Baculites cf. vertebralis Lamarck, 1801

Machalski, Marcin, Jagt, John W. M., Alekseev, Alexander S. & Jagt-Yazykova, Elena A., 2012, Terminal Maastrichtian ammonites from Turkmenistan, Central Asia, Acta Palaeontologica Polonica 57 (4), pp. 729-735 : 731

Baculites cf. vertebralis Lamarck, 1801

Fig. 4C .

Material.—NHMM 2011 041a, Sumbar River section, Turkmenistan, topmost part of the upper Maastrichtian.

Description.—Small, fragmentary body chamber, 42 mm in length; greatest whorl height 11.8 mm, whorl breadth to height ratio ca. 0.48, but diagenetically compressed, making measurements approximate; straight, slowly expanding, whorl section oval, sides flattened and smooth; no sutures seen.

Discussion.—Although no sutures are seen and the specimen is slightly diagenetically compressed, the lack of ornament and the oval whorl section compare favourably with late Maastrichtian material from northwest Europe assigned to B. vertebralis Lamarck, 1801 (see Kennedy 1986, 1987).

Stratigraphical and geographical range.—Where well dated, Baculites vertebralis is apparently restricted to the upper Maastrichtian, with records from Denmark, the southeast Netherlands, northeast Belgium, northwest and southern France, southern Sweden, northern Germany, Poland, Ukraine, southern Russia, and southwest Turkmenistan.

Figures

Fig. 4. Ammonites from the Sumbar River section, Turkmenistan, upper Maastrichtian, Upper Cretaceous, collected by ASA and Mikhail A. Nazarov, with indications in brackets of centimetres below K–Pg boundary (where known). A, B, E, F. Scaphitid ammonoid Hoploscaphites constrictus johnjagti Machalski, 2005a. A. NHMM 2011 044, microconch body chamber. B. NHMM 2011 043, apertural portion of body chamber, with epizoic craniid brachiopod (arrowed). E. NHMM 2011 042b, pair of phragmocones (10–15 cm). F. NHMM 2011 042a, set of phragmocones (10–15 cm). C. Baculitid ammonoid Baculites cf. vertebralis Lamarck, 1801, NHMM 2011 041a, partial body chamber. D. Scaphitid phragmocone from the Danian portion of the Sumbar River section, NHMM 2011 046, probably Hoploscaphites constrictus johnjagti Machalski, 2005a (= Pachydiscidae indet. sensu Alekseev et al. 1988: fig. 1).