[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Cretaceous diplodocids in Asia?



From: Ben Creisler
bh480@scn.org


In case this paper has not been mentioned yet:

JOHN A. WHITLOCK, MICHAEL D. D?EMIC, JEFFREY A. WILSON 
(2011)
Cretaceous diplodocids in Asia? Re-evaluating the 
phylogenetic affinities of a fragmentary specimen.
Palaeontology
Early View (Articles online in advance of print)
DOI: 10.1111/j.1475-4983.2010.01029.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1475-
4983.2010.01029.x/abstract

The recent description of an anterior caudal vertebra 
purportedly belonging to a diplodocid sauropod from the 
Early Cretaceous of China has the potential to 
drastically alter our interpretation of the evolution and 
timing of geographical dispersal of a major dinosaur 
lineage. However, comparison with a wider taxonomic 
sample points more strongly towards titanosauriform 
affinities for this specimen, which is in keeping with 
the affinities of all other sauropods known from the 
Cretaceous of Asia. We explain the disparity in 
phylogenetic interpretation of this isolated vertebra as 
a by-product of scoring differences and analysis of 
fragmentary material using repurposed data matrices. 
Rescoring the isolated vertebra based on our 
interpretation of the anatomy and rerunning the original 
analyses removes the specimen from Diplodocoidea but does 
not place it within Titanosauriformes, because of 
inadequacy in taxon and character sampling inherited from 
the repurposed data matrices. We suggest that 
phylogenetic analysis must begin with an initial 
hypothesis of affinity, based on comparative anatomy and 
spatiotemporal distributions, that must be adequately 
tested by the data matrix employed ? i.e. data matrices 
should be tailored to sample anatomically, geographically 
and temporally relevant clades, and new characters should 
be added in tandem with new taxa so that the potential 
synapomorphy pool is not diluted. This is especially 
important for analyses of fragmentary specimens, which 
are likely to return coarse phylogenetic results with 
general evolutionary and palaeobiogeographical 
implications.