[dinosaur] Dinosauria craniodental and postcranial characters implying different trees (free pdf)

Ben Creisler
[email protected]

A new paper in open access:

Free pdf:

Yimeng Li, Marcello Ruta & Matthew A Wills (2019)
Craniodental and postcranial characters of non-avian Dinosauria often imply
different trees.
Systematic Biology, syz077 (advance online publication)
doi: https://urldefense.proofpoint.com/v2/url?u=https-3A__doi.org_10.1093_sysbio_syz077&d=DwIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=_bOtRhHKDfJrXq_8UjpyJD_8hB4jH3NXIpum0KD6CLw&s=d1bxt0gKo19DRea4VR8E1zv4Z5DCAMYHBqwi71jAVpc&e= 
https://urldefense.proofpoint.com/v2/url?u=https-3A__academic.oup.com_sysbio_advance-2Darticle_doi_10.1093_sysbio_syz077_5643850&d=DwIBaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=_bOtRhHKDfJrXq_8UjpyJD_8hB4jH3NXIpum0KD6CLw&s=s4DoxMksvPwICEQ6exQcw29djsn9YRqtYnOvnVB4LUk&e= 


Despite the increasing importance of molecular sequence data, morphology
still makes an important contribution to resolving the phylogeny of many
groups, and is the only source of data for most fossils. Most systematists
sample morphological characters as broadly as possible on the principle of
total evidence. However, it is not uncommon for sampling to be focussed on
particular aspects of anatomy, either because characters therein are
believed to be more informative, or because preservation biases restrict
what is available. Empirically, the optimal trees from partitions of
morphological data sets often represent significantly different hypotheses
of relationships. Previous work on hard-part versus soft-part characters
across animal phyla revealed significant differences in about a half of
sampled studies. Similarly, studies of the craniodental versus postcranial
characters of vertebrates revealed significantly different trees in about
one third of cases, with the highest rates observed in non-avian dinosaurs.
We test whether this is a generality here with a much larger sample of 81
published data matrices across all major dinosaur groups. Using the
incongruence length difference (ILD) test and two variants of the
incongruence relationship difference (IRD) test, we found significant
incongruence in about 50% of cases. Incongruence is not uniformly
distributed across major dinosaur clades, being highest (63%) in Theropoda
and lowest (25%) in Thyreophora. As in previous studies, our partition
tests show some sensitivity to matrix dimensions and the amount and
distribution of missing entries. Levels of homomplasy and retained
synapomorphy are similar between partitions, such that incongruence must
partly reflect differences in patterns of homoplasy between partitions,
which may itself be a function of modularity and mosaic evolution. Finally,
we implement new tests to determine which partition yields trees most
similar to those from the entire matrix. Despite no bias across dinosaurs
overall, there are striking differences between major groups. The
craniodental characters of Ornithischia and the postcranial characters of
Saurischia yield trees most similar to the 'total evidence' trees derived
from the entire matrix. Trees from these same character partitions also
tend to be most stratigraphically congruent: a mutual consilience
suggesting that those partitions yield more accurate trees.