Table 7 in Late Viséan (late Mississippian) ammonoids from the Barnett Shale, Sierra Diablo Escarpment, Culberson County, Texas, USA

Table 7. Conch ontogeny of Choctawites cumminsi (Hyatt, 1893); mainly based on specimens from San Saba (Elias Coll; cross sections by R. Kant, Tübingen). dmConch shapeWhorl cross section shapeAperture1.5 mmthickly pachyconic; subinvolute or subevolutestrongly depressed; very strongly embracinglow(ww / dm = 0.75–0.85; uw / dm = 0.25–0.35)(ww / wh = 2.00–2.25; IZR = 0.45–0.50)(WER = 1.55–1.65)5 mmglobular; involutemoderately depressed; very strongly embracinglow(ww / dm = 0.90; uw / dm = 0.05–0.10)(ww / wh = 1.65; IZR = 0.55–0.60)(WER = 1.60–1.75)10 mmthickly pachyconic or globular; involutemoderately depressed; very strongly embracinglow(ww / dm = 0.85; uw / dm = 0.05)(ww / wh = 1.55; IZR = 0.50–0.60)(WER = 1.60–1.75)25 mmthinly pachyconic; involuteweakly depressed; very strongly embracinglow(ww / dm = 0.70; uw / dm = 0.05)(ww / wh = 1.30; IZR = 0.55)(WER = 1.60–1.70)50 mmthickly discoidal; involuteweakly depressed(ww / dm = 0.58; uw / dm = 0.08)(ww / wh = 1.15)