Goniatites are a group of ammonoid cephalopods with relatively simple suture patterns. Sutures are the lines formed by the intersection of the outer shell wall and the internal walls (septa) that separate chambers. Nautiloid cephalopods (e.g., the modern pearly nautilus) generally have curvilinear suture patterns. Ammonoid cephalopods have goniatitic, ceratitic, or ammonitic suture patterns. Goniatitic sutures are characterized by having several broad lobes & saddles. Goniatitic sutures are seen in the earliest ammonoids.
Here’s a scarce species of ammonoid cephalopod. This is Kazakhstania colubrella (formerly Prolecanites colubrellus) from the Byer Sandstone of Chatham, Ohio, USA. It has a planispirally coiled shell (as do almost all ammonoids) and a distinctive goniatitic suture pattern (see Manger, 1971, figure 6D). Adult shells show four, narrow, external constrictions (not seen in this specimen) (see Manger, 1971, plate 12, figures 8, 10-12).
Classification: Animalia, Mollusca, Cephalopoda, Ammonoidea, Goniatitina, Imitoceratidae
Stratigraphy: float from the Byer Sandstone Member, lower Logan Formation, Waverly Group, Osagean Stage, upper Lower Mississippian
Locality: loose piece from rubble along petroleum well access road, southern side of St. Joseph Road, due east of Chatham, northwestern Newton Township, northern Licking County, central Ohio, USA (~40º 09’ 18.7” North, ~82º 26’ 29.2” West)
Kazakhstania colubrella (Morton, 1836) external mold (1.75 cm across) in slightly micaceous quartzose sandstone (Byer Sandstone, Lower Mississippian; Chatham, Ohio, USA). The yellowish-brown wavy lines are the sutures - these are goniatitic sutures.
Specimen collected & owned by Nicole Byrd.
Manger, W.L. 1971. The Mississippian ammonoids Karagandoceras and Kazakhstania from Ohio. Journal of Paleontology 45: 33-39.