Re: Suckling Sauropods and Pigeons' Milk (Altricial Sauropods?)

[Stratigraphy@aol.com]

In a message dated 7/27/01 10:01:44 PM Mountain Daylight Time, 
MarkSabercat@aol.com writes:

<< The 
 proventriculus of female sauropods may secondarily evolved this capability 
 when sauropodomorphs reached a certain point in their evolution in which 
 rapid weight gain began creating a survival advantage. >>

Nice idea, and good to see people thinking "outside the box" (Kuhn is going 
to haunt me yet).  But, even if the female sauropods were actually around and 
IF (highly doubtful) they were altricial, the amount of "nutrients" they 
would have to produce would be staggering.  Lets assume the adult contributed 
<50% of the nutrition of a single offspring, and say about 35% surviving the 
rigors of a hatchling.  As far as actual data for nest size I am unsure, 
never really looked before I guess.  I will use Tracy Fords statement 
(hopefully the number wasn't in jest?) "Ok, yea, they did, the female had 100 
teats for all the little squirts!!!!"

Under my assumption the female apatosaur would have to produce close to 250 
kg (550 lbs) a day (35 offspring x ~7 kg). That is extra, above and beyond 
what an adult needs to maintain metabolism for its own survival.  That's a 
lot of snot to produce!  Obviously with less attrition of the young the 
amount of "adult generated nutrition" would increase.  

That number of 14.5 kg a day for apatosaurs may need to be dropped a little.  

The Nature article, Erickson, Rogers, and Yerby, states:


 "For example, our analysis of a 25,952-kg_Apatosaurus_indicates a growth 
rate of 14,460 g day-1, compared with 20,700 g day-1 for a 30,000-kg gray 
whale (Eschrichtius robustus)." 

So apatosaurs would gain ~14.5 kg (31 lbs) per day. I believe the mass 
estimate that was used is pretty high, from what I remember an adult 
apatosaur should only push the 16-18 ton range.  That would drop its daily 
growth a kg or two not that that will change the discussion at hand all that 
much, 12 kg a day is still a good deal of growth!

Same article: "Despite showing growth rates accelerated from the primitive 
reptilian character state, non-avian dinosaurs never attained extremely rapid 
rates like those seen in extant altricial birds (Fig. 3). For example, even 
the largest sauropods would have grown at rates half that of a scaled-up 
altricial bird (123,025 g day-1; Fig. 3)."

In the article the mass for _Argentinosaurus_ was ~100,000 kg.  Is that 
correct?
That would mean the most extreme amount for a sauropod to gain would be ~60 
kg/day (132 lbs)

Oh, well...that's enough for this months contribution.  I really cannot see 
sauropod females as the exemplary altricial mother types. Her size and 
relative spatial awareness would probably contribute to the attrition rate of 
her own young if she were to stick around after hatching.  Talk about your 
sauropods in a China shoppe!

Cheers,

Dave Lovelace
Wyoming Paleontological Association