Late Jurassic - Early Cretaceous
El Collado Formation, Teruel, Spain
Material- vertebrae, pectoral material, humerus (1.78 m), forelimb material,
pelvic material, hindlimb material, ungual (300 mm)
Reference- Moreno, M. A. 2004. Riodeva. CÃmo buscar un dinosaurio... y
encontrarlo. Heraldo de AragÃn, domingo 29 de febrero de 2004, 26-27.

The humerus is larger than that of Paralititan, but smaller than that
estimated for Argentinosaurus (2.1 m).

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html