Two ammonites, one half, one whole, from theÂ Morondava River Basin, near theÂ town of Sakaraha, in the Atsimo-Andrefana region of southwestÂ Madagascar, in the former province of TulÃ©ar. Â They date from the Late Jurassic period, Oxfordian age (~161 to 156Â million years ago). Â Cut ammonites are uncommon from this area because the interiors are not always well preserved.
The one on the left shows the open chambers of the shell, known more technically as the camerea (Latin, “chamber, room, enclosed space”). Â The one on the right shows its sutures (Latin, “stich”), patterns created where the inner folds met the exterior of the shell. Â The ammonite Â was polished to reveal them.
Â© 2014, Images and Text, Christopher Lee Matthews