How to properly declare a self-referencing template type?

Question

How do I declare a templated type that refers to itself?

template <class T = Animal> class Animal
{
public:
    T getChild ();
}

With this, I get a compiler error concerning a missing type specifier. I tried to forward-declare Animal, without success.

I am trying to impose a type constraint. A Lion can only have a Lion as a child, a Bear has a Bear, and so on.

EDIT

I'll post part of the actual class. It is a template for classes that can appear in a linked list:

template <class T = Linked<T> > class Linked
{
private:
    T* m_prev;
    T* m_next;
}

I want to enforce that the class can only point to object of the same class (or a subclass).

Answer 1

In this case, you need to specify some type parameter to Animal in your typename definition, or else it would be an "infinite recursion" in the type construction:

template<class T> class Animal;//you'll need this forward declaration

template <class T = Animal<int> > class Animal //int is just an example
{
public:
    T getPrey ();
}