Striking Polished Puzosia Ammonite

Description: This spectacular ammonite is a member of the species Puzosia from Madagascar which has been polished to show the wonderful detail to the suture pattern. The ammonite shown here has the ammonitic suture pattern. Ammonites developed septa (separations between individual chambers) with intricate folds termed lobes and saddles. There are three basic patterns: 1) Goniatiitc - Irregular zigzag; 2) Ceratitic - Regular wavy; 3) Ammonitic - Intricate, fernlike.

These patterns are evidenced on the exterior of the shell as sutures. Suturing provided increased strength to the shell without a concomitant increase in weight, and important factor for an animal which needed to be able to move readily in the water column. The cross ribbing distinguishes it from the related Desmoceras (see my other postings). Note the shot of the living chamber shows a portion of the siphuncule, the structure by which the ammonite shift ballast to raise and lower itself much like a modern-day submarine. This is a fine example of an ammonite from the Albian (112 m.y.a) deposits of Madagascar, one that is sure to be a fine addition to any ammonite collection.