Often times in language family trees a
single parent language is shown to break apart into its descendants, which in
turn break off into others. However, some who postulate specific periods
of times (or at least chronological sequences), do something like
this:
I'll use a fictitious name for a family:
Proto-Fringelian.
From the proto language, a branch comes off
called Axelic. So now we have Axelic and a late form of Proto-Fringelian,
the parent family of the Bognoric, Telamanic and Psiltifedic branches.
Later on, Bognoric separates and now we have Telamano-Psiltifedic, which finally
splits, rounding out the four branches. Not only is one protolanguage
shown to split into four, but the chronology (or at least the sequence) is
demonstrated.
So...
PROTO- | Axelic
------------------------
FRINGELIAN ----
| |
Bognoric -------------
| ------ | |
Telamanic -
| -------- |
| Psiltifedic
~DaW~