The biggest dinosaurs that lived on Earth

[tigerluver]

One liners don't work, sorry about that one. 

I was referring to Sasso's 988 mm upper jaw (as always, I've attached the paper) and whether or not someone took the Ibrahim et al. find a step further to more correctly reconstruct the Sasso specimen. I don't think anyone has. I took the Ibrahim et al. (2014) figure and came up with a total skull length of around 1500 mm. I picked up a ruler and measured the relative total length of the Ibrahim et al. spinosaurus specimen and related it to the head length. The body in the figure isn't straight but I found a conservative ratio of 8.7 head lengths:1 total length. Applying this ratio to the Sasso specimen, its total length would be 13,050 mm (42.8 feet).

At a glance, Spinosaurus's vertebrae and rib cage looks a bit thinner than the other large carnivorous dinosaurs. The distal long bones are also relatively shorter compared to the proximal long bones, a trait of cursorial, lighter built land species. So from this, I'd think Spinosaurus is lighter for its frame.

The aquatic lifestyle theory of course makes such implications invalid. The denser bones also shred the cursoriality and lightly built theory apart. Spinosaurus looks more like a crocodile than the bipedal therapod to me. So much so, I think those interested in Spinosaurus's most accurate weight estimate should get their hands on crocodilian length and weight data. 

I'll give an amateur go, but I've no problem admitting I don't know enough or much about specific dinosaur morphology. 

I'll use a simple isometic relation. A captive crocodile measuring 6 m long and weighing 1,114.27 kg and Lolong, measuring 6.17 m and weighing 1,075 kg. Using the equation (body length a/body length b)^3=body mass a, we get an estimate of ((11,464 kg + 10,172 kg)/2) 10,818 kg. A sensible estimate I suppose. Keep in mind I'm not sure of the true allometry in total length and body mass, nor the bone density disparity between Spinosaurus and crocodilians, and also that I probably underestimated the Sasso specimen's total length. Therrien and Henderson showed that skull length and body mass were strongly postively allometric, but it looks like they used estimates to derive that formula, and that really is not a valid method in my opinion.


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