Sorry, Olgar, I went through there earlier and must have missed it the first time. Here's the info for those interested, snipped from Olgar's thread.
. Animal companions: The animal companion rules have changed; it's no longer purely a "HD = level" link. (There's a lot more to it than that, of course.) Since an awakened animal isn't an animal any more (it's a magical beast), it won't be able to serve as an animal companion (or a familiar or paladin's mount, for that matter). The animal friendship spell is no longer on spell lists. Characters with the animal companion class feature will only have one animal companion at a time. Rangers use the druid rules for animal companions, at ½ their ranger level. Animal Companion ability changes by level (Bonus tricks required no training time):
1-2: HD+0 AC+0 Str/Dex+0 Bonus Tricks 1 Link (+4 Wild Empathy and Handle Animal checks), Share Spells
3-5: HD+2 AC+2 Str/Dex+1 Bonus Tricks 2 Evasion
6-8: HD+4 AC+4 Str/Dex+2 Bonus Tricks 3 Devotion (+4 Save vs. Enchantments)
9-11: HD+6 AC+6 Str/Dex+3 Bonus Tricks 4 Multiattack (if no multiple attack forms the creature gets an addition strike at -5)
12-14: HD+8 AC+8 Str/Dex+4 Bonus Tricks 5
15-17: HD+10 AC+10 Str/Dex+5 Bonus Tricks 6 Improved Evasion
18-20: HD+12 AC+12 Str/Dex+6 Bonus Tricks 7
Higher level Animal Companions (treat gaining level as Level 1):
Level 4: Ape, Black Bear, Bison, Boar, Cheetah, Crocodile, Dire Badger, Dire Rat, Dire Weasel, Leopard, Monitor Lizard, Large Shark, Constrictor Snake, Large Viper Snake, Wolverine.
Level 7: Brown Bear, Giant Crocodile, Deinonychus, Dire Ape, Dire Boar, Dire Wolf, Dire Wolverine, Elasmosaurus, Lion, Rhinoceros, Huge Viper Snake, Tiger.
Level 10: Polar Bear, Dire Lion, Megaraptor, Huge Shark, Giant Constictor Snake, Orca Whale.
Level 13: Dire Bear, Giant Octopus, Elephant
Level 16: Dire Shark, Dire Tiger, Giant Squid, Triceratops, Tyrannosaurus.
http://enworld.cyberstreet.com/showthread.php?s=&threadid=53488