Marvelous Meta-Mammal Multiverse

While there is the traditional Multiverse consisting of infinite number of parallel planets, each with an Earth populated by humanity as the predominate species, there is also another type of Multiverse. This myriad of realities are populated by anthropomorphic versions of men and women. This "Mammal Multiverse" is actually a series of dimensions, with each one embedded within a corresponding universe dominated by human-centric civilizations.

• Earth-C is a part of the Earth-One universe, populated by Captain Comet and his Amazing Zoo Crew. This world’s first superhero was the Terrific Whatsit, mirroring Jay “Flash” Garrick. This world was visited by the heroes Superman, Changeling as well as villains Starro and Gorilla Grodd of Earth-One. Its inhabitants included:
• Dunbar Dodo
• Frankie and Fanny Flipper
• Frogzilla (Fennimore Frog)
• Hardluck Harry
• Hugo Hornspred
• Jumpin' Juniper
• King Oscar
• Nero Fox
• Patrick Parrot
• Pelican Pete
• Peter Panda
• Salty the Sailor
• Spylot Bones
• Terrific Whatzit
• Wuz-Wolf (Wolfie)
• Zoo Crew
• Alley-Kat-Abra
• Captain Carrot
• Fastback
• Little Cheese
• Pig-Iron (Peter Porkchops)
• Rubberduck
• Yankee Poodle

• 
  Earth-C-Minus is part of the Earth-Two universe, populated by Super-Squirrel and Justa-Lotta Animals. These costumed creatures mirrored the Justice League. These Animals met the Justice Society while visiting Earth-Two. Its inhabitants included:
• Amazoo
• Boyd, the Robin Wonder
• Feline Faust
• Hector Hamhock
• Kangar-Roo
• Lex Lemur
• The Porker
• Shaggy Dawg
• Weather Weasel
• Just'a Lotta Animals
• Aquaduck
• Batmouse
• The Crash
• Elong-Gator
• Firestork
• Green Lambkin
• Green Sparrow
• Hawkmoose
• The Item
• Martian Anteater
• Rat Tornado
• Stacked Canary
• Super-Squirrel
• Wonder Wabbit
• Zap-Panda

• Earth-C-Plus is part of the Earth-S universe, populated by Hoppy the Marvel Bunny and his friends and family. Hoppy and his friends mirrored Captain Marvel and his family. Mary Marvel visited Hoppy’s world, and later Marvel Bunny traveled to Earth-S.

• Earths of other types were also shown to exist, including'
• A Disney world
• A wacky "Krazy Kat" world
• A bayou world
• A world of giant animals. 

These may've been the corresponding animal-dimensions attached to Earth Prime, Three, Four, and X.

Tornado Terrapins of Twin Terras

Concurrent to the adventures of the original Flash, aka Jay Garrick, a similarly clad super-speedster had adventures on a parallel plane of existence. A lazy yet honorable shopkeeper named McSnurtle the Turtle was selected by a pair of alien entities known as Princes Highness and Lowness as a test case, to see if such an individual would use superpowers for good rather than evil. Adopting the alter ego of Terrific Whatsit, McSnurtle was the first record superhero of Earth-C, and like his counterpart the Flash of Earth-Two he chose to wore a near-identical uniform. Diverging from Garrick's suit, Whatzit's colorful costume had the chest emblem of TW instead of a lightning bolt. Additionally, this terrific terrapin was guided in his adventures by an "automatic conscience", an invisible and intangible turtle ally. 

On another world, Earth-C-minus, a scarlet speedster known as the Crash appeared on the scene. Mirroring the Justice League member the Flash of Earth-One, aka Barry Allen, the Crash was a founding member of the Justa Lotta Animals. he would eventually encounter McSnurtle's nephew, Timmy Joe Terrapin, who thanks to being struck by a radioactive meteor gained superspeed abilities. As Fastback, Timmy Joe joined Captain Carrot's Zoo Crew, and eventually encountered the Crash and his allies.

There are indications that the Crash and Whatzit had previously encountered one another, early in the former and late in the latter’s costumed careers. Undoubtedly this tale may well have mirrored that of Barry and Jay’s first and subsequent meetings. And it is quite possible that the Crash’s nephew may have eventually adopted the alias of Kid Crash, much as Barry’s nephew was Wally had as Kid Flash. Whether this Kid Crash and Fastback ever met is unknown.

Interestingly, a recurring nemesis of each Flash was a version of the Turtle, a criminal dressed as a terrapin.

Twice-Told-Tales: Anthropomorphize Avengers

In 1983, the Greatest Superheroes of Two Worlds met anthropomorphize avengers* with powers and eqiupment that could pose a serious threat to them.

On Earth-One, this took the form of the Ani-Men. These included the Maximus Rex, Reena, Rowl, and Gargantus... among others. They were originally the board of directors for Repli-Tech Industries, a company about to go bankrupt and be investigated by the Security and Exchanges Commission. Rather than face imprisonment, the board members and their president Rex Rogan transformed into beast-men spawned by Doctor Lovecraft’s technology. Hosting a gladiatorial game on their island off the New Brunswick coast, they were exposed and opposed by the Justice League. In the  end, all the Ani-Men inevitably transformed into full animal forms, losing their higher brain functions.

On Earth-Two, it was Justa-Lotta Animals who rivaled the Justice Society. Visiting from Earth-C-Minus, this team were analogues to the Justice League. These included Super-Squirrel, Wonder Wabbit, Batmouse, Aquaduck, the Crash, and Green Lambkin. This team traveled to various Earths in the Multiverse until they eventually found Earth-C, where they enlisted the aid of Captain Carrot and his Zoo Crew. Before this, the Justalotta Animals had a brief yet tense stand-off with the Justice Society, who were amazed to find sentient  anthropomorphized  animals.

* Like Rex Rogan and his cronies, another evil entrepreneur named Ivan Caroff and his henchmen also transformed into animals which battled Starman  on Earth-Two decades earlier. And Starman’s sometimes partner a Black Canary on Earth-One battled weapons-supplier Marcel Moreau and his human/animal hybrids.

Crazy Costumed Creature Crossovers

Among the multitude of Earths where humans are the predominant, there are at least a few dominated by anthropomorphic civilizations. Of these worlds, two who have interacted with each other as well as other humanoid-centric realities were labeled Earth-C and Earth-C-, where the Zoo Crew and Just'a Lotta Animals were their respective superheroic teams. A third Earth would be where Hoppy the Marvel Bunny and his friends resided.

When a strange meteorite plummeted to Earth-One, with its radiation threatening mankind, Superman intercepted the space rock which shattered into several pieces that fell through a dimensional rift. Landing on Earth-C, the effects of this alien item effected six residents below. These became known as the Zoo Crew, consisting of Captain Comet, Pig Iron, Yankee Poodle, Rubber Duck and Alley Cat Abra. They would later be joined by Little Cheese and American Eagle. During their initial adventure, the Crew teamed up with Superman to track down and defeat the source of the meteor, Starro.

Rodney Rabbit, the alter ego of Captain Carrot, was a writer and artist for funny animal comics including Just'a Lotta Heroes. He soon learned that his mind was tuned in to their actual tales that occurred on their native world, when the Captain and his allies encountered three old foes of the Zoo Crew and three arch enemies of the Heroes. Battling these criminals led to the twin teams traversing dimensional barriers to Earth-C- where the villains had the ultimate goal of world conquest.

That planet's protectors consisted of Super-Squirrel, Bat-Mouse, Womder Wabbit, Crash, Elongator, Zappanda, Item, Hawkmoose, Green Lambkin, Aquaduck, Martian Anteater, Green Sparrow, Stacked Canary, Rat Tornado, and Firesstork.

While attempting to journey to the Heroes' homeworld, the two teams encountered the Justice Society on Earth-Two, which was tied to Earth-C- just as Earth-One and Earth-C has been.

Shortly thereafter, two other natives of Earth-One encountered the Zoo Crew in the heroic Changeling, and the sinister simian whom he had been pursuing in Gorilla Grodd. Grodd has been drawn to Earth-C by a tyrant.

This led to a tale involving the so-called Oz-Wonderland War which that individual had been formenting. During this occasion, Marvel Bunny and Wonder Wabbit were brought there and teamed up with Captain Carrot.

After having wrapped this case up, the Zoo Crew returned to their universe during the critical last days of the Crisis on Infinite Earths, whereby a dimension-lost Inferior Five were trying to find their native Earth-Twelve. Whether they did or remained on Earth-C is unknown.