Hi!
A cover of LBT XI has now been released. You can find it (in black and white) at:
http://www.dvdanswers.com/index.php?c=4958&s=1 The release date is January 11th 2005 (I don't get why they are wasting money by not releasing it BEFORE christmas).
It looks like the Tinysauruses are little longnecks. The text on the page also says a bit about the story itself:
"Universal has announced Land Before Time Volume XI: The Invasion of the Tinysauruses which is an all-new direct to video animated adventure. This time around the Tinysauruses invade the valley to teach Littlefoot a big lesson about a little lie. The disc will be available to own from the 11th January this year, priced at around $19.98. The film itself will be presented in 1.33:1 full frame along with an English Dolby Digital track. Extras will include a Land Before Time music video and sing-along songs from all eleven Land Before Time adventures. We've attached a black and white shot of the official artwork below."
A big lesson about a little lie? It sounds a bit like the lesson in LBT 8. The cover looks quite different from the covers we have seen so far. It's the first time there is only Littlefoot and non of the other maincharacters. This picture of Littlefoot (his face at least) has been used before already, for example on the cover of LBT 8. Maybe there are still different versions of the cover to come up (it was that way when LBT 8 appeared, where at first they had a cover released with a grownup spiketail in the place of Tippy).
I'm sure that now there is going to be more information on LBT 11 up soon. I checked imdb already, but there are no more information yet. Maybe in just a few hours or days.