CRETACEOUS BIODIVERSITY

[darren.naish@port.ac.uk]

The Cretaceous Biodiversity conference was held at Portsmouth 
University, England, on 10th and 11th July (not 11th and 12th as 
advertised). Talks covered several aspects of Cretaceous biodiversity 
including coral reefs, forams and insects. Emphasis was on tetrapods 
- this was not actually intentional, and was also unfortunate because 
tetrapods are not informative with regard to biodiversity as a 
whole. What the hey, they are the most interesting animals of them 
all :) Here are the highlights (i.e. the tetrapod talks).

Michael BENTON spoke about the diversity of European and African 
Cretaceous dinosaurs. The record is patchy but new discoveries in 
eastern Europe (e.g. Romania) show that dinosaurs were abundant, but 
living at relatively low taxic diversity. Biogeographically 
problematic taxa, such as _Pelecanimimus_ and the supposed 
pachycephalosaur _Yaverlandia_, show that we do not have anywhere 
near the full picture.

Darren NAISH spoke about aspects of diversity seen within Wealden 
Group theropods. 

Paul DAVIS reviewed Mesozoic birds and showed loads of amazing 
pictures. Among these were the raquet-tailed _Confuciusornis_ we are 
all now familiar with (and, incidentally, the male specimen in the 
_National Geographic_ article is not the same as the male specimens 
Paul showed.. are they different species?), as well as about three 
new genera from the Yixian and Jiufotang Formations. All are unnamed, 
and all are very odd little creatures indeed. Because skeletal 
reconstructions of _Confuciusornis_ thus far published are not 
accurate, Paul produced his own.

By throwing (nearly) all Mesozoic birds into a cladistic analysis, 
Paul produced a totally new Mesozoic avian phylogeny, full of 
surprises. I can believe it mainly because I have heard of 
cases where similar results have been generated by other workers. 
Paul is due to publish on it, so I'll keep quiet for now.

Susan EVANS gave overviews of lepidosaur and lissamphibian diversity 
in Cretaceous faunas. The fossil record of both groups  basically 
does not approach extant faunas in terms of number of taxa, and 
different community structures are sometimes present: some of this is 
because of taphonomic bias, but other factors are also in play such 
as the predominantly Tertiary radiation of frogs, and the fact that 
high-profile publications are not willing to publish papers on things 
like Mesozoic frogs and lizards... for some reason they do not 
consider them as interesting as birds or mammals. 

In terms of ecotype, lizards are not very diverse in the Jurassic 
(all are insectivorous), and in the Early Cretaceous ecotype 
diversity is low too. Toward the end of the Cretaceous, they exhibit 
far greater size ranges and occupy many different ecological niches.

David UNWIN gave an absolutely excellent talk on Cretaceous pterosaur 
diversity. The pterosaur fossil record is very incomplete and lists 
of pterosaur diversity charted against time are misleading. Many 
bits of the Cretaceous lack pterosaur fossils, or only have little 
bitty pieces as representative. Some of the 'best known' pterosaurs, 
including _Quetzalcoatlus_ and _Dsungaripterus_, have not been 
adequately described, and the current approach of institution 
departments and of funding bodies provides a hostile environment for 
the construction of detailed monographs. 

Suggestions that latest Cretaceous pterosaurs were all 
gigantic are not correct, nor are claims that only latest 
Cretaceous pterosaurs were gigantic. However, some of the smaller 
latest Cretaceous taxa may be juveniles of the gigantic taxa (i.e. 
_Quetzalcoatlus_ and _Arambourgiania_, which may be synonymous). What 
is notable is that Cretaceous pterosaurs do not exist at sizes 
smaller than 1 m wingspan, whereas Triassic and Jurassic pterosaurs 
were (virtually without exception) within this size range. A new 
generic name for _Phobetor_ was used: this name is actually 
preoccupied by a fish.

On Saturday 11th we embarked on a field trip to Cretaceous localities 
on the Isle of Wight. The weather made it hell, but at Sandown Museum 
bits of the new theropod were displayed. I found a dead cormorant 
which is currently decomposing in a hole in the ground somewhere in 
the university grounds. 

"Seems to me that you seem to be confused"

DARREN NAISH
darren.naish@port.ac.uk