new paper: Butler et al 2009

[jigruiz@unizar.es]

http://www3.interscience.wiley.com/journal/121591231/abstract

R.J. Butler, P.M. Barrett , P. Kenrick & M.G. Penn. 2009.  Testing  
co-evolutionary hypotheses over geological timescales: interactions  
between Mesozoic non-avian dinosaurs and cycads. Biological Reviews,  
84(1), 73-89

ABSTRACT
The significance of co-evolution over ecological timescales is well  
established, yet it remains unclear to what extent co-evolutionary  
processes contribute to driving large-scale evolutionary and  
ecological changes over geological timescales. Some of the most  
intriguing and pervasive long-term co-evolutionary hypotheses relate  
to proposed interactions between herbivorous non-avian dinosaurs and  
Mesozoic plants, including cycads. Dinosaurs have been proposed as key  
dispersers of cycad seeds during the Mesozoic, and temporal variation  
in cycad diversity and abundance has been linked to dinosaur faunal  
changes. Here we assess the evidence for proposed hypotheses of  
trophic and evolutionary interactions between these two groups using  
diversity analyses, a new database of Cretaceous dinosaur and plant  
co-occurrence data, and a geographical information system (GIS) as a  
visualisation tool. Phylogenetic evidence suggests that the origins of  
several key biological properties of cycads (e.g. toxins,  
bright-coloured seeds) likely predated the origin of dinosaurs. Direct  
evidence of dinosaur?cycad interactions is lacking, but evidence from  
extant ecosystems suggests that dinosaurs may plausibly have acted as  
seed dispersers for cycads, although it is likely that other  
vertebrate groups (e.g. birds, early mammals) also played a role.  
Although the Late Triassic radiations of dinosaurs and cycads appear  
to have been approximately contemporaneous, few significant changes in  
dinosaur faunas coincide with the late Early Cretaceous cycad decline.  
No significant spatiotemporal associations between particular dinosaur  
groups and cycads can be identified ? GIS visualisation reveals  
disparities between the spatiotemporal distributions of some dinosaur  
groups (e.g. sauropodomorphs) and cycads that are inconsistent with  
co-evolutionary hypotheses. The available data provide no unequivocal  
support for any of the proposed co-evolutionary interactions between  
cycads and herbivorous dinosaurs ? diffuse co-evolutionary scenarios  
that are proposed to operate over geological timescales are plausible,  
but such hypotheses need to be firmly grounded on direct evidence of  
interaction and may be difficult to support given the patchiness of  
the fossil record.

the pdf file is free


-------------------------------------------
Jose Ignacio Ruiz-Omeñaca
Museo del Jurásico de Asturias (MUJA)
E-33328 Colunga, Spain
www.dinoastur.com
www.museojurasicoasturias.com
www.aragosaurus.com
-------------------------------------------