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David Marjanovic referred to:
"Gerard Gierlinski: Feather-like Impressions in a
Theropod Resting Trace from the Lower Jurassic of
Massachusetts"...
Several years ago when I first came
across this paper, I was thrilled at the thought that a Theropod had left
impressions of down or feathers that are preserved from the early
Jurassic. I held this enthusiasm for Gierlinksi's interpretation of the
dinosaur body impressions for several years, even after I met Dr. Paul Olsen,
probably the world's most experienced researcher on tracks from the Newark
Supergroup, in Philadelphia at Dinofest '98. When I brought up the
subject of Gierliski's paper, to Olsen, he told me that he has studied the
ichnite carefully and that the shapes interpreted by Gierlinski as probable
feather or down impressions definitely are NOT any such thing. He
had examined them very carefully and at length.
:.-(
Frankly, at the time I was a bit taken
aback and even slightly offended. Olsen, I felt, was just too skeptical
and most likely wrong. Being the outspoken person that I am,
I flatly told him so!
Within the next year, however, a friend
brought some Newark Supergroup dinosaur ichnites to my home. One of them
-- much to my astonishment -- was covered with (all around, and any and
everywhere beyond, a theropod footprint) precisely (yes, identical in every
characteristic) the kind of traces that Gierlinski interprets as probable
feather or down-like imprints. What is clear, however, is that these are
not impressions made by a body covering of any sort. To my eye, the most
probably cause was some type of plant material having been dragged across the
wet or damp, very fine-grained substrate by action of shallow water, wind, or
both.
Do you have a figure of that?
Now I have no doubt -- having seen this
(and the slab in now in my collection) -- that Paul Olsen's interpretation of
Hitchcock's item AC1/7 is the correct one, and Gierlinski's is
incorrect. After all, Olsen -- unlike Gierlinski -- has spent many years
(beginning in his youth) studying Newark Supergroup ichnites, and his
experienced opinion should carry considerable weight in evaluating
Gierlinski's paper.
Of course, I would be delighted
to be provided with evidence that both Dr. Olsen
and I are wrong, but because of what I have now seen (the Newark Supergroup
ichnite now in my collection) it seems well advised to stick with the more
conservative interpretation of AC 1/7.
The feather impressions from the squatting
condor look indeed like the impressions in
question...
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