New Papers: Bird evolution and Triceratops combat

[bh480@scn.org]

From: Ben Creisler bh480@scn.org
In case these papers have not been mentioned here yet:
Zoological Journal of the Linnean Society
Volume 141 Issue 2 Page 153 - June 2004
DYKE, GARETH J. and MARCEL VAN TUINEN, 2004. The 
evolutionary radiation of modern birds (Neornithes): 
reconciling molecules, morphology and the fossil record. 
Zoological Journal of the Linnean Society 141 (2): 153 - 
177 (June 2004)
The pattern, timing and extent of the evolutionary 
radiation of anatomically modern birds (Neornithes) 
remains contentious: dramatically different timescales for 
this major event in vertebrate evolution have been 
recovered by the 'clock-like' modelling of molecular 
sequence data and from evidence extracted from the known 
fossil record. Because current synthesis would lead us to 
believe that fossil and nonfossil evidence conflict with 
regard to the neornithine timescale, especially at its 
base, it is high time that available data are reconciled 
to determine more exactly the evolutionary radiation of 
modern birds. In this review we highlight current 
understanding of the early fossil history of Neornithes in 
conjunction with available phylogenetic resolution for the 
major extant clades, as well as recent advancements in 
genetic methods that have constrained time estimates for 
major evolutionary divergences. Although the use of 
molecular approaches for timing the radiation of 
Neornithes is emphasized, the tenet of this review remains 
the fossil record of the major neornithine subdivisions 
and better-preserved taxa. Fossils allowing clear 
phylogenetic constraint of taxa are central to future work 
in the production of accurate molecular calibrations of 
the neornithine evolutionary timescale. © 2004 The Linnean 
Society of London, Zoological Journal of the Linnean 
Society, 2004, 141, 153-177.

http://palaeo-electronica.org/2004_1/horn/issue1_04.htm
Palaeontologica Electronica 7 : 1 June 2004 (free online)
Farke, A. 2004. HORN USE IN TRICERATOPS (DINOSAURIA: 
CERATOPSIDAE): TESTING BEHAVIORAL HYPOTHESES USING SCALE 
MODELS. Palaeontologica Electronica 7 : 1 June 2004
ABSTRACT 
Triceratops, a common chasmosaurine ceratopsid dinosaur 
from the Late Cretaceous of North America, is known for 
its cranial ornamentation, including a single nasal horn 
and large, paired supraorbital horns. It is commonly 
surmised that Triceratops used its horns in intraspecific 
combat, but this hypothesis has not been rigorously 
tested. Scale models of Triceratops skulls were used to 
determine if it could physically lock horns as has been 
suggested. Three hypothetical horn locking positions were 
found, involving varying orientations of the combatants' 
skulls. Based on these positions, it was hypothesized that 
injuries caused by horns were especially likely in certain 
portions of the frill, jugals, and postorbital horncore 
tips. This corresponds to some previously reported 
pathologies in chasmosaurine specimens. Uncertainties in 
this modeling exercise center around variations in horn 
orientation, size, shape, and the possible existence of a 
keratinous supraorbital horncore sheath. Triceratops 
differs from modern horned mammals in its horn 
orientation, which suggests that if it engaged in 
intraspecific combat, its fighting style was quite 
different from these modern animals. During hypothetical 
horn locking in Triceratops, most of the force was 
directed against the medial and lateral surfaces of the 
horn cores. This has implications for future studies of 
ceratopsid cranial functional morphology, especially as 
related to horn architecture and the development of the 
frontal sinus complex.