[Taxacom] 53 million year rabbit foot

Scott Lyell Gardner slg at unl.edu
Mon Nov 28 22:38:55 CST 2011


My question:  Is a 53,000,000 year old rabbit foot still lucky? Just 
wanted to know for the next time we find one when we are on a field 
trip. -Scott Gardner

On 11/23/2011 9:12 PM, Kenneth Kinman wrote:
> Hi Jason,
>         Well, it depends on the particular case.  In some cases, I can
> see making the assumption that the stem is "practically" nonexistent.
> However, if there is very good evidence that taxon X and taxon Y are
> sister taxa, but one has a long stem-lineage containing uncontroversial
> fossils and the other does not have such stem fossils, then it seems to
> me more parsimonious (conservative?) to assume that the taxon lacking
> known stem fossils also has a stem lineage that is just as long, but for
> some reason the fossils have not been discovered.
>
>        The reason could be relatively low population numbers, very
> restricted habitat, less fossilizable body parts, or something else.
> But I think it would be unwise to assume the stem is nonexistent in such
> a case.  Of course, on the other hand, if the evidence that X and Y
> actually are sister taxa is not very strong, one could then hypothesize
> that one is actually paraphyletic with respect to the other, and the
> daughter taxon could thus have such a short stem that lack of fossils
> could be because of that.  It all depends on the particular case, which
> assumptions I would make.
>                 ---------Ken
>
> ------------------------------------------------------
> Jason wrote:
> Hi Ingo and Ken,
> sorry for what will be a rather short and uninteresting clarification. I
> actually meant that without fossils, and for all practical reasons, we
> can assume that the stem is non-existant if we are being conservative.
> It is a matter of choice on how many assumptions you can make regarding
> timing, but this becomes a moot point when you have fossils belonging to
> the stem and crown. Hence I think we are in general agreement in this
> regards. That was a fun exchange!. Best Jason
>
>
>
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-- 

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Scott Lyell Gardner, Ph.D.
Curator and Professor
Harold W. Manter Laboratory of Parasitology
W-529 Nebraska Hall
University of Nebraska State Museum and
School of Biological Sciences
University of Nebraska - Lincoln
Lincoln, Nebraska 68588-0514

e-mail:   slg at unl.edu
Web:      http://hwml.unl.edu
ASP Page: http://asp.unl.edu

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