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Félix Landry wrote-
fact is that, as far as I know, not one of the recent discoveries (let's
fuzzy ones from Yixian) has been correctly described, and we're already
building heaps of trees including these taxa.
Sinosauropteryx (Currie and Chen, 2001)
Huaxiagnathus (Hwang et al., 2004)
Sinornithosaurus' skull and pes (Xu and Wang, 2000; Xu and Wu, 2001)
Microraptor (Hwang et al., 2002)
Confuciusornis (Chiappe et al., 1999)
Sapeornis (Zhou and Zhang, 2003)
In addition, Caudipteryx (Zhou et al., 2000), Changchengornis (Chiappe et
al., 1999), Eocathayornis (Zhou, 2002) and Vescornis (Zhang et al., 2004)
have fairly detailed descriptions, though not monograph quality.
Of course new discoveries should be
reported as quickly as possible, but am I really wrong when I say that
and superficial descriptions are more and more frequent. Well, maybe it's
just me, or maybe it's because we find more new species and have too
time to do the job really well.
I'm not sure. Let's look at pre-90's Morrison theropods as a comparison to
the Yixian theropods you used as an example above.
Ceratosaurus- described in 1884, first monographed in 1920
Torvosaurus- described in 1979, monographed in 1991
Marshosaurus- partially preserved so easily described in detail in its short
Allosaurus- described in 1877, first monographed in 1920
Saurophaganax (="Saurophagus)- barely described in 1941, monograph will
appear in Chure's upcoming publication
Coelurus- described in 1879, first monographed in 2005
Stokesosaurus- partially preserved so easily described in detail in its
short original paper
Ornitholestes- described in 1903, postcrania monographed in 2005, skull will
be monographed in Norell et al.'s upcoming publication
I don't think we're doing too badly with Yixian theropods. We have six
monographed within five years of their original descriptions.
And while the rate of species description has gone up, it also seems to me
the proportion of new species based on fairly complete skeletons has risen
too. The pre-90's Morrison workers had eight fairly complete theropods to
deal with, we have over 40 Yixian theropods.
Yes, or maybe more, paleobiology and ecology being largely based on
speculation as soon as they intend to be precise (what I have in mind is,
example, the debate about T. rex as a scavenger or not). Phylogeny
science. Crappy analyses aren't, just like bad paleobiology isn't.
Ironically, I think the crappy analyses are the non-quantified ones. Like
any attempt by the BAND/ABSRD/MANIAC crowd, for instance, is pretty
unscientific. And even good qualitative analyses, like Welles' (1984)
monograph on Dilophosaurus, really don't end up being as useful as good
qualitative ones like Rauhut's (2003) on ceratosaurs sensu lato.
Agreed. But out of ten analyses, how many do really contribute to a better
knowledge of these patterns? I feel that having a tree at the end of your
paper is not really enough to make a valuable contribution to phylogenetic
If people use the analyses the right way, I think most contribute. First of
all, they're a condensed description of taxa. Sure, it's easier to make an
important typo in a matrix than a paragraph, but it's nonetheless equivalent
information. And no, a 1 or 0 doesn't substitute for a good illustration,
but a sentence doesn't either. Second, they provide new characters for
other analyses to use. Too many authors don't bother to actually test prior
hypotheses by including all the characters used in them, but ideally they
>published morphological cladistic analyses are crap. Too few characters
>taxa, too subjectively defined states.
Yes, that's exactly what I was saying. I love cladistic analyses, when
they're good. The time used to make the crappy ones could be used to
the anatomy of the critters they're trying to classify, no?
Well, I think of this time as the beginning of the cladistic era, when we're
all learning how to improve the method. I think we need to suffer through
this stage to get everyone doing things right. And I see some encouraging
steps being taken. When a new coelurosaur is described now, for instance,
it's usually placed in the Theropod Working Group's matrix, along with some
new characters. Then later papers describing new taxa and characters
include the updated matrix, and thus the database is built up instead of
starting from scratch every time. Also, the online databanks of characters
and codings being developed by Sereno are going to be a huge step in the
right direction. Much like GenBank is for molecular analyses.
>OR I could reverse your argument. Once we get the basics of
>down, let's move on to determining low level relationships. We already
>Tyrannosaurus is a terrestrial carnivore, I can't see the sheer utility
>all these papers trying to determine its speed, cranial strength,
>overlap, etc.. You change some assumptions in Hutchinson's running
>and come up with completely different results. ;)
Point taken. However, even if it is very tricky and largely based on
speculation, if I had to chose, I would better learn how T. rex behaved as
animal in a living environment than whether Daspletosaurus is more closely
related to it or to Gorgosaurus. I don't expect everybody to share this
aesthetic, as you say, but I do expect not to be the only one...
Fair enough, and no doubt true. I think you have as much right to be happy
with the current trends in paleontology as I do though, for along with
quantitative phylogenetics comes quantitative biomechanics. And the latter
seem far more reliable than the traditional "robust jaws means a strong
bite" or "big cnemial crest means a fast runner" statements that dictated
paleobiology before the 90's.
This is fine for me, but... I get the impression than most published
analyses are somewhat hiding behind the fact they were calculated, by a
you include a thorough description of characters used, coding methods,
and seriously discuss the results (concordance with fossil record, and the
like), then using PAUP is perfect. Just stuffing some unjustified matrix
it and publish the result is not.
I agree the things you mention make a MUCH better paper. Rauhut's (2003) is
a perfect example (at least the version in his thesis was, I don't know if
the resulting paper included all the character discussion and illustration).
But like I said, even crappy analyses contribute in some ways, and we're
passing through a learning stage for cladistics now.
>PAUP only does work we could do ourselves if we weren't so slow. We
>use parsimony because it's easy, we use it because it's objective.
>what makes cladistics more scientific than non-quantitative
Well character definition is not that objective. Or it would be if we had
absolutely complete picture of the organism including ontogeny, individual
variation and the like. But since we don't... Basically, as I understand
using parsimony is saying "there 51% chances that tree A is the right one,
49% that it's tree B, so we'll accept tree A". Evolution acts on the whole
organism, not on separate parts of it; I always feel like determining a
of shared characters involves a reasonable amount of cheating with logics.
Character definition is very subjective now, but I'm trying to reduce that
in my analysis, and I'm sure others have their own ideas too. For example,
instead of having states defined as "structure a more than x% of structure
b", where x is an arbitrary value chosen because it supports some
preconceived clade, I look at the entire range of variation in my sample and
define each state as a tenth of that variation space. The character is
ordered, of course. Yes, the choice of 1/10 is still subjective, but it's
the highest PAUP allows in various ways, and getting much more detailed than
that starts potentially involving individual variation and taphonomic
distortion. Another example- when a growth range is known for a taxon, I
note how and if a character coding differs between ontogenetic stages.
Then, I can use this information to code other taxa known only from
juveniles or subadults in ways that will limit the effects of ontogeny on
phylogeny. This will all be detailed in my publication, and is one of the
many reasons it's taking so long. :)
As for your dispute with parsimony, perhaps you can suggest an alternative
objective method for morphological phylogenetics?
David Marjanovic wrote-
To be fair, Chure's has been upcoming for years. How old is his thesis?
I have seen computer-free cladistics, however.
Yup. Like Paul's (1984) paper on segnosaur relationships. 50 characters
are used, and it takes 20 more steps to make segnosaurs theropods than it
does to make them ornithischian relatives. I should try to add
oviraptorosaurs to the matrix and run it in PAUP. :)
Yeah. The paper's not much more than an osteology. Half a page of
comparison to Megalosaurus, half a page to Acrocanthosaurus, and a couple
sentences about Chilantaisaurus.