[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Dromeosaurid behavior........Pack hunting! (long)

At 10:10 AM 4/29/99 -0400, you wrote:
>I like this discussion.
>My interest in the dromeosaur kill sites is in what it says about how
>advanced dinosaurs were in terms we usually apply to modern predators.
>Pack hunting implies fairly advanced neuroanatomy, probably even
>methods of signaling. (Maybe the wagging of feathered tails!)

If it *is* pack hunting, and not opportunistic gang hunting or other form of
mass kill.  That's why we need to test the hypothesis that the
_Deinonychus_-_Tenontosaurus_ sites were evidence for pack hunting **prior**
to using this as evidence for degree of social sophistication.

(As for neuroanatomy, I'd prefer to go by endocasts first, and taphonomy
afterwards... :-)

>In the end years of the 20th c. we have mental images of dinosaur
>behavior based on our modern footage of  lions, hyenas, etc.

And hopefully on birds, and on crocs, and on lizards, and on...

>In the end years of the 19th c. we might have based our mental images
>on observations of lizards.

Or on mammals.  (Many late 19th C. paleontologists had a more dynamic view
of dinosaurs than early 20th C. types).

>In the 21st c. we may learn (I think we will) that we should base
>our mental images of dinosaurs more on observations of eagles
>and secretary birds, modified by considerations of prey mass that
>we take from lions, etc. I have been very impressed by the
>the work of Irene Pepperberg on bird intelligence in African Grey
>parrots and by recent  observations and tests of intelligence in crows.

Indeed.  However, no non-ornithothoracine dinosaur approaches the level of
encephalization found in these modern birds.  I am impressed by the brain
power of humans and racoons and cetaceans and pigs, but it would be
inappropriate to argue that deltatheroids or multituberculates or other
Mesozoic mammals had comparable brain power.  Evolution happens.

>Social interaction appears to be more important than brain mass
>in driving intelligence.

Ummm... Based on...?  It's an interesting hypothesis, and might well be
true, but I don't know that this has been established.  (It might: I don't
know that literature).

>We have to test these theories against the fossil sites with a critical eye,
>but not avoid theorizing because the data is incomplete.

No, don't avoid theorizing; but don't assume your theories are supported or
demonstrated prior to finding that support!

>Also note:
> If we count ants raising aphids, domestication may have occured in
>the Cretaceous.

Indeed.  However, as I noted, we can't just assume it was present: we have
to find supporting, falsifiable evidence to demonstrate the presence of this
behavior.  (Hypothetical case, and I'm not an entomologist, so please excuse
my ignorance: if the species of ant which domesticate aphids form a clade,
or in any case if aphid domestication is a trait at the base of some
formicid clade (potentially lost later), then evidence that this clade of
ants was present in the Cretaceous would be supporting evidence for aphid
domestication in the K.  Even more secure, though, might be ant-aphid
assoication preserved in ashbeds or amber).

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