Bradley Livezey & Richard Zusi 2001

[Stephan Pickering <stefanpickering2002@yahoo.com>]

    It should have been in the Gauthier/Ball
compendium (when I first received it from Bradley
Livezey, and was reading it with keen interest and
growing excitement, I opened the Gauthier/Ball volume,
thinking I had overlooked it)... and I do not recall
it having been mentioned in this forum:
Bradley C. Livezey & Richard L. Zusi, 2001.
Higher-order phylogenetics of modern Aves based on
comparative anatomy. Netherlands Journal of Anatomy
51(2):179-205.
    I shall not (and cannot do it justice) fully
outline the importance of this paper for systematics
of dinosaurs. But, briefly outlined: Livezey/Zusi,
combining the resources of the collections of the
Carnegie Museum and the National Museum of Natural
History, have begun the task of a
cladistic/phylogenetic analysis of living dinosaurs
(they write: "...Aves are members of the
Theropoda..."), using skeletons and anatomical
specimens (including juveniles), and the best
available skulls and skeletons of subfossil dinosaurs.
   They are also using ca. 12 Mesozoic taxa as
comparative outgroups: Archaeopteryx, Alvarezsauridae,
Eoalulavis, Hesperornithiformes, Confuciusornis,
Protoarchaeopteryx, Caudipteryx, Sinosauropteryx, and
more distant outgroups (troodontids, oviraptorsaurs,
Dromaeosauridae, Velociraptor, Deinonychus "being most
critical").
    Their character matrices use MacClade transposed
onto PAUP, and 175 taxa with the parameters of ~1416
characters derived from integument, skeleton,
musculature, and alimentary system. With the addition
of "cutting-edge" pre-K/T non-avian theropod
systematics (cf. Thomas Holtz's work), the list of
characters could be expanded. The 175 exemplar taxa
"include representiatives of all modern avian orders
and 116 modern avian families". Where there have been
persistent questions re: monophyly of some
nonpasseriform families, their analyses are more
intense. Of the passeriform taxa, they chose 7
exemplar taxa, "including the basalmost suboscines".
   The anticipated goal is to combine this
breathtaking morphological analysis with molecular
analyses of extant dinosaurs, and to correct the fact
that, often, there have been no phylogenetic taxonmic
analyses of morphologies of many taxa, even though
some papers allude to "morphology" being the
determining factor of the phylogenetic placement of
taxa. As Livezey/Zusi point out, morphological
systematists are "running about five years behind
their molecular peers in general accomplishment, about
even with respect to the resolution of higher-order
relationships".One can only hope that Gregory Paul,
whose appendices 1-5 seem to echo the goals of the
Livezey/Zusi project, will join them vis-a-vis
extrapolations from Mesozoic taxa, along with the
pioneering work of Julia Clarke, L.M. Chiappe, Kevin
Padian, and Thomas Holtz...and the Cantino/Gauthier/de
Queiroz teams of the PhyloCode.
    One area they do point to is the need for
uniformity of anatomical nomenclature, using Nomina
Anatomica Avium (Baumel et al. 1993). The characters
of the dinosaurs are numerically sequenced, with
elaborations for variations encountered in specimens.
This ICAAN standard, already used by most major papers
on Mesozoic theropods, particularly with respect to
locomotion, e.g., means all can understand what is
being discussed. They use the example of femoral
trochanters, viz. m. caudofemoralis caudalis,
absent/reduced in Recent theropods. Another example is
the often used "pubic apron" re: theropods. The
nomenclature should be "symphysis pubica". By
standardizing the features used to describe pre-K/T
theropods, one can make links between outgroups and
sequence data of Recent dinosaurs.
    Livezey/Zusi began the project, in part, with a
2000 paper:
    Richard L. Zusi & Bradley C. Livezey, 2000.
Homology and phylogenetic implications of some
enigmatic cranial characters in galliform and
anseriform birds. Annals of Carnegie Museum
69(3):157-193.
    These two clades are the sister groups of "modern
neognathous birds" -- being the Galloanserae of Sibley
et al. 1988 and a converted clade name, the crown
clade Galloanserae of Gauthier/de Queiroz 2001:31-32.
Although not addressed by them, I have long believed
that these were the two avian theropod groups to have
survived the K/T extinction events, the small
feathered theropod fliers having already driven the
small, unsuccessful flying pterosaurs into extinction.
As Gregory Paul discusses, bats (who have never been
secondarily flightless)have genuine morphological
similarities to agile pterosaurs, even if they lack
the speed and visual acuity of flying dinosaurs
(compensating with nocturnal sonar vocal systems).
    Another area Livezey/Zusi are thoroughly revising
is the often contradictory literature concerning the
avian theropod palate starting with Thomas Huxley's
1867 attempts. They will be precisely delineating all
of the palatal characters rooted in an "analytical
reinterpretation of the features being described".
    I do not believe I am exagerrating when I say that
we are about to see dreams fulfilled (one dream, the
side-lining, as it were, of those who cling to the
delusion that avians are not dinosaurs, is already
operative), namely the joining of the best of pre-K/T
systematics with rigorous anatomical studies from
Livezey/Zusi and molecular data...so that the
never-fulfilled hopes of Charles Sibley, John Ostrom,
and others are realized. 
 


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