Ślady nieznanego organizmu zwierzęcego z serii gielniowskiej (dolnego pliensbachu) liasu świętokrzyskiego

Abstract

TRACES OF AN UNKNOWN ANIMAL IN THE GIELNIÓW SERIES (LOWER PLIENSBACHIAN) OF THE SWIĘTOKRZYSKIE MOUNTAINS LIAS

Summary

Lenticular recesses occur on the top surface of the fine-grained sometimes thinly bedded sandstone (tabl. I, fig. 2; tabl. II, fig, 4; tabl. III, fig. 6). Their longer axis is 7-12mm, the shorter axis being 4-8 mm. The maximum depth does not exceed 5 mm. In the individual recesses two funnel-shaped hollows can be noticed situated symmetrically on either side of the longer axis. In some specimens these hollows have the same depth, in others they fairly clearly differ in size. In some specimens traces of sand removed from the hollows can be observed but their margins are not turned-up into a colar-like shape as those known from Calycraterion samsonowiczi (W. Karaszewski 1971). No mud cracks commonly occurring with the Calycraterion samsonowiczi have been found on the sandstone surface. Thus it may be inferred that the form discussed originated under water surface (unlike the Calycraterion), but probably at a small depth and close to the shore. The form discussed continues into the rock as indicated by the fact that convexities strictly corresponding to the recesses observed on the top sandstone surface occur on the bottom surface of thin sandstone beds (tabl. I, fig. 3; tabl. II, fig. 5; tabl.IV, fig. 7). This proves that, like the Calycraterion, the animal moved upwards as the deposits accumulated. Probably, like the Colycraterion end Monocraterion (A. H. Westergård, 1931), this is a new variety of marine worm. Similar recesses from the Crimea Upper Jurassic are shown on Tabl. 70, fig. 20 in the Gosgeoltechizdat Atlas (1962). The note says that they are possible traces of Amphiopoda activities, which in the light of my description does not seem very likely. The form distinguished is described under the name of Lenticraterion bohdanowiczi n.sp. Deriv. nom. - lens (Latin) = a lense, crater - a latinized for mof krater (Greek) = a jar used for mixing wine, a depression. By the second portion of the name I am honouring the memory of professor Karol Bohdanowicz (l864-1947), a great Polish geologist.