Using Computers To "UnDeform" Deformed Fossils

["Richard W. Travsky" <rtravsky@uwyo.edu>]

http://www.buffalo.edu/news/fast-execute.cgi/article-page.html?article=66490009

BUFFALO, N.Y. -- It's bad enough that fossils, buried deep in layers of
rock for thousands or millions of years, may be damaged or missing pieces,
but what really challenges paleontologists, according to University at
Buffalo researchers, is the amount of deformation that most fossils
exhibit.

That's why Tammy Dunlavey, a master's degree candidate in the Department
of Geology in the UB College of Arts and Sciences, and her colleagues are
working on a computational method to morph fossils back to their original
shapes by calculating and excising the deformation.

"Our goal is to develop computer programs that can reliably solve the
deformation problem," noted Dunlavey, who on April 1 presented research on
a new suite of "retrodeformation" programs at a Geological Society of
America meeting (North-Central section) in St. Louis.

The main program is called "MsWellman," written by the UB researchers in
collaboration with H. David Sheets, Ph.D., professor of physics at
Canisius College and adjunct associate professor of geology at UB.

MsWellman adapts an approach developed by a structural geologist named
Wellman, and works on multiple rock slabs at once.

"Fossils are deformed because they are fossils," said Dunlavey. 
...
While paleontologists traditionally have tried to concentrate on the rare,
well-preserved fossils for which deformation is not a significant issue,
they increasingly are interested in the many fossils that clearly have
been deformed.

"The question our computer program is designed to address isn't, 'Are
fossils deformed,' but rather 'By how much?'" said Dunlavey, noting that
millions of years of being buried causes different levels of deformation
in fossils.

According to the UB researchers, MsWellman calculates the degree and form
of the deformation and then a second program the UB team developed called
Retrodef6, uses this understanding to "correct" a representation of the
deformed fossil back to its original form.

"We wanted to design a methodology that determines at what point,
statistically, fossils can be considered deformed and calculates the
amount of deformation based on how much strain they were subject to when
embedded in rock, as well as other variables," she said. "The program then
will restore the virtual fossils to their original shape."

To do that, the UB scientists employed a technique called geometric
morphometrics, which documents aspects of shape and size in a specimen
based on landmarks, discrete anatomical points that generally are uniform
for related specimens. 
...
To gauge the reliability of the new retrodeformation programs, Dunlavey
used several fossils of graptolites, which are the remains of an extinct
group of marine organisms.

The fossils Dunlavey used lived during the Middle Ordovician Period, some
472 million years ago, before land animals or large land plants had
evolved.

Since graptolites were common and evolved rapidly, Mitchell explained,
they tend to be useful markers for constructing a timescale in the
Ordovician period.

Because their original shape is well-known, he continued, several sets of
deformed, slightly deformed and non-deformed graptolites served as an
excellent test case for the new computer programs. 
...