SV: don' t think that flies

[Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com>]

Actually megapode nesting strategies varies considerably. Some species
do practice the "lay 'em and leave 'em" strategy using, usually, black
lava sand on beaches. One species actually uses geothermic sites! The
megapode mounds vary a great deal in composition, many contain a large
proportion of sand or soil (especially the Malleefowl). Such mounds are
recognizable for a long time after being abandoned and are potentially
fossilizable (they would be recognizable by shape and the eggshell
content of the soil). Species living in rainforest habitats trust less
to the sun and more to the heat of fermentation. A species on Vanuatu is
supposed to use the heat from rotting tree-roots. 
The degree of attendance by the male also varies greatly. The Maleefowl
is at one extreme being in attendance at the mound for 11 months of the
year. The Maleo is at the other extreme. There the male digs a laying
burrow and then helps the female fill it in. Then he is done.

Tommy Tyrberg   

-----Ursprungligt meddelande-----
Från: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] För Dann
Pigdon
Skickat: den 24 november 2008 01:34
Till: dinosaur@usc.edu
Ämne: Re: don' t think that flies

Quoting Graydon <oak@uniserve.com>:

> On Sun, Nov 23, 2008 at 11:20:31PM +0100, David Marjanovic scripsit:
> >> Nest Structure for Sauropods: Sedimentary Criteria for Recognition
...
> >> PALAIOS; February 2004
> >
> > Oops.
> 
> That's not evidence against piling heaps of vegetation over the nests
> and walking away, is it?
> 
> It's evidence against a buried-in-sand, sea-turtle style nest; it's
not
> evidence against a Mallee fowl style nests, though.

The problem with burying eggs in vegetation is that it heats up as it
rots. Mallee fowls and 
megapodes have to constantly tend their nest mound, checking the
temperature inside them with 
their beaks and either scraping vegetation out (if it's getting too hot)
or adding more to the mound 
(if it's cooling down). If the nest mound gets too cold or too hot, then
the eggs die.

Burying in sand is the better option for the lay'em and leave'em types,
since the temperature tends 
to remain fairly constant.

-- 
___________________________________________________________________

Dann Pigdon
GIS / Archaeologist              http://geo_cities.com/dannsdinosaurs
Melbourne, Australia             http://heretichides.soffiles.com
___________________________________________________________________