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Re: SIMILAR BIRD TRACKS 70 MILLION YEARS APART



Ray,
I certainly wasn't trying to discourage you from publishing a paper on these tracks. On the contrary, being the first avian tracks from the Mesozoic of Maryland would alone make it worth publishing. I was just pointing out that foot structure can be subject to convergence, and it would be even more difficult to detect such convergence from the tracks alone. Just look at the debate over whether certain tracks are pterosaurs or crocodylomorphs.
The migration explanation is possible, but I believe botanical evidence indicates the K-T impact occurred in the spring (of the Northern Hemisphere), so any long-migrators in the New World would probably have been in the wrong place to help them survive. And even if there were migrators in the southern regions when this happened, their populations would still have been badly decimated, and I can't see normal migration patterns being reestablished for quite some time. Migration is dependent on the birds being in good health and well fed along the way, and in my opinion migratory birds would have actually been more vulnerable to this extinction than are birds who could "tough it out" in one place, rather than migrating.
It could be that you had primitive Charadriiform birds (for example) in Maryland in the Early Cretaceous, but I wouldn't even assume that the tracks you found are definitely Neornithean. So I would say these tracks are definitely worthy of study and publication, but don't be surprised if they turn out to be birds that aren't particularly closely related to those in the Green River Formation. Therefore, I wouldn't recommend making this the primary thrust of your paper, although it would certainly be even more interesting if there was strong evidence that they are Neornithean. I would certainly be shocked if they turned out to be made by a Cenozoic genus or family of birds (delighted, but still shocked).
---Cheers, Ken
P.S. By the way, it would be also very cool if you someday happened to find another one of those Early Cretaceous ticks.
******************************************* 
From: "Ray Stanford" <dinotracker@earthlink.net>
Reply-To: "Ray Stanford" <dinotracker@earthlink.net>
To: "Ken Kinman" <kinman@hotmail.com>
CC: <dinosaur@usc.edu>
Subject: Re: SIMILAR BIRD TRACKS 70 MILLION YEARS APART
Date: Thu, 20 Sep 2001 17:47:58 -0400

Ken,

    Thanks for your input.

You commented, "...And even if these birds were somewhat related, I
doubt that this would indicate a surviving population of any birds in
eastern North America. The surviving birds were probably much farther away,
and that area would have been repopulated with birds during the Paleocene."

    Certainly it seems reasonable that birds in North American at the time
of the K/T impact might not have survived the K/T event and its
after-effects.  Yet, since we are dealing with shore bird type tracks, and
some modern shore birds (such as the Golden Plover) are famous for their
very long inter-hemisphere migrations, the possibility should be considered
that many specimens of the at-this-point purely hypothetical line of birds
possibly implicated in the virtually identical type tracks under discussion
could have been (via migration) in the relative (and only relative) safety
of the opposite hemisphere when the impact happened.

By the way, it was not I who noted this identicality of the track types
70 million years apart. Credit goes to Mark Symborski, a professional
geologist and a very experienced naturalist. We are not dealing with 120
and 50 million-year-old tracks that have some vague resemblance. No. Each
observable and measurable parameter (each angulation and size) is identical,
within limits of measurement accuracy. Although you could be right, Ken, I
personally think that this identicality of tracks so temporally separated
should be a catalyst toward consideration of the possibility (however remote
it may seem) that a lineage of some sort might (but not necessarily does)
explain it. Mark concurs. I guess we will have to do a paper so anyone
interested can think about the possible significance after seeing the
comparative photos and reading the descriptions. Aside from my conjecture
about any relationship between the Maryland tracks and those from Utah (70
million years later), they are -- so far as I can determine -- the first
clearly avian tracks ever discovered from the Mesozoic of Maryland.

    For those that missed my partial description of the tracks, let me
repeat: three virtually identical bird tracks (two successive, and a third
one, unassociated, on a different type of substrate) each with the same 132
degree angle of divarication (digits II through IV), and with a reversed
digit I at roughly 104 degrees from digit II.  Pes width is approximately
3.8 cm (about 1.5 in).  Digit impressions are very narrow.

    Ray Stanford

"You know my method.  It is founded upon the observance of trifles." --
Sherlock Holmes in The Boscombe Valley Mystery



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