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Elephants & Pack Hunting (two topics...)



At 10:21 PM 5/15/99 -0700, George Leonard wrote:

[with regards to my comment about "Early Tertiary" proboscideans]

>"Early Tertiary"? Could you be slightly more specific? How close to KT 
>(very, I hope)? 

Depends on how you define "close".  _Moeritherium_ is Early Eocence, so some
ten million years or more after the K-T boundary, so some 15% of the current
duration of the Cenozoic had already passed.  I don't know about the other
basal proboscideans: haven't heard (or can't remember) if any of the others
are Paleocene or not.

>In the talk of mammals at the KT, I can't remember talk of aquatic 
>mammals.

At present, no one has reported aquatic adapted mammals crossing the K-T
boundary.  Also, please note that _Moeritherium_ is hippo-like in the broad
sense, so "semi-aquatic" might be more appropriate.

Now, on to pack hunting.

Several of the posters are reading things into comments by myself which were
not there.  I did not say:
* that dinosaurs could not have been pack hunters;
* that dinosaurs were too stupid to have been pack hunters;
* that dinosaurs were too stupid to have lived in groups (a truly bizarre
concept!);
* that dinosaurs weren't the coolest things ever to stride the face of the
Earth.

Okay, what I (and others) have been emphasizing is:
* that the data, at present, demonstrate at best that there are multiple
incidents of dead _Deinonychus_ associated with dead _Tenontosaurus_;
* that these data are consistent with group feeding, and possibly even group
killing, of the _Tenontosaurus_ specimens by multiple individuals of
_Deinonychus_;
* that this would be consistent with an hypothesis of true pack hunting, but
(here's the clincher) IT DOES NOT DEMONSTRATE IT, and IT IS CONSISTENT WITH
OTHER MODELS AS WELL.  Period.

If you do not understand the difference between what I and others were
pointing out, and what people seem to think we were saying, please write me
and I will try to make it even plainer.  (How, I don't know, but I'll try...).

Okay, related topics:
Nathan Myrhvold posted an excellent summary of recent work on pack hunting.
Time for me to go back to some of those references, which I haven't touched
for a while.  One I *have* reread recently, and which I alluded to in an
earlier posting, was Heinsohn & Packer (1995, Science 269:1260-2) and
related articles.  This body of work suggests that there is more to pack
(social) hunting than the hunting episode itself: that what separates packs
from other group hunting activity is what they do during "down time".

Can we demonstrate down time group activity for dromaeosaurids?  No (or at
least not yet).  Does this eliminate the possibility that they had group
activity in non-hunting hours?  No.  Should we assume that they *did* have
complex social interactions while not hunting?  No.  They might have, and I
noted (only partially facietiously) that feather grooming would be an
activity that dromaeosaurids could share while not hunting.  Personally, I
suspect that at least some dromaeosaurids did have complex social
interactions, and I find the concept quite satisifying.  However, we don't
have evidence for it, and like it or not, evidence rather than appealing
stories is what science is based on.

Group hunting in birds: thanks for those posted.  As I wrote:
> Of course, there is
> nothing (to my knowledge) PREVENTING birds and other reptiles from forming
> semi-permanent coalitions of kin who cooperate during hunting and
> non-hunting activities, but it isn't observed (to my knowledge).
Thank you for adding to my knowledge.  (I would like to point out, though,
that the Washington Times is not exactly a peer-reviewed scientific journal,
so if you can find a somewhat more reputable (and citable) source, I'd
appreciate it).

Also, groups of sibling blue jays actively operating together to drive off
cats or dogs or hawks is not an example of pack hunting, or even group
hunting.  A group of sibling blue jays actively operating together to kill
and eat cats or dogs or hawks would be...

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661