Gonatocyrtoceras longissimum Dzik, 1984 from Cheiloceras Zone, Famennian, Poland. 1. Adult living chamber in lateral (a) and dorsal (b) views; bed J. 6, Jabłonna. 2. Adult living chamber in ventral (a ) and lateral (b) views, probably Kadzielnia. 3. Longitudinal section through a phragmocone, Jabłonna. 4. Adult living chamber in lateral (a), dorsal (b), and septal (c) views,probably Kadzielnia. 5. Holotype adult specimen in ventral (a), lateral (b), dorsal (c), and septal (d) views, bed J . 7, Jabłonna. 6. Adult specimen in dorsal (a) and lateral (b) views, Kadzielnia. 7. Longitudinal section through the phragrnocone, Kadzielnia.
Gonatocyrtoceras longissimum Dzik, 1984 from Chelloceras Zone, Famennian, Kielce-Kadzielnia and Jabłonna, Poland; reconstructed adult shell in lateral and ventral views, and the outline of its aperture (a), pedal retractor scar and variation in septal suture (b), and longitudinal section through the siphuncle (c).
Diagnoza
Long, weakly curved shell with siphuncle situated between the shell center and venter; aperture laterally constricted and the plane of funnel sinus situated normally to the depressed head part of peristome.
Porównanie
G. longissimum differs from its congeners in its elongated shell with laterally constricted aperture. Its phragmocone fragments resemble Lysagoraceras in external view, but differ in the siphuncle lying away from the venter. G. longissimum differs from its relatives also in the separation of the ventral pair of retractor muscle scars. There is a wide intrapopulation variability in the collections from Jabłonna and Kadzielnia, mostly in the size of mature shell, the length of the mature living chamber, and shell curvature. Specimens from Jabłonna are generally smaller.
Autekologia
Występowanie geograficzne
Cheiloceras Zone at Kadzielnia and Jablonna (beds J. 6 to J. 7).
Zasięg czasowy
Cheiloceras Zone (beds J. 6 to J. 7).
Materiały muzealne
ZPAL N/223, 224, 227, 237, 301 IG
Literatura
Dzik, J. 1984. Phylogeny of the Nautiloidea. Palaeontologia Polonica 45, 1-255