upper ordovician bryozoa from dalmanitina beds of...

53

Geologica et Palaeontologica s. 53-72 l Abb., l T ab., 6 Taf. Marburg, 15. 7. 1978

U p per Ordavieian bryozoa from Dalmanitina beds of Borenshult,

Östergötland, Sweden

Krister BROOD

with 1 Textfigure, 1 Table and 6 Plates

BROOD, Krister: Upper Ordovician bryozoa from Dalmanitina beds of Borenshult, Ostergötland, Sweden.- Geologica et Palaeomologica 12: 53 - 72, l fig., l tab., 6 pi., Marburg, 15. 7. 1978.

Bryozoan fauna from samples collected in 1823 during construction of Göta Channel in exposures no more accessible since that time comprises 14 idemified species belonging to 11 genera. One genus, Radiotrypa, and 13 species are established herein. Fauna differs in composition from other contemporary faunas in Balto-Skandia, probably because of differences in ecological conditions.

Die Bryozoenfauna stammt aus Proben, die 1823 in heute nicht mehr zugänglichen Aufschliissen beim Bau des Götakanals gesammelt wurden. Sie setzt sich aus 14 spezifisch bestimmren Arten zusammen, die zu 11 Gattungen gehören. Die Gattung Radiotrypa und 13 Arten werden neu aufgestellt. Von anderen gleichaltrigen Faunen Balto-Skandiens unterscheidet sich diese in ihrer Zusammensetzung, wahrscheinlich aus ökologischen Grunden.

Address of author: K. Brood, Section of Palaeozoology, Swedish Museum of Natural History, S- 104 05 Stockholm.

In troductian

This study deals with the Bryozoa of the Upper Ordavieian of Borenshu!t, Östergötland. The material comes from a locality which is no longer exposed and comprises an almost unique fauna, which is therefore of special interest. The locality was exposed during excavations for the construction of the >>Göta Kanal<< , and the fossils were collected at the lower sluices approximately 4 km east of the town of Motala. The material was collected in 1823 by Prof. J. J. B e r z e l i u s and deposited at the Swedish Museum of Natural History. In 1824 J. W. D a l m a n revisited the locality in an attempt to increase the collections (DALMAN,

1825), hut by then the beds were no longer exposed. Later attempts to find the Dalmanitina beds at Borenshult through core drillings have proved unsuccessful (J. B e r g s t r ö m , personal communication). The Dalmanitina Beds at Borenshult consist of a grey, calcarenitic limestone with an abundance of weil preserved fossils. The bulk of the limestone is made up of a weil winnowed, sparitic, skeletal sand, which is partly ruditic and even conglomeratic in character. In parts, the limestone contains rounded remnants of an older fossil rich mar!, which is pelletal in character. Many of the fossils are greatly worn and fragmented, suggesting a high water energy. The limeston e includes the stratigraphically diagnostic trilob i te M ueronaspis mucronata (W AH LENBERG) and the brachiopods Hirnantia sagittifera (McCoY), Dalmanella testudinaria (D ALMAN) and Leptaena rugosa D ALMAN, indicating a late Ashgill (Hirnantian) age for the fauna.

Discussion of the fauna

There are few bryozoan faunas described from strata of the same age as the Borenshult material, though Middle Ordavieian faunas are weil known (AsTROVA, 1965; BEKKER, 1921; BOARDMAN &

UTGAARD, 1966; BoRK & PERRY, 1967, 1968, a, b; BRoWN, 1965; KARKLINS, 1965; Ross, 1963 and ToOTs, 1953 ). The Parkuni (»Borkholm« Stage (Fn) in Estonia (BASSLER, 1911; MoszALEVSKA

JA, 1953 ), the Oj! e Myr fauna from erratics on Gotland, Sweden (WIMAN, 1901 ), and the Ellis Bay Formation of Anticosti (BAss.

LER, 1928; Ross, 1960, a, b, c) contain material which has been studied, bu t in each case the number of species is small. In addition, a fauna from an Ashgillian fissure filling in Dalarna has recently been investigated (BROOD, ms). Comparisons between the present material and that of other areas are therefore difficu!t because of the limited knowledge of the bryozoan faunas, and also because the major part of the fauna from Borenshult consists of hitherto undescribed species. The fauna is dominated, both in number of species and specimens, by trepostomes. The numerically most common species areHallapor a solbergiensis n. sp. , Radiotrypa gothica n. sp. Hallopara multipara n. sp. , andEridotrypa suecica n. sp . . The dominance of the trepostomes can possibly be correlated with their preference for an argillaceous facies type. This appears to be in accord with observations of Silurian bryozoan faunas, where trepostomes tend to be more common relative to the cryptostomes in marly sedimentary rocks (BROOD, in press). This dominance is different from that in other investigated areas in BaltoSeandia of late Asgill age, where cryptostomes form an important part of the fauna. This indicates that there is possibly an ecological control of the difference between the faunas from Porkuni, Ojle Myr, Dalarna and Borenshult rather than a geographical one. The Parkuni fauna of Estonia is dominated by !arge cryptos.tomes such as Pteropora pennula (EICHWALD), Proavella obliqua (BASSLER), Haltopara solbergiensis and Phylloporina tenella (EICHWALD) . This limestone is a calcarenite, algal-rich, limestone with little day material. The facies differs greatly from that of the limestone at Borenshu!t, though both formations were apparently deposited in a shallow water environment.

54 BROOD Ordavieian bryozoa

The fauna from Oj le Myr was described by WIMAN (1901) from drift boulders, which probably originated from the outcropping Ordovician at the bottom of the Baltic, north of Gotland. The boulders consist of limestones with chert which have yielded a well preserved silicified fauna, with the bryozoans Stictoporella borkholmiensis (WIMAN), Clauconomella plumula (WIMAN), and Nernatopara cf. sublineata MANNIL. These species are common in the material from Dalarna bu t are not present or rare in the Borenshult and Porkuni collections. The bryozoan fauna from the fissure filling at Solberga, Dalarna (BROOD, MS) is dominated by cryptostomes with Stictoporella borkholmiensis, Protocrisina oilensis WIMAN, Pseudohornera orosa (WIMAN) and Penestella striolata EICHWALD the most common. In addition Hal/apara solbergiensis also occurs. Within the fissure fauna two facies-dependent groups can be distinguished; the bifoliates and Hallapor a solbergiensis form one group characteristic for a clay-rich facies and the fenestrate cryptostomes are typical of a calcarenitic facies. Both these groups differ in composition from the Borenshult fauna.

-3 ... E "' ..c: >-. ö ., :s Oll

s:: ..c: ... "' "' � ..... ...c: ... ... Species

o

6 o ö

1'0 1'0 "'

Ceramopora berzelii n. sp. x

Corynotrypa cf. dissimilis (VINE) x

Nernatopara sublineata MANNIL x x

Glauconomella plumula (WIMAN) x

Glauconomella strigosa (BILLINGS) x

Pseudohornera orosa (WIMAN) x x

Protomsina oilensis (WIMAN) x x

Sceptropora furcata? ULRICH x

Graptodictya boreniensis n. sp. x x

Ptilodictya bifurcata n. sp. x

Pteropora pennu/a EICHWALD x

Proaveila obliqua (BASSLER) x

Pachydictya bifurcata (HALL) ? Stictoporella borkholmiensis (WIMAN) x x

Phaenopora wimani BROOD x x

Phylloporina tenel/a (EICHWALD) x

Penestella striolata EICHWALD x x

Heterotrypa compressa n. sp. x

Asperopara crustulenta n. sp. x

Trematopara corenshultensis n. sp. x

Batostoma gracilis n. sp. x

Hallopora dalmani n. sp. x

Hallopora multipara n. sp. x

Hallopora solbergiensis n. sp. x x x

Diplotrypa baltica n. sp. x

Eridotrypa suecica n. sp. x

Radiotrypa gothica n. sp. x

Table l. Distribution of known Upper Ashgill bryozoan species in Balto-Scandia.

The following abbreviations are used in this study: x = arithmetic mean, given with confidence interval O. R. = observed range s = standard deviation N = number of measured specimens V = coefficient of variation azw = width of autozooecial aperture mpw = width of mesopore

az/mm2 = number of autozooecial openings in a square of l mm2 mp/mm2 = number of mesopores in a square of l mm2 daz/mm = number of diaphragms in l mm length of an autozooecium dmp/mm = number of diaphragms in l mm length of a mesopore

The terminology employed is mainly after BASSLER (1953), with additions as used by BOARDMAN (1959, 1960) and BOARDMAN & UTGAARD (1966).

Systematic descriptions

Ceramopora berzelli n. sp. Pl. 4, Figs. 7, 8; Pl. 6, Figs. l, 3

? 1911 L i c h e n a l i a c o n c e n t r i c a HALL: BASSLER, p. 168.

H o l o t y p e : RM BY 1472, illustrated in Plate 6, fig. l .

M a t e r i a l : RM By 23513, 23514 (paratypes) .

D i a g n o s i s : A Ceramopora with moderately sized autozooecia, weil developed lunaria and few mesopores.

D e r i v a t i o n o f n a m e : After Prof. J. J. BERZELIUS, who collected the material.

D i m e n s i o n s : Holotype and paratypes.

O. R. x v azw . . . 0.267-0.400 0.308 ± 0.010 10.78 azl . . . 0.265-0.465 0.381 ± 0.013 11.39

0.0332 0.0434

N 44 44

D e s c r i p t i o n : The zoarium is thin, forming enerusting plates, with the centre generally depressed and hearing no autozooecial apertures. The autozooecia radiate from the centre of the colony and have oval apertures. The lunarium is well developed and projects above the surface in well preserved zooecia. Between the autozooecia there are few mesopores. Zooecial openings are small for the genus. The interzooecial walls are thin (approximately 0.015 mm), in the endozone, and the exozonal walls are approximately 0.030 mm thick. The interzooecial walls are penetrated by several large pores, especially in their distal ends. The mesopores are few and have thick walls with laminar structures. Diaphragms are generally lacking. The lunarium is small in the endozone bu t becomes conspicuous in the exozone. lt is approximately 0.05 mm wide and horseshoe-shaped, and in tangential section it does not project into the zooecial cavity. A few acanthopores are visible in tangential sections.

R e m a r k s : This species is rare in the Borenshult material, but is not uneoromon in the Dalmanitina beds of Kinnekulle. C. berzelii is characterized by its comparatively small autozooecial dimensions and the presence of weakly developed acanthopores. Possibly, it is identical with the »Lichenalia concentrica<< of the Porkuni Stage of Estonia reported by BASSLER (1911 ). Ceramopora niagarensis var. germana BAssLER is similar in appearance to this species bu t differs in having more mesopores and slightly larger autozooecia.

Neamatopora cf. sublinesta MANNIL, 1959

? 1911 Nernatopara lineata (BILLINGS) : BASSLER, p. 158. ? 1959 Nernatopara sublineata MANNIL, p. 39.

R e m a r k s : In the Borenshult material one bifurcating specimen and a few transvers e sections of a N ematopora species are known. These specimens are insufficient to warrant specific determination, but are possibly conspecific with N. sublineata MANNIL form the Porkuni Stage. lt appears probable that this is

BROOD Ordovician bryozoa 55

the same as the Porkuni species which BASSLER (1911) called N ematopora lineata (BILLINGs), bu t the present material differs from the Anticosti material in lacking weil developed acanthopores. Possibly, the unidentified species (species No : 1) illustrated by WIMAN (1901) from the Ojle Myr material is also conspecific.

VÄTTERN

�--�--._ __ ._ __ �--�Skm

Text-fig. l: Sketch-map showing position of the sampling locality.

Graptodlctya borenlensis n. sp. PI. 6, Figs. 2, 4

H o l o t y p e : RM By 23472.

M a t e r i a l : Paratypes: RM By 23411, 23473 - 23479.

D e r i v a t i o n o f n a m e : After lake Boren.

D i a g n o s i s : A Graptodictya with small zooec1a and a zigzagshaped mesotheca.


O. R. x azl ... 0.154-0.187 0.167 ± 0.003 azw . . . 0.074-0.094 0.084 ± 0.002

v 6.69 8.19

0.0112 0.0069

N 46 46

D e s c r i p t i o n : The zoarium consists of thin bifurcating stems which are approximately 1 mm wide and 0.5 mm thick. The autozooecia open in Iongitudinal lines on the surface,-separated by thick interzooecial walls. The aperture of the autozooecia is longitudinally oval. There are approximately 5 autozooecial apertures in 2 mm length. The lateral sides of the stems are free from zooecial apertures. The surface of the stems between the autozooecial apertures is ornamented by thin, longitudinally arranged, bifurcating and anastomosing ribs which form a reticulate pattern. Transverse sections show that the mesotheca is zigzag-shaped and thin, being approximately 1 O Jlm thick in the central area and 15 #ffi laterally.

Longitudinal sections show that the endozonal part of the autozooecia is arranged parallel with the mesotheca and that the zooecium curves strongly at the exozonal part and opens almost transversall y to the stem surface. No superi or hemiseptum is present. The interzooecial wall is thin at the endozone but thickens distinctly in the exozone, through the secretion of calcium earbonate on the exterior surface.

R e m a r k s : This species is characterized mainly by its zigzag-shaped mesotheca and the lack of hemisepta. It differs from Middle Ordovician Graptodictya species from Balto-Seandia in ha ving longer autozooecial apertures and a distinctly zigzagging mesotheca.

Pt/lod/ctya blfurcata n. sp. PI. 6, Figs. 5-8

? 1911 Ptilodictya gladiola B!LLINGS: BAssLER, p. 114.


M a t e r i a l : Paratypes: RM By 1384, 1392, 1446, 1475, 1484, 1516, 1518, 1519, 23414-23416, 23480-23485.

D i a g n o s i s : A Ptilodictya with irregularly placed autozooecia, bifurcating stems, autozooecia of small size and approximately seven autozooecia in 2 mm length.

D e r i v a t i o n o f n a m e : bifurcata (latin) = bifurcation, referring to the growth of the stems.


O. R. x v N azl . .. 0.210-0.250 0.234 ± 0.004 5.99 0.0134 48 azw ... 0.087-0.120 0.101 ± 0.005 15.82 0.0159 48 az/2mm 6-8 6.6 ± 0.2 9.24 0.609 48 z/2mm 11-14 11.9 ± 0.2 5.66 0.672 48

D e s c r i p t i o n : The zoarium consists of thin (approximately 2-3 mm wide) ribbon-like stems frequently bifurcate. The stems are approximately 0.5 mm thick. The autozooecia open in Iongitudinal lines in the middle of the stem and irregularly on the lateral sides. The middle zooecia are generally rhombic in outline, but may be elongated hexagonal or even oval. The laterally placed zooecia are generally hexagonal. The centrally placed zooecia are smaller than the lateral ones. The interzooecial walls are thin (approximately 0.025 mm), smooth, and bear no acanthopores. There are 6 or 7 autozooecia in 2 mm length in the middle part of the stem and 12 autozooecial lines in 2 mm width. The autozooecial apertures are small compared with other species of the genus. Transverse sections show a straight middle lamina, approximately 10 /)-m thick, consisting of a middle granular layer which thickens at the junction of the zooecial walls, and flanking laminar layers. Longitudinal sections show that the basal lamina is wrinkled in a longitudinal direction. The autozooecia are Iong and grow obliquely towards the stem. The zooecium bends slightly at the transition from the endozon e to the exozone and a small thickening of the zooecial wall exists at the bend, which reserobles a minute hemiseptum. The endozonal wall is approximately 10 /)-ffi thick.

R e m a r k s : This species is parti y intermediate between Ptilodictya and Clathropora, so that the arrangement of the zooecia in a medial group of Iongitudinal lines with rhombic zooecia and a lateral group with irregularly placed zooecia is not fully developed. Further, the bifurcating stems can sometimes be seen to fuse with each other so that an oval fenestrula is formed.

56 BROOD Ordovieian bryozoa

P. bifurcata differs from Clathropora? baltica MANNIL from the Purgi Stage in ha ving thinner zooecia and in lacking the reticulate growth of the zoarium. It differs from SilurianPtilodictya species in having smaller zooecia and bifurcating stems. P. gladiola BIL· LINGS from the Upper Ordovician of Anticosti Island has smaller zooecia and thinner stems.

Heterotrypa compressa n. sp. PI. 4, Figs. 3, 5, 6

H o l o t y p e : RM By 23504, illustrated in Plate 4, fig. 5.

M a t e r i a l : RM By 23503 - 23507.

D e r i v a t i o n o f n a m e : eompressus (latin) = eompressed, referring to i ts enerusting growth.

D i a g n o s i s : An enerusting Heterotrypa with weil developed endoaeanthopores and exoaeanthopores.


O. R. x azw . . . 0. 100-0. 160 0. 139 ± 0.004

az/mm2 16-22 18.7 ± 0.4

v 1 1. 59

7.36

0.0 154

1.37

N 48

48

D e s c r i p t i o n : The zoarium forms thin, enerusting plates. The autozooecial apertures are polygonal or rarely oval. Acanthopores are of two sizes. Large endacanthopores are approximately 40 ttm thick with central cores l O ttm thick. Smaller exoacanthopores are approximately 20ttm thick with cores 5 ttm thick. Mesopores are approximately equally as numerous as the autozooecia and about half their si z e. They are polygonal in outline. Longitudinal sections show short endozones and slightly longer exozones. Diaphragms are abundant both in endo- and exozones. Cystiphragms are also common. There are approximately 8 -lO diaphragms in one mm length of an autozooecium. The diaphragms in the mesopores are mo re common than in the autozooecia, with approximately 20 in one mm length. The zooecial walls are approximately 5 ttm thick in the endozone and 25 ttm in the exozone.

R e m a r k s : H. compressa is characterized by its enerusting growth, !arge endacanthopores and its many exacanthopores.

Asperopara crustulenta n. sp. PI. 4, Figs. l, 2, 4


M a t e r i a l : Paratypes: RM By 23412, 23508- 2351 1.

D e r i v a t i o n o f n a m e : erustulentus (Latin) = erustose, referring to its growth form.

D i a g n o s i s : An Asperopara with enerusting growth, polygonal autozooeeia, many aeanthopores, small maeulae and few mesopores.


O. R. x asw . . . 0.087- 0. 120 0. 102 ± 0.003

az/mm2 25-34 29.5 ± 0.7

v 8.60

8. 18

0.0088

2. 4 14

N 43

43

D e s c r i p t i o n : The zoarium is enerus ting, formin g crusts which are up to 50 mm wide and a few mm thick. The autozooecia open irregularly on the surface, separated by few mesopores w hi ch are approximately of the same number as the autozooecia.

The autozooecia are polygonal in outline, surrounded by weil developed acanthopores which indent the autozooecial cavities. There are approximately 3 or 4 acanthopores in an ordinary autozooecium and approximately 6 in a maeular zooecium. Small maculae of 5 to 10 large zooecia occur on the surface. The autozooecia in a maeula are approximately 0.125 mm in diameter. The acanthopores are approximately 15-20 ttm thick with a core of approximately 7 j-lm. Longitudinal sections show that the endozone is short and that the autozooecia turn at right angles into the broader exozone. The endozonal part of the wall is thin (approximately 5 ttm), the exozonal part approximately 20 j-lm. There are a few diaphragms in the endozonal part of the zooecia. The exozonal part of the autozooecial walls are slightly wrinkled. The mesopores are few and cystose. The central pore of the diaphragms within the mesopores is generally closed by a thin diaphragm.

R e m a r k s : This species is characterized by its many acanthopores and the few mesopores. It differs from the Silurian species A. aspera (HALL), A. multiporum (BASSLER) and A. densiporum (OWEN) in having fewer mesopores.

Trematopara borenshultensis n. sp. PI. 3, Figs. 3, 5, 9

H o l o t y p e : RM By 23529, illustrated in Plate 3, fig. 3.

M a t e r i a l : Paratypes: RM By 23530.

D e r i v a t i o n o f n a m e : After Borenshult, the type loeality.

D i a g n o s i s : A Trematopara with small autozooeeia and many, !arge aeanthopores.

D i m e n s i o ns : Holotype and paratypes.

O. R. x v azw . . . 0.090- 0. 120 0. 1 10 ± 0.002 6.78

mpw . . . 0.055-0.080 0.063 ± 0.002 9. 18

0.0074

0.0058

N 43

43

D e s c r i p t i o n : The zoarium is erect, ramose and consists of cylindrical stems which are approximately 1.5-2 mm wide. Overgrowths are common. Zooecia are densely crowded. Acanthopores project as Iong spines above the surface in weil preserved zoaria. The zooecia are budded from the centre of the stem. They are Iong and thin-walled. The endozone is approximately l mm thick. The proximal parts of the zooecial walls are approximately 5 ttm thick. The zooecia b end outwards in the exozone so that the apertures open almost normal to the stem surface. There are several diaphragms in the endozonal part of the zooecia. The ex ozon e is generally thin, but contains two zones. The inner zone is characterized by beaded mesopores, and by a moderate thickening of the zooecial walls. The laminae in the zooecial walls tend to be arranged longitudinally. The ou ter zon e is characterized by heavy calcification and extensive development of acanthopores. The laminae of the zooecial walls tend to become arranged transversely towards the growing direction in the ou ter exozone. The acanthopores are numerous, approximately l O ttm thick, with a calcareous rod which is approximately lO ttm thick. Tangential sections show circular or oval autozooecia surrounded by many smaller mesopores. The acanthopores are conspicious in tangential sections near the stem surface.

R e m a r k s : This species differs from the Niagaran (Silurian) species T. tuberculosa HALL, T. halli ULRICH, and T. whitfeldi ULRICH (ULRICH, 1882, 1883, 1890) in having smaller zoaria and zooecia and in having more diaphragms inside the autozooecia.

BROOD Ordavieian bryozoa 57

Batostoma gracilis n. sp. PI. 5, Figs. 4-9

H o l o t y p e : RM By 23502, illustrated in PI. 5, fig. 8.

M a t e r i a l : Paratypes: RM By 23487-23501.

D i a g n o s is : A Batostoma species with thin stems, no diaphragms within the autozooecia, few mesopores and small zooecia.

D e r i v a t i o n o f n a m e : Gracilis (latin) = gracile, after its general shape.


O. R. x azw . . . 0.067- 0. 094 0.08 1 ± 0.002

mpw . . . 0.024- 0.047 0.035 ± 0. 001

v 7. 1 1 0.0058

12.72 0.0044

N 44

44

D e s c r i p t i o n : The zoarium is erect and consists of cylindrical stems which are approximately 1-3 mm wide. The autozooecia open irregularly on the stem surface, surrounded by few mesopores. The autozooecial apertures are oval in outlin e. Acanthopores are generally absent. There are approximately 25 autozooecial apertures in one mm2• Longitudinal thin seetians show autozooecia budding from the central part of the stem. The autozooecia tum gen dy outwards, opening obliquely to the stem surface, and generally lack diaphragms. The interzooecial walls are approximately 5 ftm thick in the proximal part and lOftm in the exozone. Locally in the exozone the walls ma y be up to 40 ftm thick. The mesopores are few and narrow and contain numerous diaphragms, of which there are approximately lO in one mm length. Acanthopores are rare or absent.

R e m a r k s : This species is characterized by its small size, lack of diaphragms inside the autozooecia, and the numerous diaphragms of the mesopores, features which separate i t from the. American Upper Ordavieian B. manitabense ULRICH, B. maysvillense NICKLEs and B. prasseri CuMINGS & GALLOWAY.

Hallopora dalmani n. sp. PI. 3, Figs. 9-10



D e r i v a t i o n o f n a m e : After J. W. DALMAN.

D i a g n o s i s : A H allopor a species with moderat! y sized autozooecia, many mesopores, few diaphragms in the autozooecia and no acanthopores.


O. R. x v N azw . . . 0. 100-0. 147 0. 1 18 ± 0.003 7.7 1 0.0092 44

mpw . . . 0.033-0.067 0. 051 ± 0.002 12.32 0.0063 44

D e s c r i p t i o n : The zoarium consists of cylindrical stems which are approximately 2-3 mm wide. The autozooecia open irregularly on the surface with circular apertures, and are surrounded by numerous polygonal mesopores. Acanthopores are lacking. Zooecial walls are of moderate thickness. Longitudinal seetians show budding of autozooecia from centre of stems. Mesopores are restricted to the exozone. The endozone is approximately l mm wide. The proximal part of the autozooecia runs almost paraHel with the stem. In the exozone it bends distinctly and opens transversally to the stem surface. The interzooecial walls are approximately 5 ftm thick in their proximal part and ma y be up to 50 fl m in the exozone. Diaphragms occur in the endozon e, bu t they are widely spaced. They become more

common in the exozone. Diaphragms are common in the mesopares where approximately 20 occur in on e mm length. There are approximately 20 autozooecia and 40 mesopores in a square of one mm2•

R e m a r k s : H allapara dalmani is characterized by its small size, its few diaphragms in the autozooecia, and comparatively thick exazonal walls.lt differs from H. multipara in having fewer mesopores and smaller autozooecial dimensions. lt has much smaller zooecia than H. wesenbergiana BAssLER and H. multipara n. sp.

Hallopora multipara n. sp. PI. 2, Figs. l, 2, 5-8

H o l o t y p e : RM By 23461, illustrated in PI. 2, Fig. 2.

M a t e r i a l : Paratypes: RM By 23413, 23457-23459.

D e r i v a t i o n o f n a m e : The name refers to the presence of many mesopores in the zoarium.

D i a g n o s i s : A Hallopora with moderately !arge zooecia, many mesopores, numerous diaphragms and comparatively thick walls in the exozone.

D i m e n s i o n s : Holorype and paratypes.

O. R. x v N azw . . . 0. 160-0.2 14 0. 187 ± 0.004 7.07 0. 0132 46

mpw . . . 0.054-0.120 0.083 ± 0.005 22.58 0.0186 46

az/mm2 5-10 7.7 ± 0.3 12.40 0.949 46

mp/mm2 18-32 28. 2 ± 0.9 1 1. 13 3. 13 46

D e s c r i p t i o n : The zoarium is erect, camposed of cylindrical stems which are approximately 2 mm wide. The apertures of the autozooecia are circular in outline and surrounded by many mesopores with polygonal openings. Acanthopores are lacking. Zooecial walls in the exozone are of moderate thickness. Longitudinal seetians show budding of autozooecia from the central part of the stem. Mesopores are restricted to the exozone. The autozooecia are comparatively short, curve gradually outwards, and open transversally to the stem surface. The zooecial walls are approximately 5 ftm thick in the endozon e and 30 fl m in the exozone. The endozone is approximately l mm wide. There are diaphragms in the autozooecia both in the endozon e and exozone, with approximately 6 diaphragms in one mm length. The diaphragms in the mesopores are closely grouped at approximatively 20 per mm.

R e m a r k s : This species is characterized by moderate! y sized autozooecia, numerous diaphragms and lack of acanthopores. lt differs from H. wesenbergiana in having more mesopares and smaller autozooecia. H. solbergiensis n. sp. is a larger speCies.

Hallopora solbergiensis n. sp. PI. l, Figs. 6-8

191 1 Hallopora elegantula (HALL) : BASSLER, p. 334, fig. 210.


M a t e r i a l : Paratypes: RM By 1485, 23417-23456, 23466-23471.

In addition numerous specimens from Solberga, Dalarna have been investigated.

D e r i v a t i o n o f n a m e : After Solberga Quarry, Dalarna.

D i a g n o s i s : AHallopora species with few mesopores, a thin exozone and without acanthopores.


58 BROOD Ordovician bryozoa

O. R. x v N apw ... 0.195-0.275 0.229 ± 0.008 11.53 0.0264 30 mpw ... 0.058-0.100 0.074 ± 0.002 6.54 0.0048 30 ap/mm2 5-9 7.4 ± 0.4 16.11 1.192 30

D e s c r i p t i o n : The zoarium is ramose with bifurcating and sometimes anastomosing stems with circular cross-section. The stems are approximately 3-5 mm wide. Maculae and monticulae are not observed. The apertures of the autozooecia are closely grouped along the branches. They have circular or slightly oval outline. There are approximately 7 autozooecial apertures in one mm2• The autozooecia are separated by a small number of mesopores. The diameter of the autozooecial aperture averages 0.23 mm. The aperture of a mesopore approximates 0.075 mm in diameter. In longitudinal section the autozooecia run almost parallel with each other for a considerable distance and turn outwards in their distal end. They open at an almost straight angle to the surface. The exozone is approximately 1/6 of the total width of the stem. The zooecial wall is approximately 50 �-t m thick in the exozone and 10�-tm in the endozone. Diaphragms are common in the autozooecia, both in the axial and peripheral region. They are placed with in tervals of 0.2-0.3 mm in the endozone and approximately 0.05 mm in the exozone. The diaphragms are spaced approximately with 0.05 mm distance in the mesopores. Acanthopores are not observed in the zooecial walls.

R e m a r k s : The present species was by BASSLER ( 1911) considered as a synonym to H. elegantula (HALL) from the Rochester Shale of New York. However, H. solbergiensis differs from this form in having fewer mesopores and smaller autozooecia. H. solbergiensis differs from H. wesenbergiana in having more spaced autozooecia and more mesopores. The present species is common in the Borenshult material. lt is also common in the Siljan District and in the Porkuni Stage of Estonia.

Dlplotrypa balt/ca n. sp. PI. l, Figs. l, 4, 5

H o l o t y p e : RM By 23534, illustrated in PI. l, Fig. 4.

M a t e r i a l : Paratypes: RM By 1560, 23531-23533.

D e r i v a t i o n o f n a m e : After the Ba!tic.

D i a g n o s i s : A Diplotrypa with man y mesopores, densel y group ed diaphragms and !arge autozooecia.


O. R. x v N asw ... 0.275-0.500 0.351 ± 0.014 13.11 0.0459 47 mpw ... 0.093-0.234 0.145 ± 0.009 21.48 0.0312 47 daz/mm 2-6 3.9 ± 0.3 22.32 0.860 47 dmp/mm 3-6 5.1 ± 0.2 10.46 0.536 47 mp/mm2 7-14' 9.9 ± 0.4 14.18 1.402 47

D e s c r i p t i o n : The zoarium is hemisphaerical with a diameter of 2 - 30 mm and a height of approximately lO mm. The autozooecia tend to be circular in outlin e and are surrounded by numerous mesopores which are polygonal and much smaller than the autozooecia. There are approximately 3 times more mesopores than autozooecia in a zoarium. The zooecial walls are thin and lack acanthopores. There are approximately 23 autozooecial apertures in one mm2• In tangential section the autozooecia curve in the very proximal part of the zooecium and grow transversely towards the basal surface for most of its length. The autozooecium contains numerous thin, tabular diaphragms. Cystiphragms occur rarely. The

mesopores contain more diaphragms than the autozooecia. The interzooecial walls are approximately 5�-tm thick proximally and up to 20 �-tm distally.

R e m a r k s : Diplotrypa baltica resembles D. petropolitana (NICHOLSON) in general appearance bu t i t differs in having smaller autozooecia, more mesopores and fewer cystiphragms.

Eridotrypa sueclca n. sp. PI. 5, Figs. 1-3



D e r i v a t i o n o f n a m e : Narned after Sweden.

D i a g n o s i s : An Eridotrypa species with small zooecia, weak calcification and many diaphragms.


O. R. x v azw . . . 0.067-0.125 0.094 ± 0.003 10.89 O .Dl O l

N 42

D e s c r i p t i o n : The zoaria are ramose and slender with circular cross-sections. The width of the stem is 1-3 mm. The aperture of the autozooecia is oval or polygonal. Calcification is generally weak. The mesopores are generally fewer than the autozooecia and much smaller. Acanthopores are rare or lacking. Transverse sections show three to five large tubes occupying the centre of the stems. From their lateral sides the zooecia are budded. The zooecia curve gently outwards and open obliquely towards the stem surface. The interzooecial walls are very thin in their proximal part, approximately 5�-tm wide. The endozone is approximately 5 �-tm wide. The exozone is generally thin. The zooecia are polygonal in transverse section. Longitudinal sections show comparatively short autozooecia. The interzooecial walls thicken in the exozone, where they are approximately 20 �-t m wide. Thin diaphragms are common in the exozone and the distal parts of the endozon e. Mesopores are few and short. Acanthopores are rare. The central tu bes are generally free of diaphragms.

R e m a r k s : E. suecica differs from E. aedulis (EICHWALD) and E. aedulis minor (ULRICH) in having smaller autozooecia and more diaphragms in the zooecia.

Radiotryps n. gen.

T y p e s p e c i e s : Radiotrypa gothica n. sp.

D e r i v a t i o n o f n a m e : After its budding pattern.

D i a g n o s i s : Zooecia are budded from several budding laminae, radiating from the centre of erect stems. Mesopores few. Acanthopores rare.

O c c u r r e n c e : Upper Ordovician (Ashgill).

D e s c r i p t i o n : The zoarium is erect, composed of thin stems. The exozone is thin. The zooecia originate from several budding laminae which radiate from the centre of the stem. Mesopores are few or absent. Acanthopores are few.

R e m a r k s : This genus is characterized by its budding pattern which is very characteristic both in transverse and longitudinal sections.

BROOD Ordovician bryozoa 59

Radiotrypa gothica n. sp. P l. 2, Fig. 4, P l. 3, Fig. l, 2, 4, P l. 5, F i g. l O



D e r i v a t i o n o f n a m e : Gothica, latinization of Götaland.

D i a g n o s i s : A Radiotrypa species with small zooecia, few mesopores and radiating budding pattern.


O. R. x V azw . . . 0.047-0.094 0.071 ± 0.004 17.09 az/mm2 16-25 21.5 ± 0.7 10.79

0.0121 2.32

N 47 47

D e s c r i p t i o n : The zoarium consists of thin, cylindrical stems which are approximately 2 mm wide. The apertures of the autozooecia open irregularly on the stem surface. The autozooecial aperture is polygonal or longitudinally oval in outline. Tangential sections show 5-l O laminae radiating from the centre of the stem. These laminae are approximately twice as thick as the

interzooecial wall. The zooecia are budded from these laminae, which generally bifurcate near the stem centre. The laminae are 15 - 20 f.im thick on the average. The interzooecial wall is approximately lO f.im in the endozone. The endozone is approximately l mm thick and the exozone generally thin. The autzozooecia are generally short, growing obliquely outwards for their whole length. They open obliquely towards the stem surface. The interzooecial walls are thin in the endozone but thicken distally. Diaphragms are rare and limited to the exozone. Mesopores are rare. In the exozone there are a few acanthopores which are approximately 20 f.im thick.

R e m a r k s : The present species is easily recognized by its characteristic budding pattern.

Acknowledgements

I am very grateful to Drs. M. Bassett and V. Jaanussen who read the manuscript and made several very valuable suggestions. Technical assistance have generously been given by E. Norrman, M. Berggren and U. Samuelsson.

Literature

AsTROVA, G. G. (1965): Morfologiya, istoria, razvitya i sistema Ordovikskikh mshanok. - Akad Nauk SSSR, Trud. Paleontol. lnst. 106: 1-431. Moscow.

BASSLER, Ray S. (1906): The Bryozoan fauna of the Rochester Shale. Bull. U. S. geol. Surv. 292: 1-137, 31 pi. Washington.

- (1911): The ear! y Paleozoic Bryozoa of the Baltic Provinces. - Bull. U. S. nat. Mus. 77: 1-382, 226 fig. , 13 pi. , Washington.

- (1928): Bryozoa, In: TWENHOFEL, W. H.: Geology of the Anticosti Island. - Mem. geol. Surv. Canada. 154: 143-168, pi. 6-14, Ottawa.

- (1953): Bryozoa, In: (Raymond S. MOORE, ed.): Treatise on Inverteb rate Paleontology. G: 1-253. 175 fig., Lawrence, Kansas.

BEKKER, H. (1921): The Kuckers Stage of the Ordovician rocks of N. E. Esthonia. - Acta et Comment. Univ. Dorpatensis, A 2, 1: 92P. 12 pi. , Tartu.

BOARDMAN, Richard S. (1959): A revision of the Silurian bryozoan genus Trematopora. - Smiths. Mise. Coli. 139, 6: 1-14, l textfig., 3 pi. , Washington.

- (1960): A revision of the Ordovician bryozoan genera Batostoma, Anaphragma, andAmplexopora. - Smiths. Mise. Coli. 140,5:28 p., 7 pi. , Washington.

- & UTGAARD, John (1966): A revision of the Ordovician bryozoan generaMonticulipora, Peronopora, Heterotrypa, and Dekayia. -J. Paleont. 40,5: 1082-1108, 9 textfig., 10 pi. , Tulsa, Oklahoma.

BORK, Kennard B. & PERRY, T. G. (1967): Bryozoa (Ectoprocta) of Champlainian age (Middle Ordovician) from northwestern Illinois and adjacent part of lowa and Wisconsin, Part l. -J. Paleont. 41,6: 1365-1392, 5 pi. , Tulsa, Oklahoma.

- (1968 a): Bryozoa (Ectoprocta) of Champlainian age (Middle Ordovician) from northwestern Illinois and adjacent parts of Iowa and Wisconsin. Part Il. Bythopora, Diplotrypa, Hemiphragma, Heterotrypa, Stigmatella, Eridotrypa, and Nicholsonella.-J. Paleont. 42,2: 337-355, l text-fig. , 5 pi. , Tulsa, Oklahoma.

- (1968 b): Bryozoa (Ectoprocta) of Champlainian age from northwestern Illionois and adjacent parts of Iowa and Wisconsin, part III, Homotrypa, Orbignyella, Prasopora, Monticulipora, and Cyphotrypa. -J. Paleont. 42,4: 1042-1065, 6 pi. , Tulsa, Oklahoma.

BROWN, George D. (1965): Trepostomatous Bryozoa from the Logana and Jessamine Limestones (Middle Ordovician) of the Kentucky Bluegrass Region. -J. Paleont. 39,5: 974-1006, 2 text-fig., 8 pi. , Tulsa, Oklahoma.

D ALMAN, J. W. (1825): Några Petrificater funne i Ostergötlands Ofvergangskalk. -K. Vetensk. Acad. Hand!. 1824. Stockholm.

EICHWALD, Edouard (1860): Lethaea Rossica. 1:682 p., 59 pi. , Stuttgart (Schweizerbart).

KARKLINS, Olgerts (1969): The cryptostome Bryozoa from the Middle Ordovician Decorah Shale, Minnesota. - Minnesota Geol. Surv. Spec. Pub!. sp-6: 1-121 figs., tabl., Minneapolis.

MODZALEVSKAJA, E. A. (1953): Trepostomaty Ordovika Pribaltiki i ihk stratigraficheskoe znachenie. - Trudy VNIGRI. 78: 91-167. Moscow.

MANNIL, Ralph (1958): New cryptostomatous Bryozoans from the Ordovician of Estonia. - Eesti NSV Teaduste Akademia Toimetised, 7: 330-347. Tallin. [In Russian with English summary].

(1959): Voprosy stratigrafii i mshanki ordovika Estonii. - Au toreferat dissertatsii Akad. Nauk. Eston. USSR: 1-40. Tallin.

PERRY, T. G. (1962): Spechts Ferry (Middle Ordovician) Bryozoan fauna from Illinois, Wisconsin, and Iowa. - Illinois State Ge o!. Surv. Circ. 326: 36, p. 4 Text-fig. , 7 pi. , Urbana.

Ross, June Philipps (1960 a): Restudy of seven Ordovician bifoliate Bryozoa. - Palaeontology 3,1: 1-25. Oxford.

- (1960 b): Larger cryptostome Bryozoa of the Ordovician and Silurian Anticosti Island, Canada - part l . -J. Paleont. 34,6: 1057-1076, 2 text-fig., 7 tab., 4 pi. , Tulsa, Oklahoma.

- (1960 c): Retevaluation of the type species ofArthropora ULRICH.-J. Paleont. 34,5: 859-861, Tulsa, Oklahoma.

- (1963 ): Trepostorne Bryozoa from the Caradox Series, Shropshire.Palaeontology 6,1: 1-11, 3 text-fig. , 4 tab., pi. 1-3, Oxford.

TOOTS, Heinrich (1952): Bryozoen des estnischen Kukersits. - Mitt. Geol. Staatsinst. Hamburg. 21:113-137, 7 Abb., Taf. 6-11, Hamburg.

60

ULRICH, E. O. ( 1882): American Paleozoic Bryozoa.- Cincinnati Soc. natur. Hist. J. 5: 232-257, pl. 10-11, Cincinnati.

- (1883): American Paleozoic Bryozoa.- Cincinnati Soc. natur Hist. J. 6: 82-92, p l. 1 , Cincinnati.

UTGAARD, John & PERRY, T. G. (1964): Trepostomatous Bryozoan fauna of the Upper part of the Whitewater Formation (Cincinnatian) of eastern Indiana and western Ohio. - Indiana Dept. Conservation, Geol. Surv. Bull. 33: 1-1 1 1. Bloomington.

W IM AN, Carl ( 1902): Db er die B orkholmer Schicht im Mittelbaltischen Silurgebiet. - Bull. Geol. Inst. Uppsala, 5,2: 149-222, 11 Abb., 2

Tab., Taf. 5-8, Uppsala. - (1890): Paleozoic Bryozoa.-Illinois State Geol. Surv. 8: 283-688, 18

text-fig., pl. 29-78, Urbana.

Plate 1

Fig. 1, 4, 5: Diplotrypa baltica n. sp. 1: Tangential section showing autozooecia and mesopores. RM By 23531, paratype. X 50. 4: Longitudinal section showing autozooecia and mesopores. RM By 23532,

holotype. X 25. 5: Longitudinal section. RM By 23533, paratype. X 10.

Fig. 2: Peel section of Borenshult limestone showing numerous brachiopod valves in clay rich matrix. X 5.

Fig. 3: Peel section of Borenshult limestone showing a sparitic, c alearenitic limestone. X 5.

Fig. 6 - 8: Haltopara solbergiensis n. sp. 6: Longitudinal section showing autozooecia and mesopores. RM By 23469, paratype. X 25. 7:

Longitudinal section showing autozooecia and mesopores. RM By 23469, paratype. X 25. 8: Transverse section showing zooecia. RM By 23468, paratype. X 25.

All specimens from Borenshult.

Brood, Tafel 1

Plate 2

Fig. l, 2, 5-8: Hallopora multzpora n. sp. l: Longitudinal seetio n. RM By 23459, paratype. X 20. 2: Longitudinal section. RM By 23461,

paratype. X l O. 5: Tangential section showing autozooecia sur

rounded by numerous mesopores. RM By 23458, paratype. X 55. 6:

Longitudinal section of thick stem showing presence of numerous

diaphragms. RM By 23457, holotype. X 20. 7: Longitudinal section

of thin stem. RM By 23540, paratype. X 1 O. 8: Longitudinal seetio n

showing wall structure and diaphragms. RM By 23540, holotype. X 80.

Fig. 3, 9. 10: Hallopora dalmam n. sp. 3: Transverse section. RM By

23465, paratype. X 15. 9: Tangential section showing autozooecia

and mesopores. RM By 23465, paratype. X 100. 10: Transverse sec

tion of exozone. RM By 23463, paratype. X 100.

Fig. 4: Radiotrypa gothzca n. sp. 4: Longitudinal section of exozone.

RM By 23519, paratype. X 100.


Brood, Tafel 2

Plate 3

Fig. l, 2, 4: Radiotrypa gothica n. sp. l: Transverse section of specimen with destroyed interior. RM By 23543. X 100.2: Transversesection of stem. RM By 23544. X 100.4: Tangential section. RMBy 23530, paratype. X 50.

Fig. 3, 5-9: Trematopara borenshultensis n. sp. 3: Longitudinalseetian through stem, immediately below an overgrowth showing weil developed acanthopore spines. RM By 23529, holotype. X 125. 5: Tangential section showing thick distal walls with acanthopores. RM By 23542. X 100. 6 : Longitudinal section. RM By 23541, paratype. X 50. 7: Transvers e seetio n. RM By 23542. X 100.8: Longitudinal seetio n through exozone. RM By 23541. X 100.9: Longitudinal section of exozone showing acanthopores. RM By 23541. X 100.

Specimens in figs. l, 2, 5 and 7 from Kinnekulle, the other from Borenshult.

Brood, Tafel 3

Plate 4

Fig. l , 2, 4: Asperopara crustulenta n. s p. l : Tangential section showing

autozooecia and mesopores. RM By 23511, paratype. X 100. 2:

Longitudinal section. RM 23508, paratype. X 100. 4: Tangential

section. RM By 23509, paratype. X 100.

F i g. 3, 5, 6: Heterotrypa compressa n. sp. 3: Tangential section showing

exoacanthopores and endoacanthopores. RM By 23507, paratype.

X 100. 5: Longitudinal section. RM By 23504, holotype. X 100. 6: Tangential section, RM By 23507. X 40.

Fig. 7, 8: Ceramopora berzelii n. sp. 7: Tangential section showing wall

structure. RM By 23513, paratype. X 100. 8: Tangential section.

RM By 23514, paratype. X 40.


Brood, Tafel 4

Plate 5

Fig. 1- 3 : Eridotrypa suecica n. s p. l: Transverse section through stem. RMBy 23560. X 100. 2: Longitudinal section. RM By 23528, paratype. X 25. 3 : Transverse section. RM By 23560. X 25.

Fig. 4 - 9: Batostoma gracilis n. sp. 4: Transverse section. RM By 23476,

paratype. X 50. 5: Transverse section. RM By 23496, paratype. X 125. 6 : Transverse section. RM By 23504. X 100. 7 : Tangential section showing exozone with acanthopores. RM By 23490, paratype. X 80. 8 : Longitudinal section. RM By 23501, holotype. X 30. 9: Oblique section. RM By 23478, paratype. X 60.

F i g. l 0 : Radiotrypa gothica n. s p. l 0: Longitudinal seetio n showing characteristic budding pattern. RM By 23519, paratype. X 15.

All specimens from Borenshult, except fig. l and 3, which are from Kinnekulle.

Brood, Tafel 5

Plate 6

Fig. J, 3: Ceramopora berzelii n. sp. J: Transvers e seetio n. RM By J472,

holotype. X 60. 3: Longitudinal seetion. RM By J472, holotype. X 60.

Fig. 2, 4: Graptodictya boreniensis n. sp. 2: Transverse seetion. RM By

23474, paratype. X 100. 4: Transverse seetian above and longitudi

nal seetian below. RM By 23478, paratype. X 100.

Fig. S - 8: Ptilodictya bifurcata n. sp. 5: tangential seetion. RM By

23486, paratype. X 10. 6: Tangential section. RM By 23480, para

type. X 100. 7: Tangential section. RM By 23480, paratype. X SO. 8:

Longitudinal section. RM By 2348S, paratype. X 40.


Brood, Tafel 6

upper ordovician bryozoa from dalmanitina beds of...

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