Contr. Tert. Quatern. Geol. 30(1-2) 41-73 15 figs, 4 tabs, 4 pis. Leiden, June 1993

Early Danian species of the echinoid genus Tylocidaris

(Cidaridae, Psychocidarinae) from eastern Denmark

Palle Gravesen

Geological Museum

Copenhagen, Denmark

Palle. Danian of the echinoid from Denmark. — Contr. Gravesen, Early species genus Tylocidaris (Cidaridae, Psychocidarinae) eastern

Tert. Quatern. Geol., 30(1-2): 41-73, 15 figs, 4 tabs, 4 pis. Leiden, June 1993.

of the echinoid 1883 were used index fossils for the Danian Primary spines genus Tylocidaris Pomel, formerly widely as key (Early

In their value such has been discredited and distribution has been shown be Palaeocene). recent years as tylocidarid species to

diachronous in relation todinoflagellatebiostratigraphy as well as be facies-dependentto the extent that they are missing from important

facies of Difficulties in correlation between the Danian of Denmark and southern Sweden have types the Danian. establishing a strata

also affected their practical use. A biostratigraphical study based onspecimens collected bed by bed at Stevns Klint and additional studies

localities situated in the Danian have evidence that the at Karlstrup quarry (both Stage type area, eastern Denmark), provided Early

Danian tylocidarid zonation of Denmark and southern Sweden is essentially the same with T. oedumi Brünnich Nielsen, 1938 and T.

for Limhamn abildgaardi Ravn, 1928 being restricted to two distinct zones, and thus not co-occurring as suggested by Brotzen (1959) the

locality in Sweden. One major discrepancy between the Danish and Swedish biozonation schemes has thus been eliminated. Material

collected shows that Middle Danian rosenkrantzi Zone is that this been at Karlstrup quarry an early present at locality, zone not having

recorded from Denmark far. collected material of T. oedumi and T. so Especially interesting amongst newly are tests abildgaardi. Finally,

bryozoan mound growth is discussed. It is suggested that the growth ofEarly Danian mounds was affected by palaeocurrents which swept

sediment from thus formation take there. The have existed for a away intervening troughs, allowing hardground to place troughs must

considerable time At Stevns shows series ofconsecutive In the span. Klint, alarge trough structure an impressive (incipient) hardgrounds.

bryozoan mounds, net growth rate is shown to have been rather slow, allowing typical T. oedumi to evolve via ’overlap forms’ to T.

the formation of the first series ofmounds. A model for evolution in the Danian is with abildgaardi during new tylocidarid type proposed,

the lineage oedumi- -’overlap forms’-abildgaardi-ravni-bruennichi becoming extinct in the late Middle Danian, then being replaced by vexilifera,

from originating a lineageoedumi-rosenkrantzi-vexilifera.

— Key words Danian, biozonation, Cidaridae (Psychocidarinae), Tylocidaris, evolution, bryozoan mounds, Denmark, Sweden.

P. Gravesen, Geologisk Museum, 0ster Voldgade 5-7, DK-1350 Copenhagen K, Denmark.

Contents mark and southern Sweden. Although still very use-

doubts their index ful, as to importance as fossils Introduction 41 p. have recently been expressed, their place being of biozonation 42 History tylocidarid p. taken by micro- and/or nannofossils such as for- Localities 43 p. aminifera, dinoflagellates and calcareous nanno- Methods 47 p. plankton. Systematic descriptions p. 49 Two factors have contributed to this situation: Conclusions p. 56 — the conclusion that their geographical distribu- 56 Phylogeny p. tion is diachronous in relation to dinoflagellate bio- Patterns of bryozoan mound growth p. 61 zonation (Hansen, 1977), being evidently facies Acknowledgements p. 64 that dependent to the extent they are missing from References 64 p. facies of the many important Danian;

— difficulties related to the definition and identi-

fication of within the Introduction species genus.

The work Danian is that For a long time tylocidarids, i.e. the disarticulated most recent on tylocidarids

of various of primary spines species the genus of Brotzen (1959), who presented a detailed bio-

have been considered zonation for the Limhamn Tylocidaris Pomel, 1883, quarry (Skane, SW

important key index fossils for the Danian of Den- Sweden) comprising the following zones: 42

Tylocidaris herupensis (= Late Danian) [top] Danian. Rosenkrantz (1965) presented compelling

the Zone arguments in support of view that Schliiter's

Tylocidaris briinnichi (= late Middle Danian) specimens must have come from the former quarry

Zone at Herfolge, south of Koge (eastern Sjaelland) and

rosenkrantzi Middle thus must be of Late Danian Tylocidaris (= early Danian) age.

Zone In 1909, Brtinnich Nielsen was the first to point

Tylocidaris oedumi (= Early Danian) out that the various forms of T. vexilifera Schltiter

in the Danian be useful index Zone [bottom] occurring might as

fossils. It was not until 1926 that 0dum subdivided

A similar, but different, zonation had already been Schliiter's species into three 'forms', viz ■ forma beta established in Denmark by Brtinnich Nielsen (1938), (= T. vexilifera Schliiter, 1892 s. str.), forma alpha (=

amended Rosenkrantz & T. and forma T. which was subsequently by abildgaardi Ravn, 1928), gamma (=

Wienberg Rasmussen (1960) as follows: oedumi Briinnich Nielsen, 1938).

Ravn (1928) proposed the following division of

Tylocidaris vexillifera (= Late Danian) [top] Schliiter's species: forma typica (= T. vexilifera

Zone Schliiter, 1892 s. str.), var. Brünnichi (= T. bruennichi

Tylocidaris bruennichi (= Middle Danian) Ravn, 1928), and var. Abildgaardi (= T. abildgaardi

Zone Ravn, 1928 and T. oedumi Briinnich Nielsen, 1938).

Ravn's Brünnichi introduced and Tylocidaris abildgaardi (= late Early Danian) var. was newly is

Zone now known to characterise the Middle Danian. In

Tylocidaris oedumi (= early Early Danian) his var. Abildgaardi, Ravn grouped not only the Early

Danian known under that but Zone [bottom] species now name

also 0dum's forma T. (1926) gamma (= oedumi).

Since their introduction, differences between these Later, Briinnich Nielsen (1938) presented the fol-

correlations zonation: zonations have frustrated based on lowing tylocidarids between the Swedish and Danish Dan-

Late Danian ian and have contributed to the view that bio- Tylocidaris vexilifera Schliiter

based hitherto useful Ravn, stratigraphical dating on spe- (.sensu 1928) cies of this is with difficulties. Tylocidaris bruennichi Ravn, genus fraught 1928 The discrepancies between Brotzen's (1959)

Danian zonation and the Danish zonal scheme were the Early Tylocidaris abildgaardi Ravn,

1928 main reason for a renewed investigation reported

in the of Tylocidaris oedumi Briinnich upon herein, hope shedding new light on

Nielsen, 1938 on forma some of the main problems. However, many ques- (based tions since the 0dum, remain, especially present paper gamma 1926) focuses Danian only on Early tylocidarids. Middle and Late Danian should be stud- This zonation also used in tylocidarid species new was the virtually ied in the along similar lines (near) future. simultaneous Rosenkrantz the paper by (1938) on

stratigraphy and tectonics of the Danian of eastern

Wind without Sjaelland. (1953, 1954), any justifica- HISTORY OF TYLOCIDARID BIOZONATION tion, referred T. oedumi to the late Turonian-?late

the of this Santonian T. sub- At beginning century, only a single spe- (T.) clavigera (Mantell, 1822) as a cies of T. and T. T. bruennichi and Tylocidaris, vexilifera Schltiter, 1892, was species abildgaardi, T. vex- recorded from the Danian. Ever since its erection, ilifera to the Campanian-Maastrichtian T. pomifer this species has presented problems. To start with a (Leymerie, 1851) [now referred to the genus Sar-

Schltiter docidaris Smith minor point: (1892, p. 126 [54], pi. 17, figs Lambert, 1907; see & Wright, 1989]

the trivial while also T. T. Brünnichi 3, 4) spelt name as vexilifera, many as subspecies, viz. p. pomifer, p. palaeontologists after him have preferred vexillifera. and T. p. herupensis Wind, 1954, respectively. Wind's

Much more serious confusion arose from the fact taxonomy has not been adopted by later workers, that Schltiter stated that his species originated from with the exception of Brotzen (1959), who used the

Maastrichtian white chalk of Stevns the Klint, name Tylocidaris herupensis Wind, 1954 for T. vex- which is an error, the species being typical of the ilifera Schliiter, 1892. 43

Brotzen's the biozonation of resolve the between eastern Denmark paper on tylocidarid discrepancies the Danian of Limhamn is of prime importance; and southern Sweden. Two localities in eastern

windi Denmark three new species were erected, viz■ T. (Early (Karlstrup and Stevns Klint) were selected

T. and T. ravni Mid- for this and with Limhamn Danian), rosenkrantzi (both early purpose, compared (SW dle the sides the 0resund. All three Danian). According to Brotzen, Danian of Sweden) on opposite of

Limhamn shows the in localities situated in the of the Danian following pattern tylocidarid are type area

and distribution: Stage (compare Brotzen, 1959, fig. 1) are thus

of prime importance in biostratigraphical studies of

— Late Danian herupensis Zone the type Danian. Detailed descriptions and sections

T. of Limhamn [species represented: quarry may be found in Brood (1973),

herupensis (= T. Cheetham (1971), Holland& Gabrielson (1979) and

vexilifera)] Holland (1982).

— late Middle Danian bruennichi Zone

T. [species represented: LOCALITIES

bruennichi] 1. — Karlstrup early Middle Danian rosenkrantzi Zone quarry

[species represented: T. The quarry at Karlstrup (formerly Kagstrup) is situ- T. and rosenkrantzi, ravni, ated in 10 km north eastern Sjaelland, c of Koge, T. abildgaardi] south of Copenhagen. Quarrying was ceased in the

— Danian oedumi Zone Early mid-1970s. The of the exhibit- deeper part quarry, [species represented: T. ing more than 14 m of Late Maastrichtian white T. and T. oedumi, windi, is chalk, now flooded; the remaining part is in the

abildgaardi] of the sides of process becoming overgrown. Along

the there still sections the water are fine exposing

As mentioned above, this zonal scheme differs from Cretaceous/Tertiary boundary (see Gravesen,

the Danian Ekdale & the biozonation used then and now for 1983; Bromley, 1984). Bryozoan lime- of main oedumi and Denmark. The problems concern the Early stones of the Early Danian abildgaardi

Danian, where Danish palaeontologists distinguish Zones are still beautifully exposed at the W, N, and

earliest Danian E faces. a separate Early oedumi Zone, quarry overlain the late Danian Zone. thus series of strata by Early abildgaardi Karlstrup quarry exposes a

The Middle Danian in the Danish zonal scheme more or less identical to that seen at Stevns Klint.

but of T. The of Middle Danian comprises a single zone, that bruennichi, presence at Karlstrup early since T. rosenkrantzi has been recorded from strata is discussed in detail below. The is not yet sequence

follows: the Danish Middle Danian (see below). as

Hansen (1977) complicated matters even more by — white chalk showing tylocidarid distribution to be diachronous in relation to the proposed dinoflagellate biozona- This unit [latest Maastrichtian, equivalent of tion. To this be that from field Brotzen's may added, my own (1959) 'Stevnsian', brachiopod zone 10 of work and of the it has become Belemnella casimirovensis a study literature, Surlyk (1970, 1972),

that Zone in belemnite and apparent tylocidarids are extremely rare in or terms Pseudotextularia ele-

absent from of Zone of foraminiferal even some the major facies types of gans biozonation], comprises the such of the micritic and bio- 'normal' white chalk facies with Danian, as many a some bryozoans micritic limestones and diverse macrofauna in known collectively under infor- a [list Gravesen, 1983; mal old 'kalk- also or names as 'blegekridt', 'slamkalk', see Surlyk (1979a, p. 47)]. sandskalk' or 'Saltholmskalk', thus diminishing — Fish Clay (Fiskeler) further their value as key index biota. Tylocidarid

in lime- This laminated marl species most commonly occur bryozoan unit comprises a finely with a stone facies. maximum thickness of 10 It contains cm. many

The aim of the is to the remanie Late Maastrichtian fossils. present paper investigate

which still extent to tylocidarid species may be used — Cerithium Limestone biota for the Danian of as key index Early eastern

Denmark. It considered essential is 30-100 thick soft limestone was to attempt to This a cm reminiscent 44

it is 1959. In from the footof ofthe white chalk facies. At the present locality, Brotzen, addition, scree at of of the the northern face a number spines referred to as 'streaky chalk', on account quarry proba-

marl. On microfaunal evi- from the uppermost parts of the section many streaks of greyish bly coming been collected. These here dence (foraminifera) it is assigned to the exposed have are

referred to T. aff. Eoglobigerina danica Zone (Bang in Gravesen, as rosenkrantzi (PI. 4, Figs 5-11).

' The occurrence of both T. ravni’ and T. aff. rosen- 1983). Two spines herein referred to as Tylocidaris

known date from the krantzi at this indicate the at the aff. oedumi are the only ones to locality presence face of earliest Middle Danian Cerithium Limestone in Denmark (see discussion northern quarry

referable the rosenkrantzi Zone. below). strata to

— ’Karlstrup Chalkstone’

2. Stevns Klint the Cerithium Limestone and Resting upon sepa-

unit is rated from that a flint band a 25-40 and classic first by (-50) This well-known locality was prop-

indurated limestone of hardground has cm thick type erly described by Abildgaard (1759) and since siliceous with thalassinoid burrows and common remained to local Danish very important not only

cf. alveolites Roemer, but also because of the Cre- sponges ((Aphrocallistes 1841). geology, internationally external moulds Aragonitic biota are preserved as taceous/Tertiary (K/T) boundary strata being well

and include gastropods and bivalves. Echinoids are exposed along this cliff section. For a historical

found locally. Spines of T. oedumi demonstrate that review of the research of Stevns Klint the reader is

of the oedumi Zone at this discussions this unit forms the base referred to Gravesen (1979a). Detailed

be found in Forchhammer Ravn locality. may (1825), (1903),

Milthers (1908), Briinnich Nielsen (1917), Rosen- — Early Danian bryozoan limestones krantz (1924, 1940, 1966), Andersen (1944), Rosen-

These limestones display well-developed biohermal krantz & Wienberg Rasmussen (1960), Berthelsen

similar those Rasmussen structures, which lithologically are to (1962), Berggren (1964), Wienberg

found at Stevns Klint and contain the same macro- (1967, 1971), Hakansson (1971), Christensen et al.

faunas, including echinoids, crinoids, asteroids, (1973), Birkelund & Bromley (1979), Bromley

bivalves, brachiopods, gastropods, octocorals and (1979b), Floris (1979) and Surlyk (1979b, 1984).

addition the Danian sponges. In to two Early spe- — Korsnæb section cies T. oedumi and T. abildgaardi also spines occur

that forms' this Stevns Klint are attributable to 'overlap (see below) For the present study part of was Klint and referred T. as found at Stevns spines to as chosen because here the Cretaceous/Tertiary

aff. rosenkrantzi and T. ravni, both indicative of the boundary is closer to beach level than anywhere else

early Middle Danian. along the cliff, which makes the earliest Early Dan-

of this ian strata more easily accessible. Because

select the access at the Korsnaeb section, it was possible Originally, it was intended to bryozoan easy collect bed bed. limestone sections at Karlstrup for detailed bed-by- to specimens by

of lack The is of the southernmost bed collections of tylocidarids; because a of Korsnaeb section part

of of faces this had to be aban- of Stevns Klint, situated east Rodvig stability quarry plan exposure

therefore It the easternmost 400 m of doned. The emphasis of the field work was (Figs 1, 2). encompasses

the in the shifted to the Korsnaeb section at Stevns Klint cliff, ending prominent point (headland)

described below. by the name of Korsnaeb.

well the Danian The Karlstrup section is of particular importance The section exposes Early biohermal in having yielded the first tylocidarid spines from bryozoan limestones with well-developed

known In the the Late the Cerithium Limestone of Denmark to structures. some parts of section,

Cretaceous/Ter- date (see PI. 1, Figs 1, 2). Because of this limited Maastrichtian white chalk and the

also number of specimens their specific assignment is far tiary boundary strata are exposed.

here T. aff. oedumi. The here is follows: from clear; they are referred to as sequence exposed as

Ex situ abildgaardi-like spines with diminutive crowns a - Late Maastrichtian white chalk characterise the transition from T. appear to the abildgaardi to the Middle Danian coronate forms of This unit most probably corresponds entirely to

T. ravni chalk' the classic T. bruennichi; they are best referred to 'grey ('Grakridt') as exposed at 45

Fig. 2. The Korsnæb section seen from the beach at Rødvig

(summer of 1984).

Korsnaeb section it is generally thinner (maximum

thickness often only c 10 cm or even as thin as one to

Due action it is often a few centimetres). to wave

fissure in the cliff face. washed out leaving an empty

c - Cerithium Limestone

In the Korsnaeb section this unit generally attains a

thickness of 20-40 in the of the c cm; western part

which is section it is much thicker, up to 70 cm,

about the maximum thickness encountered at

Stevns Klint. Where it is thickest, it consists of two

Fig. 1. Maps showing location of Karlstrup, Stevns Klint and different lithological entities merging imperceptibly

the Korsnaeb the Korsnæb section is situated headland; into each other.

directly west of Korsnæb. lower is The part a whitish, chalk-like, and soft

sediment with numerous streaks of grey marl. The

is hard upper part a yellowish or yellowish-white,

with Thalassinoides burrows and section at Hojerup a few kilometres to the north. limestone numerous

in chalk with nodular and is as a This is a white bryozoans, developed typical hardground, places

tabular streaks and burrows with slickensides. Within this flints, grey marly showing well-developed

fossils marly infill. For a detailedlithological description of hardground, aragonitic are preserved as

this facies at Hojerup, the reader is referred to external and internal moulds, showing fine details of

Hakansson et al. (1974). This unit yields in the ornament. The macrofauna includes gastropods,

siliceous and echinoids. Korsnaeb section a varied macrofauna. As at solitary corals, sponges

the of The Hojerup, the top parts (between depressions marginal parts of the Thalassinoides burrows

the Fish indurated form the so-called often converted into tubular Clay) are to are flints, correspon-

of the burrows. 'Indurated white chalk' with aragonitic fossils pre- ding to the original shape Internally

moulds. these flints often sediment served as internal and external Together contain unconsolidated

with the earliest Danian Cerithium Limestone the with bryozoans and extremely well-preserved Early

echinoid 'Indurated white chalk' forms part of the complex Danian fossils, e.g. the shallow-burrowing

danicus 1897 the hardground at the Maastrichtian/Danianboundary Brissopneustes Schliiter, (referred to

1856 in (see e.g. Surlyk, 1979b). genus Cyclaster Cotteau, by Asgaard, 1976),

T. other parts of Stevns also spines of oedumi, gastro- b - Fish Clay and bivalves. This fauna match that pods appears to

found in the lowest beds of the This unit reach thicknesses of 35 cm at may locally overlying bryozoan

Stevns Klint (Christensen et al., 1973). In the limestone. 46

Reference point Height Reference point Height

KO -175 367 KO -45 251

KO -165 343 KO -35 202

KO -155 315 KO +10 194

KO -145 312 KO +20 190

KO -135 285 KO +30 204

KO -120 244 KO +40 190

KO -115 255 KO +50 178

KO -110 248 KO +60 143

KO -65 231 KO +90 203

KO -60 244 KO +95 226

KO -55 246 KO +100 193

KO -50 255

Table 1. Height of lower boundary of bryozoan limestone at

the Korsnæb section, Stevns Klint (vertical height in

centimetres above beach level on 27 July 1985; level-

ling by Peter Toft and Palle Gravesen).

d - Early Danian Bryozoan Limestone

This unit has lower (Table 1) a sharp boundary

formed (probably an originally erosive contact under submarine conditions, compare Surlyk,

1979b, p. 169; Birkelund & Hakansson, 1982, p.

As be in Table this lower bound- 375). may seen 2,

is situated at different levels above the ary present

of 400 beachline even over a short distance m, as occupied by the Korsnaeb section. If this boundary

be assumed have been plane can to originally rea-

Fig. 3. The westernmost part ofKorsnæb section showing Late the variation in vertical sonably even, present posi- Maastrichtian white chalk and K/T boundary strata tion be attributed the must to a slight folding of (March 1987). For horizontal co-ordinates see text. B - strata in times Rosenkrantz, post-Danian (compare lowermost part of Early Danian Bryozoan Limestone 1938). forming bulk of cliff (marked is the base of the oedumi

Zone); C - Cerithium Limestone (earliest Danian); F - The Bryozoan Limestone (Fig. 3) typically con-

Fish Clay (basal Danian marl); S - Late Maastrichtian of benthic sists of numerous skeletal fragments white chalk (baltica Zone). biota, mostly bryozoans, in a micritic matrix. Its

% of benthic fauna may make up as much as c 40 the sediment (Birkelund & Hakansson, 1982, p.

still the in mud- and infaunal danicus 375), but fabric remains large part (Goldfuss, 1829) Brissopneustes

A closer look Schluter, supported (Bromley, 1979a, p. 17). 1897], A closer look also reveals the of reveals the presence of a wide range of subfacies: presence finely

laminatedlimestones little bioturba- marly layers, incipient as well as well-developed (with apparent typical hardgrounds, the latter being the so-called tion) as opposed to limestones where bioturbation

have disturbed much ofwhatever 'Krabbelag' of Briinnich Nielsen (1917; compare seems to primary

lamination there have been. In also Rosenkrantz, 1966, p. 724), echinoderm might places,

'coquinas' with winnowed micrite, comprising Thalassinoides forms complex networks (Figs 11,

skeletal the flanks of also A detailed solely debris, on some bio- 12; see Bromley, 1979a, p. 27). of The an herms, etc. (see Surlyk 1979b, p. 170). coquinas sedimentological study comprising analysis is bound wealth consist of of the ichnofauna to a of new may randomly orientated echinoid tests yield

information epifaunal Echinocorys sulcata (Goldfuss, 1829) [at on the details of formation of these

Karlstrup also of epifaunal Phymosoma aff. granulosum bryozoan limestones. 47

Biostratigraphically, these limestones have tradi-

tionally been divided into two tylocidarid zones:

that of T. oedumi in the lowermost beds and that of

The T. abildgaardi in the remaining part. macro-

fauna of these be less two zones appears to more or

identical. The lower beds of the Bryozoan Lime-

and stones are almost horizontal, only some metres

higher do typical biohermal structures start to

appear. Having once started to form, however, they

into bioherms must have grown impressive standing

out several metres above the sea floor at that time

with deep, current-swept, elongated troughs

between them (see discussion below). The bryozoan

limestones and contain a number of distinct impres-

sive flint bands which have all been numberedand

used in the course of the present investigation.

METHODS

The field work at the Korsnaeb section (Figs 4, 5)

the lines: was conducted along following

Fig. 4. The Korsnæb section: western flank of a large bioher-

1 - of section preparation a drawing of the entire mal in structure Early Danian bryozoan limestones

(Fig. 8a, b); (March 1987). For horizontal co-ordinates see text.

The section: Fig. 5. Korsnæb part of biohermal structure in section KO +25, illustrating the practical use of the co-ordinate system

described in the text (March 1987). Flint bands are numbered consecutively. 48

of - of all flint bands so as to have a set 2 numbering Section Local flint band

marker horizons for bed-by-bed collection numbering

(Table 2); KO +25 KO +25/F6

3 - establishment of a co-ordinate covering system KO +75 KO +75/F6 the the entire cliff face of section; KO +100 KO +100/F10

of detailedsections dif- KO +130 KO +130/F7 4 - measurement at twenty

KO +150 KO +150/F4 the cliff face as ferent locations as high up possi- KO +185 KO +185/F6 4 6 ladders. ble, making use of or m long

Table 2. Example of numbering of a marker horizon within these shown in 11-15. Some of sections are Figs various sections of the Korsnæb section, Stevns Klint Points 2 and 3 in need of further are explanation: (here, the flint band marking the lower boundary of

Due to the complexity of the biohermal structures the abildgaardi Zone). occurring in this bryozoan limestone unit, bed-by-

In bed collecting presents problems immediately.

the KO 0 From this passing from one biohermal structure to other, to as [short for KO(rsnaeb)]. point,

the individual limestone beds and flint bands tend to distances were measured horizontally to right

and other and the left either thin out disappear or merge with (positive figures) to (negative figures). beds flint limestone beds and the vertical and horizontal reference or bands; also, new Using systems,

intercalated. A closer how- co-ordinate was out over flint bands may be look, a system effectively spread

of marker flint the cliff face. The individual sections were named ever, reveals a pattern horizons, the axis in the bands in particular, but also marly horizons and after their position along horizontal

which be from bioher- hardgrounds, can traced one following way:

of them mal structure to an adjacent one, some even 1 - section KO -150 (from KO —175 to KO -115) these marker horizons over long distances. Tracing — - KO KO 2 - section KO 90 (from -115 to 70) results in a first tentative basis for correlation of - - KO - 3 - section KO 30 (from KO 70 to 10) individual beds from one structure to the next.

- 4 - section KO + 25 (from KO 10 to KO + 70) Numbering the individual limestone beds and flint 5 - section KO + 75(fromKO+ 70 to KO + 85) within each bands is possible only separate bioherm. + KO 6 - section KO +100 (from KO 85 to +120) This necessitates the establishment of a number of KO 7 - section KO +130 (from KO +120 to +140) different which reference systems, each of can only 8 - section KO +150 (from KO +140 to KO +170) be used within the individual bioherm for which it

9 - section KO +185 (from KO +170 to KO +210) worked This be the has been out. appears to only 10 - section KO +220 (from KO +210 to KO +223) practical solution to the problem.

the 400 Korsnaeb section was Within each individual biohermal structure a In this way, m long

limestone beds and flint divided into individual sections of numbering system for ten unequal

flint conform with the individual biohermal bands was established, in practice focusing on length to

bands, numbered consecutively from bottom to top structures.

F3 each section has its individual numbe- Fl, F2, and so on. Bed-by-bed collecting can Thus, own

limestone beds As then be undertaken with reference to this system ring system for and flint bands.

collected be documented as the numbers of these do from one and specimens may not correspond band be numbered follows: section to the other, a flint may

'4' in one section and '6' in another where more

+ 13 cm above of F3 top ..., or, Table flint bands are developed (see 2). To avoid

- below base of F4 17 cm .... which flints bands confusion as to particular are

indicated both all bands should be a However, because of extreme lateral variations seen meant, by well the number. does 'section index' KO as as in biohermal structures a vertical reference not (e.g. -30)

4 KO from where within Flint no. from within section suffice. To be able to tell exactly (counted below)

-30 should then be indicated as KO -30/F4. a biohermal structure (top, flank, intervening

has A combination of the horizontal reference troughs etc.) a specimen been collected, a means system

with the numbered flint bands within of referring to the horizontal plane is also needed. individually

also the different sections co-ordinate To this end, a horizontal division was estab- provides a system

for the entire Korsnaeb section, the collec- lished starting from an arbitrary zero point referred enabling 49

tinctive that be identified to tion of specimens along the entire section and a they may immediately reference the location of this to of T. to precise specimens, e.g.: species; applies fully-grown spines e.g.

oedumi, T. abildgaardi, T. bruennichi, and T. vexilifera,

- horizontal KO vertical parameter: -30,76 m; which have been held explains why they to repre- 18 KO parameter: + cm above top of flint -30/F3, sent good index fossils for the Danian. However, or, there serious In it is often are problems. practice,

- difficult to individual as shown horizontal parameter: KO +220,24 m; vertical identify spines, and, the bound- - below base of flint KO there is level parameter: 5 cm +220/F7. below, a ('overlap zone') at

of the oedumi and Zones Stevns ary abildgaardi at All bed-by-bed collecting at the Korsnaeb section Klint where a proper assignment of spines is diffi- has been done this co-ordinate using system. cult. In my opinion, the individual populations

Danian ('species') of Tylocidaris within the can only SYSTEMATIC DESCRIPTIONS be defined statistically, meaning that a single or a

few not be an basis for the — spines may adequate Introductory remarks The genus Tylocidaris was identificationof erected for cidarid with clavate a species. echinoids or glan-

Morphotype analysis — Putting the various shapes of diform primary spines and imperforate primary

the Danian tylocidarid spines into a scheme that tubercles. Like most other regular echinoids, be treated In tend can statistically presents a problem. tylocidarid tests to disintegrate rapidly upon practice, I ended with the following method death resulting in fossil assemblages consisting of up (Table 3) based on an assessment of the form of the scattered spines, dissociated lantern elements and the of of interam- spines (= morphotypes) according groupings tests mostly consisting a single row shown in 6 and described below: with Fig. bulacral plates two adjacent rows of ambu- lacrals or even single plates. For a full discussion of

various of of echi- the stages disintegration regular noids Schafer Smith and see e.g. (1971), (1984) espe- cially Kidwell & Baumiller (1990).

Danian of almost exclu- As species Tylocidaris are sively found in bryozoan limestone facies, which to a large degree consists of more or less broken skele-

of bra- tal parts bryozoans, crinoids, asteroids, chiopods, irregular and regular echinoids etc., it is not surprising that the tylocidarid remains are mostly found in a state of advanced disintegration

(loose spines, lantern elements and test plates).

associated with Complete tests are rare; tests spines such as the specimen figured by Ravn (1928, pi. 4, fig. 35) or the specimen figured herein (see PI. 2, Fig.

7) are rarities.

However, during field work it appeared that test

with segments (interambulacral segment adjacent ambulacral in the columns) are fairly common Early

Danian bryozoan limestones both at Karlstrup and at Stevns Klint and also that tests complete (without Fig. 6. Morphotypes of tylocidarid primary spines as here

- A - spines) are not quite as rare as previously thought. defined: type 3 typical T. oedumi; type 4 overlap

5 - T. 6 - T. forms; type abildgaardi; vexilifera; dozen or so complete tests of T. abildgaardi have type type

3a - T. baltica; type 3b - T. rosenkrantzi. See text for been collected at Karlstrup and at Stevns Klint. Of details.

T. oedumi, however, only a single complete test has so far been encountered (see PI. 2, Figs 1-3).

Danian show wide of tylocidarid spines a range morphotype 1: elongate clavate, sides parallel variation far is this has sides as as morphology concerned; morphotype 2: elongate clavate, straight as

the erection several well led to of 'species' (Brotzen, as divergent

1959). The primary spines of some taxa are so dis- morphotype 3: elongate clavate, sides divergent 50

but forming concavity; gradual Type species — Cidaris clavigera Mantell, 1822.

head taper from neck to head; Tylocidaris (Tylocidaris) oedumi Brünnich longer than neck. Maximum Nielsen, 1938 width of spine distally. PI. 1, Figs 17-33; PI. 2 morphotype 4: short clavate with elongate head;

claviculae echinorum 4a head and neck approximately of 1759 Abildgaard, p. 15, pi. 3, fig. (?b). equal length, Schliit. 1923 Tylocidaris vexillifera ? —Jessen & 0dum, pp. 22, short neck morphotype 5: very clavate, thin, pass- 23, pi. 2, fig. 3. into ing abruptly globose head; forma 1926 Tylocidaris vexillifera Schluter gamma 0dum, p. lacking 'crown', 160, pi. 1, fig. 3a-d.

but Schliit. var. Ravn, 35, morphotype 6: as type 5, with shorter or 1928 Tylocidaris vexillifera Abildgaardi p. pi. 4, figs 27, 29 (non 26, 28, 30, ?31, 32-35). longer 'crown'. Ødumi Briinnich 126. 1938 Tylocidaris Nielsen, p. To these main be added the types may following: 1944 Tylocidaris oedumi — Andersen, fig. 231.

1953 Tylocidaris clavigera Ødumi (Briinnich Nielsen) — Wind, morphotype 3a: elongate clavate to semiglobose. tab. 2. morphotype 3b: elongate clavate, maximum width 1954 Tylocidaris clavigera Ødumi (Briinnich Nielsen), 1937 — at c mid-length. 481, 13, 59-63. Wind, p. pi. figs 1-10,

1959 Tylocidaris ödumi Briinnich Nielsen — Brotzen, p. 38, pi.

38, figs 15-19, 24-30; text-fig. 12a-e.

ødumi — Rosenkrantz & Morphotypes 1960 Tylocidaris Wienberg

7. II III IV V Rasmussen, p. 6, figs 1,

ødumi — 61 1966 Tylocidaris Wienberg Rasmussen, p. (fig). T. abildgaardi 2.4 12.0 22.4 63.2

"overlap" forms 2.9 50.5 41.9 4.8 Type — Brünnich Nielsen (1938) failed to designate

T. oedumi 3.6 76.8 19.6 0 Brotzen a type specimen. (1959, p. 41) proposed to

designate 'holotype' the spine illustrated by 0dum Table 3. Morphotype analysis of three tylocidarid populations (1926, pi. 1, fig. 3b). This specimen is herein of the Korsnaeb section, Stevns Klint (see text for selected as lectotype. details). Locus typicus — Barmer 1 (Jylland, Denmark).

Stratum typicum — early Early Danian, oedumi Zone.

Test morphology — The terminology used in the Diagnosis (amended) — Test: small to medium-sized

the follows that used Moore 16 descriptions of test by et (maximum height c mm); only a single complete al. (1952), Fell (1966), and Smith (1984). Below, test has so far been collected (P. Gravesen Coll., no.

north of Kulsti reference is made to test characters which ideally 3350, from Stevns Klint, Rende, see

bivariate PI. 12.5 ambital diameter should have been treated statistically using 2, Figs 1-3), height mm,

the thus there 8-13 ambulacral analysis. Due to limited material collected 25.1 mm. Adapically are far I have refrained from but future interambulacral the number of this, obviously plates per plate,

based should tubercles in scrobicular 12-17. work, on an adequately large material, a ring amounting to include of all char- Adradial and admedian of interambulacrals a proper statistical analysis test parts

much reduced. Adradial of interambulacrals acters suited for such an analysis. The differences parts

the described below not be as either without or with a row of between species may just single irregularly

and Table 4 would admedian of the pronounced as descriptions spaced miliary tubercles; parts

determined with 1-3 indicate. It still remains to be same interambulacrals such rows. appear to

between T. whether or not the differences oedumi, Spines: typically long, rather narrowly clavate,

forms' and T. in fact from head. 'overlap abildgaardi are related, gradually tapering narrow neck to wider

least in size maximum of at part, to differences. Fully- grown spines attaining length

referable 3 defined 28-30 mm, to morphotype as

Classification — This follows Smith & Wright (1989). above (Fig. 6), most probably originating from

ambital and adapical test regions. Some spines

Order Cidaroida Claus, 1880 belong to morphotypes 2 and 4. Distal parts of

Family Cidaridae Gray, 1825 spines with small, rounded to slightly acute

Subfamily Psychocidarinae Ikeda, 1936 mamillae, which become gradually smaller towards

Genus and the absent in base and are proximalmost part above

subgenus Tylocidaris Pomel, 1883 the collar. 51

An of 138 from the sec- and Late Danian 0dum analysis complete spines Early age. Later, (1926) ond bryozoan limestone bed between flint bands F2 distinguished three formae: f. alpha (= T. abildgaardi

and F3 of the Korsnaeb section resulted in the fol- and f. Ravn, 1928), f. beta (= T. vexilifera s. str.)

2 - 3.6 T. oedumi Briinnich lowing picture: morphotype %, morphotype gamma (= Nielsen, 1938). Ravn

3 - 76.8 and 4 - 19.6 %. erected %, morphotype (compare (1928, p. 35, pi. 4) a new var. Abildgaardi to

6 and Table Fig. 3). encompass 0dum's f. gamma and f. alpha. In 1938

Comparisons — Tylocidaris (T.) oedumi is distinguished (paper misdated 1937) Briinnich Nielsen considered

from the Late Maastrichtian T. bal- 0dum's f. (Oedematocidaris) gamma to represent a separate species for

tica the features which he the T. (Schluter, 1892) on following test suggested name Ødumi, currently

(compare Salah & Schmid, 1982; Smith & Wright, correctly spelt oedumi. Wind (1953, 1954) referred T.

in 8-13 oedumi 1989): the former, adapically there are to T. clavigera as a subspecies, but failed to

ambulacral interambulacral and plates per 12-17 justify this action. Brotzen (1959) presented the

scrobicular tubercles to 13-18 detailed per ring as compared most description of spines of T. oedumi so

(-20) and 18-20, respectively, in the latter species. far.

Adradially, adapical interambulacrals in T. oedumi

show either mili- a single row of irregularly spaced Numer of Species sec. Number of sec. ary tubercles or none at all, while in T. baltica there tubercles in tubercles in in the former are 1-2; species there are 1-2 rows of adradial parts admedian parts tubercles in admedian of interam- miliary parts T. abildgaardi mostly 0 0-2 bulacrals, whereas in the latter there are 2-4 (Table (loose finds) (0-1) Aboral 4). primary spines of T. baltica are typically T. abildgaardi mostly 0 0-2 and while those of T. glandiform stout, oedumi are (in situ) (0-1) much more narrowly clavate. Adoral primary spines forms" of the "overlap 0-1 0-2 former species are not so easily distinguished (in situ) from those of the latter.

T. oedumi be from T. T. oedumi 0-1 1-3 may distinguished abildgaardi (loose finds) (late Early Danian) as follows: adapically the former

T. oedumi 0-1 species has more (8-13 vs 4-11) ambulacrals per 1-2 interambulacral plate; 12-17 scrobicular tubercles (in situ) in 10-15 in the latter Adradial a ring vs species. parts T. baltica mostly 2 2-4 of interambulacrals in T. oedumi are reduced to such an extent that they show but a single row of miliary Table 4. Number of miliary tubercles in adradial and adme- tubercles or none at all; in T. a similar abildgaardi dian zones of interambulacral plates in T. abildgaardi, reduction is In T. the admedian of forms, T. seen. oedumi parts ’overlap’ oedumi and T. baltica, all from Stevns Klint (Korsnæb section and other localities). interambulacrals bear 1-3 rows of miliary tubercles, while in T. abildgaardi this number varies between

0-2. The spines of these species are clearly different:

All work has concentrated the typical oedumi spines are clavate and belong to mor- previous on range

those of refer- ofvariation of this photype 3; abildgaardi generally are displayed by spines species. Here,

for the time able 4 and and 3 first also test characters are included in to types 5, only rarely to type (or the 2). Type 3 spines of abildgaardi are herein referred to diagnosis.

'oedumoid difficult as spines'; they are to distinguish from true oedumi spines. Tylocidaris (Tylocidaris) abildgaardi Ravn,

— 1928 Geographical and stratigraphical distribution T. oedumi is widely distributed in the earliest Danian bryozoan PI. 3, Figs 1-14; PI. 4, Figs 1-4 limestone facies of Skane and Den- (SW Sweden) 1759 claviculae echinorum Abildgaard, p. 15, pi. 3, fig. 4f. mark. Records from the Late Maastrichtian of Den- 1926 Schliiter forma Tylocidaris vexillifera alpha 0dum, p. 160, mark and northern Germany (Voigt, 1954; Wind pi. 1, fig. la-h.

1928 Schliit. Tylocidaris vexillifera var. AbildgaardiRavn, p. 35, 1954) probably refer to T. (O.) baltica. pi. 4, figs 26, 28, 30, ?31, 32-35 (non 27, 29). Discussion — Briinnich Nielsen (1909, p. 143) was 1938 Tylocidaris Ravn — Brilnnich Nielsen, 126. Abildgaardi p. the first to realise that T. as described vexilifera by 1944 — Tylocidaris abildgaardi Andersen, p. 299, fig. 231.

in fact — Schliiter (1892) comprised various types of 1953 Tylocidaris pomifer (Boll) Wind, table 2. 52

— 1954 Tylocidaris pomiferpomifer (Boll, 1846) Wind, p. 483, pi.

13, figs 11-24.

Ravn — 1959 Tylocidaris abildgaardi Brotzen, p. 41, figs 11,

14a-f; pi. 1, figs 1-14; pi. 2, fig. 1.

Type — Ravn (1928) failed to designate a type speci-

the men. Brotzen's (1959) proposal to designate

spine illustrated by 0dum (1926, pi. 1, fig. la) 'holo-

type' is invalid. Ravn (1928, pi. 4, fig. 35) figured a

near-complete test with four associated spines,

clearly demonstrating their conspecificity. In view

of this, this specimen is here designated lectotype

(Geological Museum Copenhagen collections, no.

MMH 2543).

Locus typicus — Stevns Klint, Denmark.

Stratum typicum — late Early Danian, abildgaardi

Zone.

— A Diagnosis Test: small, largest height 8.6 mm.

of 7.3 has ambital specimen with a height mm an

of 14.9 there 4-11 diameter just mm. Adapically are

ambulacral and number plates per interambulacral,

10-15. of tubercles per scrobicular ring amounts to

Adradial of parts interambulacrals are reduced to

such that tubercles an extent well-developed miliary

rarely occur; when present, they are arranged in a

interam- single irregular row. Admedian parts of

reduced and bulacrals are extremely very narrow,

of tubercles. bearing between 0 and 2 rows miliary

7. Reconstruction of of Spines: almost 65 % of spines assigned to this Fig. development a trough structure

with hardground formation. Abbreviations are as fol- with species have a very distinctive appearance an lows: f- Early Danian bryozoan limestones (abildgaardi narrow neck and an almost extremely completely zone’ Zone); x - upper abildgaardi/lower ’overlap

to head. The of vari- globose slightly elongate - d - limestones of range boundary; e ’overlap zone’; bryozoan

ation from the oedumi Zone, bioherms at this displayed by a typical population upper forming typical

- limestones oflower oedumi Zone, in basal abildgaardi Zone at Korsnteb (section level; c bryozoan

horizontal phase’); b - K/T between co-ordinates KO +200 and KO +222.40, position (’pre-biohermal boundary strata, with indurated Late Maastrichtian and KO +185/F7'/2 and 1 below = m this, n 125) is white chalk, Fish Clay and earliest Danian Cerithium

as follows: 5 - 63.2 %, 4 - 22.4 %, morphotype - Maastrichtian white chalk. type Limestone); a Late

3 - 12.0 and - %. Whereas 5 The of is follows: type %, type 2 2.4 type sequence events as

A - the first Danian limestones oedumi spines are so typical that they are easily identified, Early bryozoan (lower here and at most other localities are in horizontal position 3 Zone) type 2 and spines cannot be easily distinguished along Stevns Klint; representing the ’pre-biohermal phase’ prior from typical spines of T. oedumi. In situ finds within to the onset oftrue build-up of mounds; B - overlying are lower the Zone and co-occurrence of such abildgaardi oedumi Zone bioherms, leaving current-swept troughs between with 'normal' of spines spines T. abildgaardi (see PI. them; non-deposition in troughs resulting in hardground forma-

show that these fall within the of tion; C - bioherm growth continues; transition of oedumi type 3) clearly range forms to ’overlap’ forms. Note that the ’overlap zone’ is thin variation of the very present species. Typical spines are in or even absent from the trough; D - eventually a thick series of maximum of 14-15 very short, attaining a length c bryozoan limestones (abildgaardi Zone) fill in the troughs. 'oedumoid be mm; spines' may considerably longer

(up to c 20 mm).

— 4-11 ambu- Comparisons Adapically, there are

Adme- lacral interambulacral and 10-15 tuber- reduced with 0-1 row of tubercles. plates per miliary

dian 0 cles scrobicular for are reduced with to 2 rows of per ring. Corresponding figures parts similarly

Adradial tubercles in T. Table T. oedumi are 8-13 and 12-17, respectively. miliary (1-3 oedumi) (see 4).

and distribution— This parts of interambulacral plates are extremely Geographical stratigraphical spe- 53

the for These cies is extremely common in bryozoan limestone Kagstrup, older name Karlstrup).

and Denmark. facies of Skane (SW Sweden) spines clearly originate from a single individual;

Discussion — Brotzen (1959) presented the hitherto they bear strongly protruding ridges that form an

'crown'. The most detailed description of the spines of the present impressive smallest spine carries only

of the that T. this with species. He was opinion abildgaardi co- ridges; specimen corresponds nicely many

of the smaller of T. illustrated occurred with T. oedumi in his zone of T. ödumi. As spines rosenkrantzi by

Brotzen These demonstrated herein, these species do not co-occur (1959, pi. 2). Karlstrup specimens

different levels. It here held to taxon which is either and occupy stratigraphical was are to belong a

T. probably the 'oedumoid spines' that misled Brotzen conspecific with or closely related to rosenkrantzi,

in show wide of in this respect. a species which the spines a range

variation 'Overlap forms'-. Although both spines and test mate- (Brotzen, 1959, p. 45).

rial the zone' the The under discussion bear certain are available from 'overlap at spines a resem-

Korsnaeb section, I have refrained from erecting a blance to those of T. vexilifera s. str., but the angle

between the neck and the basal of the head new species for this material.A morphotype analysis part

= T. of such spines (n 105) indicates the intermediate is c 45° in aff. rosenkrantzi, while in T. vexilifera

T. oedumi and this transition is and often between more amounts to position they occupy typical abrupt

- In the latter the is wide and in T. abildgaardi: morphotype 3 50.5 %, type 4-41.9 80-90°. species head

- 4.8 and 2 - 2.9 % its width 50 % of %, type 5 %, type (compare some spines may equal or surpass T. bruennichi Middle Table 3). Test remains collected so far comprise half total spine length. From (late

T. aff. is distin- a test and four test segments, which allow the fol- Danian), rosenkrantzi primarily lowing characterisation: Test small (maximum guished by the size of the massive spines with broad

9 with 6-10 ambulacral heads. height c mm); adapically

interambulacral. Both adradial and and distribution — plates per Geographical stratigraphical Typical

much T. of Middle Danian and admedian parts of interambulacrals are rosenkrantzi are early age

of at Limhamn reduced; adradial parts with 0-1 row miliary occur (Sweden).

Scrobicu- tubercles, admedian parts with 0-2 rows. lar ring with 11-13 tubercles. Tylocidaris (Tylocidaris) ravni Brotzen, 1959

Test characters thus be intermediate appear to Discussion — To this species I refer spines that origi- between T. oedumi and T. abildgaardi, but the limited from the Zone of Stevns nate upper abildgaardi material does not allow additional observations. Klint and from the early Middle Danian of Lim-

hamn, and resemble those of T. abildgaardi, but have

The a diminutive or small crown. stratigraphical Tylocidaris (Tylocidaris) aff. rosenkrantzi of T. ravni Brotzen, 1959 range (if accepted as a separate species) probably extends from the latest Early Danian PI. 4, Figs 5-11

(upper abildgaardi Zone) to the early Middle Dan- Discussion — A number of peculiar spines found at ian (rosenkrantzi Zone). In my opinion, this species most fall within the of Karlstrup probably range T. forms an evolutionary link between abildgaardi variation of T. (T.) rosenkrantzi Brotzen, 1959. They and T. bruennichi. For a detailed discussion the have must obviously belonged to a fairly large-sized reader is referred to Brotzen (1959). species; they were almost exclusively found loose on

foot of the northern face. scree at the quarry Fully- Tylocidaris (Tylocidaris) windi Brotzen, between 26 and 28 in grown specimens are mm 1959 clavate with less length; they generally are a more or

'crown' with — I well-developed papillae often arranged Discussion consider this to be an ill-defined in small All bear illustrated Brotzen rows, resembling ridges. spines species. Spines by (1959, pi. 1, prominent tubercles, which extend to rather low on figs 20-23) do not show enough distinctive features

the neck. The illustrated in PI. 6 is which specimen 4, Fig. upon a separate species could be based. The

reminiscent of the of is type T. rosenkrantzi (Brotzen, type specimen (pi. 1, fig. 23) indistinguishable

Plate 11 illustrates from the 'crowned' in the 1959, pi. 2, fig. 22). 4, Fig. an minutely forms occurring

collected in the late Zone Stevns and exceptional specimen 1922 by upper abildgaardi at Klint, are

Alfred Rosenkrantz and Christian Poulsen at 'Sol- perhaps better referred to T. ravni. Brotzen's (1959, rod. Brud indication that T. windi occurred 'in all beds Ny v. Kagstrup' (— Solrod, new quarry at p. 47) 54 55

Early on text the and Numbers in (KT) till. described 11-15. strata Figs boundary sections in the here K/T of indicated. shown (UM), boundaries are sections chalk bands white indicate detailed flint of Arrows Maastrichtian prominent positions system. more mark latest the showing of co-ordinate Asterisks Some of 1993). Klint, (LD). part to Stevns redrawn limestones-Q Quaternary section, correspond 1987, bryozoan axis Korsnæb measured

The Danian horizontal (first

b.

8a,

Fig. 56

between KO of the Lower Danian at Limhamn' cannot be cor- section KO +150: flints +150/F3

and /F4 roborated by the present study. section KO +185: base of flint KO +185/F6

CONCLUSIONS - the base of the abildgaardi Zone generally is easily

distinguished by a truly mass occurrence of spines In the Late Maastrichtian white chalk facies at (about two thirds belonging to the easily recognised Korsnaeb spines of T. (Oedematocidaris) baltica are morphotype 5) and of fairly common test fragments The Danian Cerithium fairly common. earliest far (mostly segments) of this species. It has so been Limestone has so far yielded no tylocidarids. documented at the following levels (** indicate Although details of some parts of the Korsnaeb sec- where the of the places top 'overlap zone' and the in of the of the tion are need clarification, picture base of the abildgaardi Zone are situated at the of within distribution pattern of species Tylocidaris of the same flint of this base/top band): the Early Danian bryozoan limestones sec-

clear: - base flint KO -150/F5 tion is now fairly section KO 150: of

beds - throughout the entire section the lowermost section KO - 90: top of flint KO -90/F7

- KO of the Bryozoan Limestone exclusively yield T. section KO 30: top of flint -30/F4

also oedumi, mostly spines, but locally fragmentary section KO + 25: top of flint KO +25/F6**

KO flint KO tests. section +185: top of +185/F6**

+220/F1 - be traced section KO flint KO the highest levels to which T. oedumi can +200: top of with certainty are:

- Zone the the abildgaardi extends over entire upper

-150/F3 of the section to the erosive contact section KO - 150: base of flint KO part exposed, up

KO -30/F3 between the Danian Limestone and KO - 30: of flint section top Early Bryozoan

of flint KO the Pleistocene till. section KO + 25: top +25/F4 overlying glacial

KO +100: limestone section directly overlying From this the emerges following picture: flint KO +100/F4 top of

1 - the oedumi Zone is confined to the lowermost section KO +130: limestone directly overlying beds of the Bryozoan Limestone, the beds at first of flint top KO +130/F4 being horizontal, and showing a slight tendency section KO +150: limestone directly overlying towards biohermal formation in the topmost parts. of flint KO top +150/F2

- in the and 2 the 'overlap zone' occurs only cores section KO +185: limestone directly overlying

on the flanks of the biohermal mounds between KO top of flint KO +185/F2 -80 and KO -30, KO +5 and KO +50, thinning out oedumi Zone is the - the zone', in but overlying 'overlap here an easterly direction remaining con-

base of which is difficult to define the generally nected to the next maximum in the double bioher-

because of combination of a of an apparent rarity KO and KO mal structure occurring between +90

at this unfavourable condi- Tylocidaris spines level, +200. This 'overlap zone' is absent from the large

tions for crusts and last but not collecting (salt etc.) trough between KO -25 and KO +5 and from the

least, the character of the change from T. in the the gradual giant trough structure western part of

oedumi forms'. The lowermost levels at to 'overlap Korsnaeb section (west of KO -85). This latter

which the forms' has so far been docu- is 'overlap trough characterised by an impressive multiple

mented are: bioturbated hard- sequence of intensely horizons,

grounds and incipient hardgrounds, all with section KO - 90: base of flint KO -90/F5'/2

numerous Thalassinoides burrows.

- -30/F3 section KO 30: top of flint KO

KO of flint section + 25: top KO +25/F5 PHYLOGENY section KO +150: base of flint KO +150/F3

section KO +185: base of flint KO +185/F5 Data available to date allow the following recon-

struction of evolution in the Danish and The this tylocidarid topmost levels of zone documented so far Swedish Danian: being:

In the earliest Danian section KO - 90: base of flint KO -90/F6 Early (Cerithium Limestone)

of T. aff. oedumi far - KO -30/F4 section KO 30: base of flint rare representatives occur (so

oedumi Zone section KO + 25: base of flint KO +25/F6 only at Karlstrup). In the overlying 57

the index species is the sole representative of the bruennichi-vexilifera lineage there exists a possible

this is transition of T. Middle genus. Apparently gradually species subject to rosenkrantzi (early Danian)

into I follow Brotzen in change leading to 'overlap forms' demonstrating a T. vexilifera. (1959) assuming

morphological variation in their primary spines T. rosenkrantzi to have evolved from T. oedumi during

from oedumi via the late Danian Zone This ranging true type spines intermedi- Early (abildgaardi times).

characteristic of T. took in the near-coastal of the ate types to spines abildgaardi probably place areas

(morphotype 5 spines). In places where the 'overlap Dano-Swedish Danian basin which, unfortunately,

zone' first be inter- in is thin, one might at tempted to are not preserved (see palaeogeographical maps

the of forms' further in pret development 'overlap as an exam- Thomsen, 1989), or possibly even afield,

link be ple of the mechanism of punctuated equilibrium an adjacent basin. This evolutionary cannot

Eldredge & Gould, 1972), but the fact that the documented in the late Early Danian of the central

'overlap zone' is actually thick in the cores and on parts of the Dano-Swedish basin as now preserved.

As T. first in the Middle the flanks of well-developed bryozoan mounds (in rosenkrantzi appears early

thicknesses identical that of the its is confined the places reaching to Danian, presence typically east-

oedumi is in view best ernmost of the Dano-Swedish basin Zone, see Fig. 9a, b), my parts (SW

explained as being the result of straightforward evo- Skane, eastern Sjaelland).

time In the Danian of the Dano-Swedish lutionary change over a reasonably long span. Early area, 'zone of The change from T. oedumi to the 'overlap forms' is Brotzen (1959) distinguished a Tylocidaris

apparently gradual and thus the actual boundary ödumi’ yielding both T. windi and T. abildgaardi. This

between the often be difficult calls for comment: as mentioned I have been two zones may to above,

find referred to draw. The boundary between the 'overlap zone' unable to any spines that could be

T. windi in the oedumi Zone either and the abildgaardi Zone, on the other hand, is at Karlstrup or

defined the sudden Korsnaeb and have serious doubts about the mostly easily by mass occur- at sta-

of of this Nor have I found T. rence typical abildgaardi spines (morphotype 5). tus 'species'. ever

in the oedumi which be At present, it is difficult to determine whether the abildgaardi Zone, may

of sudden the when picture a change at boundary 'overlap explained as follows: collecting at Limhamn,

Zone that is i.e. Brotzen 'oedumoid' T. zone'/abildgaardi emerges, real, a mistook spines belonging to

for T. oedumi in result of a truly heightened evolutionary turnover, abildgaardi (see above) genuine spines

mounds the Zone there. he or that the growth of bryozoan slowed abildgaardi Consequently,

assumed both in this The down so as to give the false impression of such a species to co-occur zone. turnover. Alternatively, the change from T. oedumi present study shows this conclusion to be incorrect;

these define and in the via 'overlap forms' to T. abildgaardi might be species separate zones only

zone' of the Korsnaeb section does inter- explained by the entry of an immigrant tylocidarid 'overlap an species in the Dano-Swedish basin which inter- mediate population occur. breeded with oedumi As mentioned the of T. to form a new population. above, occurrence a rosen-

krantzi Zone has so far not been recorded from

firm of T. the bruennichi Zone Following the establishment abildgaardi a Denmark, where only repre-

the Middle Danian. The rosenkrantzi Zone long time elapsed during which there were no sents

is with but local distribution changes. Not until the boundary between the Early probably a zone being and Middle Danian reached did restricted the Limhamn else- was T. abildgaardi apparently to area;

where Skanör and exhibit evolutionary changes; it gradually started in Skane, e.g. at Trelleborg this

is which be either developing diminutive 'crowns' and by doing so zone missing, may explained by

into T. ravni Brotzen. A continuation changed sensu non-deposition or penecontemporaneous erosion of this led T. bruennichi Middle Dan- 1959, In this herein process to (late (Brotzen, p. 24). light, spines

referred to T. aff. and ian). What exactly happened at the Middle/Fate as rosenkrantzi spines possibly

Danian remains unresolved. For Lim- T. ravni collected transition belonging to at Karlstrup are of

Brotzen in evidence hamn, (1959) postulated a gradual change prime importance providing not only

for the Middle Danian from T. bruennichi into T. vexilifera. In the NE corner occurrence of strata at of Fakse these levels at northern quarry (Sjaelland) species co-occur Karlstrup (highest quarry face),

but also for the of the Middle Danian (personal observations), but it remains to be deter- presence early

rosenkrantzi Zone in mined whether this is a gradual evolutionary change Denmark, not previously

recorded. or an abrupt replacement. As an alternative to a 58 59

(Late areas baltica White overhanging

or 11-15.

Tylocidaris Danian). crusts Figs

in - salt a Early here heavy section: (late of shown Korsnæb abildgaardi because sections

T. the (either of d detailed Danian forms; certainty of

Early ’overlap’ with positions and c unknown mark Danian); Maastrichtian are Asterisks Early-- Late conditions (early collecting). the where in oedumi T. section bed-by-bed

b distribution of - parts preventing Tylocidarid Maastrichtian); indicate rocks

b.

9a,

Fig. 60

Fig. 10. Key to Figs 11-15. 61

macrofossils: Selected To sum up, the tylocidarid lineage of the Dano-

Swedish Danian is by no means straightforward,

Echinoids and I requires two separate evolutionary lineages.

propose the scheme: Tylocidaris abildgaardi following

(or 'overlap forms')

1 - main a evolutionary lineage including represen-

tatives T. aff. Tylocidaris oedumi of the oedumi (Cerithium Limestone),

(or 'overlap forms') T. oedumi, 'overlap forms', T. abildgaardi, T. ravni,

and T. bruennichi. This line end with the last- may

named species in the latest Middle Danian; Tylocidaris baltica

- and 2 a local lineage of T. oedumi T. rosenkrantzi,

the situated outside the preserved parts of Dano- Stereocidaris primary spine Swedish Danian and T. sea leading to rosenkrantzi (S. rosenkrantzi or of this in S. danica) entering the easternmost parts sea early

Middle Danian times and evolving during the late Stereocidaris test plate(s) Middle Danian into T. vexilifera. This transition (S. rosenkrantzi or also have taken outside the Dano-Swed- S. danica) must place

ish Danian as now preserved. At the Middle-Late

Phymosoma aff. granulosum T. Danian transition, vexilifera may then have spine(s) entered the central of the Danian parts sea to com-

pete with T. bruennichi of the main lineage causing

Phymosoma aff. granulosum that become T. species to extinct, leaving vexilifera as test fragment the sole of the for the remain- representative genus

der of the Danian Stage. Phymosoma aff. granulosum

complete test

PATTERNS OF BRYOZOAN MOUND GROWTH

Echinocorys sulcata Ifthe above of distribution in the (uncrushed) pattern tylocidarid Korsnaeb section is evolu- accepted to represent an

tionary lineage (as here advocated), this pattern has Echinocorys sulcata a significant bearing on the interpretation of the (crushed) formation of biohermal mounds (Fig. 7). At the time

of formation a system of alternating mounds and

must have existed, and have for a Brissopneustes danicus troughs persisted considerable period of time. This assumption is

based on the way in which the 'overlap zone' occurs Other biota in the bryozoan mounds between KO -80 and KO

-30, in that occurring between KO +5 to KO + 50 Spondylus danicus and in the 'double biohermal structure' between

KO +90 and KO +200.

Mound growth is assumed to have been so slow as

to allow time for the from T. oedumi Pycnodonte ample change

via 'overlap' forms to T. abildgaardi to take place,

either evolution the of through or through entry a

Glomerula aff. 'foreign' tylocidarid species, that hybridised with T.

form T. gordialis oedumi to a new species, abildgaardi. During

the time there for same span was ample opportunity

hardgrounds to develop in the troughs between the Octocorals in the between KO mounds, e.g. trough occurring

-25 and KO +10 and in the of (+15) sequence

and in the ‘Terebratula fallax hardgrounds incipient hardgrounds large of KO var. tenuis’ trough structure west -85. 62

Fig. 12. The Korsnæb section, detailed section at KO -30,

eastern flank of bryozoan mound with hardground Fig. 11. The Korsnæb section, detailed section at KO -139 (for formation at the ’overlap’/abildgaardi Zone bound- position see Fig. 8a), showing very large trough struc- the in the the of which took ary, hardgroundbecoming more prominent ture, filling up apparently a long further and section KO time for A of hard- trough east continuing to (see text details). sequence multiple + 15. Note the thin ’overlap zone’ here. Four grounds or incipient hardgrounds and thorough bio- very

tylocidarid zones are represented (measured 1985). turbation is indicated by numerous Thalassinoides bur-

rows. Three tylocidarid zones are represented

(measured 1985).

This that the considerable time In the between KO implies span trough -25 and KO +10

limestones with needed for mound formation equals the time during (+15) the bryozoan T. oedumi are which the with little sedi- of which troughs persisted or no capped by a hardground, on top rest mentation. is evidence of limestones T. Hardground development bryozoan yielding abildgaardi. Thus, a such of That such hiatuses a period non-deposition. typical non-deposition sequence in which the hiatus comprise long periods of time was already pointed (marked by hardground) equals the sedimentary out by Bromley (1979a, pp. 28, 29). sequence with a well-developed 'overlap zone' in 63

Fig. 14. The Korsnæb section, detailed section at KO +75,

lower of wide Here there is showing parts very trough.

no hardground at the ’overlap’/abildgaardi Zone

boundary; the width of the trough probably lessened

the of submarine and Fig. 13. The Korsnæb section, detailed section at KO +44, momentum current here so

allowed certain to take showing the eastern flank of a bryozoan mound with a deposition place during

time. Four zones thin ’overlap zone’. Three tylocidarid zones are repre- ’overlap’ tylocidarid are represented

sented (measured 1985). (measured 1985). 64

ernjylland, Thomsen's (1976, 1977a, b) studies of

bryozoan mound growth have demonstrated the

existence of such currents in the Early Danian sea,

Klint from direc- coming at Karlby a southeasterly

For Den- tion (Thomsen, 1977a, p. 135). eastern

Fakse 16 kilometres mark, at quarry (only away

from the Korsnteb section) Bernecker & Weidlich

demonstrated the existence of (1990, p. 118) a

southerly to northerly palaeocurrent during the

Their the mid-Danian. findings seem to substantiate

of southeast existence a palaeocurrent going from to

from south northwest, or locally to north, through

Denmark in the the narrow sea across Early and

Middle Danian. In the existence of such my view, a

well with the of current corresponds very pattern

found the Korsnaeb bryozoan mound growth as at

section and described herein.

ACKNOWLEDGMENTS

The author wishes to thank the late Prof. Dr Tove

Birkelund for her take the encouragement to up

of the Ulla present study. In the course investigation

Asgaard, Richard Bromley, and Peter Toft have

taken interest in the of the an inspiring progress

work and provided extremely valuable discussions.

Walter Kegel Christensen has been of assistance

with discussions on taxonomic problems; Sten Len-

nart Jakobsen took care of the painstaking work of

the and photographing many specimens, Ragna

how Larsen was exceedingly helpful in teaching me

of sections to convert the many field drawings into

acceptable figures.

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45-50. 23 April 1993.

PLATE 1

With the exception of the specimen illustrated in Plate 4, Fig. 11, which is housed in the collections of the Geological Museum at

Copenhagen, all other specimens are in the P. Gravesen Collection, currently curated at the Midtsønderjyllands Museum at Gram

(Denmark).

2. aff. oedumi. chalk’ Cerithium Gravesen Figs 1, Tylocidaris ’Streaky (= Limestone), Karlstrup quarry, Collection,nos 3032, 3033,

respectively, x 2.

x Figs 3-16. 3-6 and 8-16 - selected spines illustrating typical oedumi and abildgaardi type and intermediate forms, 2; 7 - fragmentary

test, x 3. All specimens from the ’overlap zone’ as exposed at the Korsnæb section, Stevns Klint. Gravesen Collection,

3441 3431 3393 3449 nos 3446 (3), 3236 (4), 3432 (5), 3240 (6), 3394 (7), 3214 (8), 3211 (9), (10), 3484 (11), (12), (13), (14),

3392 (15) and 3235 (16).

Figs 17-33. Tylocidaris oedumi Brünnich Nielsen, 1938; 17-19, 25, 26 from the stratigraphically oldest oedumi populations from the first

Gravesen 3378 3376 3369 and bryozoan limestone bed at Korsnæb section, x 2. Collection,nos 3373 (17), (18), (19), (25)

3372 (26); 20-24, 27-30 represent the ’second oedumi population’, from the second bryozoan limestone bed at Korsnæb,

Gravesen being the population used for morphotype analysis (see text), 21 representing a pathological specimen, x 2,

Collection, nos 3420 (20), 3108 (21), 3187 (22), 3425 (23), 3096 (24), 3129 (27), 3120 (28), 3162 (29) and 3080 (30); 31, 32

from the first bryozoan limestone bed at Korsnæb, x 3, Gravesen Collection, nos 3364 (31) and 3516 (32); 33 from the

bed Korsnæb, Gravesen Collection, 3388. second bryozoan limestone at x 2, no. 67\1

PLATE 1 68

PLATE 2

Tylocidaris oedumi Brünnich Nielsen, 1938

Figs 1-3. The sole complete test known to date, Stevns Klint, north of Kulsti Rende, found loose in scree. P. Gravesen Collection,

no. 3350, x 3.

Figs 4-6. From stratigraphically oldest oedumi populations (first bryozoan limestone bed at Korsnæb section). Note spine of

Phymosoma aff. granulosum (Goldfuss, 1829) in 5, and isolated demipyramid and unidentified interambulacral plate in 6.

2. Gravesen Collection, nos 3379 (4), 3380 (5) and 3375 (6), x

Fig. 7. A crushed test with associated spines, Korsnæb section, found loose in scree. Gravesen Collection, no. 3414, x 2. 69\2

PLATE 2 70

PLATE 3

Tylocidaris abildgaardi Ravn, 1928

1-3. A Gravesen 3. Figs complete test, Karlstrup quarry, Collection, no. 3354, x

Fig. 4. Fragment of test of ’reference population’ used in morphotype analysis (see text), Korsnæb section. Gravesen

Collection, no. 3900, x 5.

Fig. 5. Fragment of test, ex situ, north of Højerup church. Gravesen Collection, no. 3901, x 3.

Figs 6, 8, 13. Fragments of test with associated spines, all from Stevns Klint; 6 - of ’reference population’ used in morphotype

analysis (see text); 8 and 13 - from fallen blocks north ofHøjerup church. Gravesen Collection, nos 3384 (6), 3355 (8)

and 3390 (13), x 2.

Figs 7, 9-11. Spines ofthe ’reference population’ used in morphotype analysis (see text). Note ’oedumoid’ spines in 7, 10, 11; 9

illustrates two typical spines. Gravesen Collection, nos 3342 (7), 3313 (9), 3301 (10) and 3335 (11), x 2.

Fig. 12. A crushed test with associated spines. Korsnæb section, of’reference population’ used for morphotype analysis (see

text). Gravesen Collection, no. 3404, x 2.

Fig. 14. Bedding plane with different spine types, all referred to T. abildgaardi, the one in the centre being ofthe ’oedumoid’

of church. Gravesen Collection, no. 3351, x 1. type. Stevns Klint, fallen block 400 m north Højerup 71\3

PLATE 3 72

PLATE 4

1-4. 1 and 2 from Stevns 3 and 4 from Figs Tylocidaris abildgaardi Ravn, 1928, complete tests, Højerup, Klint, Karlstrup quarry.

Gravesen 3352 and 3. Collection, nos 3367, respectively, x

5-11. aff. 5-10 from Gravesen 3902-3905 3005 Figs Tylocidaris rosenkrantzi Brotzen, 1959; Karlstrup quarry. Collection, nos (5-8), (9)

and 3906 11 - collected Rosenkrantz and Poulsen in Museum (10), x 2; specimen by 1922, Karlstrup quarry. Geological

Copenhagen Collections, no. 1925. 191, x 2. 73\4

PLATE 4