CREATE EXTENSION postgis; ERROR: “postgis.control”: No such file or directory

CREATE EXTENSION postgis; ERROR: "postgis.control": No such file or directory

I have installed PostgreSQL 9.x and PostGIS 1.5/2.0 several times and have
never had this problem.
I just got a new CentOS 6.3 server up and running and and I have Postgres
9.3 functioning as expected. I have run
yum install postgis2_93
and I can see the files in
/usr/pgsql-9.3/share/contrib/
however, when I run
CREATE EXTENSION postgis;
I receive
ERROR: could not open extension control file
"/usr/pgsql-9.3/share/extension/postgis.control": No such file or
directory
the tutorials (#1, #2) I have used don't show any steps between installing
PostGIS and creating the extension.
What am I missing?