I am trying to use a third party TypeScript module and am having trouble creating an abstract type that other types can extend.

The base type Animal will be either Mammal, Reptile, or Amphibian.

The action method from a third party ActionModule will take a slightly different type as input for each action, but I wanted to create a base type that can be given for the generic U from ActionModule for my ACTIONS type.

Here's what I have so far, which doesn't seem to work (getting an error saying types are incompatible).

type Animal = Mammal | Reptile | Amphibian;

type Mammal = {
  name: string,
  furColor: number
};

type Reptile = {
  name: string,
  scaleCount: number
};

type Amphibian = {
  name: string;
};

// Third-party module
interface ActionModule<T = {}, U = {}> {
  description: string,
  action: (args: Arguments<U>) => void
}

const ACTIONS: {
  [key: string]: ActionModule<{}, Animal>
} = {
  actionOne: {
      description: '',
      action: (args: Arguments<Mammal>) => {},
    },
  actionTwo: {
    description: '',
    action: (args: Arguments<Reptile>) => {},
  },
  actionThree: {
    description: '',
    action: (args: Arguments<Amphibian>) => {},
  }
}