422


Journal of Paleontology 92(3):412–431


Figure 7. Discoceras lindstroemi n. sp. preserved in reef cephalopod coquinas, late Sheinwoodian, Slite Beds, Gotland; (1, 4) RM Mo 40265, Othem, Spillings; (2) Polished slab with cross section of D. lindstroemi, RM Mo 59882, Othem, Spillings; (3) Two aggregated specimens, one from anterior and one from posterior view, RM Mo 59891, Othem, Samsuguns 1; (5) Lechritrochoceras sp. and two fragments of D. lindstroemi, RM Mo 59891, Othem, Samsuguns 1. Specimens in Figure 7.1 and 7.3–7.5 were coated by ammonium chloride before photographing. Scale bars 10mm.


Table 3. Dimensions (in millimeters) and aperture characteristic of selected specimens of D. lindstroemi n. sp. SD1: shell diameter at beginning pseudoumbilicus; SD2: shell diameter at termination of pseudoumbilicus; PL: pseudoumbilicus length; PW: pseudoumbilicus width; LPS: length of protruding shell (ND: not developed); A: Aperture (O: open, C: contracted); for other abbreviations, see Table 1.


N


59416 59419 59420 59422 59425 59426 59427 59428 59442 59443 59499 59504 59511 59877 59884 59891a 59891b 155975 158752 181926


SD WW WH WWI WER 64,7


39 39


19 13


37.3 65.4 69.3 60


— —


52.9 51


67.7 53.8 56.7 69.6 —


59 64 67


54.1 49.5 72,5


19.2 18 14 16


—


17.8 18


16.5 17.7 21.8 16


18.7 13.5 13 10 22


1.02 0.96 — —


18.8 16.7 18


21.3 20.3 18.3 12.4 14


14.5 18.2 15.2 16.3 22.7 24.4 18.6 21


24.3 19


12.9 19.1


0.87 0,96 0.84 0.89 —


0.98 1.18 1.01 0.78 0.89 0.86 1.01 0.84 0.96 0.96 0.73


1.98 2.34 2.25 1.87 2.27 1.88 1.92 2.30 1.95 1.87 1.94 1.97 2.2 —


2.22 2.46 2.38 1.83 1.84


RI


0.54 —


0.53 0.44 0.5 —


0.46 0.36 0.47 —


0.6


0.48 0.33


0.44 0.37 0.4


0.55


SD1 14


14.7 15 16


14.8 16.9 17.5 —


13.2 —


2.13 —— 24 ——— — — — ——— O — — ——— C 37.2 ——— — 5.5 —— —


0.44 —— — 0.53


13.7 15.8


11.9 18.8 19.3


in a belt between 20°N and 50°S when the Ordovician recon- struction of Torsvik and Cocks (2013) is used. It is known from the Baltica, North China, NE Gondwana, Kazakhstania, Laur- entia, and Tibet paleocontinents. Discoceras inhabited


36.4 —


29


O O


22.5 27.5


ND O


carbonate platforms, in shallows as well as in their deeper parts up to a depth of ~100 m. Some species are also known from off- shore shales deposited under dysoxic/anoxic conditions (Kröger et al., 2009, 2011; Kröger and Ebbestad, 2014).


24.3 ——— O 24


SD2 35.2


22.2 29.7


17


PL PW LPS A 4


41.6 45.4 46


32.2


— ——— — 20.8 20


14.4 16.1 —


— — ——— — 46.19


37.3 ——— — 22.8


26.4 17.4


6.2 8.5 4.7


10 ND


5.2 ND —


O O O O


ND ND


6


4.8 —— 5.6


4.2 ND O


46.7 ND


C O


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