How do you measure a dinosaur? Scaling help needed.

[Blade-of-the-Moon]

I've run into the same trouble when scaling my Lambeosaurus magnicristatus. I got as many measurements of individual bones from the (incomplete) type specimen as I could find in the literature and entered them into a spreadsheet. Then I got measurements from the single referred specimen and from specimens of other lambeosaurines and entered those in a separate column for each specimen; then I calculated the proportion of the femur length of each specimen to the type specimen and used that to correct for size differences between specimens. This gave me a table of measurements of individual skeletal elements which I used to lay out the skeletal drawing. It was a lot of tedious work, but it hopefully resulted in as accurate proportions as I can get without access to a complete skeleton of the animal.

One other caveat to accepting total length estimates at face value is that few specimens include the entire tail - especially for things like diplodocids and many theropods whose tails just taper away to nothing. Who knows how long the missing piece was?

When it comes to tails i usually add a 1-2 on the larger ones, like Apatosaurus, just using my own eye for length and curves and tapering.  individual variation and all that.

[Doug Watson]

"In palaeontology length is measured as though the skull and vertebrae were laid out on the floor in straight  line"
This is usually true but not always, and I challenge you to find a single paper that explains which way they did it!

Never found it stated in a paper but what I did do is ask a couple palaeontologists who wrote the papers I was using, plus the palaeontologists at CMN when I worked there and that is how they said they measured specimens and it was their contention it was the norm, so I take them at their word.

Yeah, it's similar with fish in that there's a convention, though the convention itself is different. We basically always measure in a straight line, and if you're reading a fish description that gives the length, everyone assumes you measured in a straight line, but rarely does anyone go to the trouble to specify.

and just to confuse things further don't you have standard length, fork length and total length?

[Halichoeres]

"In palaeontology length is measured as though the skull and vertebrae were laid out on the floor in straight  line"
This is usually true but not always, and I challenge you to find a single paper that explains which way they did it!

Never found it stated in a paper but what I did do is ask a couple palaeontologists who wrote the papers I was using, plus the palaeontologists at CMN when I worked there and that is how they said they measured specimens and it was their contention it was the norm, so I take them at their word.

Yeah, it's similar with fish in that there's a convention, though the convention itself is different. We basically always measure in a straight line, and if you're reading a fish description that gives the length, everyone assumes you measured in a straight line, but rarely does anyone go to the trouble to specify.

and just to confuse things further don't you have standard length, fork length and total length?

Eeeyup. To me fork length seems like it should mean the length of the fish that consists of edible meat!

[Doug Watson]

Eeeyup. To me fork length seems like it should mean the length of the fish that consists of edible meat!

[Papi-Anon]

I've run into the same trouble when scaling my Lambeosaurus magnicristatus. I got as many measurements of individual bones from the (incomplete) type specimen as I could find in the literature and entered them into a spreadsheet. Then I got measurements from the single referred specimen and from specimens of other lambeosaurines and entered those in a separate column for each specimen; then I calculated the proportion of the femur length of each specimen to the type specimen and used that to correct for size differences between specimens. This gave me a table of measurements of individual skeletal elements which I used to lay out the skeletal drawing. It was a lot of tedious work, but it hopefully resulted in as accurate proportions as I can get without access to a complete skeleton of the animal.

One other caveat to accepting total length estimates at face value is that few specimens include the entire tail - especially for things like diplodocids and many theropods whose tails just taper away to nothing. Who knows how long the missing piece was?

When it comes to tails i usually add a 1-2 on the larger ones, like Apatosaurus, just using my own eye for length and curves and tapering.  individual variation and all that.

Looking at 'Big Al' and his nearly compete skeleton made me redo scaling with tail-to-body length ratios. Eyeballing it got me about 3/5 to 2/3 the whole length being in the tail. Obviously this ratio doesn't work for every dino, at the very least just Allosaurs and makes more sense for some other large therapods in some ways. I keep thinking about my Thrasher Rex toy and how thin and short her tail is, and the 3/5 to 2/3 ratio seems to work for it.

Also, I read somewhere that Allosaurs' skulls grew bigger as they got bigger too in larger specimens, but couldn't find anything on it being length, depth or all together in proportions that grow out.

[DinoToyForum]

"In palaeontology length is measured as though the skull and vertebrae were laid out on the floor in straight  line"
This is usually true but not always, and I challenge you to find a single paper that explains which way they did it!

Never found it stated in a paper but what I did do is ask a couple palaeontologists who wrote the papers I was using, plus the palaeontologists at CMN when I worked there and that is how they said they measured specimens and it was their contention it was the norm, so I take them at their word.

Yeah, it's similar with fish in that there's a convention, though the convention itself is different. We basically always measure in a straight line, and if you're reading a fish description that gives the length, everyone assumes you measured in a straight line, but rarely does anyone go to the trouble to specify.

This is the convention in plesiosaurs as well. But then their spines basically are a straight line, so there's no difference.