Ecology and Taxonomy of Silurian Crinoids from Gotland

Ecology and taxonomy of Silurian crinoids from Gotland

Christina Franzén

Uppsala universitet 1983

Ecology and taxonomy of Silurian crinoids from Gotland

Christina Franzén

Franzén, Christina, 1983 01 21: Ecology and taxonomy of Silurian crinoids from Gotland. Acta Universitatis Upsaliensis. Abstracts of Uppsala Dissertations from the Faculty of Science 665. 31 pp. Uppsala. ISSN 0345-0058. ISBN 91-554-1363-3.

The author's previous work on the ecology and other aspects of Silurian crinoids from Gotland is summarized to meet the formal requirements of a thesis. The summary is supplemented by further discussion of the role played by crinoids in the sedimentary environments represented in the Silurian of Gotland. One hundred and ninety-three crinoid species (assigned to 55 genera) so far published are listed and a critical compilation of information on their stratigraphical distribution is presented. Crinoids lived on a variety of substrates and occupied different trophic niches depending on heigth above the sea floor and the flexibility of their stems. The densest crinoid meadows grew on the flanks of reefs. It is suggested that the crinoids may to a great extent have brought sustenance to their peripheral parts (holdfasts, stems, arms) by epidermal uptake and absorption of dissolved amino-acids and other nutrients taken directly from the surrounding sea water, this in a manner similar to that adopted by many Recent soft-bodied marine invertebrates. Radiating canals in the median and distal parts of large stems and holdfasts probably facilitated this process of uptake. The possibility of identifying crinoids by analysis of the disarticulated parts of their skeletons receives comment. Great care must be taken because of the wide range of morphological vari¬ ation that exists in crinoid skeletons. Mutualistic relationships between crinoids and other organisms are discussed. The most common case of the kind is represented by the parabolic pits of Myzostomites, which are interpreted as owing their origin to epizoic, rather than parasitic attachments.

Christina Fransen, Department of Palaeobiology, Box 564, S-751 22 Uppsala, Sweden.

Doctoral dissertation to be publicly examined in the lecture hall of the Geological Survey of Sweden, Villavägen 18, Uppsala, on 18th February, 1983, at 10 o'clock c.t., for the degree of Doctor of Philosophy at Uppsala University. ACTA UNIVERSITATIS UPSALIENSIS Abstracts of Uppsala Dissertations from the Faculty of Science 665

Ecology and taxonomy of Silurian crinoids from Gotland

Christina Franzén

UPPSALA 1983

ACTA UNIV[RSITATIS UPSALIENSIS Abstracts oj Uppwlo Dissertations fro111 rhe Faculty vf Science 665 ------·-- --·-

Ecology and taxonomy of Silurian crinoids from Gotland

Christina Franzen

UPPSALA 1983 Doctoral thesis at Uppsala University 1983

ISSN 0345-0058 ISBN 91-554-1363-3

Printed in Sweden 1933

Repro-C HSC Uppsala Universitet Ecology and taxonomy of Silurian crinoids from Gotland

Christina Franzén

Doctoral dissertation at Uppsala University, 1983, consisting of the following separate articles:

1974: Epizoans on Silurian—Devonian crinoids. Lethaia 7, 287-301. (Offprint.)

1977: Crinoid holdfasts from the Silurian of Gotland. Lethaia 10, 219-234. (Offprint.)

1982: A Silurian crinoid thanatotope from Gotland. Geologiska Föreningens i Stockholm Förhandlingar 103, 469-490. (Offprint.)

1983: Radial perforations in crinoid stems from the Silurian of Gotland. Lethaia. 21 pp. (Preprint.)

1983: [Summary and review:] Ecology and taxonomy of Silurian crinoids from Gotland. Acta Universitatis Upsaliensis. Abstracts of Uppsala Dissertations from the Faculty of Science 665. 31 pp.

Ecology and taxonomy of Silurian crinoids from Gotland

Christina Franzén

Christina Franzén, Department of Palaeobiology, Box 564, S-751 22 Uppsalaj Sweden. 2 Christina Franzén

The present paper is a summary of the work I have published so far on various aspects of the life and role of crinoids in the Silurian sequence of Gotland (Franzén 1974, 1977, 1982, in press). It has been compiled to meet the formal requirements set for academic disser¬ tations at Swedish universities.

The long-term aim of this and future work is to establish the fullest possible view of the role crinoids have played in forming some of the most conspicuous and voluminous organic deposits in the area. This requires an assessment of their relative significance and also of the conditions in which they lived when producing the deposits. An inventory of the crinoid faunas is necessary. So, too, is a revision of their systematics. The forbidding task of attempting to refer disarticulated skeletal ossicles to their ori¬ ginal taxa awaits attention. Some aspects of these projects have already matured. I take this opportunity of setting my summary within a larger context of longer-term concerns.

Geological setting

The island of Gotland is situated in the Baltic Sea ca. 100 km east of the southern Swedish mainland. Its geographic position during

Silurian time was close to the equator (Smith 1981). The bedrock comprises a succession which ranges in age from late Llandoverian to late Ludlovian. Thirteen topostratigraphical units are recog¬ nized (Fig. 1; for English summaries see Hede 1960 and Laufeld 1974).

Large areas of limestone outcrop occur in the northern, central and southern parts of the island and are separated by occurrences of more argillaceous (marlstone) deposits. Structural strike runs SW-NE and dip is to the SE so that the oldest rocks crop out in the north¬ western part of the island and the youngest in the south. Sedimen¬ tation proceeded in a shallow, epicontinental sea where water depth never exceeded 200 m (Gray et al. 1974). Extensive reef growth occurred in early and mid Wenlockian time (Högklint and Slite Beds), latest Wenlockian (Klinteberg Beds) and mid and late Ludlovian (Hemse and Hamra-Sundre Beds).

Grinoidal remains occur in all of the Silurian deposits on

Gotland and profusely in most of them. There are, however, con- Silurian crinoids from Gotland 3

Fig. 1. Geological map of Gotland (From Hede 1942) and stratigraphical scheme (mainly after Martinsson 1967, with modifications after Bassett & Cocks 1974, Bassett et al. 1975 and Holland et al. 1930).

siderable and conspicuous differences between occurrences in different

lithologies. Crinoid remains in the marlstone areas indicate small,

delicate animals with slender stems and crowns. Substrates here

were probably soft and unconsolidated and lay below wave base;

current velocities were low. Holdfasts found are either of a

branching type adapted to an unconsolidated substrate, or attachment

discs cemented to skeletal debris or to other hard objects on the

sea floor (Franzén 1977).

As a rule, dissociated ossicles in the marlstones are well

preserved, indicating burial on the spot or transport over a short

distance only. Yet crowns, even calices (with the exception of

Pisoorinus) are rare, which suggests that slow sedimentation rates

permitted almost complete disarticulation of the skeletal elements before burial. Isolated columnals and calyx plates, and brachials

in particular, often have a highly characteristic ornamentation and

arrangement of the articular facets. Some complete specimens or

crowns with parts of their stems attached are available and will 4 Christina Franzén

provide a possibility of putting an identity on isolated ossicles.

This work is in progress now. Results will be presented in future papers.

Population densities, and likewise size and number of crinoid species and genera, increased with increasing proximity to the reefs.

Major accumulations of crinoid material occur in the immediate vicinity of the bioherms (Hadding 1941; Ilanten 1971; Ruhrman 1971).

The flanks of the reefs and the pockets within them bore dense crinoid meadows, as is evidenced by the large amounts of bioclastic debris found in close association with the bioherms. Lowenstam's

(1957) studies of the Niagaran reefs of the Great Lakes area sug¬ gested that the reef-induced turbulence, which prevented suspended fine elastics from settling, provided more favourable conditions on the flanks than were available on adjacent quiet-water bottoms. Stem fragments constitute a large part of the talus enveloping the Gotland bioherms. Calices and even crowns occur in the marl pockets between the reef build-ups; they are more frequently found in the Högklint reefs than in the younger part of the succession, probably because of the more massive state of the recrystallized matrix in reefs higher in the succession (cf. Manten 1971). The holdfasts found in the flank deposits are frequently of a reptant type which were cemented to the substrate by thin strands of stereom (Franzén 1977; stoloniferous holdfasts of Brett 1931). The camerate genera

Euoalyptoarinites, Calliocrinus, Clonocrinus and Dimerocrinites, and the inadunate genera Crotaloerinites and Enallocrinus are the most conspicuous and therefore the most commonly found. They were large animals, wich columnal diameters several times greater than in the crinoids found in the marlstone areas.

The sea was shallower during episodes of reef construction.

Water energy was high, which produced a rapid break-down of indi¬ vidual crinoids but also provided for rapid burial, and therefore

conservation of the fragments. Silurian orinoids from Gotland 5

Taxonomy and stratigraphical occurrence

One hundred and ninety-three crinoid species assigned to 55 genera have so far been described from Gotland (Inadunata, 18 genera

and 50 species; Camerata 21 and 106; and Flexibilia, 16 and 37,

respectively). They are listed in Fig. 2 and their stratigraphical

positions if known, are indicated. The list is compiled from Angelin (1878), Bather (1893, 1898), Springer (1920), Jaekel (1918), Ubaghs (1958) and Franzén (1982); generic affiliations have been updated

according to Moore & Teichert (1978).

Stratigraphic positions are based on personal observations and

on locality names in the publications mentioned. It is often diffi¬

cult to reconcile stratigraphic information in the literature with

that given on museum labels dating from before the 1920s and it is

often difficult to accomodate these data within modern concepts.

Several different interpretations of the stratigraphy of Gotland were

published during the 19th century and the early years of the 20th

(for a review see Hede 1921 and Manten 1971). Modern terminology is

based on Hede's (1921, 1925, 1927a, 1927b, 1928, 1929, 1933, 1936 and 1940) 13 topostratigraphical units.

Angelin's practice was to cite only a place-name, in some

cases supplemented by the name of the parish to which it belongs; a

large number of his specimens are labelled only as coming from "Got¬ land". Bather and Springer followed Lindström's (1888) "stratigra¬

phical" subdivision with letters added to the locality names in

order to indicate the lithological facies (for collation see Hede

1921; Manten 1971). But there are still problems of correlation,

especially where the different units occur close to each other as

is the case along the northwestern coast. A locality name such as

"Wisby" covers four of Hede's units, namely the Lower and Upper

Visby Beds, the Högklint and the Tofta Beds. I have assigned "Wisby"

Fig. 2 (overleaf). Crinoid genera and species so far described from the Silurian of Gotland and their stratigraphical distribution. List compiled from Angelin (1878), Bather (1893, 1898), Springer (1920), Jaekel (1918), Ubaghs (1958) and Franzén (1982); generic affiliations updated according to Moore & Teichert 1978). 6 Christina Franzén

Camerata

Diplobathrida Anthemocrinus minor

A. venustus

Dimerocrinites interradialis

0. laevis

D. longimanus

D. medius

D. ornatus

0. quinquangularis D. speciosus

Monobathrida

Abacocrinus capelleri

A. medius

A. tessellatus

A. tesseracontadactylus

Periechocrinus annulatus

P. grandiscutatus

P. laevis

P. lindströmi

P. longidigitatus P. longimanus

P. major

P. mutticostatus

P. nubilus

P. radiatus

P. schulzianus

P. undulatus

Carpocrinus affinis C. angelini

C. annulatus

C. cariosulus

C. comtus

C. decadactylus C. elegantulus C. faretus

C. grandis C. granulatus C. laevis C. longimanus C. ornatissimus Carpocrinus ornatus

C. petilus C. pinnulatus

C. pulchellus C. raridigitatus

C. robustus

C. simplex

C. tenuis

C. umbonatus

Barrandeocrinus sceptrum

Desmidocrinus heterodactylus

D. macrodactylus D. pentadactylus D. tridactylus

D. n.sp.

Paramelocrinus angelini

Melocrinites angustatus M. ?granulatus M. rigidus M. spectabilis

M. volborthi

Ctenocrinus gotlandicus

Promelocrinus sp.

Clonocrinus coroliferus

C. grandis C. grandistellatus

C. klintbergi

C. laevis

C. panderi C. polydactylus

Eucalyptocrinites decoratus E. elegantissimus

E. excellentissimus

E. granulatus

E. minor

E. ovatus 8 Christina Franzén

>< ra je ra ra o a> 0» o o 75 > X 1- ä) X

Eucalyptocrinites plebejus • E. regularis •

E. rigens • E. speciosus • •

E. spp.

Calliocrinus beyrichianus •

C. costatus •

C. diadema •

C. koninckianus •

C. minor •

C. murchisonianus •

C. roemerianus • •

C. sedgewickianus •

C. sp.

Polypeltes granulatus • •

Stelidiocrinus capitulum • S. laevis •

S. ovalis •

Patelliocrinus chiastodactylus • P. duplicatus

P. fulminatus • P. interradiatus

P. leptodactylus

P. pachydactylus • P. pinnulatus •

P. plumulosus • P. punctuosus

Briarocrinus angustus •

B. inflatus • •

Macrostylocrinus gotlandicus

Marsupiocrir.us depressus

M. dubius

M. puicher •

M. radiatus

M. rugulosus •

Cordylocrinus comtus Silurian arinoids from Gotland 9

Visby Högklint Tofta Slite Halla Mulde Klinteberg Hemse Eke Burgsvik Hamra Sundre

Inadunata

Disparida Calceocrinus interpres •

C. pugil •

C. tenax • •

C. sp. •

Chirocrinus gotlandicus • •

Chiropinna pinnulatus • • • •

Synchirocrinus nitidus • •

S. tucanus • •

Pisocrinus pilula • • • • P. pocillum •

P. spp. • • • • • •

Parapisocrinus ollula • •

Herpetocrinus ammonis • •

H. convolutus

H. flabellicirrus • •

H. fletcheri • • •

H. gracilis • •

H. interradialis •

H. spp. • • • • • •

Cladida

Cyathocrinites acinotubus • • •

C. dianae •

C. distensus •

C. glaber •

C. longimanus •

C. monilifer •

C. muticus •

C. ramosus • •

C. striolatus •

C. visbycensis •

Gissocrinus campanula • G. elegans • G. goniodactylus • •

G. incurvatus • 10 Christina Franzén

« C ■Q > o o O 0) a >» (0 4) X e <0 «0 ■o A O) O) 2 C E o i c :0 o n « 3 e JÉ 3 a 3 > X »-

Gissocrinus macrodactylus •

G. typus • G. umbilicatus •

G. verrucosus •

G. sp. •

Euspirocrinus spiralis •• •

Crotalocrinites pulcher • •

C. rugosus • • • C. superbus •

Enallocrinus assulosus • •

E. scriptus • •

E. n.sp. •

Petalocrinus angustus •

P. expansus • P. visbycensis ••

Botryocrinus corallum • B. cucurbitaceus •

B. ramosissimus • •

B. sp. •

Gothocrinus gracilis •

Thenarocrinus callipygus

Antihomocrinus tenuis • •

Streptocrinus crotalurus •

Flexibilia

Haereticotaxocrinus asper •

H. oblongatus • •

Gnorimocrinus expansus •

G. punctatus

Meristocrinus anceps •

M. interbrachiatus O •

M. tuberosus • Silurian arinoids from Gotland 1 1

JÉ

> (/> o)

3 Visby Högklint Tofta Slite Halla Mulde Klinteberg Hemse Eke CD Hamra Sdnuer

Protaxocrinus distensus • P. interbrachiatus • P. ovalis •

P. salteri • •

Lecanocrinus angulatus •

L. billingsi • • • • • L. facietatus • • L. lindströmi

Cholocrinus obesus •

• Hormocrinus gotlandicus

• • Pycnosaccus nodulosus • • • • P. scrobiculatus

Icthyocrinus intermedius • • • • 1. gotlandicus • •

1. laevis • •

1. pyriformis • • •

• Cleistocrinus humilis

• Clidochirus pyrum

Homalocrinus Iii je v a II i •

H. parabasalis •

Anisocrinus angelini

A. interradiatus • •

A. irregularis •

• Sagenocrinites expansus

Calpiocrinus fimbriatus • C. heterodactylus

C. ovatus

C. rotundatus • •

Lithocrinus divaricatus •

L. milleri 12 Christina Franzén

Sundre □ =0 Hamra

ÉL Burgsvlk

Ex.

Hemsa 3

I I Klinteberg I 1 in

En.

Högklint

Visby

Fig. 3. Crinoid genera and species of Fig. 2 plotted against stratigraphical units. I=Inadunata, C=Camerata, F=Flexibilia, T=Total.

crinoids to the Högklint Beds when their locality is given as "Wisby f" or when I have found members of the genera in the Högklint Beds but not in the or Lower Upper Visby Beds. Wisby f may include the

Tofta Beds, but since I have found no identifiable specimens from this unit and since the localities given in the literature are not precise enough, no species have been referred to that unit. Silurian orinoids from Gotland 13

The numbers of crinoid genera and species as listed in Fig. 2 are plotted against the stratigraphical units in Fig. 3. Salient features are the large variety found in the Högklint and Slitc Beds and the low variation in the higher part of the sequence. The figure may to some degree reflect the accessibility of localities and the distance from the preferred base of operations of collecting

scientists rather than stand as a record of unbiased variation of genera and species.

The Lower and Upper Visby Beds have here been treated as one unit, since locality references in the literature do no permit a separation. They have yielded surprisingly few identifiable crinoids considering their easy accessibility along the north-western coast and their proximity to the town of Visby (where the collectors usually stayed). Well preserved crinoidal remains are abundant

(cf. above) but few genera are identifiable from disarticulated

skeletal elements alone. Columnals of Herpetocrinus are found in most samples and the compact calices of Pisocrinus are fairly corrcaon in the Lower Visby Beds. The characteristic basals of Calaeocrinus

and the arm fans of Petalocrinus are easily identifiable at generic

level but they do not occur very frequently. Crinoids of this age were small and delicate. Inadunates were dominant; strangely enough no camerate crinoids have so far been reported from the Visby Beds.

The Högklint and Slite Beds have yielded the majority of the

crinoids identified (Figs. 2-3), most of them from a limited number

of localities. The Högklint reefs along the northwestern coast —

especially their flanks — are highly fossiliferous, both in terms of

number of individuals and of diversity of genera and species. Crinoids

abounded and their remains formed a large proportion of the flank

deposits (cf. Lowenstam 1957). Crinoid calices and even crowns are

frequently found, usually in a good state of preservation, set in

marl pockets within the reef frame. Thirty genera and 65 species have been identified from the Högklint Beds, the most notable

genera being the camerates Calliocrinus, Eucalyptocrinites and Dimerocrinites.

The Slite Beds show the largest variation in crinoid genera and species, 37 and 88 respectively. Among these Angelin labelled

26 genera and 66 species as coming from "Follingbo". We do not know

exactly what he meant. Lindström (1884, p. 11) gives the locality 14 Christina Franzén

name Follingbo, Storwede, and remarks that the limestone is exten¬ sively quarried. On the geological map (Hede 1940) there is a ca.

5 km long, 50-250 m wide, outcrop of bedded, crystalline limestones and equivalent reef limestones shown trending SW-NE about one kilo¬ metre NW of Follingbo church. Several quarries along this belt of outcrop are marked on the map. Considering the lithologies in this area it is surprising that so many well preserved specimens have been found. Complete crowns, frequently with part of the stem attached, occur embedded in very coarse-grained bioclastic debris composed of worn fragments of (mainly) bryozoans, stromatoporoids and corals.

The crinoids appear to have been buried very rapidly.

The upper Wenlockian and Ludlovian part of the sequence (Halla —

Sundre Beds) show a more restricted range of genera and species, the

Klinteberg Beds being the most productive. Most of the Klinteberg crinoids in museum collections are from the large quarry at Klinte¬ berget .

Considering the very fossiliferous character of the Hemse and

Eke Beds and the crinoidal limestones found in the Hamra and Sundre

Beds one might expect a larger variation than is actually found. The rocks in the main area of outcrop of the Hamra and Sundre Beds consist to a large extent of rather pure, bedded limestones, crystalline limestones and biohermal limestone. The Sundre reefs at, e.g.,

Holmhällar are largely formed of stromatoporoids. The calcareous matrix represents a low proportion of the total volume (Manten 1971) which makes fossil collecting difficult. Holdfasts are frequently found in marl pockets within the reef frame, but crowns are very rare.

Also, the calcareous matrix at Holmhällar is much harder than that of, e.g., the Högklint reefs. Four crinoid genera and five species from the Hamra Beds and two of each from the Sundre Beds can hardly be a true reflection of the diversity of crinoids present, considering the large volumes of crinoidal material represented in these units.

This is probably largely a reflection of sampling difficulties but may nevertheless perhaps carry some indication of a specialized crinoid fauna rich in individuals but poor in genera and species.

Angelin's material (containing 173 species which he assigned to 42 genera) represents 23 labelled localities only, of which five

(Follingbo, 26 genera and 66 species; Visby, 16 and 28; Klinteberg, Silurian orinoids from Gotland 15

11 and 16; Lickershamn, 9 and 13; and Fårö, 8 genera and 10 species, respectively) are the most important. All the others have yielded only 1-3 genera and species each. In addition to these from Ltie localities named there are a large number of specimens, representing

21 genera and 44 species, which are labelled only "Gotland".

Angelin devoted large amounts of time to field-work and his journeys in Skåne and on Öland were the sources of many anecdotes.

I am not aware of any evidence for time spent on Gotland, and there is nothing in the collections of the National Museum of Natural

History (SMNH) in Stockholm to suggest that Angelin ever visited

Gotland personally. This might indicate that the material on which

Angelin based his Ioonographia was entirely the museum collections available at the time in Stockholm. It might also explain the restric¬ ted number of his localities.

Visby and Lickershamn are easily accessible along the north¬ western coast; the Visby and Högklint Beds are highly fossiliferous with well preserved faunas. Follingbo is situated only ca. 8 km southeast of Visby. With several quarries operating along the limestone outcrop, quarrying methods less mechanized than they are today (the quarrymen could easily remove the fossils they found) and a good market in Visby, considerable fossil collections could rapidly be assembled. We do not know who the middlemen may have been; but considering tha large collection of crinoids from Follingbo, one is inclined to believe that dealers or collectors were active in organizing and/or encouraging the fossil-hunting (paying quarrymen for fossils was the simplest means of rapidly accumulating large collections during the 19th and 20th centuries). It is reasonable to accept that the crinoid faunas from Follingbo fairly well reflect the crinoid diversity from limestone facies of middle Wenlockian age, simply because they were so thoroughly sampled.

One may be sure that the crinoid diversity from the southern

(younger) part of the island as represented in Fig. 2, is too low, partly because of sampling difficulties (cf. remarks above) and partly also, perhaps, because of the distance from Visby.

Most of the 19th and early 20th century quarries are now abandoned, overgrown with lichens and other vegetation and strongly 16 Christina Franzén

weathered. Quarries still operating employ modern methods and pro¬ cess material on a large scale which does nothing to facilitate fossil collecting. Consequently the bulk of the museum collections are of a fairly early date.

The names of crinoid genera cited in Fig. 2 have been updated according to the Treatise (Moore & Teichert 1978); the species, how¬ ever, have not. Very little work has been done on the taxonomy of

Gotland crinoids since Bather revised the Crinoidea Inadunata in

1893 and Springer the Flexibilia in 1920. Nothing has been done on the Camerata except for a few papers by Ubaghs (1956a, 1956b, 1958), so that the Gotland Crinoidea, the Camerata in particular, are badly in need of revision. I have commenced work on the carpocrinid genera

Carpocrinus and Desmidocrinus. Angelin erected 19 new species of

Carpocrinus (under the synonyms Habrocrinus, Pionocrinus and Lepto- arinus), ten of them from Follingbo. Although the generic diversity of Crinoidea from Follingbo may be accurately reflected in Fig. 2 the species diversity is not. Many of Angelin's species are syno¬ nyms .

Ecology

Modern sea-lilies and feather-stars are muco-ciliary filtration-fan feeders; most of them are rheophilic. The crown or the arms are held in a vertical to subvertical attitude, with the aboral side facing the current, to produce a flat net in feather-stars or a parabolic filtration-fan in sea-lilies Magnus 1964; Macurda & Meyer 1974;

Meyer & Macurda 1979) . Plankton and other food particles are inter¬ cepted by the tube-feet, enveloped in mucus secreted by the tube-foot papillae, flicked into the ambulacral grooves and conveyed along the grooves to the mouth (Nichols 1960, 1969) . The size of the prey in¬ gested is limited by the width of the ambulacral groove of the pinnules (Rutman & Fishelson 1969) .

In the shallow epicontinental Silurian seas of what is present-day Gotland stalked crinoids flourished. Their dissociated skeletal remains are found in all Silurian deposits on the island, in some areas in such masses as to be rock-forming. As mentioned above, crinoids from the marlstones tend to be small and delicate with thin Silurian arinoids from Gotland 17

stems and those from the areas where limestone is dominant, par¬ ticularly in the neighbourhood of the reefs, frequently are large with stout stems. Manten (1971) described the progressive general increase in stem diameter from the Slite to the Sundre Beds.

The Gotland crinoids show wide-ranging variations in stem and crown morphology which represent adaptations to various eco¬ logical niches. Interpretation of life habits is necessarily largely based on extrapolation from what is known of the ecology

of Recent forms. The animals may either be rheophobic, spreading

their arms to form a horizontal collecting bowl which traps organic detritus settling gravitationally, or rheophilic, forming a subvertical brachial filtration-fan which intercepts plankton and other

food particles carried along by the currents.

Rheophobic crinoids may in turn be either active rheophobes,

creating their own currents by specialized arrangements of the arms

and pinnules (e.g., Barrandeocrinus, Ubaghs 1956a), or passive

rheophobes which do not themselves create currents. Rheophobic crinoids were adapted to quiet water conditions or sluggish currents.

Some may have lived in pockets within the reef structure, where no

regular pattern of current directions could become established.

Stem length and morphology had (and have) a decisive bearing

on the life habits of crinoids. The possibility of elevating the

crown above the bottom brings a clear advantage in competition for food with other sessile benthic organisms. On the other hand, prob¬

lems of a hydrodynamical and a mechanical nature arise in consequence

of shifting the crown from the sea floor to a position well above it.

Stems in some fossil crinoids were short and almost rigid,

(e.g., Euspiroorinus spiralis) in which case the crinoids are inter¬

preted to have been rheophobic. A crown on a rigid stem cannot be

tilted to form a brachial filtration fan. Some stems were long and

slender with great flexibility, and acted more or less as a mooring

rope for the elevated crown, which received a certain amount of lift

from horizontal currents. Flexible stems are an adaptation to a

rheophilic mode of life in which the crown is held in a vertical

position perpendicular to the prevailing currents. Certain crinoid

stems were to some extent flexible, usually with a certain amount of

rigidity in the lower portion. For a detailed discussion of various 18 Christina Franzén

aspects of the ecology of fossil crinoids see e.g. Breimer (1969), Breimer & Webster (1975), and Breimer (1978).

Associations of many species of stalked, rheophilic fossil crinoids frequently grew in dense thickets, arranged in layers according to the length and flexibility of their stems (Lane 1973; Brower 1973; Ausich 1980; Franzén 1982). This vertical zonation would guarantee the various species maximum utilization of the plankton content of surrounding waters with minimum of competition.

The well-preserved crinoid thanatotope from När on Gotland (Franzén

1932) is an excellent example of this kind of stratification. Two species of Carpoarinus (C. affinis and C. petilus), Desmidoarinus pentadaotylus (Camerata) and Haeretiaotaxocrinus asper (Flexibilia) were attached to points within one single square metre of the

Silurian sea floor. Young Carpoarinus constituted the lower associ¬ ation, adult Carpoarinus and desmidoarinus the middle (ca. 0.2 m above the sea floor) and Haeretiaotaxocrinus stood ca. 0.6 m high.

Variations in stem flexibility and differing widths of the ambulacral grooves of the pinnules reflect the individual trophic niches of the various species. The maximum size of particles captured by Desmido¬ arinus is estimated to have been ca. 170 ym, by Carpoarinus somewhat

larger. Taxocrinid flexibles like Haeretiaotaxocrinus, with non- pinnulate arms, deployed very coarse-meshed filtration-fans, and it

is suggested that they had feeding mechanisms similar to those of

recent gorgonocephalid ophiuroids (Meyer & Lane 1976). Planktic organisms captured by Recent basket-stars range in size from 10 to

30 mm (Davis 1966; Fricke 1968); this may have been the case with

Palaeozoic ramulate flexible crinoids also.

The stems in Palaeozoic crinoids are frequently very large

compared to the size of the crown, and the visceral mass is very small

in relation to the rest of the body tissues; there are no extensions

of the gut into the stem. It therefore seems doubtful that the

coelomic fluids alone could have supplied the nutrition necessary

for maintaining stems and holdfasts. It is suggested (Franzén, in press)

that fossil crinoids to a considerable extent sustained their peri¬

pheral parts through cutaneous digestion and epidermal uptake of

exogenous free amino-acids and dissolved nutrients from the surround¬

ing sea water. Recent echinoderms and other marine soft-bodied Silurian crinuids from Gotland 19

invertebrates maintain parts of their tissues in this manner (see, e.g., Stephens & Schinske 1960; Péquignat 1966; Ferguson 1967, 1980;

West 1978). According to Ferguson (1980) net flux in,e.g., hcnin— aster under normal conditions is inward by a ratio of nearly 4:1.

A characteristic feature of large (ca. 10 mm or more in dia¬ meter) crinoid stems from Gotland in which columnal height exceeds ca. 1 mm, is the presence of radiating, intracolumnal canals

(Franzén, in press). These canals, termed canali.cu.li, penetrate the columnals and appear as small pores on the external surface of the stem. They may be simple or branched. They provide a connection between the sea water and the axial canal. They are found both in nodals and in internodals and were formed secondarily in the median and distal portions of the stems and in holdfasts. They have not been found in the proximal stem portions where the columnal height is less than ca. 1 mm. Presence or absence of pores appears to be directly dependent on the stem diameter in the adult animal: column¬ als with wide diameters are usually perforated, thin ones are not.

Canaliculi are interpreted as a means of increasing the sur¬ face area of the axial canal in relation to volume within the distal portions of large, fossil crinoid stems. They provided open communi¬ cation between the external sea water and the internal body fluids and facilitate fluid exchange and the uptake of dissolved exogenous nutrients and gases. They probably served a function similar to that undertaken by the ciliated funnels in Recent crinoids.

Intercolumnal canals, fossulae, occur in the distalmost parts of stems and holdfasts with true cirri irrespective of the size of the stem. They formed a connection between the axial canal and the canals of the cirri. In large holdfasts the cross-section of the cirral canals frequently is dumbbell-shaped, suggesting a circulatory function. Fossulae are presumed to have performed the same function as canaliculi.

Dissociated skeletal remains

Crinoid taxonomy is usually based on the morphology of the crown or calyx. The Treatise on Invertebrate Paleontology (Moore & Teichert

1978) lists 838 genera (Echmatocrinea, 1; Camerata, 211; Inadunata, 20 Christina Franzén

491; Flexibilia, 61; and Articulata, 74). However, much work has been done on columnals, stem portions ahd holdfasts, particularly during the 19th century, and several genera and species have been based on dissociated crinoid remains only. Moore & Jeffords (1968,

Table 3) list 443 palaeontologists, authors of 698 papers containing first descriptions of crinoid genera and species based on disarticu¬ lated stems or on holdfasts. Ninety-three genera are listed (73 from the Palaeozoic, 21 from the Mesozoic and 5 from the Cenozoic;

Moore & Jeffords 1968, Table 4). The type species of 53 of these genera is based on a stem portion or a holdfast; subsequently 13 of these genera have been declared invalid (Moore et al. 1978; Ubaghs

1978; Rasmussen 1978).

The large quantities of disarticulated crinoidal remains, particularly columnals and stem portions encountered in the normal course of work have made pressing the need for some means of identi¬ fying and classifying these scattered remains. Artificial classifi- catory schemes based on the morphology of stems and columnals have been proposed by, e.g., Croneis (1938), Moore (1939), Yeltysheva

(1955, 1956, 1959), and Moore & Sylvester-Bradley (1957). Most of the names proposed in the papers mentioned above or based on their schemes are unavailable under the International Code of Zoological Nomenclature (cf. Moore & Jeffords 1968).

There are few crinoid genera which can be identified by dis¬ sociated skeletal elements or portions of their skeletons alone.

The characteristic holdfasts of Ancyroarinus and Camaroorinus are well known as are the stems and columnals of Myelodactylus, Herpeto- arinus and Camptoorinus. The arms of Crotaloarinites and Fetalo- arinus are immediately recognized, and so are the tegminal plates of Euaalyptoarinites and Pterotoorinus and the calycal spines of Callioorinus.

Moore & Jeffords (1968) and Moore et al. (1968) established an elaborate nomenclature and system of indices for the classifica¬ tion of disarticulated parts of crinoid stems. This system must be used with great caution, however, because of the infinite morpho¬ logical variation found in crinoid stems. As a rule longitudinal sections are needed as a complement to external views. Internodals of various generations may be intercalated between biconcave nodals Silurian orinovds from Gotland 21 without being visible in lateral view. In such cases the exter¬

nal noditaxis patterns do not

correspond to the real condition.

Franzén (in press, Fig. 1A) gives

a good example of the difficul¬

ties that arize when trying to

classify pluricolumnals by means Fig. 4. DA. proximal OB. distal columnal of 92 mm long of noditaxis patterns: three stem segment. Note conspicuous different formulae are available difference in shape of axial lumen. SMNH, Stockholm, No. (=three different species!) de¬ Ec 27856; Lärbro, Slite Beds; pending on which side of the xl.5.

stem they are taken from.

The shape of the axial lumen is regarded as an important

feature for purposes of identification. Great care must be taken

here too, however. Fig. 4 shows the rapid change in morphology

which may occur even within a short stem section: the two terminal

columnals might be referred to two different species if they were

encountered as isolated ossicles.

Mutualistic relations

Extant crinoids are infested by and associated with a wide range of

organisms representing several phyla, e.g., protozoans, hydroids,

ophiuroids, polychaetes, gastropods and various crustaceans (for a

summary, see Clark 1921; Hyman 1955). The relationship varies from

true parasitism over semi- and non-parasitic commensalism to casual

association. According to Clark (1921) only about 10% of the animals

which derive part or all of their nutrients from the body tissues of

or by the physical activities of the crinoids are direcLly parasitic.

Ninety percent are indirectly parasitic in varying degrees. Only

few of these parasites affect the skeletal parts of the crinoids,

notably some myzostomid polychaetes which form cysts in the pinnules, and carnivorous, boring snails of the family Helanel1idae.

Malformations caused by various epizoans on crinoid stems

occur throughout the Palaeozoic. Corals (Etheridge 1881; Hudson 22 Christina Franzén

et al. 1966), bryozoans (Etheridge 1881), brachiopods (Etheridge

1881), cornulitids (Franzén 1974), Phosphannulus (Warn 1974; Welch

1976) have induced abnormal, excessive secretion of stereom in the attachment area. These attachments were permanent, and the epizoan apparently restricted the normal growth of the crinoid. Crinoid stems with identifiable epizoans are rare on Gotland. Only Cornu- lites have been found, attached to some stem fragments from the Högklint Beds (lower Wenlockian), the Klinteberg Beds (uppermost

Wenlockian; Franzén 1974, Fig. 12), and the Eke Beds (middle Lud- lovian.

Tha association between crinoids and platyceratid gastropods is well known and has frequently received comment (e.g. Clarke 1921;

Bowsher 1955) . The relationship was fairly casual during the Ordo- vician with the snail apparently using the crinoid only as a firm, elevated substrate. By the Devonian a firm association had developed in which the gastropod invariably was attached over the anal opening of the crinoid (Lane 1978) . This crinoid—platyceratid relationship was not fully established on Gotland during the Silurian. Lindström

(1884) states that "This, the most common of all Silurian Gastropoda of Gotland [=Platyaeras cornutwr, (Hisinger)], has been found almost everywhere, and in all strata between Hoburg and the northernmost point of Fårö" (Lindström 1884, p. 66). This gives P. oornutnm a stratigraphical range from the Högklint to the Sundre Beds, inclu¬ sive, i.e. from lower Wenlockian to the upper Ludlovian (upper

Ludfordian). Lindström does not mention crinoids in connection with

Platyceras either in text or figures; and there are no such specimens in the crinoid or gastropod collections of the Swedish Iluseum of

Natural History in Stockholm. I have found one single specimen

(from the Högklint Beds at Häftingsklint on the northwestern coast) attached to the tegmen of a Dimerocrinites quinquangularis.

Parabolic, shallow pits on stems and crowns are the most fre¬ quently occurring malformations found in Gotland crinoids. Earlier this type of deformity was almost invariably ascribed to the activity of myzostomid annelids (for a summary see Franzén 1974) . But although myzostomes are parasitic, feeding off the particles conveyed along the ambulacral grooves of Recent crinoids, it is doubtful whether the parabolic pits were caused by parasites. The pits are located Si lur Lan crunuuds frum Gu t. Land

on columnals and calyx plates but only rarely penetrate into the lumen of crown or stem. Whatever organisms caused the pits they stimulated the crinoid to excessive secretion of stereom round these pits. Affected plates were strongly deformed and frequently spread over their neighbours, which seriously diminished flexibility and often completely inhibited it. When brachials and pinnulars were fused, feeding cannot have proceeded in a normal way. Pits on brachials and pinnulars are always located on the aboral side. Brett (1978) describes the relationship between pit-producing epizoans and crinoid hosts as a form of dependent commensalism, in which particular epizoan species settled on given crinoid hosts. In the Upper Silurian Rochester Shale of New York and Ontario only seven crinoid species (Icthyocrinus laevis, Synchirocrinus typus, calceocrinid n.sp., Eucalyptocrinites cf. tuberaulatus, E. caelatus,

Asaphocrinus ornatus, and Lecanocrinus macropetalus) were infested out of a total of 30 pelmatozoan species. Host-specificity apparently applies in Gotland also. Only 13 identified crinoid species out of 193 show deformation, namely the inadunates Botryocrinus sp. (Högklint, Högklint Beds), B. ramosissimus (Follingbo, Slite Beds),

Cyathocrinites visbycensis var. moniliformis (Upper Visby Beds),

C. aoinotubus (Klinteberg, Klinteberg Beds), Enallocrinus n.sp. (Hörsne canal, Halla Beds), the flexibles Lecanocrinus hillings i (Visby, Högklint Beds), Iothyocrinus pyriformis (Fårö, Högklint and/ or Slite Beds), I. gotlandicus (Lickershamn, Upper Visby Beds), and the camerates Clonccrinus sp. (Follingbo, Slite Beds), Eucalypto¬ crinites (localities not stated), Carpocrinus sp. (Klinteberg, Klinteberg Beds), Calliocrinus murchisonianus and C. roemerianus

(Visby and Flrö, Högklint and Slite Beds). It is noteworthy that although the species differ, three out of the six Rochester genera serving as hosts for pit-forming epizoans also occur as hosts on Gotland, namely Iothyocrinus, Eucalyptocrinites and Lecanocrinus.

The number of malformed crowns or calices in Swedish museum collections is very low indeed; as a rule there is only a single specimen of each species. Only in Calliocrinus, Eucalyptocrinites and Lecanocrinus have several specimens been found.

Pitted stems are more frequent than pitted crowns or calices.

They have been found from the Lower Visby Beds to the Sundre Beds 24 Christina Franzén

(inclusive). No pitted crinoid material has yet been reported from the Tofta, Hemse, Eke or Burgsvik Beds.

Most of the pitted stems from the old collections in the

Swedish Museum of Natural History in Stockholm are from the Klinte¬ berg Beds (probably from the large quarry at Klinteberget). Nowadays specimens are found in the talus deposits of the Högklint reefs at

Lickershamn and Häftingsklint, but even there they are fairly rare.

Acknowledgements

Anders Martinsson has encouraged my efforts ever since my first day at the Department of Palaeobiology. He has supported me at all stages of my work. I am deeply grateful to him for continuous in¬ spiration and frienship.

My husband Stefan Bengtson, never failing in patience and generosity has given his support and backing to all of my endeavours.

His encouragement and assistance are acknowledged with deep grati¬

tude .

Many colleagues at home and abroad have contributed aid and inspiration by word and deed. Those not mentioned individually here are not by any means forgotten.

My work has benefitted considerably by stimulating discussions with Valdar Jaanusson, Stockholm, Lennart Jeppsson, Lund, Christopher

R.C. Paul, Liverpool, and J. Fredrik Bockelie, Bergen. Sven Laufeld,

Uppsala, Björn Sundquist, Lund, and Anders Martinsson introduced me to the geology of Gotland in the course of highly instructive travels on the island.

Much of my work has been done on collections in museums and in private hands. Valdar Jaanusson and Sven Laufeld deserve my thanks for providing access to, and loans from, the collections of, parti¬ cularly, the Swedish Museum of Natural History in Stockholm and the

Swedish Geological Survey in Uppsala. I have also had full access to the collections of Stefan Bengtson, Kent Larsson, Lund, and Anders

Martinsson. These courtesies, too, are gratefully acknowledged.

I thank Meit Lindell, Uppsala, for her patient and skilful work in preparing fossils, picking marl samples and doing much Eooloijy of Silurian orinoids 25

routine dark-room work. Monica Siewertz, Uppsala, assisted at

the typewriter.

I thank Michael G. Bassett, Cardiff, and Crosbie Matthews,

Uppsala, for considerable linguistic improvements of my manuscripts.

This is a contribution to Project Ecostratigraphy (IGCP

Accession Number 53) and has been funded by the Swedish Natural

Science Research Council (NFR). Travel grants from R. Otterborgs

donationsfond and C.F. Lilgewalchs re sestipendiefond are grate¬ fully acknowledged.

References

Angel in, N.P. 1878: Ieonographia crinoideomm in stratis Sueoiae

Siluricis fossilium. 62 pp. Samson & Wall in, Holmiae. Stockholm.

Ausich, W.I. 1980: A model for niche differentiation in Lower Mississippian crinoid communities. Journal of Paleontology 54,

273-288.

Bassett, M.G. & Cocks, L.R.M. 1974: A review of Silurian brachiopods

from Gotland. Fossils and Strata 3. 56 pp.

Bassett, M.G., Cocks, L.R.M., Holland, C.H., Rickards, R.B. & Warren,

P.T. 1975: The type Wenlock Series. Natural Environmental Research Council, Institute of Geology, Science Report 75/13.

London.

Bather, F.A. 1893: The Crinoidea of Gotland I. The Crinoidea Inadunata. Kongliga Svenska Vetenskapsakademiens Handlingar

25, 1-200.

Bather, F.A. 1898: Petalocrinus, Weiler & Davidson. Quarterly Journal of the Geological Society 54, 401-441. Bowsher, A.L. 1955: Origin and adaptation of platyceratid gastropods. University of Kansas Paleontological Contributions, Mollusca, Article 5, 1-11.

Breimer, A. 1969: A contribution to the paleoecology of Palaeozoic

stalked crinoids. Koninkl. Nederland.se Akademie van Weten-

schappen. Proceedings, B, 72, 139-150.

Breimer, A. 1978: Autecology. In R.C. Moore & C. Teichert (eds.):

Treatise on Invertebrate Paleontology, Part T, Echinodermata 26 Christina Franzén

2(1), T331-T343. The Geological Society of America, Boulder,

Colorado, and the University of Kansas, Lawrence, Kansas.

Breimer, A. & Webster, G.D. 1975: A further contribution to the paleoecology of fossil stalked crinoids. Koninkl. Nederlandse Akademie van Wetenschappen, Proceedings, B, 78, 149-167.

Brett, C.E. 1978: Host-specific pit-forming epizoans on Silurian

crinoids. Lethaia 11, 217-233.

Brett, C.E. 1931: Terminology and functional morphology of attach¬

ment structures in pelmatozoan echinoderms. Lethaia 14, 343-370.

Brower, J. 1973: Crinoids from the Girardeau Limestone (Ordovician). Palaeontographica Americana 7(46), 261-499-

Clark, A.H. 1921: Sea-lilies and feather-stars. Smithsonian

Miscellaneous Collections 72(7), 1-43.

Croneis, C. 1938: Utilitarian classification for fragmentary fossils. Journal of Geology 46, 975-984.

Davis, W. 1966: Observations on the biology of the ophiuroid

Astrophyton muricatum. Bulletin of Marine Science 16, 435-444.

Etheridge, R. 1881: Observations on the swollen conditions of

Carboniferous crinoid stems. Proceedings of the Natural History Society of Glasgow 4 [for 1878-1880], 19-34.

Ferguson, J.C. 1967: Utilization of dissolved exogenous nutrients by the starfishes Asterias forbesi and Henricia sanguinolenta. The Biological Bulletin 132, 161-173.

Ferguson, J.C. 1980: Fluxes of dissolved amino acids between sea

water and Echinaster. Comparative Biochemistry and Physiology 66A, 291-295.

Franzén, C. 1974: Epizoans on Silurian-Devonian crinoids. Lethaia

7, 287-301.

Franzén, C. 1977: Crinoid holdfasts from the Silurian of Gotland.

Lethaia IG, 219-234.

Franzén, C. 1982: A Silurian crinoid thanatotope from Gotland. Geologiska Föreningens i Stockholm Förhandlingar 103, 469-490.

Franzén, C. (in press): Radial perforations in crinoid stems from

the Silurian of Gotland. Lethaia.

Fricke, H.W. 1968: Beiträge zur Biologie der Gorgonenhäupter Astrophyton muricatum (Lamarck) und Astroboa nuda (Lyman)

(Ophiuroidea, Gorgonocephalidae). 107 pp. Ernst-Reuter Gesellschaft, Berlin. Ecology of Silurian crinoids 27

Gray, J., Laufeld, S. & Boucot, A.J. 1974: Silurian trilete spores

and spore tetrads from Gotland: Their implications for land plant evolution. Science 185, 260-263.

Hadding, A. 1941: The pre-Quaternary sedimentary rocks of Sweden. VI. Reef limestones. Kungliga Fysiografiska Sällskapets Handlingar 52(10), 1-137. Lund.

Hede, J.E. 1921: Gottlands silurstratigrafi. Sveriges Geologiska Undersökning C 505, 1-100.

Hede, J.E. 1925: Berggrunden (Silursystemet). In H. Munthe, J.E.

Hede & L. von Post: Beskrivning till kartbladet Ronehamn, 14-51. Sveriges Geologiska Undersökning Aa 156.

Hede, J.E. 1927a: Berggrunden (Silursystemet). In H. Munthe, J.E.

Hede & G. Lundqvist: Beskrivning till kartbladet Klintehamn, 12-54. Sveriges Geologiska Undersökning Aa 160.

Hede, J.E. 1927b: Berggrunden (Silursystemet). In H. Munthe, J.E. Hede & G. Lundqvist: Beskrivning till kartbladet Hemse, 15-56. Sveriges Geologiska Undersökning Aa 164.

Hede, J.E. 1928: Berggrunden (Silursystemet). In H. Munthe, J.E.

Hede & G. Lundqvist: Beskrivning till kartbladet Slite, 13-65. Sveriges Geologiska Undersökning Aa 169.

Hede, J.E. 1929: Berggrunden (Silursystemet). In H. Munthe, J.E.

Hede & G. Lundqvist: Beskrivning till kartbladet Katthammars- vik, 14-57. Sveriges Geologiska Undersökning Aa 170.

Hede, J.E. 1933: Berggrunden (Silursystemet). In H. Munthe, J.E.

Hede & G. Lundqvist: Beskrivning till kartbladet Kappelshamn, 10-59. Sveriges Geologiska Undersökning Aa 171. Hede, J.E. 1936: Berggrunden. In H. Munthe, J.E. Hede & G. Lundqvist: Beskrivning till kartbladet Fårö, 11-42. Sveriges Geologiska Undersökning Aa 180.

Hede, J.E. 1940: Berggrunden. In G. Lundqvist, J.E. Hede & N. Sun-

dius: Beskrivning till kartbladen Visby och Lummelunda, 9-68. Sveriges Geologiska Undersökning Aa 183.

Hede, J.E. 1942: On the correlation of the Silurian of Gotland.

Meddelanden från Lunds Geologisk-Mineralogiska Institution 101, 205-209.

Hede, J.E. 1960: The Silurian of Gotland. International Geological

Congress, 21 session, Norden 1960. Guide to excursions A22 and

Cl 7, 44-87. 28 Christina Franzén

Holland, C.H., Lawson, J.D., Walmsley, V.G. & White, D.E. 1980:

Ludlow stages. Lethaia 13, p. 268.

Hudson, R.G.S., Clarke, M.J. & Sevastopulo, G.D. 1966: The palaeo-

ecology of a lower Viséan crinoid fauna from Feltrim, Co. Dublin. Scientific Proceedings, Royal Dublin Society A 2(17), 273-286.

Hyman, L.H. 1955: The Invertebrates: Echinodermata 4. 763 pp.

McGraw-Hill, New York.

Jaekel, 0. 1918: Phylogenie und System der Pelmatozoen. Paläontolo¬ gische Zeitschrift 3(1), 1-128. Lane, N.G. 1973: Paleontology and paleoecology of the Crawfordsville fossil site (upper Osagian: Indiana). University of California Publications in Geological Sciences 99, 1-141. Lane, N.G. 1978: Mutualistic relations of fossil crinoids. In R.C.

Moore & C. Teichert (eds.): Treatise on Invertebrate Paleontology Part Tj Echinodermata 2(1), T345-T347. The Geological Society

of America, Boulder, Colorado, and The University of Kansas,

Lawrence, Kansas.

Laufeld, S. 1974: Silurian Chitinozoa from Gotland. Fossils and Strata

5, 1-130.

Lindström, G. 1884: On the Silurian Gastropoda and Pteropoda of Got¬ land. Kongliga Svenska Vetenskapsakademiens Handlingar 19(6),

1-250.

Lindström, G. 1888: Über die Schichtenfolge des Silur auf der Insel Gotland. Heues Jahrbuch für Mineralogie und Geologie, Petrefakten- kunde 1, 147-164.

Lowenstam, H. 1957: Niagaran reefs in the Great Lakes area. In H.S.

Ladd (ed.): Treatise on marine ecology and paleoecology, 215-248. The Geological Society of America Memoir 67(2).

Macurda, D.B. & Meyer, D.L. 1974: Feeding posture of modern stalked

crinoids. Nature 247, 394-396.

Magnus, D.B.E 1964: Gezeitenströmung und Nahrungsfiltration bei Ophi-

uren und Crinoiden. Helgoländer Wissenschaftliche Meeresunter¬ suchungen 10, 104-117. Manten, A.A. 1971: Silurian reefs of Gotland. Developments in Sedi- mentology 13, 1-539. Elsevier, Amsterdam. Martinsson, A. 1967: The succession and correlation of ostracode faunas in the Silurian of Gotland. Geologiska Föreningens i Stockholm Förhandlingar 89, 350-386. Ecology of Silurian crinoids 29

tleyer, D.L. & Lane, N.G. 1976: The feeding behaviour of some Paleo¬ zoic crinoids and Recent basketstars. Journal of Paleontology

SO, 472-480.

Meyer, D.L. & Macurda, D.B. 1979: Alive and well after millions of

years. Natural History 88(1), 58-69.

Moore, R.C. 1939: The use of fragmentary crinoidal remains in stratigraphic paleontology. Denison University, Journal of the Scien¬ tific Laboratories 33, 165-250. Granville, Ohio. Moore, R.C. 1978: Flexibilia. In R.C. Moore & C. Teichert (eds.):

Treatise on Invertebrate Paleontology, Part T., Echinodermata

2(2), T759-T812. The Geological Society of America, Boulder,

Colorado, and The University of Kansas, Lawrence, Kansas.

Moore, R.C. & Jeffords, R.M. 1968: Classification and nomenclature

of fossil crinoids based on studies of dissociated parts of

their columns. University of Kansas Paleontological Contribu¬ tions. Echinodermata, article 9, 1-86.

Moore, R.C., Jeffords, R.M. & Miller, T.H. 1968: Morphological fea¬

tures of crinoid columns. The University of Kansas Paleontologi¬ cal Contributions. Echinodermata, article 8, 1-30.

Moore, R.C., Lane, N.G., Strimple, H.L., Sprinkle, J. & Fay, R.O.

1978: Inadunata. In R.C. Moore & C. Teichert (eds.):

Treatise on Invertebrate Paleontology, Part T, Echinodermata 2{2),

T520-T759. The Geological Society of America, Boulder, Colorado,

and The University of Kansas, Lawrence, Kansas.

Moore, R.C. & Sylvester-Bradley, P.C. 1957: Proposed insertion in the

"Regies" of provisions recognizing "parataxa" as a special cate¬

gory for the classification and nomenclature of discrete fragments

or of life-stages of animals which are inadequate for identfica-

tion of whole-animal taxa, with proposals for procedure for the nomenclature of "parataxa". Bulletin of Zoological Nomenclature

15, quadruple pt. 1/4, 5-13.

Moore, R.C. & Teichert, C. (eds.) 1978: Treatise on Invertebrate

Paleontology, Part T, Echinodermata 2(2), T403-T812. The Geo¬ logical Society of America, Boulder, Colorado, and The University

of Kansas, Lawrence, Kansas.

Moore, R.C. & Teichert, C. (eds.) 1978: Treatise on Invertebrate- Paleontology, Part T., Echinodermata 2(3), T813-T1027. The Geo- 30 Christina Franzén

logical Society of America, Boulder, Colorado, and the Univer¬ sity of Kansas, Lawrence, Kansas. Nichols, D. 1960: The histology and acitvities of the tube-feet of Antedon bifida. Quarterly Journal of Microscopical Science 101,

105-117.

Nichols, D. 1969: Echinoderms. 192 pp. Hutchinson University Library, London. Péquignat, E. 1966: "Skin digestion" and epidermal absorption in irregular and regular urchins and their probable relation to the outflow of spherule-coelomocytes. Nature 210, 397-399.

Rasmussen, H.W. 1978: Articulata. In R.C. Moore & C. Teichert (eds.):

Treatise on Invertebrate Paleontology, Part T, Echinodermata 2(2), T813-T927. The Geological Society of America, Boulder,

Colorado, and the University of Kansas, Lawrence, Kansas.

Ruhrman, G. 1971: Riff-nahe sedimentation paläozoischer Krinoiden- Fragmente. Neues Jahrbuch für Geologie und Paläontologie, Ab¬ handlungen 128, 56-100.

Rutman, J. & Fishelson, L. 1969: Food composition and feeding be¬

haviour of shallow-water crinoids at Eilat, Red Sea. Marine Biology 2, 46-57.

Smith, A.G. 1981: Phanerozoic equal-area maps. Geologische Rund¬ schau 70, 91-127.

Springer, F. 1920: The Crinoidea Flexibilia. Smithsonian Institution

Publication 2501, 1-486.

Stephens, G.C. & Schinske, R.A. 1960: Uptake of amino acids by marine invertebrates. Limnology and Oceanography 5, 175-181.

Ubaghs, G. 1956a: Recherches sur les Crinoides Camerata du Silurien

de Gotland, (Suede). Introduction generale et partie I: Morpho¬ logie et paléobiologie de Barrandeocrinus sceptrum Angelin. Arkiv för zoologi 9(26), 515-550.

Ubaghs, G. 1956b: Recherches sur les Crinoides Camerata du Silurien

de Gotland (Suede). II. Morphologie et position systématique du Polypeltes granulatus Angelin. Arkiv för zoologi 9(27), 551-572.

Ubaghs, G. 1958: Recherches sur les crinoides Camerata du Silurien de Gotland (Suede). III. Melocrinicae. Arkiv för zoologi 11(16), 259-306. Ecology of Silurian crinoids 31

Ubaghs, G. 1978: Camerata. In R.C. Moore & C. Teichert (eds.):

Treatise on Invertebrate Paleontology, Part T, Echinodermata 2(2), T408-T519. The Geological Society of America, Coaiaer,

Colorado, and the University of Kansas, Lawrence, Kansas.

Warn, J.11. 1974: Presumed myzostomid infestation of an Ordovician crinoid. Journal of Paleontology 48, 506-513.

Welch, J.R. 1976: Phosphannulus on Paleozoic crinoid stems. Journal of Paleontology 50,'218-225.

West, B 1978: Utilisation of dissolved glucose and amino acids by Leptometra phalangium (J. Müller). The Scientific Proceedings of the Royal Dublin Society A, 6, 77-85.

Yeltysheva, R.S. (EjiTbiweBa, P.C.) 1955: Knacc Crinoidea, MopcKne

.timamm, cTeGnu mopckmx jimjimm . Class Crinoidea, sea lilies,

crinoid stems. In O.M. HMKM0opoBa (ed.): rioneBOM amac

OpflOBH kc KOM m CMAypMMCKOM 0ayHbl CmGmpckom rmaT0OpMbl, 40-^7.

Tpyflbi BCETEH 140.

Yeltysheva, R.S. (EjiTbiweBa, P.C.) 1956: cteöjim mopckmx jimjimm m mx

Knaccm0mkammm. Crinoid stems and their classification.

JleHMHrpaflckmm yhmbepcmtet, BecTHMK, cep. TeonorMn m reorpa0MB

12, 40-46.

Yeltysheva, R.S. (EjiTbiweBa, P.C.) 1959: 11 pmhamiim knaccm0mkagmm,

metoflmka M3yMeHmb m CTpaTMrpa0MuecKoe 3HaueHMe CTe6neM mopckmx

jimjimm. Principles of classification, methods of study, and

stratigraphic importance of crinoid stems. In: Bonpocbi

naneoÖMO/iorMM m 6MOCTpaTMrpa0MM, 230-235. Bcecoi03Hoe naneoH-

TonorMuecKoe oGmectBo, EweroAHMK, TpyAbi 2.

ACTA UNIVERSITATIS UPSALIENSIS Abstracts of Uppsala Dissertations from the Faculty of Science Editor: The Dean of the Faculty of Science

Doctoral dissertations from the Faculty of Science are published either as monographs or as summaries of articles. It is these summaries that are collected in the series "Abstracts of Uppsala Dissertations from the Faculty of Science". Distributor: Almqvist & Wikseil International

Stockholm — Sweden

UPPSALA UNIVERSITET ISBN 91-554-1363-3 REPRO-C HSC 1983 ISSN 0345-0058