I think the Troglidites seeem like a decent Saurus substiture. and the skull crackers would made for good coldones. Some of the old Dragon Blood minis make for ok Kroxigors.
Who makes those big birds? Would love to snatch a few of those for my budding lizardmen army. The real trick is figuring out how to mount a saurus on one of those. Those dragonblood minis look like they could make excellent substitutes for saurus as well, if they could ranked up.
I've had this guy bookmarked for quite some time now: http://www.davidkrentz.com/Krentz_Presentz_Sculpture/1_72.html They're about the right scale, and very realistic as well.
Yes, Krentz's stuff is awesome. I'd really like a readily available Coatl figure from somewhere. All the best one's have been out of production for quite some time and are very rare, even on ebay.