Hi all, I have a very basic question :D

Nov 2019
4
0
Germany
Hi all, you are my biggest hope :D

This is probably really dumb, but I have the following problem and my stats courses are just too long ago: I need to visualise the change of surface area of two bones (A and B) over time. So, for example, in one dinosaur, bone A is 300 cm² in surface area and bone B is only 100 cm². In a later occurring, but much smaller dinosaur, bone A is 5 cm² and bone B is 2cm². An extent taxon of alligator has a bone A with a surface area of 30cm² and bone B is 90cm².

Since all the animals are of different size, I want to reduce that factor. I am thinking that simply the ratio could probably help. But what if one super old dinosaur has no bone A because it has not evolved yet and an extant bird does not have bone B anymore? Then I have values of 0, which makes ratios impossible.

I just need to plot this nicely, to track whether there is a trend over time. And my brain feels fried. :D Plz send help!
 
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romsek

Math Team
Sep 2015
2,969
1,676
USA
Are you trying to establish the relative sizes of the creatures by comparing the surface area of similar bones?

If so you're going to have to find bones the two creatures have in common.
 
Nov 2019
4
0
Germany
Yes, I am always comparing the same two bones of the creatures, basically the relative change of size of these two.

The same things might happen in a huge T-Rex (just as an example) and a tiny sparrow. Is bone A always a lot smaller than bone B, just on different scales? Or does bone A get relatively bigger compared to bone B?

My dataset kind of looks like this:
dinosaur,boneA,boneB
TRex,300,100
OtherDino,5,2
Alligator,30,90
SomeOldDino,0,30
Sparrow,2,0

Just random examples... but yes... how do I get all of them on the same scale to make them comparable?
 
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skipjack

Forum Staff
Dec 2006
21,482
2,472
Are bones A and B related to each other? For example, are they shaped similarly? For how many dates do you have examples of both bones? Why are you interested in the surface area, as distinct from, for example, the length?
 
Nov 2019
4
0
Germany
Well, they are (probably) functionally related but not similar shape-wise.
I have values for both bones for all of the creatures. But probably will only have 15-20 creatures in total. But some animals just only have one and not the other bone (hi evolution!).
And I thought area would capture the shape change best. And I think I would have the same issues if I took the length instead, don’t you think?
 
Jun 2019
493
262
USA
Ratios (area:area, length:length; maybe length:body length, area:body mass, etc. where possible) make sense for comparison purposes. My guess, though, is that it's going to be exceedingly difficult to draw any meaningful conclusions with such a small sample size (especially given the taxonomical distance between samples).
 
Nov 2019
4
0
Germany
Thanks y'all. I found a way to make ratios work, guess there's no other way! But really, thanks a lot for all of your input :)