Using Computers To Morph Deformed Fossils

crem_d_genes writes "At the University of Buffalo, Tammy Dunlavey, a master degree candidate in the Department of Geology has used a technique called geometric morphometrics to produce restored images of fossils that had been deformed by the processes of preservation. The computer program - 'MsWellwood' (named for a structural geologist) - calculates the degrees and forms of deformations, and should be capable of providing a clearer view of what the organisms looked like when alive."

Lateral symmetry

[ObviousGuy]

One of the assumptions of the software and morphing process is that the fossil's original form has lateral symmetry (left and right sides match up), but I wonder how much this can be assumed? While for most bipeds and quadrapeds this holds true, for other forms of life, especially water-based fauna, this assumption cannot be taken as true in all cases.

Cephalopods and flatfish are the most obvious animals that have no lateral symmetry. While it is unlikely that such soft-fleshed/boned animals would survive the fossilization process, other animals lacking lateral symmetry could have made it and befuddle this software.

Re:Lateral symmetry

[sapbasisnerd]

Considering the stuff with odd symmetries they fould fossils of in the Burgess Shale it is certainly an issue to keep in mind.

Re:Lateral symmetry (recontructing odd beasties)

[G4from128k]

If you have multiple samples of the same species of beasty in a uniform chunk of rock, then you could reconstruct them by mapping homologous points between the beasties and finding the best-fit deformation that brings all the specimens into congruence. IANAG, but I suspect that the basic fossil deformation equation has only 4 relevant unknowns in it (magnitude of flattening, direction of flattening, magnitude of shear, and direction of shear). A fifth unknown, overall shrinkage is irrelevant to reconstructing shape and would be difficult to estimate without a yardstick -- some fossil with a known or incompressible size. (Note: more complex rock deformations might have 8 or 9 unknowns). The point is that cross mapping a handful of points across a handful of fossils lets you find the best fit values for the unknowns and then undeform the fossils.

For intra-fossil deformations, I see two possible solutions. First, one could create a more complex model of the deformation that breaks up the fossil into polyhedral voxels and assumes that soft and hard tissue deformations follow certain invariants across sample fossils. A second solution is to study the microstructure of the rock matrix. If parts of the fossil deform differentially, I would expect that to leave some evidence in the spacing and orientation of any grains in the matrix - the grains would be looser and show evidence of flowing into the area around zones that shrank more (e.g., decayed soft tissues).

Yummy, me download ;)

[jago25_98]

1) Do you need to know the stress fields that have operated on the fossil and how do you input this info I wonder? Ah, hang on, I can see that it doesn't do that, it's just preservation.

then - I wonder what processes of preservation it can work with.

2) Yummy, where can I download it? ;)

And where are the pictures?

[Jailbrekr]

Some of prefer pictures books over pages of text y'know.