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Re: Segregated vs age-mixed sauropod herds



John Bois wrote:
> On Sun, Mar 14, 2010 at 10:19 AM, Thomas R. Holtz, Jr. <tholtz@umd.edu>
> wrote:
>> there are phylogenetic arguments (parental
>> care for at least several weeks is present in crocs and birds, and hence
>> in Archosauria ancestrally)
>

[snip]

> My students wondered, then: why wouldn't the parents protect the
> hatchlings from the snakes (I suppose this is where the non-attendance
> assumption came from, i.e., if parents were there, they would have
> killed the snakes!)?
>
> I responded that while the parents were likely hanging around, they
> had strict genetic rules that said: under no circumstances enter the
> nest-ground proper...the risk of crushing babies being the strongest
> selective pressure here.
>
> The students said that was pretty stupid...that they could have leaned
> over with their long necks and bitten the snakes.

Let's not forget, snakes are MAJOR predators of baby birds today, even for
species with biparental care.

Parental care =/= total immunity of the babies from all attacks!!

-- 
Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA