Spinosaurus News ~

[DrZapxX]

I'd like to contribute towards the new mass measurements, for spinosaurus...


Using supplementary data 2, available we can get some of the values of mass and density values from FSAC KK11888
https://www.nature.com/articles/s41586-020-2190-3#Sec9

*This image is copyright of its original author

The question is what value of mass is appropriate to use, it would seem the 3219kg would be, Spinosaurus aegypticus/Sigilmassasaurus (Smyth et al 2020 considers them to be same taxa based on dentition similarity) https://www.sciencedirect.com/science/a ... 7120302068) has been reported to have air sacs in the vertebra (FSAC-KK-7280 (pneumatic foramen and FSAC-KK-18122 known from posterior cervical vertebra with air spaces at the bottom), Lakin et al 2019

Using the improvement of Hendeson's spinosaurus, from the table, a density of 833kgm^3 density is most logical.

By using the equations...
Mass = Density x Volume
Volume = Mass / Volume
Specimen FSAC KK11888
Length 10.37m
Mass 3219 kg
Density 833 kgm3
Volume = 3.86434574m^3 x (3219kg/833 kgm3)

MSNM V4047 (largest specimen of spinosaurus)
Length: 12.566, despite the common misconception, there is a sort of myth of MSNM v4047's skull length, 1.75m is a overstatement, a revisited measurement indicates 1.5 metres.

*This image is copyright of its original author

Here is a direct quote from Therrien et al 2007,
''A note of caution concerns the dimension of the reconstructed Spino-
saurus skull. First, the proposed skull restoration (Dal Sasso et
al. 2005:fig. 5B) is a composite reconstruction with the front and
back halves being from different genera. Because skull shape
varies among spinosaurids (i.e., the shape of the rostrum, the
relative dimensions of the maxillae and premaxillae, and the
shape of posterior region of the skull differ among spinosaurids;
Fig. 3), there is potential for overestimating the length of a com-
posite spinosaur skull. Second, Dal Sasso and colleagues’
(2005:fig. 5) skull length estimate represents the distance be-
tween the premaxilla and the squamosal, which is greater than
the measurement (premaxilla-occipital condyle) used in our pre-
dictive equations. Therefore, the body length estimate derived
above (14.34 m) exceeds what must have been the total body
length of the animal. It only takes a skull length (premaxilla-
occipital condyle) of 1.50 m, that is, 0.25 m (14%) shorter than
originally suggested, to predict a substantially shorter (22% to
31%) total body length of 12.57 m''

According to Ibrahim et al scaling the subadult neotype's skull (112 cm) to 32% larger gives a skull length for MSNV 4047 147.84cm.
https://d3qi0qp55mx5f5.cloudfront.net/p ... 1591805883
Hendrickx et al 2016 also agrees with this but slightly exaggerates the skull length to 160cm.
https://journals.plos.org/plosone/artic ... 695.ref022

Speaking of Lakin et al, the paper also favours a 12-15m long spinosaurus too.
https://www.sciencedirect.com/science/a ... 7118302052

With all of this in mind, using the formula from Therrien 2007, 
Body Length=1.03161 * 10 ^(0.85673*Log(1.5 metres)+0.93482)

This equates to 12.566 metres for a length.

Using the equation of square cube law

*This image is copyright of its original author

The new volume is 3.86434574m3 x(12.566m/10.37m)^3

6.87592090769 m3

Using Mass = Density 833kgm3 vs Volume (6.87592090769m3)
mass = 5727.64211611 kg

Just to get a misconception out of the way, Henderson 2018 includes a pneumatic and non-pneumatic spinosaurus
https://peerj.com/articles/5409/

Quoting...
''As a test of how sensitive the buoyant Spinosaurus model was to the assumed presence of avian style air sacs and pneumatized bone, an alternate model lacking these features was tried. This model assigned a uniform axial density of 1,000 gm/l from the tip of the tail to the tip of the snout. The limb and sail densities were unchanged, and the same lung was retained. This alternate model can also be thought of as one with a denser skeleton. This model has higher mean density of 918 gm/l and is heavier, 7,160 kg,''

Some may wonder why Campione et al, using the circumference of the femur for Spinosaurus well according to Person's et al 2019 spinosaurus lacked a open medullary cavity that most over theropods have, increasing femora as a result,
https://anatomypubs.onlinelibrary.wiley ... 2/ar.24118

(Therrien & Henderson, 2007) mass method overexaggerates theropod mass, in the case of other megatheropods.

The only available option is square cube law (isometric scaling) Lakin 2019 also confirms this.

''The disarticulated and fragmentary nature of this material makes it difficult to arrive at robust estimates of body length, and even more difficult to estimate mass given the lack of reliable indicators such as skull length (Therrien & Henderson, 2007), or limb bone dimensions (Campione and Evans, 2011, Benson et al., 2014). However, the proportions and shapes of the vertebrae are very similar to adult material described in previous work (Stromer, 1915, Dal Sasso et al., 2005, Ibrahim et al., 2014b), suggesting a broadly isometric growth pattern for Spinosaurus ''

https://www.sciencedirect.com/science/a ... 7118302052

But what if spinosaurus was 14.34 m (overexaggerated length - We know it's not bang on 15 metres because not only because Therrien et al's forumla but also Ibrahim et al 2014 scaling a ''supposed'' 11 metre individual an extra 32% which is 14.5m)?

Body Length=1.03161 * 10 ^(0.85673*Log(1.75 or 1.6 metres)+0.93482)

Volume =  3.86434574m3 (14.34m/10.37m) ^3 = 10.2185m3

Using Mass = Density 833kgm3 vs Volume 
1.75 skull length = 14.34m in length = 10.21 m3 volume = 8504 kg

1.6 skull length = 13.28m in length = 8.11m3 volume = 6760 kg

In conclusion the largest spinosaurus specimens were around 5.72 metric tonnes to 6.76 metric tonnes in mass, a 15 metre ong spinosaurus would still be less than 10 tonnes around 9.5. Reply