sorry i seem to have missed this to help you Mooncrow... here's from one of my many lists of animal companions... hope its helpful, i don't remember the last time it was updated but there's quite a bit on it
level 1
Baboon Eberron
Badger Eberron, PHB
Barracuda Storm
Brixashulty RotW Halflings only
Camel Eberron, PHB
Chipmunk Dr279 Gnome only
Chordevoc RotW Halflings only
Dinosaur, Compsognathus Dr318
Dinosaur, Fastieth Eberron
Dinosaur, Rhamphorhynchus Dr318
Dinosaur, Swindlespitter MM3
Dire Rat Eberron, PHB
Dog Eberron, PHB
Dog, Riding PHB
Eagle Eberron, PHB
Eel Storm
Goblin Dog Path#1 Goblins only
Groundhog Dr279 Gnome only
Hawk Eberron, PHB
Horse, Heavy Eberron, PHB
Horse, Light Eberron, PHB
Horse, Valenar Riding Eberron
Hyena Dr279 Orc only
Jackel Dr279 Orc only
Lizard, Giant Gecko Path#1
Monkey Dr279 Elf only
Owl Eberron, PHB
Phynxkin DragM
Pony PHB
Porpoise Storm
Sea Lion Storm
Seal Storm
Shark, Medium-size Storm
Snake, Sea, Medium Storm
Snake, Sea, Small Storm
Snake, Viper, Medium Eberron, PHB
Snake, Viper, Small Eberron, PHB
Squid Storm
Stingray Storm
Turtle, Snapping Storm
Vulture Eberron use Eagle stats
Vulture Dr279 Orc only
Wolf Eberron, PHB
level 4
Ape Eberron, PHB
Bear, Black Frost, PHB
Bison PHB
Boar Eberron, PHB
Branta Frost
Brixashulty RotW
Cheetah Eberron, PHB
Chordevoc RotW
Crocodile Sand, PHB
Dinosaur, Dimetrodon Dr318
Dinosaur, Fleshraker MM3
Dinosaur, Pteradon Dr318
Dire Badger Eberron, PHB
Dire Bat Sand, PHB
Dire Eel Storm
Dire Hawk RotW Raptorans only
Dire Rat, Horrid Eberron
Dire Toad Sand
Dire Weasel Eberron, PHB
Leopard Eberron, PHB
Leopard, Snow Frost
Lizard, Monitor Sand, PHB
Lizard, Quicksilver Drow
Peccary Sand
Puma Sand
Shark, Large Frost, PHB
Snake, Constrictor Eberron, PHB
Snake, Sail MM4
Snake, Sea, Large Storm
Snake, Viper, Large Sand, PHB
Spider, Watchspider FR:CoS
Wolverine Frost, PHB
level 7
Bear, Brown Frost, PHB
Bear, Brown, Magebred EberrFN
Crocodile, Giant Sand, PHB
Dinosaur, Deinonychus Sand, PHB
Dinosaur, Elasmosaurus Storm, PHB
Dinosaur, Protoceratops Sand
Dire Ape Eberron, PHB
Dire Badger, Horrid Eberron
Dire Barracuda Storm
Dire Bat, Horrid Eberron
Dire Boar Eberron, PHB
Dire Hawk RW, Sand
Dire Peccary Sand
Dire Phynxkin DragM
Dire Weasel, Horrid Eberron
Dire Wolf Frost, PHB
Dire Wolverine Frost, PHB
Lion Eberron, PHB
Lizard, Footpad Drow
Megaloceros Frost
Rhinoceros Sand, PHB
Snake, Sea, Huge Storm
Snake, Viper, Huge Sand, PHB
Terror Bird FF
Tiger Eberron, PHB
Tiger, Magebred EberrFN
level 10
Bear, Polar Frost, PHB
Dinosaur, Bloodstriker MM3
Dinosaur, Glyptodon Frost
Dinosaur, Helicoprion Dr318
Dinosaur, Megaraptor PHB
Dinosaur, Pachycephalsaurus Dr318
Dire Ape, Horrid Eberron
Dire Boar, Horrid Eberron
Dire Horse, Horrid Eberron
Dire Lion Eberron, PHB
Dire Puma Sand
Dire Snake Sand
Dire Tortoise Sand
Dire Vulture Sand
Dire Wolf, Horrid Eberron
Dire Wolverine, Horrid Eberron
Dragonhawk EberrFN
Hippopotamus Sand
Sea Tiger MM3
Shark, Huge Frost, PHB
Snake, Constrictor, Giant Eberron, PHB
Tiger, Smilodon Frost
Whale, Orca Frost, PHB
level 13
Dinosaur, Diprotodon Sand
Dinosaur, Ichthyosaur Storm
Dinosaur, Parasaurolophus Dr318
Dire Bear Frost, PHB
Dire Elk MM2
Dire Lion, Horrid Eberron
Elephant Sand, PHB
Elephant, Wooly Mammoth Frost
Lizard, Giant Banded Sand
Octopus, Giant Frost, PHB
level 16
Dinosaur, Archelon Storm
Dinosaur, Stegosaurus Dr318
Dinosaur, Triceratops Sand, PHB
Dinosaur, Tyrannosaurus PHB
Dire Bear, Horrid Eberron
Dire Elephant Sand
Dire Elk, Horrid Eberron
Dire Rhinoceros FF, Sand
Dire Shark Frost, PHB
Dire Tiger Frost, PHB
Elephant, Mastodon MM3
Megatherium FF
Roc Sand
Squid, Giant Frost, PHB
Whale, Zeuglodon Frost
level 19
Dinosaur, Mosasaur Storm
Dinosaur, Plesiosaur Storm
Dire Elephant, Horrid Eberron
Dire Rhinoceros, Horrid Eberron
Dire Shark, Horrid Eberron
Dire Tiger, Horrid Eberron
level 21
Dinosaur, Diplodocus Dr318
Dinosaur, Giganotosaurus Dr318
level 24
Dinosaur, Liopleurodon Dr318