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Re: sauropod breeding



Consider the trackway evidence which seems to show that small sauropods travelled with adults and sub-adults surrounding them. This does NOT apply to sauropods under a certain age or size [say, less than 7 feet (~2.1 m) long, or less then 4 years old. (Note that I do not have references for these numbers)]. These young and small sauropods are not represented in trackways that we've found.

This may be preservational bias (i.e. the young ones were too small to leave a deep enough track, and those that they did leave, were obliterated by the passage of the large ones) or maybe the young did not travel until they reached the cut-over size/age. (They may have lived in isolated, somewhat protected areas until the next swing of the herd's migration - and then moved when they were old or large enough).

So the intermediary size young adult (and sub-adult) travelled with the herd(s). Based on other estimates of growth that I've heard/read, three years should be enough time to allow the young saropods to grow to a size acceptable to travelling with the herd.

BTW, I think that sauropods (in general, of course) nested each year. This would give us the interesting scenario of the 3 year olds (as they wait for the return of the herd) protecting the much younger ones. Possibly, in lieu of parental care, we have sibling care [or some other such similar altruistic arrangement - cousin care, pseudo-sibling care, etc].

One more thing - It is highly likely, in the scenarios we've been describing, that recently matured young males would leave the herd for a different herd (possibly going solo for a while) to prevent genetic problems (Of course, they wouldn't think of the reason that way... Or would they........
:-)).


Hope this helps (or at least stirs someone's thinking),

Allan Edels


From: paleo@ncf.ca
Reply-To: paleo@ncf.ca
To: dinosaur@usc.edu
Subject: Re: sauropod breeding
Date: Sun, 12 Mar 2006 18:16:09 -0500

So, We probably have a situation where juveniles could
survive without having to resort to adults carrying them
around, lifting them into trees, or little tiny fangs.

My questions are:
What would the intermediate young adult look like?
It couldn't hide, but could it's relatively small size allow
it to defend itself more easily (rearing on it's hind legs
and ramming)?

Would it eventually link up with other sauropods for
protection?
If so, would non-blood relatives be willing to take it in
(are new genes worth adopting non-relatives)?
Would this lead to different group compositions (ie.
non-affiliated males "rutting groups" as separate from
female herds?)

Would the need for relatives to pass through a local area to
pick up the juveniles of a few years ago effect migration
patterns and how would relatively regional populations
effect a predators ability to track that population (I am
thinking mara masai here).
Is this consistent with the highly mobile Carnosaur
juveniles?

Is there any way to test these possibilities?

-Jonas Weselake-George
Ottawa Paleontological Society


----- Original Message ----- From: David Marjanovic <david.marjanovic@gmx.at> To: DML <dinosaur@usc.edu> Sent: Sunday, March 12, 2006 5:54 PM Subject: Re: sauropod breeding


> Well, you can probably assume highly cryptic colouring and a deeply > skittish nature,

A skittish nature at the same time as an inability to run?
Is that of much
use? :-/

> but consider sea turtles --

Yes, but they are armored and can swim at reasonable speeds.

> Also note that the whip-tail sauropods and mace-tail
sauropods probably
> have these defensive measures from a small size, and that
they'd apply
> to equivalently sized predators just fine.  So
Ornithosteles is fine
> with the hatchlings, and maybe even the yearlings, but has
some serious
> cost-benefit concerns thereafter.

Imaginable, but that's where, say, juvenile carnosaurs may
start...