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Anchisauripus (RE: ABOUT THE REVERSED HALLUX AND...)



Wait ANOTHER minute.
Let's NOT look at Lull 1953!

To be sure, every ichnospecies of Anchisauripus illustrated has the 'hallux'
- although, if you read closely, in several instances the hallux is added by
Lull b/c he presumes it is there - it is in some species, so it must be in
all of them. 
If you go further and compare Lull 1915 (the 1st edition of Triassic Life of
the Conecticut Valley), the same illustrations are used BUT oh-so-many of
the lines are dotted..... alas, by 1953, the master drawings were lost, he
was almost blind, and his family redrew all the 1915 figures, using solid
lines throughout (even in those instances where dashed lines were used in
1915).

Then, when you look at the specimens themselves - those that according to
Lull, exhibit this hallux (claw impression) - the only specimens that have
the hallux are on large footprint slabs literally covered with tracks
(Anchisauripus and others). Hitchcock himself referred to small triangular
indentations covering the slab. Lull interpreted these to be the
Anchisauripus hallux claw impressions. I guess he wasn't too concerned that
there were far more 'halluxes' than Anchisauripus prints, and most of them
were not associated with any prits. But wait, the plot thickens. If you look
at the position of these little triangular indents, you can see how they
are, in fact, the claws on digits II-IV of tracks that must have been made
on a higher stratigraphic surface - these 'halluxes' are actually the
undertracks (as the claws went in deepest into the substrate).

Gotta love ichnology.

Oh, and although Lull was convinced (when he named the ichnogenus, until his
death) that Anchisauripus was the track made by Anchisaurus - well, in 1904
and 1915, Anchisaurus was thought to be a theropod (cool quote from Lull
1953, p166: "That the makers of these tracks were all dinosaurian is obvious
and that they belong to the Theropoda is also without question..." [golly,
I'd LOVE to know HOW Lull "knew" this]), though we now know Anchisaurus to
be a prosauropod - although, Anchisauripus is almost certainly a Theropod
(and therefore NOT the track of Anchisaurus).
I think there's a warning on how (not) to name tracks in there
somewhere.....

:-)

 emma


Emma C. Rainforth
Curator, Mesalands Dinosaur Museum and
Natural Science Instructor
Mesalands Community College
911 South Tenth St.
Tucumcari, NM 88401
505/461-4413 x192
fax 801/838-4126
emmar@mesalands.edu


> -----Original Message-----
> From: dinotracker [mailto:dinotracker@earthlink.net]
> Sent: Tuesday, July 09, 2002 4:15 PM
> To: Dinosaur Mailing List
> Subject: ABOUT THE REVERSED HALLUX AND...
> 
>     T. Michael Keesey wrote, >- The only group known to have reversed
> halluces (_Avialae_) also appears to
> have hyperextendable second pedal digits (at least primitively).<
> 
>     Hey, wait a minute!  Here is a situation where we might best have a
> look
> at the track record.
> 
>     For example (and there are many), have at look at pages 167 through
> 173
> in TRIASSIC LIFE OF THE CONNECTICUT VALLEY (REVISED) by Richard Swann
> Lull,
> Ph.D., Sc.D,, being Bulletin No. 81, State Geological and Natural History
> Survey of the State of Connecticut.  Every ichnospecies of Anchisauripus
> illustrated (including the trackways of A. sillimani and A. hitchcocki)
> shows the mark of a very reversed hallux.  The reversal is not quite 180
> degrees, and varies from roughly 147 to 158 degrees in those examples
> illustrated.
> 
>     As Swan assures us, the Anchisauripus ichnogenus is unquestionably
> theropodan.
> 
>     Other ichnospecies with a very reversed hallux are illustrated in the
> publication, but that well-known example should suffice to make the point
> that it is NOT true that the only group known to have a reversed hallux
> also
> appears to
> have hyperextendable second pedal digits (at least primitively).
> 
>     The Anchisauripus ichnogenus trackmaker (thought to be the theropod
> genus Anchisaurus) has left a clear record of 'four on the floor'.
> Specifically, digits II, III, and IV were each firmly on the ground (every
> phalanx of each), while it was only the tip (claw) of digit I that touched
> the ground, with the proximal end of that digit evidently elevated well
> above the ground.
> 
>     One might conclude that, to use a pun, the Anchisaurus hallux was
> 'getting around to perching'  :), if it wasn't being used for that
> already.
> In this context, note that the tip of the hallux mark extends as far from
> the place on the footprint that would be just beneath its location of
> origin, as about 70% to 100% of the length of digit II, excluding the
> digit
> II claw mark! (And I'm only talking about its as-seen-from-above length,
> which would be appreciably shorter than its actual length.)  With that
> much
> reversal and length, one might conclude that digit I is 'coming' (into
> usefulness) instead of 'going' (vestigial).
> 
>     O.K., the ichnological evidence regarding the pes morphology of
> Anchisaurus might be variously interpreted, but it should give us food for
> thought, lest we jump to unwarranted 'bare bones' (Pun intended.)
> conclusions.
> 
>     Also, I have collected some theropod footprints from the Early
> Cretaceous of Maryland with the impression of a very reversed hallux,
> including tracks by both non-avian theropods and those of seeming avians,
> and none of the specific ones I'm referring to show any signs of a
> specialized digit II.
> 
>     Paleoichnologists might well declare, "Blessed is the substrate that
> retains a long memory of those which trod upon it!"  :)
> 
>     Ray Stanford
> 
> "You know my method.  It is founded upon the observance of trifles." --
> Sherlock Holmes in The Boscombe Valley Mystery