And of course, some specimens might be bacteria and some might be
melanosomes. This is not an all or nothing game.
Dan
On 3/7/2014 5:50 AM, Thomas R. Holtz, Jr. wrote:
Greetings,
Just a few notes to add to the comments on the new Moyer et al. paper on
bacteria vs. melanosomes:
There are some good observations in this. However, I think it is fair to say
this is not the final word on the subject. I know that
the UT Austin group that has previously published on melanosomes (including a
former student) are hard at work on new studies which
point to the paleo-examples as being actual melanosomes, and I await news from
Jakob Vinther's lab.
Regardless of the final truth, this is good for science: we have to test our
claims!!
Towards that end, a test I'd like to see. In crystal-level geochemical studies,
it is standard operating procedure to publish
"sample maps" of the crystal being probed, for verification and replication
purposes. I do not recall seeing these for the previous
melanosome studies. That might help to give confidence that a pattern of color
was real, and thus probably original rather than
postmortem bacterial growth. For instance: tracing down and across both left and right
"wings" of Anchiornis and find the same
distribution of supposed-white and supposed-black patterns would increase our
confidence in their reality.
Take care,
Thomas R. Holtz, Jr.
Email: tholtz@umd.edu Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661
Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843
Mailing Address: Thomas R. Holtz, Jr.
Department of Geology
Building 237, Room 1117
University of Maryland
College Park, MD 20742 USA
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