Re: Devonian extinctions

[hrlane@xxxxxxxxx]

     Perhaps the generic level is an artificial one.  What about species?  
     How many fish species are there in the Devonian and how significant is 
     the extinction at the taxonomic level?


______________________________ Reply Separator _________________________________
Subject: Re: Devonian extinctions
Author:  paleonet-owner (paleonet-owner@nhm.ac.uk) at unix,in
Date:    1/29/95 4:12 PM


You could easily put what I know about Devonian fishes in a fortune  
cookie, but I'll comment anyway. Ahlberg mentions seven genera.  
However, I see that Carroll lists three "amphibians"; seven  
"palaeoniscoids"; 40 "rhipidistians"; four onychodontids; four  
actinistians; and 20 lungfish for the entire Devonian. That's the  
good news. But with only 78 genera for an interval of about 50  
million years, it would seem difficult to establish significant  
differences in standing diversity or turnover rates among  
sub-intervals such as stages - even assuming that the lengths of  
those stages and the correlations of faunas to those stages were  
well-establish. Based on the Foote paper in the latest Paleobiology,  
standardizing turnover rates for time when working with data like  
these would seem a nightmarish task. Also remember that one should at  
least compute binomial confidence intervals on diversity/turnover  
data when dealing with small sample sizes (e.g., as in multiple Foote  
papers), and one might end up with nothing to talk about after doing  
so.