The size of...

Today we look at...

Tyrannotitan Chubutensis; the Tyrant titan

As the name suggests, this guy was a big one. Within the family Carcharodontosauridae, this theropod gives us some basic insight on the evolution of this family and a new look taxonomical placement within it.

From A large Cretaceous theropod from Patagonia, Argentina, and the evolution of carcharodontosaurids (novas)

This dispells the (shockingly) widespread belief that T. chubutensis is only known from a single, fragmentary individual. Clearly, this is not the case.

From what i can tell... The holotype, MPEF - PV 1156, ~35% while the paratype, MPEF -PV 1157, is ~40% complete. 

What's interesting about this is that MPEF - PV1157 is ~7% larger then the holotype.

From Novas et. al:

"Tyrannotitan helps to clarify the confusing aspects of the
skeletal anatomy of its close relative Carcharodontosaurus.
This Saharan taxon was recently diagnosed (Sereno et al.
1996) and reconstructed (Currie 1996) on the supposed
overlapping characters of specimens of Carcharodontosaurus
saharicus (Stromer 1931) and the problematic
theropod “Spinosaurus B”[we know now is a specimen of S. aegyptiacus] (Stromer 1934). Pivotal in the
purported overlap is a stout cervical vertebra, characterized
by its low and very broad centrum, strong ventral keel,
and reduced neural spine (Sereno et al. 1996)."

"...Hindlimb bones are also
massive, and exhibit two remarkable carcharodontosaurid
synapomorphies: the femoral head is proximomedially
projected, and the fibula is proportionally short with
respect to femoral length (less than 70%).[something we see with the large tyrannosaurs]The femur of
MPEF-PV 1157 is almost complete; its estimated length f 140 cm is slightly shorter than that in Giganotosaurus
(143 cm) The transverse width
of the femoral shaft of Tyrannotitan is 16.5 cm"

Presumably, this is discussing the Giganotosaurus holotype. This minimal (~1%) difference isn't enough to show that G. carolinii is larger then T. chubutensis.

T. chubutensis' holotype had a dentary 68cm(2.2 feet)Now, the paratype for Giganotosaurus(MUCPv-95 ) is a fragment of the dentary ~61cm(2 feet)

"The preserved portion of the dentary( of MUCPv - 95)
is 61 cm in length and lacks its posteriormost extreme."

http://www.arca.museus.ul.pt/ArcaSite/obj/gaia/MNHNL-0000776-MG-DOC-web.PDF

MUCPv-95, estimated to be ~6.5% larger then the G. carolinii holotype, would measure 13.1 meters in length (based on the median 12.4 estimate for the holotype) Getting back on topic(sort of) In fact, according to Novas et. al 2013, They're very closely related

 Taking note of this, we look at the recent skull estimate for G. carolinii. The most recent publshed estimate is 1.53 meters. Now, i don't advice everyone go off and do this, but i'll use the 8ths rule here. Carcharodontosaurs seem to follow more along the lines of 8.5, but  i'll use both here to play it cautiously.

1.53 x 8 ~ 12.24

1.53 x 8.5 ~ 13.005

See that? fits perfectly.

Now, based on the dentary length of G. carolinii MUCPv - 95, i've come up with an(unofficial) skull estimate -- paratype and holotype individuals --  for T. chubutensis. Now, we apply the 1:8 & 1:8.5 ratios..

First, MPEF - PV 1156:

1.46 x 8 ~ 11.68

1.46 x 8.5 ~ 12.4 meters

now MPEF - PV 1157:

1.52 x 8 ~12.16

1.52 x 8.5 ~ 12.92

Seems to work just fine

Based on what we have, it's my belief that T. chubutensis was 12 - 13 meters in length, and 6 - 8 tons. Basing off of phylogenic relations, these estimates fit "like a glove" so to speak. I find it highly inprobable the paratype being any percentage larger then the holotype is due to individual variation, as this feature isn't prominant within the Carchardontosauridae. Lack of unfused cranial and neural sutures in either specimen indicate that both are fully grown, so that rules out the possibility of one being a subadult.