Re:Precision

[Mike Taylor <mike@indexdata.com>]

Tim Williams writes:
>> I think this book would be written in the early 90's, but even by
>> then most of the more accurate estimates had been done. Seriously,
>> take Gillete and the dsicoverers of Bruhathkayosaurus (forget their
>> names, too tough too spell, lol), then you realize that the actual
>> professionals aren't too professional. One of them gave estimates
>> 55% to large, and the other actually didn't know what kind of
>> creature they were looking at. Go's to show that you REALLY can't
>> trust anyone. But then again, Mike was pretty clear on that.
> 
> I'm not sure if that's precisely what Mike said.  I interpreted his
> posts as saying that some estimates are better than others, and so
> probably can be trusted.

Right.  But the problem is known _which_ estimates are better than
others.  And to find that out, there's really no substitute for
reading a _lot_ of stuff.

> Certain estimates are less trustworthy - like Colbert's 78-tonne
> uber-brachiosaur, for example.  It all depends upon the method(s)
> used to estimate body mass, including the accuracy of the 3-D
> ("flesh-and-blood") reconstructions.

... and indeed the accuracy of computer models.  Here I am thinking of
Gunga et al's (1995) Colbert-like mass estimate of 74.4 tonnes, which
is based on a computer model built out of tubular sections ... that's
circular, rather than elliptical, in cross-section.  Using this method
they managed to estimate 11 tonnes for the neck alone(!), i.e. three
quarters of the mass that Russell et al. (1980) came up with for the
whole animals.  So the moral is that more recent estimates, such as
that of Gunga, are not necessarily better.

> The Kallamedu Formation in southern India has yielded more material
> besides _Bruhathkayosaurus_.  Matley poked around there at the
> beginning of the 20th century; and much more recently a turtle came
> to light (_Kurmademys kallamedensis_), including a beautifully
> preserved skull.

Yeah, but did it weigh 200 tonnes?

:-)

> BTW, _Dystylosaurus_ (cursed with an un-sexy name, as stated by
> Gillette) is quite possibly the same as _Supersaurus_, just like
> _Ultrasaurus_/_Ultrasauros_.

What's wrong with the name?

Curtice and Stadtman (2001) made a pretty convincing case for the
_Dystylosaurus_ specimen being an anterior dorsal of _Supersaurus_
(not least because it was found between the two _S._ scapulae :-) but
I noticed that Upchurch et al. (2004) still lists _D._ as a
brachiosaurid, which was the assessment made by McIntosh (1990).
I've not spoken to Paul about this, so I don't know whether this
constitutes a disagreement with Curtice and Stadtman's assessment; but
I think it's more likely that their manuscript was submitted before
C&S's became available.

> If there is some doubt that _Supersaurus vivianae_ can be
> distinguished from _Diplodocus_, this merely makes _Supersaurus_ a
> junior subjective synonym of _Diplodocus_, not a nomen dubium.

Really, "if there is some doubt"?  Does the burden of proof really lie
all on one side?  By the way, _Supersaurus_ is generally considered to
be closest to _Barosaurus_, not _Diplodocus_ -- for good reasons I
think.  I know there is another hypothesis out there, but that
hypothesis doesn't bring _Supersaurus_ any closer to _Diplodocus_.

 _/|_    ___________________________________________________________________
/o ) \/  Mike Taylor    <mike@indexdata.com>    http://www.miketaylor.org.uk
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