I figured it out just a few moments ago! Apparently the latest WordPress update (3.5.1) disabled the feature. You need to install the free Jetpack plug-in to restore the Type selector.
I may be mistaken when I say “disable”. I forget whether Jetpack was previously part of, or was installed with previous versions of WordPress. At any rate, installing Jetpack fixed the glitch! You can download Jetpack here: https://www.ads-software.com/extend/plugins/jetpack/
Good luck!