The ammonoids from the Dalle àMerocanitesof Timimoun (Late Tournaisian-Early Viséan; Gourara, Algeria)

The ammonoids from the Argiles de Teguentour of Oued Temertasset (early Late Tournaisian; Mouydir, Algeria)

“…Discussion. Imitoceras dimidium differs from I. altilobatum Korn, Ebbighausen & Bockwinkel, 2010 from the area of Timimoun in the shallower external lobe, the more asymmetric adventive lobe, and in the umbilicus, which in I. altilobatum is not funnel-shaped as in I. dimidium. I. dimidium has, in comparable growth stages, a more slender conch than I. altilobatum (ww/dm ¼ 0.60 in I. altilobatum but 0.50 in I. dimidium and I. strictum at 15 mm dm).…”

“…Discussion. Acrocanites disparilis differs from A. imperfectus Korn, Ebbighausen & Bockwinkel, 2010 from Timimoun in the higher number of sutural elements. A. disparilis possesses five large lobes on the flank and two or three small lobes on the umbilical wall, whereas A. imperfectus shows only three large lobes on the flank and one or two small lobes on the umbilical wall.…”

“…The new family differs from the families Pericyclidae and Muensteroceratidae mainly in the suture line, which possesses flexed flanks of the external lobe. Such a shape of the external lobe is also known from the stratigraphically younger subfamilies Maxigoniatitinae Mapes, 1999 andBollanditinae Bockwinkel, Korn &Ebbighausen, 2010. The members of these two subfamilies, however, differ strikingly in their conch ontogeny with a prolongued evolute juvenile stage and their much weaker ornament.…”

“…Suture line with very narrow, V-shaped external lobe and very low median saddle; ventrolateral saddle almost symmetric, broadly rounded; adventive lobe V-shaped, symmetric. For a detailed discussion of the genus, see Ebbighausen et al (2010). Separation of the new species.…”

“…Rotopericyclinae n. subfam. Trimorphoceratinae Ebbighausen, Korn & Bockwinkel, 2010 Discussion. The spectrum of characters of the new family suggests that it derived from the family Muensteroceratidae by the modification of the conch ontogeny.…”