Yes, that is a giant spike sticking out of the center of her carapace.

Straight Horned Baboon Ceratogyrus marshalli These are the most spectacular of the "horned" tarantulas, as the protrusion from the carapace is a large spike that may approach an inch in length in older individuals.  Like their cousins in the Pterinochilus genus, Ceratogyrus ssp. prefer a dry habitat with room to burrow. C. marshalli has dark legs after a molt, a mottled opisthosoma, the typical "starburst" on the carapace, and, of course, that great big ol' horn.  The leg coloration is unique- it's more ash gray than the tawny tone of most Ceratogyrus ssp. The spermathecae of females are paired, not fused. They were formerly known as Ceratogyrus cornuatus until 2001. Note:  The horn is not an indication of a member of Ceratogyrus.  In fact, half of the Ceratogyrus species have no horn.

Range: The Straighthorned Baboon comes from southern Africa, in Zimbabwe and Mozambique.

Habitat:  Semi-dry scrubland.

Size: Medium tarantulas.  Females may get about 5" in legspan.

Attitude:  Fairly defensive; will bite if provoked enough.  Handling is not suggested.

Dwelling: These burrowers will dig and web a lot.

Ideal Setup: A 2.5 to 5 gallon space with enough peat/potting soil for digging in (fill it about 4-5 inches deep).  Supply a water dish.  They like it somewhat dry, but moistening the soil or misting may be appropriate in August/September to mimic the S. African wet season if desired.  Keep the temperature around 75-80 degrees F if possible.

Food: Any bugs that haven't been exposed to pesticides (3-5 crickets a week for adults); baby mice, etc.
 

This picture has a better view of the big spike that protrudes from her fovea.	This photo shows her dark post-molt leg coloration.
See the light band on her underside? All Ceratogyrus species have this, whether or not they have a "horn."  Augacephalus junodi is the only other member of Harpactirinae that has this pale band. Pterinochilus spp. and others do not.	Note: Most Ceratogyrus species are quite defensive.  This one happens to be a somewhat calm individual, but handling is not recommended; I certainly don't do it often.