Re: T. rex eggs and brooding

[NEIL CLARK <NCLARK@museum.gla.ac.uk>]

CRPNTR wrote:-

Phillip Bigelow <n8010095@henson.cc.wwu.edu> wrote:

> I think that body-incubation, sensu stricto, is a likely possibility 
>in Dinosauria, based on parsimony. 

I am skeptical that a 35 ft. T. rex, let alone a 80 foot sauropod, could 
hunker down in a nest to keep the
eggs warm with their body.  Besides, the egg-body contact surface area 
would be small and heat transfer
minimal.

I have some evidence that the eggs, my research group has been 
working on, show signs of having been buried.  There is no evidence 
that this burial was due to aqueous or wind driven, as there is 
evidence of large scale bioturbation (like someone has dug a hole, 
drop the eggs and recovered them).  Bedding structures are absent and 
no vegetative remains are associated with the eggs which also 
supports the burial hypothesis.  The eggs are of the bun-shaped 
variety - supposed sauropod.  This suggests to me a more crocodillian 
nesting habit for these animals.  I also have trouble imagining these 
huge animals sitting on their eggs to keep them warm.

Neil

> The purported Montana Troodon eggs, and the alleged
>T. bataar eggs don't fit a "nest-laying" morphology (unless the 
theropods
>scratched a trench in the ground and layed the eggs---then that may be
>considered a "nest" of sorts). 

Do you assume that they were left on the ground undefended?



>Horner's Maiasaur nests were relatively high-walled, possibly to keep 
the chicks in the nest. 

Jack has never proven this.  Except for his word on the first nest of 
hadrosaurs described in Nature, the high
walled nest has not been seen in any of the two dozen or more hadrosaur 
nests found since.


> The Troodon egg rows, on the other hand, encouraged the chicks to 
leave the home-base as soon as
>they hatched; there are no physical earthen barriers to keep the chicks
>corraled.  The Troodon babies were either: 1) hunting on their own as 
soon
>as they hatched (sort of like baby snakes do today) or; 2) they were 
running
>and hunting alongside mom and/or dad as soon as they hatched. In other
>words, Troodon babies may have been pack hunters straight out of the 
shell.  

Without hatchlings to determine the degree of joint development, we 
don't know if they were precocial. 
Proof for pack hunting is not proven.  All skeletons of 
Troodon/Saurornithoides occur as isolated finds.

> If those Chinese eggs are in fact Tyrannosaurid, it shows how 
disparate
>the Mother-child size differences were for this group.  A  1 ft. 
hatchling
>and a 40 foot-long mother must be one of the greatest ontogenetic 
ranges in
>the animal kingdom. If mother T. rex's did care for their young, they 
would
.have had toe nails larger than their children.


Not quite, A 16" egg probably had a 36"+ embryo.  An alleged sauropod 
egg is 8" in diameter and would
have about 16"+ embryo.  The alleged parent, Hypselosaurus, was 40 ft. 
long.




Neil Clark
Curator of Palaeontology
Hunterian Museum
University of Glasgow
email: NCLARK@museum.gla.ac.uk

Mountains are found in erogenous zones.
(Geological Howlers - ed. WDI Rolfe)