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pterosaur eggshell or math question



>From Jaime:

In Ji et al., 2004 (_Nature_ 432:572) they identify an eggshell
surrounding
the embryo of a pterosaur which is described thusly:

  "The thin shell is brown-to-dark-brown and contrasts with the matrix
   surrounding the eggshell. The eggshell appears to be very thin (about
0.25
   mm; Fig. 1, inset)

  Meanwhile, Chiappe et al., 2004 (_Nature_ 432:571-572) identify
eggshell
associated with adult and juvenile remains of *Pterodaustro* as bearing
"[a]
smooth, carbonatic material of biotic origin." They further describe the

fossil:

  "Although the eggshell is somewhat weathered, it is extremely thin --
about
30
   microns in thickness.

>>>>>>>>

If a micron is a micrometer or .001 millimeter that makes the Chiappe
eggshell 0.030 millimeters in thickness.
That compares to Ji et al. 's eggshell at 0.25 millimeters -- or 8.33x
thicker.

Did someone get a scale bar wrong? Drop a zero? Or is my math bad?

I'm still in jammys. Could be the latter.


David Peters
St. Louis