typedef in template class with Doxygen (C++)

The typedef is part of a namespace, so you must document the namespace for it to appear, i.e.:

/// documentation for the namespace
namespace fundamental
{
   ...
   typedef Base<float> Coordinate; ///< Point coordinate class
}

Alternatively you could use @relates but it this will put the member under Related Functions of the Base class:

/// @relates Base
/// Point coordinate class
typedef Base<float> Coordinate;

You can change this title to for instance Related Members by creating a layout file using doxygen -l and then editing the two occurrences of the related element in the generated DoxygenLayout.xml as follows:

<related title="Related Members"/>

In the manual I read the following:

Let's repeat that, because it is often overlooked: to document global objects (functions, typedefs, enum, macros, etc), you must document the file in which they are defined. In other words, there must at least be a

/*! \file */ or a /** @file */ line in this file.

There's the See Also (@sa) command, useful for generating cross-references to other entities.