Reply to Gilgamesh [[Dinosaurs]]

["Terry Colvin" <colvint@CC.IMS.DISA.MIL>]

Gilgamesh: Would you please post references and context for the statements? 
attributed to Carl Sagan. Likewise, I would be interested in references to 
the Acambero tribe and their "dinosaur" sculptures.
        Actually, the question of whether a nearby supernova explosion
could have killed off the dinosaurs has been examined in detail, starting 
with a paper by Kelland Terry et al. in the late 60's or early 70's. The 
problem with this idea is that the expected isotopic signatures have not 
been found, so the idea is not taken very seriously anymore. 
        Radiation is not necessary for mutation, but may, of course,
be a factor. Genetic variation may arise without radiation
due to errors in DNA synthesis and repair as well as be caused by 
natural chemical mutagens, viruses, etc. Light per se from a supernova 
would not be a problem.
        As for the alleged human footprints among the dinosaur tracks in
the Paluxy River bed in north Texas, even the Institute for Creation 
Research (ICR) considers them dubious at best. After investigators including 
Stephen Jay Gould, Laurie Godfrey (an anthropologist) and Ron Hastings 
conclusively showed that even the best "man tracks" were eroded and 
partially weathered dinosour toe marks, the ICR removed its exhibit from 
its museum. They did not reappear in the new, improved, and expanded 
creationism museum which recently opened at the ICR headquarters east of 
San Diego, CA. However, it may still sell a videotape about them.
        The evidence against these features being human footprints is 
overwhelming.  Not only do the shape and stride not fit any known 
anthropoid species, the creatures would have to be running cross-legged. 
Furthermore, even the set of prints promoted by the ICR later showed clear 
evidence of being dinosaur middle toe marks as upon further weathering, 
prints of the outer two toes became visible.
        Other alleged human footprints are known to have been carved
in stone and are hoaxes, but these are a minority of the the cases.
        These studies have been published in Creation/Evolution 
and elsewhere.
        Happily, these investigations afforded the chance to make a genuine 
scientific discovery. Apparently, some three- toed, bipedal dinosaurs 
occasionally walked flat-footed rather than always on their toes. 
        What Darwin said or thought is not vey relevant. Vastly more data
have been adduced since his time. Moreover, much more is now known about 
evolutionary mechanisms. The fact that evolution has occurred is not
in dispute. The debate is over various explanatory theories. 
        The two-theory model pushed by creationists is intellectually
vacuous. There are an infinite number of potential origins theories 
and evidence against Darwinian evolution by natural selection does not 
automatically count as evidence for biblical creationism. 
        Extraterrestrial origin theories such as directed (or undirected) 
panspermia or "Microchloranthropobiogenesis" merely beg the question as 
to the origin of terrestrial life. Insects are clearly related to all other 
life forms on the earth.  

--John

_"Almurani lulu-ra kir-in-kud geshpu-ta  2/3 manna ku babbar ilae"_ 
(apologies to Lipit-Ishtar, Ur-Nammu, etc.)