thiolliericrinid crinoids from the lower cretaceous of crimea

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St e mÉtallon (1859, p. 445, 447) noted that the Thiolliericrinusstem had consisted only of three or four columnals.Joukovsky & Favre (1913, p. 386) found 31calyxes and only 43 columnals of Heberticrinusheberti in one of the local exposures. Similar correlationsare marked also in our materials. So, in the locality« Belbek » (see table 1), there were found 129calyxes and 638 columnals, belonging to several species.A comparison of the figures shows that theThiolliericrinidae stem included roughly five columnals.It coincides with Étallon’s data.Among Heberticrinus heberti columnals, cruciateones are the bulk, oblique ones are rare and parallelones are unique. The columnals of this species are lowand disk-shaped. A t the same time, the columnalswith parallel ridges on both articula are prevalent inBurdigalocrinus maximus. The columnals of this speciesare, as a rule, relatively high. These circumstancesallow us to suppose that the short stem of some discoidalcolumnals was peculiar to the species with wideflattened calyxes. But a relatively long stem, consistingof high columnals, was typical for species with ahigh conical calyx.The order of columnal combination in the stem isunknown. However, one can assume, after the analogyto Bourgueticrinida, that the columnals were joinedso that the fulcral ridge had an alternating « swinging» position. I doubt whether one can speak, in thepresent case, of « spiral turning » as supposed byA rendt (1974, p. 75). In the species Loriolicrinusasper, cruciate and parallel columnals are found inapproximately equal numbers. One can think thatthey were joined in a stem alternately.A powerful fulcral ridge risen above the articulumplane and deep ligament fossae on both sides of themtestify to the considerable flexibility of the stem articulationsin Thiolliericrinidae (Gislén 1924, p. 206). Itresults in flexibility, as a rule, without any markedincrease of the separate columnal height as in Bourgueticrinidawith an analogous articulum construction.The high stem flexibility with the relatively low(strong) columnals agrees with the fact that Thiolliericrinidaeinhabited very mobil waters on the coral reef.The external sculpture of columnals correspondsthat o f the centrodorsal, in most cases. The columnalsof Loriolicrinus asper are often knobby (pl. 1, fig. 5)and those of Umbocrinus umbonatus are coveredsometimes with small granules. At the same time,smooth columnals are often found, belonging evidentlyto the ornamented calyxes. In this case, thedistal or proximal position of the columnal in a stemis probably the matter. Unfortunately, the lack offinds of stem fragments (i.e. some articulated columnals)does not allow one to make the nature of a stemvariation clear.If the cirriless calyxes of Thiolliericrinidae are wellpreserved they have also well preserved stem facet.However, available specimens of Thiolliericrinus(with poverful cirri) have obviously abraded and destructedcentrodorsal basis (fig. 5 A, 6A,B) even whenthe preservation as a whole is good. This circumstancecan mean that the cirriless forms were attached to thestem (and, accordingly, to the substratum) duringtheir whole life. On the contrary, the individualshaving cirri were detached from their stem and led afree life though preserving a biletarel stem facet onthe centrodorsal (Kirk 1912, p. 75). The poor preservationof the centrodorsal basis in these forms isexplained, possibly, by their activity. The separationof the stem during the life of an animal is confirmedby the absence (among over 500 columnals) of a singlecolumnal belonging to Thiolliericrinus belbekensis, T.elongatus or T. torosus.A r m s .Thiolliericrinidae brachials are known till now onlyafter Rem e!s (1905, pi. 7, fig. 7,8). In our collectionthere are 580 brachials plates of several species of thefamily (see table 1).Only muscular articula are developed on all the brachialswithout exception, including the lower face ofaxillaries. This leads to the conclusion that there wereno immovable articulations in the arms of Thiolliericrinidae.The axillaries of the first, second and third orderscan be determined with certain among available axillarplates. Consequently, arm branching was not lessthan threefold.Not a plate has been found which should be placedbetween the primaxillary and the radial. So, one canconclude that Thiolliericrinidae have only one primibrachial(axillary) with muscular articulation directlyjoined to the radial.The primaxillaries (IAx - see figs. 2 and 15) are thelargest plates in the crown, being greater than theradiais. The form of promaxillaries is various in differentgenera. The calyxes with high free radial surfaceand with a small angle of the inclination of the radialfacets have high axillaries with vertical external
— 654 —SIS rllAxsurface (Loriolicrinus, Burdigalocrinus). The calyxeswith low radiais whose facets are steeply inclined outsidehave wide and flattened primaxillaries hung overthe centrodrosal and absolutely covering radial plates(Umbocrinus, Heberticrinus). Two upper primaxillaryfacets are of an identical size and inclined outsidenearly parallel to the facets of the subjacent radiais.The lateral faces of all available axillar plates are flattened.Consequently, thesé plates formed a closedring. The sculpture of the external surface of a primaxillarycorresponds to that of the calyx. The pinnularsockets are absent on primaxillaries.IIBr3l!Br2IIBMThe brachials of most Articulata crinoids bear onepinnular socket placed on the upper inner margin ofthese plates. The fulcral ridges are not in parallels onlower and upper brachial faces. But these ridges canhave only two positions swinging from one articulumto another. The available secondbrachials were dividedinto right and left, even and odd, accordingly(fig. 15). If one looks at the primaxillary from itsexternal surface, the left odd (first) secondbrachialwill be on its upper face to the left and right odd (first)secondbrachial to the right. The odd secondbrachialsare cuneate with a thin margin at the inner side of aradius and with a thick one at the outer side where thepinnular socket is placed. Their external surface isvery convex. The thick lateral side of the secondbrachialbears a wide flat face, i.e. these plates were closeto the corresponding brachials of the adjacent radius.The even brachials are flattened and somewhat higherat the inner margin (where the pinnular socket is placed).They have convex external surface and flat lateralsides joined to corresponding secondbrachials ofthe adjacent radii. The number of secondbrachials inthe arm branch was apparently odd and hardly morethan seven or nine (according to the relatively greatnumber of the available secondaxillaries). The externalsecondbrachial surface has the sculpture analogousto that of the calyx but feebly expressed.The secondaxillaries (IIAx - see figs. 2 and 15),according to their construction, are analogous to theFig. 15 — A scheme of the construction of Thiolliericrinidae brachials(view from above, x 2). IAx - ring of five primaxillaries,IIBrl - first secondbrachial, IIBr2 - secondsecondbrachial, IIBr3 - third secondbrachial, IIAx-secondaxillar, IIIBrl - first tertibrachial, IIIBr2 -secondtertibrachial, SI - left arm series, Sr - right arm series.The number of secondbrachials is shown conditionally.Reconstitution de l’organisation d’un tronc brachial de Thiolliericrinidae(vue en dessus, x 2). IAx - cercle des cinq primaxillaires,IIBrl - première secundibrachiale, IIBr2 - deuxième secundibrachiale,IIBr 3 - troisième secundibrachiale, IIAx - secundaxillaire, IIIBrl -première tertibrachiale, IIIBr2 - deuxième tertibrachiale, SI -sériegauche d’un bras, Sr - série droite d’un bras. Le nombre des secundibrachialesreste hypothétique et n’est donné qu’à titre indicatif.
Page 1 and 2: THIOLLIERICRINID CRINOIDS FROM THE
Page 3 and 4: TABLE OF CONTENTS1 - Introduction..
Page 5 and 6: — 628 —Name of s p ecies L o ca
Page 7 and 8: 630 —
Page 9 and 10: — 632 —not only specific but al
Page 11 and 12: — 634 —Fig. 3 — Calyxes and c
Page 13 and 14: — 636 —Fig. 4A scheme of the di
Page 15 and 16: — 638 —Thiolliericrinus elongat
Page 17 and 18: — 640 —Fig. 7 — Calyxes and c
Page 19 and 20: — 642 —cavity. The primaxillary
Page 21 and 22: — 644 —D e s c r i p t i o n :T
Page 23 and 24: — 646 —T y p e s p e c ie s :Ge
Page 25 and 26: — 648 —Fig. 12 — Calyxes and
Page 27 and 28: — 650 —T y p e l e v e l :Upper
Page 29: — 652 —5 — RECONSTRUCTION OF
Page 33 and 34: primaxillaries but are asymmetrical
Page 35 and 36: — 658 —At the same time, all th
Page 37 and 38: — 660 —AcknowledgementsThis art
Page 39 and 40: ROMAN F. (1897) - Recherches strati
Page 41 and 42: PLATE
Page 43: Geobiosn° 20, fasc. 5Pl. 1V.G. Kli

thiolliericrinid crinoids from the lower cretaceous of crimea

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