Dorsoserpula conjuncta? ( GEINITZ , 1843)

Kočí, Tomáš & Jäger, Manfred, 2013, Sabellid And Serpulid Worms From The Bohemian Cretaceous Basin (Upper Cenomanian - Middle Coniacian) Originally In The Collection Of Professor Antonín Frič, Acta Musei Nationalis Pragae Series B 69 (3 - 4), pp. 129-146 : 138-139

Dorsoserpula conjuncta? ( GEINITZ, 1843)

Pl. 3, figs 3 a–b

1843 Serpula conjuncta m; Geinitz: p. 7, pl. 4, figs 6–9. 1849 Serpula conjuncta GEIN ; Geinitz: p. 106. 1875 Serpula conjuncta GEIN ; Geinitz: p. 283, pl. 63,

figs 6–9. 1911 Serpula ampulacea [sic!], SOW; Frič: p. 72, fig. 305. 1969 Serpula conjucta [sic!] GEINITZ; Ziegler: p. 38, text-figs 1–4.? 1984 Serpula conjucta [sic!] GEINITZ, 1846 [sic!]; Ziegler:

p. 223, pl. 3, fig. 2. 1984 Mucroserpula velimia nov. spec; Ziegler: p. 229, pl. 4, fig. 6.

M a t e r i a l. The original specimen figured by Frič

(1911, p. 72, fig. 305) from the Upper Cenomanian or Lower Turonian Korycaner Schichten of Kojetice , coll. National Museum , Prague, specimen NM O7130, collected by J. Petrbok.

D e s c r i p t i o n. The specimen is limonitised. It is a slightly irregularly curved fragment of the free portion of a large robust tube. The tube diameter is 12.2 mm in the anterior portion of the fragment and 11.5 mm in the posterior portion. The transverse ornamentation is distinct and well developed, consisting of many densely packed small rings.

R e m a r k s a n d r e l a t i o n s h i p s. According to Ziegler (1984) the tube diameter of Dorsoserpula conjuncta (GEINITZ) is 13–17 mm, the diameter of the lumen is 12–14 mm, and thickness of the tube wall is 0.9–1.2 mm. Some specimens from the type area in Saxony grew to a larger tube diameter, and the thickness of the tube in these specimens is usually several millimetres (Jäger, in prep.) Protula planianica ZIEGLER, 1984 resembles D. conjuncta , but remains somewhat smaller in diameter and differs by its much thinner tube wall. Although Ziegler (1984) stated that D. conjuncta is attached along its entire length, specimens with a free anterior tube portion are found in Saxony (Jäger, in prep.), so that absence of a free portion can no longer be stated as a feature distinguishing D.conjuncta from P. planianica which possesses an attached portion and also a free portion. Such P. planianica specimens were previously mentioned by Ziegler (1984). Among the P. planianica specimens collected by one of us (T. K.) there are tubes with an attached and a free portion as well as tubes attached for their entire length which are developed as 3D coiled and meandering tubes, for example from the localities Velim and Uhelná Příbram. D. conjuncta has a more distinct transverse ornamentation in the middle and anterior parts of the tube compared to the weaker transverse ornamentation of P. planianica . T. K. noted that in the material he collected specimens of Dorsoserpula cf. conjuncta from the locality Kaňk can be distinguished from specimens of D. conjuncta from Kojetice, Velim and Uhelná Příbram by their more developed cellular layers.

P a l a e o e c o l o g y. According to Ziegler (1969, 1984) D. conjuncta was adapted to life on sandy, marlysandy and marly sediments close to characteristic surf sediment. It attached itself to the soft bottom, pebbles or oyster valves. The specimens of Geinitz’s type series and other specimens from the type area in Saxony are found in a rocky coast facies (Jäger, in prep.).

O c c u r r e n c e i n B C B. Upper Cenomanian: Velim, Holubice, Kojetice, Markovice, Nová Ves u Kolína, Plaňany, Radim near Pečky, Uhelná Příbram. Lower Turonian: Kaňk – Na Vrších.

Serpulidae gen. et sp. indet.

Pl. 3, figs 4 a-b

1911 Serpula sp ; Frič: 72, fig. 306 (as Serpula n. sp.).

M a t e r i a l. The original specimen figured by Frič (1911, p. 72, fig. 306) from the Upper Cenomanian or Lower Turonian Korycaner Schichten of Skuteč (Skuč), coll. National Museum, Prague, specimen NM O7131 .

D e s c r i p t i o n. The tube which is presumably figured upside down is three-dimensionally coiled, the tube spirals upwards to form a screw-like nearly cylindrical ‘tower‘ consisting of four somewhat ‘flattened‚ turns. The first three turns are coiled regularly, the anteriormost turn elevates obliquely and initially is nearly straight but later continues coiling. In total, the specimen is circa 40 mm high. Tube diameter increases gradually from 4 mm in the posterior part and reaches circa 9.6 mm in the anterior part. Transverse ornamentation consisting of many small, regular, densely shaped rings is not well preserved, but is visible on the surface of one coil.

R e m a r k s a n d r e l a t i o n s h i p s. This specimen, although looking quite impressive at first sight, is only moderately well preserved. No other specimen is available, and therefore variability of the species is unknown. It is indeterminable. It resembles Dorsoserpula conjuncta in its large size and by the shape of its three dimensionally coiled tube. Moreover, Dorsoserpula conjuncta occurs in strata of similar geological age at some localities of BCB, and also Frič’s original specimen (1911, p. 72, fig. 305) described above by us as Dorsoserpula conjuncta ? was found in the Korycaner Schichten and may represent the same species as Frič’s specimen (1911, p. 72, fig. 306). However, in typical Dorsoserpula conjuncta specimens the whorls are more closely and smoothly cemented together than in Frič’s specimen (1911, p. 72, fig. 306).

P a l a e o e c o l o g y. Presumable the tube had initially been attached to only a small substrate. By using its own previously built tube portions as a substrate, the tube spiralled upward like a screw or tower. By using this strategy, the whole tube became relatively stable in spite of the presumably small initial substrate, and the tube’s aperture gained a relatively high position above the sea-floor. Two tubes of an indeterminable species, presumably Glomerula serpentina (GOLDFUSS) , are attached to the basal portion of the large tube.

O c c u r r e n c e i n B C B Upper Cenomanian or Lower Turonian – Skuteč (Skuč).