Paleonet: first and last things

[Bill Chaisson]

>Chris,
>
>My understanding is that fossils occur in the rock record, and the 
>organisms they represent appeared or disappeared in geological time. 
>Hence, one should use lowest/highest occurrence (for fossils in 
>rock), and first/last appearance when dealing with time.  So, 
>Wetzeliella has a lowest occurrence in the Lower Eocene, but but it 
>evolved in the Early Eocene.
>
>Likewise for lowest common occurrence and lowest persistent occurrence.
>
>For those who contend that time and time-rock are one and the same 
>(Hughes, 1989; Harland et al. 1990; Zalasiewicz et al. 2004), then I 
>suppose lowest/highest occurrence would be replaced by first/ last 
>appearance :)

Understood, but the rule of superposition is pretty basic, and the 
use of two sets of abbreviations that share LO with it having the 
opposite sense in one set vs. the other seems needlessly confusing.

First and last do not necessarily imply time, only order. (e.g., Take 
your first right and ...)

Bill
-- 
_____________________________
William P. Chaisson
Adjunct Assistant Professor
Dept. Earth & Environmental Sciences
University of Rochester
Rochester, New York  14627
607-387-3892
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