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THE UNIVERSITY OF ALBERTA
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NORTH AMERICAN TENTACULITIDAE
A THESIS
SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE
OF MASTER OF SCIENCE
DEPARTMENT OF GEOLOGY
by
LARRY JOSEPH BILAN
EDMONTON, ALBERTA APRIL, 1961
1
Ill
ABSTRACT
Tentaculites ranges from Lower Ordovician to middle Upper Devonian. Twenty species are described from mainly western North American Devonian and Silurian formations, and a schematic representa¬ tion of the various external shapes is given. Nine species are new and eleven are referred to previously named species.
Tentaculitids are divided into two groups on the basis of internal structures, external ornament, and skeletal characteristics. The two groups are termed "Forma A" and "Forma B." This division may have fundamental significance in indicating different modes of life for the two forms.
The present investigation suggests that tentaculitids are closely related to orthoconic cephalopods and possibly ancestral to the belemnites . Previous classifications are also discussed.
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ACKNOWLEDGEMENTS
Specimens for this study were obtained from the University of Alberta Palaeontology Collection, the California Standard Company, Pan American Petroleum Corporation and several individuals. The writer expresses his appreciation to those responsible.
Members of the Department of Geology, University of Alberta, gave assistance and helpful suggestions. Special thanks are extended to Dr. C.R. Stelck and Dr. S.J. Nelson under whose supervision this thesis was written.
The writer acknowledges the support of this work given by the National Research Council during the 1959-60 university term.
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TABLE OF CONTENTS
CHAPTER Page
I INTRODUCTION . 1
Previous Work .......... . ..... . 2
II STRATIGRAPHY . 9
Generalized Stratigraphic Relationships .... 9
Stratigraphic Range of Tentaculites . 9
Morphology ... . ...... 11
Stratigraphic Range and S ignificant
Structural Variations ... . 11
Forma A..... . 11
Forma B . . . . . 13
Graphical Method For Stratigraphic Use ... 16
III ZOOLOGY ..................... 20
Structural Features of the Skeleton . 20
General Structural Features ......... 20
Forma A ................. . 20
Forma B . ............. 22
Finer Structural Details ........... 23
Forma A . i ...... . . 23
Forma B . . 27
The Problem of Cone- In-Cone Structure .... 28
Classif icatory Status ............. 31
Historical Background . . 31
Evaluation of Previous Designations ..... 34
Affinities and Classification ........ 38
Occurrence, Mode of Life, Environment ...... 40
V
vi
Page
IV PALAEONTOLOGY . . . . . . . . 43
Introduction . . 43
Formal Descriptions . 44
FORMA A . . . . . . 45
Tentaculites gyr acanthus (Eaton) ...... 45
T. n. sp. 1587 . . 47
T. n. sp. 1588 . 48
T. sp., aff. T. n. sp. 1588 . 50
T. n. sp.? 1590 . 51
T. n. sp. 1591 . 53
T. n. sp. 1600 . 55
T. n. sp. 1614 . 61
FORMA B . 62
Tentaculites gr acilistriatus Hall . 62
T. gr acilistriatus Hall, n. var. 1593B .... 64
T. gr acilistriatus Hall, n. var. 1593D .... 66
T. gr acilistriatus Hall, n. var. 1593D? .... 67
T. gr acilistriatus Hall, n. var. 1593E .... 68
T. gr acilistriatus Hall, n. var. 1594 . 69
T.. sp., ex.gr. T. gr acilistriatus Hall ..... 71
T. n. sp. 1602 . 72
T. n. sp. 420, cf. T. acuarites Richt . 74
T. sp., aff. T. n. sp. 420 . . 75
T. n. sp. 1599, aff. T. mackenzienis Kindle . . 77
T.? sp . 78
vii
Page
Styliolina sp., cf. j>. f issurella (Kail) . 79
j3. f issurella var. strigata (Hall)? . 80
S. f issurella var. intermittens (Hall)? . . 81
S. sp.? . 82
CONCLUSIONS . . 84
Bibliography
85
Vlll
ILLUSTRATIONS
Page
PLATES 1. Silurian and Lower Devonian? Specimens,
Western Canada . 90
2. Middle Devonian Specimens, Western Canada . 92
3. Middle Devonian Specimens, Eastern Canada . 94
4. Middle? and Upper Devonian Specimens,
Western Canada . 96
5. Upper Devonian Specimens, Western Canada . 99
6. Lower?, Middle and Upper Devonian Specimens,
Western Canada and Arctic Islands . • 102
FIGURES 1. Index Map of Canada . • 4
2. Location Map of Mackenzie River Area . 5
3. Schematic Representation of External Shapes
of Forma A and Forma B Tentaculitids . 15
4. Annulations per ram. vs. Rate of Cone Expansion
for Three Species of Tentaculites . 18
5. Ireton Assemblage of Tentaculites ; Length vs.
Maximum Cone Width . 59
6. Ireton Assemblage of Tentaculites ; Length vs.
Annulations per mm . 60
TABLES 1. Middle and Upper Devonian Correlations.. . 10
2. Differentiation of Forma A and Forma B
Tentaculitids . 24
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CHAPTER I
INTRODUCTION
Tentacuiitids are small conical marine invertebrates that occur very abundantly in Silurian and Devonian strata the world over.
Their taxonomic position has always been in dispute. They are found in a wide variety of rock types and faunal associations, and have often been interpreted as swimming or floating organisms.
Published information dealing exclusively with tentacuiitids has been scant in recent years. They are often recorded in general faunal studies, but little detailed work has been done. Their usefulness as zonal fossils is still relatively unexplored but tantalizing in aspect, mainly because of their ubiquitous occurrence in various lithologies.
With an eye in mind to the various problems, Dr. C.R. Stelck of the University of Alberta made the apt suggestion of a study involving these curious fossils. The purposes of the study were three' fold; to provide a limited amount of stratigraphic information on the occurrence of Tentaculites; to examine structural characteristics of the skeleton for features which might help in solving the classification problem; to arrive at some grouping of the numerous species.
Fossil suites in the University of Alberta Palaeontology Collection form the basis for most of the study. In addition, collections made in the summer of 1959 while working in the Yukon Territory and North¬ west Territories were donated to the University of Alberta by the Cali¬ fornia Standard Company. Other oil companies and individuals also made valuable contributions. All specimens examined are from either Devonian or Silurian strata and the majority are from Western Canada. A few are
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from eastern North America, and one suite is from the Arctic Islands.
Previous Work
The earliest references to tentaculitid-like fossils are found in European literature. Walch (1775) originally illustrated the fossils to which Schlotheim (1820) subsequently assigned the name Tentaculites . Schlotheim considered them to be fragmented crinoid
A
appendages, while Von Buch (1831) in a later publication described them
as spines of brachiopods.
*
McCoy (1885) concluded that Tentaculites w as more closely
allied to the Pteropoda, a group of thin shelled, or naked pelagic
*
gastropods. Later, however, Etheridge (1881) considered them to be members of the Tubicolor Annelida. Vine (1882) clarified the disagree¬ ment to some extent by producing evidence based on structural features that Tentaculites is separable and unrelated to the tubicolor annelids, yet he also disagreed with relating them to the Pteropoda.
Eaton (1832) was the first to describe tentaculitids from North America, considering them to be echinoid spines. In 1845 Austin" referred them to the Pteropoda. Hall (1879) gave a comprehensive review of North American literature on tentaculitids to that date, and also illustrated previously named, and several new species. Following Austin, Hall also referred Tentaculites to the Pteropoda.
Since Hall's time, no comprehensive compilation of species or analysis of stratigraphic range of species has been attempted. To the writer's knowledge practically all references to tentaculitids are in papers describing larger faunal assemblages. Sporadic references have been made with regard to their position in the classification such as
those of Knight (1937), Termier and Termier (1948) and Yochelson (1957).
*Not cited in bibliography, refer to Hall (1879)
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of Virginia.
4
FIGURE I
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LOCATION MAP OF MACKENZIE RIVER AREA
FIGURE 2
6
KEY TO LOCATION MAPS
MAP FIGURE 1
|
Area |
Locality |
Fossil Suite |
|
Thedford, Ontario . |
. 1 |
... 1591A-G |
|
Eastern New York .............. |
429 |
Redwater, Alberta . 2 ...... 1600
|
Swan Hills, Alberta ....................... |
3b . . . , |
, . . 1602A-C |
|
Hay River, Northwest Territories . |
3c . . . . |
|
|
Jasper, Alberta ........................... |
3d . . . . |
. .. 1599A,B |
|
Redstone River, Northwest Territories . |
4 |
1586 |
|
Bathurst Island, Canada . . . |
5 .... |
1612A-D |
|
MAP FIGURE 2 |
||
|
Carcajou River, Northwest Territories ..... |
6 .... |
1614A-E |
|
7 .... |
1590A,B |
|
|
Many Beaver River, Northwest Territories ... |
8 .... |
15 93 A- 1 1594 |
|
Snake River, Yukon Territory . . . |
9 .... |
1573A |
|
10 .... |
||
|
Bonnet Plume River, Yukon Territory . . |
11 . ... |
|
|
12 .... |
423 424 |
|
|
Wind River, Yukon Territory . . |
13 . |
1570 |
1569
1568
14
420A, B
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MAP FIGURE 2 CONTINUED
Hart River, Yukon Territory
Blackstone River, Yukon Territory Peel River, Yukon Territory .
East Porcupine River, Yukon Territory Ogilvie River, Yukon Territory .
15 1561
1562
1563
1564
1565
16 1553
17 1566
1567
18 425
426
427 1555
19 ...... 1556
1554
20 1548
21 1557
22 1558
1559 1545
1560 421
23 _ _ 1547
154 6 A- 0
24 . 1551
1552
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Northwest |
Territories ...... |
26 .... |
|
|
Carnwath |
River, |
Northwest |
Territories ...... |
27 .... |
1574 |
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28 .... |
29
1583
Wolverine River, Northwest Territories
30
1615
8
MAP FIGURE 2 CONTINUED
Andrew River, Northwest Territories . 31 . 1575
32 1585
1576
33 1578
34 _ ... 1577
35 1580
1581 1587A-C
1582
Anderson River, Northwest Territories ........ 36 ....... 1589
37 ....... 1588A-D
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CHAPTER II
STRATIGRAPHY
Generalized Stratigraphic Relationships Stratigraphic Range of Tentaculites
Tentaculites occurs in rocks varying in age from Lower Ordovician (Canadian) to Upper Devonian. It apparently underwent rapid extinction close to the end of Frasnian or possibly early Famennian time. The youngest tentaculitids are not radically different from the oldest, and no logical reason is apparent for their rapid disappearance.
The oldest known tentaculitid is T. lowdoni Fisher and Young from the Lower Ordovician Chepultepec limestone of Virginia.
In Western Canada there are no published reports or descriptions of Tentaculites from Ordovician strata, but it is known that Tentaculites occurs in Lower Silurian rocks from the Yukon Territory.
The youngest tentaculitids examined come from the Upper Devonian Imperial formation of the Yukon and Northwest Territories. Warren and Stelck (personal communication) state that to their knowledge no tentaculitids have been found in Western Canada above strata coeval with the Imperial formation (such as the Alexo formation in the Rocky Mountains, the Gramminia formation beneath the western Canadian plains, and the Bosworth sandstone of the Hay River area, Northwest Territories) . In the United States the highest reported occurrences of Tentaculites are from the Chemung formation of New York and the Hackberry stage of
the Upper Devonian in north central Iowa. The Imperial, Chemung and
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MIDDLE AND UPPER DEVONIAN CORRELATIONS
11
Hackberry formations according to Lenz (1959) are all nearly time equivalents whose tops are at the Frasnian-Famennian boundary. It is provisionally concluded that the upper limit of Tentaculites sp, corresponds to this boundary.
Morphology
There are two fundamentally different kinds of transversely annulated conical shells in the Tentaculitidae. Differentiation of the two depends upon external features, state of preservation, and also upon knowledge of their internal and skeletal structures. For the purposes of this thesis the two kinds of skeleton are designated "Forma A" and "Forma B" (see p.24). Briefly Forma A is usually larger, thick walled and uncrushed, while Forma B is smaller, thin walled, finely annulated, and often flattened in preservation.
Stratigraphic Range and Significant Structural Variations
The following discussion is divided into two sections, the first dealing with Forma A and the second with Forma B, Gross structural variations of each form are discussed, starting with the oldest and proceeding to the youngest representatives of the two groups.
A schematic diagram with essentially the same information is included (fig. 3).
Forma A
Forma A has a range corresponding to that of the Tentaculitidae as a whole, Lower Ordovician to Upper Devonian. The oldest representative of Forma A is T. lowdoni Fisher and Young from the Lower Ordovician of
Virginia. It is medium sized, approximately 5 to 9 mm. long with
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annulations increasing very slightly but regularly in spacing and height away from the apex. (See Fisher and Young 1955, pi. 29, fig. 10).
Because of the lack of specimens or comprehensive descriptions, the record of Forma A is uncertain from Lower Ordovician until the end of Middle Silurian. In Upper Silurian time however. Forma A show the opposite extreme of irregularity in annulation spacing and strength as compared to the regularity of Lower Ordovician Forma A. Tentaculites gyracanthus^- from the Upper Silurian Manlius formation of eastern New York (Cooper et al. 1942) is a typical species showing abrupt irregularity of annulation spacing and strength.
Devonian Forma A tend toward greater regularity in annulation spacing and strength, especially in Middle Devonian time.
This is exemplified by T. n. sp. 1591 (pi. 3, figs. 1-9) from the Hamilton formation of Ontario and T. n. sp. 1590 (pi. 2, figs. 3,4) from the Hume formation in the Northwest Territories. Sharp crested transverse striations usually cover the interannular area and apertural slopes of annulations in Middle Devonian specimens.
Upper Devonian Forma A tend toward a noded longitudinal profile and a reduction in prominence of tranverse striations. Even though there is considerable variation in annulation strength, the changes are cyclical and gradual rather than abrupt. In T. n. sp. 1600 (pi. 5, figs. 1-23) from the Ireton formation of Alberta, nodes near the aperture result from this cyclical variation in annulation strength.
Upper Devonian Forma A from Eastern Canada also show variation in
^ Specimens identified and described as T. gyracanthus (p. 45) became available too late to be included in the plates.
Tentaculites gyracanthus is illustrated in Index Fossils of North America, Shimer and Shrock, p. 526, pi. 214, figs. 41,42.
13
annulation prominence, but the changes are more abrupt and there is little tendency toward noding.
Forma B
The known stratigraphic range of Forma B tentaculitids is from Lower Silurian to Upper Devonian (Middle Frasnian) . Rocks of Lower Silurian age from the Yukon Territory yielded the oldest representative examined. The upper limit of Forma B seems to be slightly below that of Forma A with the youngest specimens occurring in strata of lower and middle Frasnian age such as the Fort Creek and Perdrix formations of Western Canada.
No specimens of Forma B from Eastern North America were available to the writer, consequently discussion of structural variations will be restricted to those of Western Canada.
All Forma B of definite Silurian age have a similar external appearance. Annulations are sharp crested, abruptly elevated, closely and regularly spaced over the whole length; longitudinal striations are always present, but transverse striations are absent. All specimens examined were crushed, probably a reflection of their thin walled structure and occurrence in shale facies. Tentaculites n. sp. 420 (pi. 1, figs. 1-4) is typical of Silurian Forma B.
A sequence of dark limestones and fissile black shales considered by some to be of Lower Devonian age, overlies definite Silurian strata in the Yukon Territory. Following the practice of the California Standard Company, this sequence is designated as MThe Lower
Dark Limestone and Shale Unit”.
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Tentaculites ^ of Forma B are sporadically very abundant in this unit. Tentaculites sp. ex. gr. T. gracilistriatus Hall, (pi. 1, figs. 5-17) shows the great variability of the tentaculitid fauna within the Lower Dark Limestone and Shale. Occasionally specimens indistinguishable from characteristic Silurian tentaculitids occur within this unit. However, most Lower Dark Limestone and Shale tentaculitids show wider more irregularly spaced annulations with a marked tendency for annulations to become crowded and weaker near the aperture. As in definite Silurian specimens, longitudinal striations are prominent covering the whole shell, while transverse striations are absent. Generally Lower Dark Limestone and Shale tentaculitids are stubby conical rather than aciculate.
In Middle Devonian strata such as the Ramparts formation, Tentaculites is of a somewhat different character than that in the Lower Dark Limestone and Shale. Annulations are widely and regularly spaced, and the cone is quite slender. The tendency toward crowding and reduction in prominence of annulations near the aperture is not so marked. Longitudinal striations are still present but less distinct, and transverse striations are absent. Tentaculites gracilistriatus Hall n. var. 1593 B (pi. 4, figs. 10-12) from the Ramparts formation in the Northwest Territories illustrates these characteristics.
Devonian strata which am probably younger than the Ramparts
2
Styliolina sp. of which one variety is described (p„ 80) also occurs abundantly in association with Tentaculites .
- )
|
SERIES |
FORMA A |
FORMA B |
|||
|
FAMENNIAN UPPER DEVONIAN FRASNIAN |
f /~@ NO V % RECORD W |
1 0 |
t NO RECORD 1 ! i 1 |
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CIMENS |
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MIDDLE SILURIAN |
NO SPE |
CIMENS |
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UPPER ORDOVICIAN |
NO SPE< |
:imens |
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MIDDLE ORDOVICIAN |
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all figures approximately (x3) Note: Silurian Forma B has the appearance on the diagram of Cornulites . The reader is referred to Plate 1, figs. 1-4 for an exact picture of the true external shape.
Schematic Representation of External Shapes of Forma A and Forma B Tentaculitids
FIGURE 3
.
.
16
formation have two different groups of Forma B tentaculitids . The first
contains specimens identical with those in the Ramparts formation. Tentaculites gracilistriatus Hall n. var. 1593 D (pi. 4, figs. 9, 13-15) found both in the Ramparts and Fort Creek shales is diagnostic of the first group. The second group embraces specimens which revert to the close annulation spacing which characterized Silurian Forma B.
However, members of the second group are smaller, more slender, and most important, longitudinal striations so distinctive in Silurian specimens are absent or very rarely visible. Tentaculites mackenziensis (Warren and Stelck 1956, pi. 15, fig. 11) from the Simpson shale, T. n. sp. 1602 (pi. 6, figs. 3, 10-12) from the Beaverhill Lake formation and T. n. sp. 1599 (pi. 4, figs. 17, 18) from the Perdrix formation belong in the second group and are probably all of Upper Devonian age.
Graphical Method for Stratigraphic Use
A graphical plot of two unrelated skeletal features for three species of Tentaculites indicates that bivariate graphical analysis is potentially useful as a stratigraphic tool in the Tentaculitidae.
Three species of Tentaculites from widely separated parts of Canada and from different stratigraphic levels are used as examples.
A plot of rate of cone expansion versus annulations per mm. resulted in three widely separated point clusters (fig. 4). For T. n. sp. 1600 from the Ireton formation, twenty- two specimens were plotted. They have the largest scatter on the graph, but at no place do they overlap point plots of the other species. (fig. 4, p. 18). T. n. sp. 1591 from the Hamilton formation and T. n. sp. 420 from unnamed Upper Silurian
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strata have smaller scatters on the graph but in each case a lesser number of specimens was plotted.
Although the method is not tested for smaller stratigraphic units, the possibilities of its use are indicated. Graphs of this nature could be constructed separately for Forma A and Forma B tentaculitids. Since the former are more often preserved in limestones and the latter in shales, a relatively complete stratigraphic coverage could be obtained. In Forma B tentaculitids which are often flattened, some more stable parameter, such as striation spacing or length should be used in preference to rate of cone expansion.
The use of bivariate analysis has already proven a helpful stratigraphic tool in the Mississippian of Western Canada. Nelson (1959) has plotted corallite diameter versus corallite spacing for numerous specimens of Syringopora and concludes that such plots are useful for determining stratigraphic position within the Mississippian of this area.
The very common occurrence of small, mostly fragmented specimens of Tentaculites in drill chips indicates that perfection of a graphical method of plotting even these damaged specimens would be an important aid to the petroleum industry. The drilling of outpost exploration wells through thick shale sequences often results in complete loss of stratigraphic control. It is in such situations that tentaculitids are potentially most useful. One example is cited where even the present coarse stratigraphic control may be pertinent. In northeastern British Columbia a thick shale sequence apparently straddles the Devonian-Mississippian boundary. The shelf limestones elsewhere present over much of the western Canadian sedimentary basin
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FIGURE 4
19
are absent here. Also absent is the stratigraphic control provided by fossils commonly present in the limestones. The upper limit of Tentaculites is near the Frasnian-Famennian boundary, and thus in northeastern British Columbia the first occurrence of Tentaculites can be taken to indicate strata of pre-Mississippian age. More particularly it would indicate the strata to be older
than uppermost Frasnian
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CHAPTER III
ZOOLOGY
Structural Features of the Skeleton General Structural Features
To date all tentaculitids have been grouped under the single genus Tentaculites, so that approximately one hundred and fifty species are now contained within it.
After external examination of a large number of specimens, internal structure was investigated by polished, etched, and thin sections. Although some grouping could be accomplished by observation of external features, internal structures were most important in indi¬ cating a major two-fold division of species. The two kinds of skeleton are designated "Forma A" and :iForma B", and their characteristics are as follows:
Forma A
Forma A tentaculitids are sturdy, transversely annulated cones characterized by greater skeletal complexity than Forma B. The shell wall is relatively thick, multilayered, and of variable thickness through¬ out the length.
Annulations and transverse striations result from thickening of the shell wall and are not due to wall flexure as in Forma B. The internal mould of Forma A is almost smooth and there is little reflection of the external annulations, except near the aperture where the wall is incomplete. Definite longitudinal striations have not been observed in
Forma A tentaculitids.
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Septa are common in large specimens but rare in small ones.
They are usually restricted to the apical 1/3 of the shell, and are either perpendicular to the cone axis, or slightly concave toward the
aperture. They are somewhat irregular in spacing and thickness but
3
show no evidence of septal neck or siphuncle development. Septa sometime extend a variable distance toward the aperture along the internal wall before crossing the cone. Mural segments may overlap building a considerably thicker shell wall in the septate portion. Individual layers are vague in this mural deposit (pi. 3, fig. 6, pt. f ) .
Forma A tentaculitids commonly have one or more inter¬ penetrating cones. Interpenetrations are prevalent in large specimens but usually absent in small ones. As many as four have been observed within a single large cone, yet some of the largest cones contain none (pl» 2, fig. 5). The apertures of interpenetrating cones tend to con¬ centrate at the aperture of the external cone, or else extend a short distance past it. Internal cones may have notably different shapes than the enveloping ones (pi. 5, fig. 14). Also there is a wide varia¬ tion in the maturity of internal cones, as some are thin walled, very fragile juvenile individuals and others are thick walled, sturdy and mature. The significance of cone-in-cone structure in Forma A tenta¬ culitids is discussed more fully on page 28* Generally the skeleton is strong enough to remain uncrushed, even when preserved in shaly sediments.
Forma A tentaculitids average 4 to 8 iron, in length, but can be considerably larger. Hall (1879, p. 168) reported a specimen of T. scalariformis of length 1 1/4 inches.
^Recently received specimens of T. gyracanthus (p. 45) have indications of a vague axial canal.
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Forma B
The skeleton is essentially a fragile, transversely annulated cone with a pointed or bulbiform apex and an open aperture. Relatively constant wall thickness is the most outstanding diagnostic feature of Forma B tentaculitids .
The wall appears unilayered but may have an external and internal dark film of doubtful organic origin. Wall thickness varies between 0.02 and 0.06 mm., but individual variation is usually less than 0.01 mm.
In Forma B tentaculitids annulations result from complete wall flexure (pi. 4, fig. 12), the external crest of each annulation is matched by a furrow on the shell interior. The internal mould thus displays only slightly subdued reflections of the annulations, and when preservation is poor, the moulds can easily be mistaken for external surfaces .
Although fine longitudinal striations are prominent in most Forma B tentaculitids, they are not invariably present. Striations result from minute thickness variations in the shell and are not visible on internal moulds.
Except for the apical infilling Forma B appear to be devoid of internal structures. Preservation of one cone inside another is common where the rock is highly charged with skeletons, but rare other¬ wise. When there is preservation of one or more cones inside a large cone, usually all their apertures do not point in the same direction. This indicates that interpenetrations probably were caused by bottom currents, prior to burial of the skeleton.
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23
In preservation the skeleton of Forma B tentaculitids is usually flattened, except for the short, relatively solid, calcite infilled apex. Their dominant occurrence is in shale or argillaceous limestone, the compaction of which usually results in crushing. When preserved in cleaner limestones they may retain their three dimensional aspect .
Forma B tentaculitids average 3 to 4 mm. in length and rarely exceed 10 mm. As a rule they are shorter than Forma A.
Finer Structural Details of the Skeleton
The previous section dealt only with useable gross skeletal features of Forma A and Forma B. The following discussion is primarily concerned with the finer structural details important in understanding skeletal growth, and which may also be helpful in determining zoological affinities .
Forma A
Two species of Forma A are here described in detail because of the numerous well preserved specimens available for examination, and their relatively large size. Tentaculites n. sp. 1591 is from the Hamilton formation of Ontario and T. n. sp. 1600 is from the Ireton formation of Alberta.
Tentaculities n. sp. 1591 (p.53)
Tentaculites n. sp. 1591 has a large well preserved skeleton showing details of growth and skeletal layering not visible in smaller species. The shell wall has three layers: an internal dark grey layer, a middle whitish layer and an external light grey layer. The internal
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25
layer is relatively constant in thickness and very sharply defined.
It is absent for one annulation interspace near the aperture and appears to have been deposited discontinuously as a series of cylindrical rings. The middle layer is of variable thickness and is responsible for the majority of wall thickening at the annulations. It extends slightly orad of the internal layer but is not present at the aperture. The external layer is of relatively constant thickness, and shapes all the primary surface ornamentation of the shell. At the aperture it is the only layer present, indicating that as the shell was lengthened the external wall grew forward first, and the internal layers were added later for strengthening. It is often difficult to differentiate between the external and middle layers where they appear to grade into one another at the annulations (pi. 3, fig. 5). The middle and external layers together are taken to represent the ostracum or prismatic layer of the typical molluscan shell. They are both crossed by minute fractures which everywhere approach perpendicularity to the external surface, and probably represent the minute prisms of calcite from which they are composed. The internal layer appears structureless and is probably equivalent to the hypostracum.
In one specimen a faint, minutely crenulated, adorally con¬ cave, dark line crosses the cone slightly distad of the termination of the internal layer (pi. 3, fig. 5). Possibly it represents some type of cartilagenous division between a body cavity and a living chamber, or it could be a fragile operculum for closing the aperture. There is a noticeable colour difference in the calcareous infilling on either side of the line with the orad material being considerably darker.
26
Since it is an isolated occurrence, the writer is dubious about attaching too much significance to the dark line. It might only represent a deposi- tional interface during infilling of the shell.
Septa are restricted to the apical portions of larger shells anti, are usually absent in the smaller ones. Those closest to the apex are al¬ most directly transverse but orad they become concave toward the aperture. The concave septa have overlapping mural deposits which build a thickened internal wall that may be asymmetrical in distribution. This is the only feature which departs from the characteristic radial symmetry of tentaculi- tids. No specimens showed any features from which a dorsal or ventral position could be inferred.
Interpenetrating cones are usually present in the larger shells but there never appears to be direct skeletal attachment between them.
Often the interpenetrating cone, if small, does not contact the external
\
cone at any place, and apart from the infilling appears to be suspended
i
within the larger cone. There is no conclusive evidence that inter¬ penetrations are related to growth of the organism, but they occur too commonly to all be a result of current deposition.
Tentaculites n. sp. 1600 (p« 55).
The skeletal structure of T. n. sp. 1600 is similar to that of T. n. sp. 1591. Differentiation of wall layers is less pronounced and it appears that the ostracura is no longer separable into two layers. The hypostracum is still present but indistinct. Septa are few and without overlapping mural segments.
Interpenetrating cones are prominent in larger shells, with double and triple interpenetrations common. Occasionally the cone sequence is so tightly packed that individual wall interfaces become obscure and the
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27
whole structure has the appearance of a single multilayered cone. In¬ variably the sequence is toward a thinner walled more delicate cone on the inside. Often the innermost cone is so delicate that it will only be visible by careful scrutiny of the slide. Occasionally the aperture of an interpenetrating cone extends past that of the external cone making it appear that the former is "growing" out of the exterior cone.
It seems certain that in T. n. sp. 1600 interpenetrations are related to the life cycle of the animal. The internal cones are too delicate to have withstood the necessary movement by currents and still remain undamaged.
Forma B
The unilayered wall of constant thickness which characterizes Forma B tentaculitids is notable for its similarity to the wall structure of Styliolina. The straight walled calcite skeleton of Styliolina has a very consistent optical orientation. In transverse section the struc¬ ture is radiate crystalline as in a belemnite, and under polarized light displays the dark cross associated with spherulitic structure. Longi¬ tudinal sections do not show this same radiate structure. Instead, cleavage lines emanating from the axial line pass obliquely apicad with complete continuity through the infilling, the substance of the shell and the external coating. These two sets of cleavage lines meet at the shell axis, enclosing an angle of 49 degrees (pi. 4, fig. 5).
The shell polarizes throughout with the same colour, and if the section is exactly axial, it goes to extinction simultaneously.
The same type of cleavage lines are well developed in some specimens of Forma B tentaculitids, but here the annulations produce a variable angular relationship between the axis of the shell, and the
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28
shell wall. This results in cleavage lines intersecting one another between adjacent annulations and developing a characteristic crenu- lated to wavy appearance. Under crossed nicols, extinction is no longer simultaneous for the whole shell, but similar points on each annulation go to extinction at the same time.
It has been suggested by Clark (1885) that shells of Styliolina are themselves acute representations of a scalenohedron, and that their shape has influenced calcite deposition into this crystal form. The cleavage lines and the Styliolina shell would then bear the same relationship to each other as the rhombohedron and the scalenohedron in a crystal of calcite. The same mechanism can be used to explain the cleavage lines in Forma B tentaculitids, which further suggests a close similarity between the two types of animal.
Forma B tentaculitids and Styliolina often occur in great abundance together, probably because their modes of life were similar and they occupied the same environment.
The Problem of Cone-In-Cone Structure
There is no general agreement among palaeontologists about the type of animal which produced the large numbers of skeletons now referred to the genus Tentaculites . Simplicity of structure, especially in Forma B is an important factor contributing to the lack of knowledge. Forma A tentaculitids with their generally more complex structure pro¬ vide additional information, and also more unanswered questions.
The complexity introduced by interpenetrations is not signi¬ ficant unless related to growth of the organism. Tentaculites n. sp. 1591
has common internal cones and however unlikely it may seem, there is the
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29
possibility that they all could result from chance interpenetrations.
The case for T. n. sp. 1600 is different in that occasionally internal cones appear to have delicate attachments to the external ones by fine skeletal filaments ? , perpendicular to the cone axis. Crystal boundaries of the calcite infilling are controlled by these filaments.
In one instance (pi. 5, fig. 21) wall deposits of an internal cone appear continuous with those of an external cone. Another factor suggesting the morphological relationship of cone- in-cone structure is that cone sequences are not random, but always an orderly gradation from thick walled external to fragile internal cones. The innermost cones can be extremely delicate, and possibly were in the process of formation when the animal died. They certainly appear too fragile to have xtfithstood current transport and subsequent emplacement by the same, and still to have remained undamaged. That internal cones are the youngest part of the skeleton is suggested not only by their incom¬ pletely developed structure, but also by their occasional extension past the aperture of the enveloping cone. It is known that individual cones grew away from the apex, and thus it is reasonable that the most orad extension of a complete skeleton should be the youngest.
Whatever method is used to explain interpenetrating cones, their presence as a morphologically related structure forces modifica¬ tion of the concept of tentaculitid growth. Before internal structure was studied the writer believed that each cone had a hollow living chamber inside which the animal lived, with the aperture providing access to the exterior. The large shells would have large living chambers inside which large animals could live. However, sections later showed that the interiors of large shells were often mostly
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30
filled with interpenetrating cones which left little space for the living organism. This indicated that if an animal occupied most of the internal area of a large cone, it could not occupy this same area when the internal cones became present. Two possibilities are suggested to explain this:
1. The large animal died or vacated the large cone, which later became occupied by a succession of smaller animals seeking refuge inside the larger cone.
2. A large animal may have inhabited the cone and began migrating to the exterior of the shell, partially in¬ filling the interior by cone-in-cone replicas of itself.
For T. n. sp. 1600 the first possibility is doubted because it is unlikely that refuge seeking animals should become progressively more delicate in structure. Also the suggestion of skeletal attachments weighs against it. If the second possibility is true, then the animal iN/hich formerly inhabited the interior of the largest cone would have to live mostly outside the smallest cone, unless by some unknown process it reduced in size. If the animal moved to the exterior, did it abandon the skeleton, carry it as a form of ’’tail guard", or did it possibly envelop the cones to produce an internal skeleton?
Already this discussion is in the realm of speculation, and the above questions are suggested as lines of thought, but do not appear to be answerable at the present time. Nevertheless an interesting coincidence is the rise of belemnites with internal skeletons in the Mississippian, shortly after the supposed extinction of tentaculitids in late Devonian. The possibility of such a relationship is discussed
more fully on page 39.
31
We must also consider that the animal may have abandoned the skeleton completely, and become free swimming. The great volume reduction from external to internal cone lends weight to this possibility .
Whether interpenetrations may have had some relationship to the sex or reproductive cycle of tentaculitids is a matter of con¬ jecture. One can not help speculating that possibly they did.
Presence and absence of interpenetrations in large specimens may correlate to female and male elements in the population if the sexes were separate. There seemed to be no size differentiation which might represent separate sexes as discernible from a statistical analysis of eighty-four specimens of T. n. sp. 1600 (p. 59,60).
In conclusion, cone- in-cone structure represents an increase in skeletal complexity, the significance of which is not completely understood. It is suggested they indicate emergence of mature animals from their skeleton, and partial infilling of the interior by inter¬ penetrating replicas of the external cone. If this is true then the skeleton may have become internal, been carried as a tail guard, or been completely abandoned.
Classif icatory Status
Historical Background
Taxonomic position of tentaculitids has been in a state of flux and dispute since their discovery. At least five different phyla have been suggested as receptacles for them, without any one receiving anything approaching universal support. Today there is still no general agreement. However, several of the early classifications can be discarded,
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and some of the more recent suggestions can be evaluated in the light of new information.
Schlotheim (1820), the original author of the genus, thought tentaculitids to be the fragmented tentacular appendages of Encrinites, and as such they would belong to the phylum Echino- dermata. Previous to this, Shroeter (1874) referred fossils now in¬ cluded in the genus Tentaculites to the genus Dentalium of the Scaphopoda .
Shortly after Schlotheim' s generic designation. Von Buch
(1832) added a third phylum to the two already contending possession
/
of the tentaculitids. He concluded they were spines from the inarti¬ culate brachiopod Leptaena lata .
Austin (1845) referred tentaculitids to the Pteropoda and his designation has been followed by many subsequent palaeontologists. Hall (1879), who illustrated many tentaculitids in his classical works on the Devonian of New York, was one of those who concurred with Austin's designation, and yet he must have had personal doubts because he stated:
"These bodies, however, in their comparatively thick, calcareous test, and the annulating marks which affect the interior and are visible upon the cast, are quite unlike the thin hyaline shells of most of the existing Pteropoda." (Hall 1879, p. 159).
The Annelida was the fourth phylum to be added as a potential receptable for the tentaculitids. Etheridge (1881) placed them in the Tubicolar Annelida, close to such forms as Comulites . One year later.
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Vine (1882) illustrated the wall structure of Cornulites showing it to be distinctly different from that of Tentaculites . He also dis¬ agreed with placing them in the Pteropoda, but being unable to de¬ finitely relate them to any non-extinct group, favoured keeping them under the Incertae Sedis.
Placement of Tentaculites in either the Pteropoda or the Incertae Sedis (e.g. Shimer and Shrock, 1944) have been the two designations which are still popular today. Classification in the Pteropoda however has met strong opposition. Pelseneer (1888) was convinced that Pteropoda do not appear as fossils until the end of the Lower Tertiary, and that Palaeozoic "Pteropoda" were unrelated to the Gastropoda. Knight (1941, p. 20) stated:
"Thus, all names of genera commonly referred to the Hyolithidae, Tentaculitidae, Torellellidae, Conulariidae are omitted (from the Gastropoda)^ . These in fact I do not regard as even molluscan."
Yochelson (1957) suggested that the only relationship between Palaeozoic "Pteropods" and those of today is that they are all more or less bizarre forms not clearly referable to any of the larger and better known classes.
More recently Termier and Termier (1948) suggested the creation of a new molluscan class, the Eopteropoda, to include the Hyolithidae, and Tentaculitidae along with the Conulariidae.
Moore, Lalicker and Fischer (1952, p. 458) provisionally associated the tentaculitids with the conulariids and placed them as a separate family under the extinct phylum Conulariida. Previously, Knight (1937) related the genus Conchopeltus Walcott to the
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Conulariida and suggested that conulariids along with the tentacu- litids might be more closely allied to the phylum Coelenterata as part of the class Scyphozoa. In the recent Treatise on Inverte¬ brate Paleontology (Moore, et al. 1956), the conulariids have been included with the Coelenterata just as Knight suggested, but the tentaculitids are not.
In summary, tentaculitids have been variously assigned to< the Echinodermata, Mollusca, Brachiopoda, Annelida, and Coelen¬ terata. Within the Mollusca they have been placed with either the Scaphopoda or Pteropoda. Classification under the Incertae Sedis has been a popular designation. Because of the obvious disagreement among palaeontologists, classification of the tentaculitids in the Incertae Sedis has seemed the most realistic approach.
Evaluation of Previous Designations
At least two of the earliest classifications can certainly be discarded. Structural features show that tentaculitids are de¬ finitely not fragments of echinoderms or brachiopods. They do not have the flexible plate structure of crinoid appendages nor the curved irregular shape of brachiopod spines. They were not aperturally attached as would be necessary in the case of either appendages or spines .
It may also be stated with considerable certainty that they are not members of the Annelida. Wall structures of the two are different, (Vine, 1872) and tentaculitids are completely straight, unattached and do not penetrate the bedding. They are often internally septate or contain interpenetrating cones. Tubicolor annelids on the
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other hand are often attached to some other object or to each other, have a curved axis, and sometimes grow in clusters.
Two other phyla to which tentaculitids have been related are the Coelenterata and Mollusca. Within the former, scyphozoans are suggested as a group in which tentaculitids could reasonably be placed. Tentaculites exhibits perfect radial symmetry, conical shape with a straight axis, and a completely unattached mode of life. The calcareous wall is either multilayered or unilayered and the cone may be transversely septate near the apex. On the other hand, scyphozoan coelenterates mostly exhibit tetramous radial rather than perfect radial symmetry. Their skeleton is only a tough flexible, gelatinous or chitinophosphatic material rather than a rigid calcareous framework.
Conulariids, an extinct group now included in the Scyphozoa, were originally suggested as belonging there along with the tentaculitids. Conulariids show evidence of attachment in early life although later may have been unattached. However, here the similarity ends. Neither their skeletal composition or symmetry is analagous to tentaculitids. Thus there seems to be little relationship, skeletal or otherwise between tentaculitids and scyphozoans. Other types of coelenterates have an
even more obscure relationship to tentaculitids, and thus there appears
*
to be no division in coelenterate classification where they could reasonably be placed.
Most palaeontologists wishing to classify tentaculitids with the Coelenterata are those objecting to their placement in the Mollusca, mainly because of the perfect radial symmetry atypical to most molluscs. However it is felt that this argument is not entirely
36
valid because within the rnollusca the pteropods, scaphopods, ammonoids, nautiloids and coleoids all illustrate elements of radial symmetry.
The majority of tentaculitid features are closely associated with molluscan characteristics. The shell is calcareous, multilayered or unilayered, unattached, aciculate conical, septate or non-septate, and radially symmetrical. All these features occur within the Mollusca, but unfortunately not all in any single class.
No living or extinct members of the Pelecypoda or Amphineura resemble tentaculitids and neither of these classes are considered as potential receptacles for them.
The Scaphopoda cannot be dispensed with so easily. They have radial symmetry, elongate conical shape, multilayered wall struc¬ ture and often a nearly straight axis. Nevertheless, there are three strong objections to relating tentaculitids to the Scaphopoda.
1. The tentaculitid cone is apically complete and not open at either end as in a scaphopod.
2. Scaphopods do not show the characteristic transverse annulations present on all tentaculitids.
3. Scaphopods are burrowing animals whose shells penetrate the bedding. Tentaculitids were not.
Another consideration is that scaphopods are composed of aragonite while tentaculitids are composed of calcite. Thus scaphopods are susceptible to solution and are often preserved as casts, while tenta¬ culitids are usually wholly preserved.
Within the Gastropoda, the only animals with aciculate conical, radially symmetrical shells are some of the Pteropoda* They
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are abundant in modern seas and mainly pelagic. Their skeleton is thin and semi-transparent when present, but most are naked.
The skeleton of Forma A tentaculitids is quite thick and heavy rather than the delicate structure one would associate with pelagic organisms. This casts doubt upon the supposed pelagic nature of tentaculitids, and thus also on their affinities to present day pteropods .
Not all pteropods are sharply conical, as some are coiled posteriorly in a spiral and others show bilateral symmetry. None dis¬ play transverse annulations so characteristic of tentaculitids. More¬ over, the pteropod aperture is not always directly transverse.
The great time break between occurrence of tentaculitids in the Upper Devonian and true pteropods in the Lower Tertiary indicates that any superficial resemblance is more likely the result of convergent evolution. It seems unlikely that any morphologic similarity could be due to a continuous evolutionary sequence. In conclusion, classification of tentaculitids with the Pteropoda is more a reflection of the lack of any more suitable placement.
Philip and Talent (1959, pi. 7, fig. 11) illustrated trans¬ verse "partitions" in the early whorls of the loose planispirally coiled gastropod Straparolus (Euomphalus) northi (Etheridge) . The partitions are quite widely spaced and concave toward the aperture. Presence of septa like structures in gastropods along with the occurrence of primi¬ tive limpet shaped (flat conical) forms such as Scenella indicates that gastropods cannot be completely disregarded as possible relatives of
tentaculitids .
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38
Except for size difference tentaculitids are externally similar to some of the orthoconic cephalopods such as Spyroceras ♦ Tentaculitids however, do not appear to possess a siphuncle, and those of Forma B are apparently non-septate. Possibly these structures were too delicate for preservation, or were aragonitic in composition, being dissolved previous to or after burial of the skeleton. In some specimens of T. gyracanthus received after completion of the plates, there were indications of an axial canal running through the white apical infilling. Possibly this represents vestiges of a siphuncle, but cannot be proved.
In conclusion, of all previous designations, placement with the mollusca is suggested by the majority of evidence. However, the writer disagrees with placement in either the Pteropoda or Scaphopoda and feels that the closest similarity is to the Cephalopoda. Tentacu¬ litids have elongate conical shape with a straight axis, annulated exterior, transversely septate interior (Forma A), radial symmetry, multilayered wall structure, and a bulbous apex (Forma B) . All these features are present in the Cephalopoda.
Affinities and Classification
The majority of tentaculitid features suggest placement with the Mollusca (p . 36), Some instances of analagous structure are cited and the conclusion drawn that they belong in the Cephalopoda, closely related to primitive orthoconic nautiloids, or possibly as an ancestral stock of internal shelled coleoids such as Belemnites.
The shape, symmetry and external ornament of tentaculitids is very similar to that of the othoconic nautiloid Spyroceras, which also
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39
ranges from Ordovician to Devonian. Shimer and Shrock (1944, p. 541), stated that its siphuncle structure was not well known. Two other primitive nautiloids Volborothella and Salterella are less similar to Tentaculites in shape, but more so in size and structure. Salterella has several hollow interpenetrating cones like those of Forma A tenta- culitids. The early growth stages of Protocameroceras with V-shaped adorally concave "laminae" and no siphuncle (Shimer and Shrock, 1944, p. 535, pi. 218) is very suggestive of the internal structure of T. gyracanthus (p. 45). Also, endoconic siphuncle structure of nautiloids is similar in appearance to the interpenetrating cones of tentaculitids . The major deterrent to classification of tentaculitids with nautiloids is absence of a well preserved siphuncle. Possibly this structure was too delicate for good preservation.
On page 30 it was mentioned that Devonian tentaculitid ex¬ tinction and Mississippian belemnite appearance might be related events, as inferred from tentaculitid interpenetrations indicating ex¬ terior migration of the animal. Early belemnoids from the Permian and Triassic were dominantly long and spindly with straight axes and slender to slightly club shaped rostra. This conforms with tentaculitid shape. Almost all belemnoids have a small protoconch embedded in the rostrum at the phragmocone apex, similar' to the globular to heart shaped apices of some tentaculitids. The phragmocone of the earliest recorded belem¬ nite from the Mississippian (Flower, 1945) is similar to the tentaculitid cone in having an almost circular shape with a straight axis, and closely spaced transverse septa. The incompletely preserved rostrum was inferred to be long and slightly club shaped. Annulated exterior profile of ten¬ taculitids is similar to the annulated alveoli of belemnites, reported
40
by Flower (1945 , p. 442) to occur even in those of Tertiary age.
This annulated appearance of the oldest part of the belemnite skeleton is suggestive of an ancestral tentaculitid stock.
In conclusion, features common to primitive nautiloids and tentaculitids are: conical shape with a straight axis, similar external ornament, septate interior, and cone-in-cone structure. Relationship with belemnoids is suggested by similarity of skeletal growth, annulated juvenile shape, presence of a globular protoconch and analagous phragmocone shape.
Another possibility is that tentaculitids represent a separate divergent cephalopod stock in which septa were present in some (Forma A), absent in others (Forma B), and in neither of which siphuncles were well developed.
Occurrence, Mode of Life and Environment
Tentaculitids were marine organisms preserved in a wide variety of carbonate and clastic rocks. 1 They occur in all types of limestone from coarse fragmental to crypto-crystalline as well as in sandstones, light calcareous shales, and black graptolitic shales.
This suggests that either they were adapted to numerous environments or that they were pelagic. There hgs always been doubt as to whether the latter is true. Association of thick walled Forma A tentaculitids in coarse fragmental limestones, with other benthonic organisms, such as brachiopods, bryozoans, and crinoids could be suggestive of a shallow water or possibly benthonic mode of life. A series of measurements were made on a large empty cone belonging to 1. n. sp. 1591 from the Hamilton formation. The cone weight was calculated using the density of calcite.
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41
To provide a wide margin for error the complete non- septate interior was assumed to be gas filled. It was calculated that the shells specific gravity would be 1.10, and would thus sink in sea water of specific gravity 1.027. Since the whole shell was probably not gas filled, the specific gravity would be considerably greater. Unless the animal developed external air pouches, there is little likelihood of it being a floating organism, and this argument is extended to other thick walled Forma A tentaculitids .
Nevertheless the shell may have been an internal skeleton during part of the life cycle, in which case a nektonic animal is conceivable. Forma B tentaculitids have a much more delicate skeleton and are often associated with graptolites. It is noted that their annulations may be extremely sharp and almost blade-like at the extremity. This would facilitate dispersal of pelagic organisms, and with the grap- tolite association and predominant occurrence in shale facies, is strongly indicative of a nektonic or planktonic existence.
Forma A tentaculitids although more complex than Forma B are still curiously devoid of structures indicating a dorsal or ventral skeletal orientation. If we postulate that they were benthonic and lay on the sea bottom, one would expect that over the great time range of their existence, some such structures would have evolved. However, lacking these structures suggests an upright existence. Since they appear to have been unattached throughout ixfe, it is difficult to imagine them balancing in their sharply pointed apices, and consequently they must have lived apex up. It has been suggested that the earliest cephalopods also lived with the apex up (Moore, Lalicker and Fischer, p. 343). This position is interpreted for young animals when they
42
apparently lived inside the cone. If the skeleton later became in¬ ternal, the animal could have changed to a nektonic existence.
An indication that tentaculitids were not sessile organisms is that they are rarely, if ever, encrusted by bryozoans or tubicolor annelids with which they are associated.
The wide variety of rock types preserving tentaculitids indicates that they are essentially useless as environmental indicators However, they may be helpful in determining current direction. Their elongate conical shape is at maximum stability with the apex pointed upstream and the long axis parallel to current flow. Wave action and reworking will disorient the cones, suggesting that where parallel alignment is found, burial was rapid and current direction quite uniform. An illustrated example has been given by Kindle (1938), and T. n. sp. 1591 (pi. 3, fig. 1) also shows current alignment but to a lesser degree.
In summary, the skeleton of Forma A tentaculitids appears too heavy to have belonged to a pelagic organism. In juvenile speci¬ mens the skeleton was probably external and the animal "semi-benthonic" but later as is suggested by skeletal features, the test may have be¬ come internal, the animal possibly changing to a nektonic mode of life For Forma B tentaculitids, which are much more delicate in structure and often associated with graptolites in black shales, a pelagic or nektonic existence is suggested.
43
CHAPTER IV
PALAEONTOLOGY
Introduction
Formal descriptions deal exclusively with the genera Tentaculites and Styliolina . Of twenty species referred to the former, nine are new, ten are assigned to previously named species along with four new varieties, and one is questionably referred to the genus. Partial population characteristics are indicated for three species of Tentaculites .
Of nine figured specimens of Styliolina, two are referred to S. f issurella s.l., and five to two varieties of S. f issurella . Two other figured specimens are questionably assigned to the genus.
All specimens are contained in the University of Alberta Palaeontology Museum. Museum numbers 420 to 429 indicate specimens of Silurian age and numbers 1545 to 1621 those of probable Devonian
age.
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44
Formal Descriptions
Family TENTACULITIDAE Walcott Genus TENTACULITES Schlotheim, 1820 Type Species T. scalaris
Tentaculites Schlotheim, 1820, Die Petrefactenkunde, p. 377.
Tentaculites McCoy, 1855, Sedgwick and McCoy's Brit. Pal. Rocks and Foss., p. 63.
Tentaculites Nicholson, 1872, Amer. Jour. Sci. p. 205.
Tentaculites Vine, 1882, Quart. Jour. Geol. Soc. Lond., Vol. 38, p. 385.
Shells straight or slightly curved, elongate-conical, terminating posteriorly either acutely or in a bulb; cross section circular; surface with strong transverse rings closely arranged near apex and more distant and stronger near mouth; fine transverse and rarely longitudinal striae present; apical portion often filled with calcareous material or transversely septate.
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45
Genus TENTACULITES Schlotheim 1820 FORMA. A
Tentaculites gyracanthus (Eaton)
Echinus gyracanthus Eaton, 1832, Geol. Text Book.
Tentaculites ornatus Vanuxem, 1842, Final Kept, on the Geol. of the 3rdDist. N.Y., p. 112, fig. 3.
Tentaculites ornatus Vanuxem. Mather, 1843, Final Rept. on the Geol. of the 1st Dist., N.Y., p. 349, fig. 3.
Tentaculites irregularis Hall, 1859, Nat. Hist, of N.Y., Pal., N.Y.
Geol. Surv., Vol. 3, p. 137, pi. 5, figs. 22, 23.
Tentaculites gyracanthus (Eaton). Hall, 1888, Nat. Hist, of N.Y., Pal., N.Y. Geol. Surv., Vol. 7, p. 5 (supp. to Vol. 5) pi. 114, figs. 3-17.
Tentaculites gyracanthus (Eaton). Weller, 1903, iPal. N.J., Vol. 3, p. 264, pi. 24, figs. 19, 20.
Tentaculites gyracanthus (Eaton). Ohern and Maynard, 1913, Maryland Geol. Surv., Lower Dev., p. 486, pi. 87, fig. 11.
Description: From numerous complete specimens preserved in a large
block of argillaceous limestone (suite 429).
Elongate conical; regularly tapering to a sharp apex which
remains intact; axis straight; shell often partially flattened near
aperture; length varies from 2 to 10 mm.; maximum width at aperture
2 mm.
Annulations barely visible near apex, quite even in spacing and strength, rapidly becoming thicker and higher; near aperture ex¬ tremely irregular in spacing but not so irregular in strength; slight tendency for pairs of annulations to be separated by wider unannulated areas; annulations essentially symmetrical, acute in profile near apex, more rounded near aperture; total annulations extremely variable, 15 to 40 on shells of 10 mm. length; spacing near apex indistinct, near aperture 1 to 5 annulations per mm.
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46
Transverse striations invariably present, indistinguishable from annulations near apex; cover annulations as well as interannular area; in interannular area usually of two strengths, one coarse set separated by a fine set; longitudinal striations absent.
Internal mould shows very subdued reflections of annulations; in longitudinal polished sections internal wall appears straight, except near aperture where reflection of annulations on internal mould more marked; septa absent?; apex usually infilled by variable amounts of white calcite, displaying V-shaped laminae, (septa?) concave towards aperture; some specimens show vague axial canal, (siphuncle?) in laminated deposit; white calcite often extends further towards aper¬ ture on one side of shell than other; interpenetrating cones commonly present, as many as four within a large shell, each smaller cone be¬ coming progressively more thin walled and delicate; individual wall layers not visible; cores of annulations composed of lighter grey calcite, remainder of wall dark grey calcite.
Types: Specimen 429A is considered typical of species,
not illustrated.
Horizon and Locality: Manlius formation, Upper Silurian; Locality la, label reads "Eastern New York", no other information available.
Remarks: The sample containing T. gyracanthus was obtained
after completion of the plates and thus no figured specimens are illustrated. Preservation of internal structures is good and many specimens have dark filamentous fragments inside, very suggestive of a complex internal structure. The writer feels certain that etched polished sections of specimens well preserved in argillaceous limestone will ultimately reveal the true nature of tentaculitid internal struc¬ ture. Specimens from the Manlius limestone appear to be ideally suited for this type of work.
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47
Tentaculites n. sp. 1587 Plate 2, figs. 8-10
cf. Tentaculites ornatus Sowerby. Zittel, 1913, Textbook of Pal.,
Vol. 1, p. 571, fig. 1073C.
Description: From external and internal features of numerous
specimens in a fragmental limestone (suite 1587) .
Shell small; elongate; aperturally sub-cylindrical; apically acicular; axis straight; cross section circular; length varies from 3 to 6 mm.
Annulations low, closely spaced near apex, generally coarser and more widely spaced near aperture, much stronger at irre¬ gular intervals along length; abruptly raised, symmetrical in profile, sub-rounded or acute at periphery; occasionally coarser annulations spaced at sub-equal intervals along length; total annulations 45 to 60, about 14 per mm. near aperture.
Transverse striations not evident; longitudinal striations obscure, fine, present in interannular areas of better preserved specimens .
Aperture unconstricted, circular; body cavity open; inter¬ nal mould smooth or gently undulating; apex solid, transversely septate and/or infilled by white calcite; septa straight, perpendicular to shell axis, thin, obscure, approximately 0.2 mm. apart, occasionally present from apex to mid-length; interpenetrating cones absent; shell wall medium to thick, wall layers indistinct; in longitudinal section annu¬ lations appear to have core of whitish calcite surrounded by dark grey layer .
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48
Measurements: Size variations of figured specimens
1587A-C:
Length variation 4.2 to 2.9 mm.
Width at apertures approximately 0.45 mm.
Types: Figured Specimens 1587 A-C; 1587A is considered typical of species.
Horizon and Locality: Hume formation, Middle Devonian; Locality 35, banks of the Andrew River, 68° 19' N,
129° 00' W., Northwest Territories.
Remarks: Tentaculites n. sp. 1587 is somewhat anomalous in that septation extends further towards the aperture than in any others observed, and that obscure longitudinal striations may be present, associated with a double layered wall. It has a smaller size and length variation, less annulation irregularity, and a different internal structure than T. gyracanthus (Eaton) (see p. 45) with which it might be confused.
Tentaculites n. sp. 1588 Plate 2, figs. 1,2,5,6,11
Description: From three polished sections, and from external features
of numerous other specimens all on the same slab (suite 1588) .
Elongate conical; gradually tapering to a blunt point; axis straight; cross section circular; length varies between 6 and 10 mm.
Transverse annulations abruptly raised; cover whole shell; fine, low, acute, closely and regularly spaced near apex; becoming thicker, more rounded, higher, and much more variable in spacing, strength, and crestal angle towards aperture; thicker annulations less acute and proportionately more highly elevated than thinner annulations; annulation profile essentially symmetrical near aperture;
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49
near apex tendency for apertural side of annulations to have steeper slope; occasionally apertural slope becomes almost perpendicular to cone axis; marked tendency towards aperture for strong annulations to be separated by two or three weaker annulations; average total number of annulations 50; annulation spacing 11 per mm. near apex,
3 per mm. near aperture, average for shell 5 per mm.
Transverse striations vaguely visible on apertural side of thicker annulations, absent in interannular areas; no longitudinal striations evident.
Aperture circular, open; internal mould smooth or gently undulating; apex solid, crossed by up to three transverse septa; septa perpendicular to cone axis or slightly convex towards apex; body cavity may contain a single interpenetrating cone or be empty; shell wall thick, strong, consisting of two layers, an external creamy coloured layer of variable thickness, and an internal brownish coloured one of more constant thickness; internal layer absent for short dis¬ tance near aperture; wall thickest near apex, separate layers indis¬ tinguishable; external annulations result from marked thickening of external layer.
Measurements: Size variation of figured specimens is
limited between variation of 1588A and 1588D.
Figured Specimen 1588A: Length 9.4 mm.
Width at aperture 0.88 mm.
Figured Specimen 1588D: Length 5.5 mm.
Width at aperture 0.55 mm.
Types: Figured Specimens 1588A-D; 1588C is considered
typical of the species.
Horizon and Locality: Hume formation. Middle Devonian, Locality 37, banks of Anderson Pviver, 68° 21' N.,
127o 41* Wo, Northwest Territories.
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50
Remarks: Tentaculites n. sp. 1588 is distinguished by the strong annulations of variable relief and spacing near the aper¬ ture. None of the described forms in available literature are similar to it. Its skeletal structure is comparable to T. n. sp. 1591, from the Hamilton formation. Middle Devonian of southwestern Ontario.
Tentaculites sp., aff. T. n. sp. 1588 Plate 2, fig. 7
Description: From one specimen in a coarse fragmental limestone (suite 1586) .
Elongate conical; gradually tapering to a blunt point; slightly curved by compaction; cross section circular; length 6.0 mm., width at aperture 0.82 mm.
Annulations obscured for 1 mm. orad of apex, when become visible are low, acute and regularly spaced, gradually becoming rounded, coarser, wider spaced and irregular in height towards aper¬ ture; symmetrical in profile near aperture; slight noded appearance from mid-length adorally results from successive sequences of four gradually coarsening annulations; total annulations 40 to 50, spacing near aperture 5 per mm.
Transverse striations very faint, cover both annulations and interannular area, visible only near aperture; longitudinal striations absent .
Internal structures unknown, unflattened state suggests thick walled test.
Measurements: Length 6.0 mm.
Width at aperture 0.82 mm.
Types: Figured Specimen 1586.
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51
Horizon and Locality: "Upper Nahanni Limestone",
Middle Devonian; Locality 4, North Redstone River,
63° 38' N., 125° 52' W., Northwest Territories.
Remarks: Tentaculites sp., aff. T. n. sp. 1588 is smaller than average for T. n. sp. 1588 but still falls within the length range of 6 to 10 mm. The shape and strength variation of the annulations is also similar. Although internal structures are not known, its occurrence uncrushed in a fragmental limestone, and the coarse annulations suggest thick wall structure.
The distance between locations of T. n. sp. 1588 and T. sp., aff. T. n. sp. 1588 is approximately 350 miles.
Tentaculites n. sp.? 1590 Plate 2, figs. 3,4
Description: From numerous complete but heavily weathered specimens in a fragmental limestone (suite 1590) .
Aciculate conical near apex, sub-cylindrical near aperture; axis straight, cross section circular; unflattened; length 5 to 10 mm., width at aperture 0.55 to 0.75 mm.
Annulations transverse to slightly oblique, cover whole shell; low, very fine and evenly spaced near apex, uniformly increasing in spacing and thickness towards mid-length, but near aperture higher annulations may be separated by one to four lower annulations; profile acute, symmetrical or slightly steeper on apertural side; total annulations 50 to 75, spacing near aperture 4 to 5 per mm.
Faint suggestion of transverse interannual striations?, longitudinal striations absent.
Aperture circular, unconstricted; internal mould smooth except
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near aperture; apex solid, infilled by calcite or occasionally transversely septate, septa restricted to apex, perpendicular to cone axis, usually four or less; body cavity empty or rarely with one interpenetrating cone; shell wall thick, two visible layers, an external whitish layer of variable thickness and an internal amber coloured layer, deposited after the external layer and of more constant thickness; shell thickened and layered structure obscure near apex; annulations primarily result from thickening of external layer.
Measurements: Figured specimen 1590 A:
Length 7.0 mm.
Width at aperture 0.68 mm.
Figured Specimen 1590 Bi : Length 7.5 mm.
Width at aperture 0.63 mm.
Types: Figured specimens 1590 A, Bp, B2 ; 1590 B2 is
considered typical of the species.
Horizon and Locality: Hume formation, Middle Devonian; Locality 7, Carcajou River South of Norman Wells,
64° 56' N., 126° 52' W., Northwest Territories.
Remarks: Tentaculites n. sp. 1590 has a closer annulation spacing and a thinner wall structure than T. n. sp. 1588 (p.48) and also the variation in annulation thickness, spacing and shape is less. Details of annulations near apex and interannular striations? are lacking due to poor preservation.
Tentaculites spiculus Hall (1876, pi. 26, figs. 21-25) from the Chemung of New York is similar but has more obtuse annulations
and definite interannular striations.
53
Tentaculites n. sp» 1591 Plate 3, figs. 1-9
cf. Tentaculites attenuatus Hall, 1876, Illustrations of Dev. Foss., Pteropoda, pi. 26, figs. 19,20.
cf. Tentaculites bel'lulus Hall. Hall, 1879, Nat. Hist, of N.Y., Pal.,
N.Y. Geol. Surv., Vol. 5, pt. 2, p. 169, pi. 31, figs. 15-18; pi. 31a, figs. 48-51.
Description: From numerous current aligned specimens in a block of calcareous shale (suite 1591) .
Shell large for genus; elongate conical; tapering gradually to a sharp often partially fragmented apex; axis straight; cross section circular; length usually 12 mm.; length variation 2 to 15 mm.
Transverse annulations closely and regularly spaced near apex, gradually becoming stronger and more widely and irregularly spaced adorally; due to closeness of spacing annulations commonly not visible until \ mm. orad from apex; annulations sharp crested, asymmetrical, steeper slope on apertural side; aproximately 30 annulations occur in 2 mm. as measured from apex, four in 2 mm. as measured from aperture, average of six annulations per mm. in shells of 10 to 14 mm. length.
From aperture over distance of 4 to 5 mm. from apex inter- annular area and apertural side of each annulation ornamented by closely spaced, raised, acute transverse striations, gradually increasing in strength and number from one where they become visible, to maximum of twelve between widely spaced annulations near aperture; longitudinal striations absent.
Aperture open, circular; internal mould almost smooth; apex solid, infilled with calcite and/or transversely septate; mural segments of septa may overlap building an internal deposit that may be
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54
asymmetrically thicker on one wall; body cavity open or containing one or more interpenetrating cones; shell wall thick, consisting of three layers, a thin external light grey layer, a middle whitish layer of variable thickness, an internal dark grey layer of more constant thickness; middle layer responsible for majority of wall thickening at annulations; internal and middle layers absent for approximately one annulation interspace at aperture.
Measurements: From three complete figured specimens.
A graphical plot of annulations per mm. vs. rate of cone expansion for five specimens is shown on Fig. 4, p.
Figured Specimen 1591E: Length 13 mm.
Width at aperture 1.60 mm.
Figured Specimen 1591F: Length 13 mm.
Width at aperture 1.55 mm.
Figured Specimen 1591G: Length 12 mm.
Width at aperture 1.35 mm.
Types: Figured specimens 1591A-G; 1591F is considered
typical of the species.
Horizon and Locality: Hamilton formation, Middle Devonian; Locality 1, label reads "Thedford,
Ontario", no other information available.
Remarks: Tentaculites n. sp. 1591 resembles both T. attennatus and T. bellulus but T. n. sp. 1591 is larger, the annulations show transverse striations and its annulation profile is more acute than T. attenuatus. It is smaller and has a more irregular annulation spacing near the aperture than T. bellulus . Despite these minor differences, the overall surface appearance of T. n. sp. 1591 is very similar to the same two species, which also occur in strata of Hamilton Age in southwestern Ontario (Stauffer, 1915, p. 326). No information on the internal structures of T. attenuatus and T. bellulus is available for comparative
purposes .
55
Tentaculites n. sp. 1600 Plate 5, figs. 1-23; Plate 6, fig. 7
Description: From polished sections, thin sections, and many whole specimens washed from a friable shale (suite 1600). The morphocline series 1600 A-L (pi. 5, figs. 1-12) illustrates the variations in external features. Graphical representation of variation is shown in figs. 4,5,6, (p.18 ,59 ,60)respectively.
Elongate conical; evenly or irregularly tapering to a pointed or blunt apex; axis straight or very slightly curved; cross section circular; length variation 2.5 to 7.0 mm., width variation at aperture 0.3 to 1.0 mm.
Transverse annulations cover whole shell, closely spaced, low and acute near apex, gradually and uniformly increasing in strength towards aperture if cone unnoded; majority of specimens show noded longitudinal profiles, which result from rhythmical increase and decrease in thickness of annulations along length of cone; fine annulations in internodal areas, thick annulations at nodes; annulations symmetrical in profile, acute where fine, rounded where coarse; average annulation spacing 12 per ram. for large (noded) cones, 20 per mm. for small unnoded cones .
Transverse striations present on apertural sides of annulations and in interannular areas only where annulations are thick (at nodes) ; longitudinal striations absent.
Aperture unconstricted but often occurring in internodal area making it appear externally constricted; internal mould smooth; apex solid, infilled with calcite and/or transversely septate, especially in large specimens; in small specimens body cavity usually empty; large specimens most often contain one or more interpenetrating cones, although
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56
they may also be empty; interpenetrating cones occasionally extend a short distance past aperture of external cone; total wall thickness variable, thicker at nodes, thinner at internodes, consisting of at least two layers, a thin, internal, amber coloured, dense layer of relatively uniform thickness, and an external, whitish, crystalline layer of variable thickness; internal wall straight, does not mirror noded appearance of external surface; variations in thickness of external whitish layer almost totally responsible for noded external shape.
Measurements: Size variation of morphocline is limited between variation of figured specimens 1600A and 1600L.
Figured Specimen 1600A: Length 7.0 mm.
Width at aperture 0.5 ram.
Figured Specimen 1600L: Length 2.8 mm.
Width at aperture 0.34 mm.
Types: Figured specimens 1600A-U, 1615; 1600F is
considered typical of the species.
Horizon and Locality: Figured specimens 1600A-U,
Ireton formation. Upper Devonian; Locality 2,
Redwater, Alberta; Imperial Redwater 101 Well,
Lsd. 15, Sec. 33, Twp. 57, Rge. 21, W.4 at 3275 feet.
Figured Specimen 1615, Imperial formation. Upper Devonian; Locality 30, Wolverine River, 68° 25'N.,
129° 47' W., Northwest Territories.
Remarks: The wide range of shapes shown by T. n, sp. 1600 indicates that in other "species" intraspecific variation has probably resulted in delimiting of many separate species, most of which are only variants. A population analysis of T. n. sp. 1600 is included for explanation.
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Population Analysis
Approximately three hundred specimens of T. n. sp. 1600 from the Ireton formation were obtained by partial disintegration of a two inch thickness of shale drill core. Visual examination showed a wide range of size and external ornament, divergent end members of the population being completely dissimilar. However it was noted that the gap between end members was bridged by a more or less completely gradational sequence of intermediate shapes and sizes. A statistical analysis of eighty- four of the best preserved specimens was undertaken to determine if the population represented a single species with morphochinal variation or whether it possibly represented a series of "nodal" species or subspecies.
For example, if a graph of length versus width were plotted for all the specimens, would points fall in a scattered but relatively evenly distributed pattern, or would t]iey possibly group into two or more clusters of closely spaced points ?
Two separate graphs were constructed, one a plot of length vs. width (fig. 5) the other of annulations per mm. vs. length of cone (fig. 6) In both it was found that a scattered pattern resulted, with one area of greatest concentration away from which points became more widely spaced. The areas of close spacing are partly a reflection of sampling in that they fall closer to the small end of the morphocline series where preservation was better. The larger specimens tended to be more easily fragmented. However it may also reflect a greater proportion of juvenile individuals in the population.
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The significance of the graphs is mainly in that they illustrate graphically for a relatively large number of specimens the extreme external variation apparently present in a single species.
On plate 6, figs. 1-12, an abbreviated morphocline series of T. n. sp. 1600 is illustrated. Here, as on the graphs it is readily apparent that as length decreases, annulation spacing increases and that as maximum width increases so does the length, all in a gradational manner. However if only the end members were visible, their relationship to each other would be obscure. Surely one would question their relationship to each other had they been found as isolated occurrences. Thus it appears that in Tentaculites as in many other fossils, when the population control is good, specimens are grouped together that would otherwise be considered unrelated.
There is question as to whether the graphs are valid representations of the population in that most, but not all, large cones may contain one or more interpenetrating cones. In an earlier discussion (p. 29) it was suggested that interpenetrating cones are late growth stages of the older external cones and thus should not be used as separate elements of the population. If considered in this respect, the internal cones do not affect the validity of the graphs.
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FIGURE 6
61
Tentaculites n. sp. 1614
Plate 6, figs. 4-6, 8,9
Description: From numerous poorly preserved specimens in an argilla¬ ceous sandstone (suite 1614) .
Shell aciculate conical; sub-cylindrical near aperture, tapering very gradually to a pointed apex; cone axis straight; cross section circular; length 3 to 10 mm.; width at aperture 0.25 to 0.75 mm.
Transverse annulations generally fine, regularly and closely spaced, slightly higher and thicker at very gentle nodes along length; annulation profile acute, symmetrical or asymmetrical, steep slope on either apertural or apical side when annulations asymmetrical; average annulation spacing 15 per mm.; varies from 20 per mm. at apex to 10 per mm. at nodes; total annulations 70 to 150.
No visible transverse or longitudinal striations.
Aperture circular, open, unconstricted; internal mould smooth or slightly undulating; apex solid, transversely septate for about 1/3 distance to aperture or less in large specimens; septa convex towards apex or straight and perpendicular to cone axis, usually less than ten in number, spaced four to five annulations apart; small specimens generally non-septate; no siphuncle visible; interpenetrating cones rare; shell wall multilayered, relatively thin near aperture, three or four times thicker near apex, twice apertural thickness at nodes; internal thickening of shell wall decreases orad of last septum and becomes absent near mid-length.
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Measurements: Size variation of figured specimens
is limited between that of 1614A and 1614E.
Figured Specimen 1614A: Length 7.8 mm.
Width at aperture 0.88 mm.
Figured Specimen 1614E: Length 3.2 mm.
Width at aperture 0.33 mm.
Types: Figured specimens 1614 A-E, of which 1614B is considered typical of the species.
Horizon and Locality: Imperial formation. Upper Devonian; Locality 6, Carajou River, 64° 50' N.,
126° 50' W., Northwest Territories.
Remarks: Preservation of external features was poor and most of the description is based on polished sections. The dis¬ tinctive features of T. n. sp. 1614 are: needle-shaped form, proximity of annulations, presence of slight nodes along length, thick multilayered wall, and presence of well developed septa. Tentaculites elongatus Hall (Hall, 1859, p. 136, pi. 6, figs. 16-21) is similar in shape, but does not have the noded profile, nor the variation in annulation strength.
FORMA B
Tentaculites gracilistriatus Hall Plate 6, figs. 13-16
Tentaculites gracilistriatus Hall, 1879, Nat. Hist, of N.Y., Pal., N.Y. Geol. Surv., Vol. 5, pt. 2, p. 173, pi. 31, figs. 12-14, pi. 31A, figs. 37-47.
Hall's (1879) description of T. gracilistriatus is as
follows:
"Form minute, slender, elongate conical, extremely attentuate towards the apex, and, in well preserved individuals, apparently be¬ coming slightly more cylindrical towards the aperture. Apical portion
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solid, and the surface smooth, or free from annulations; this feature gradually becoming stronger towards the aperture. Annulations sub- equidistant on some parts of the shell, but varying in individuals of the same size in the proportion of five to six in the same space; those towards the apex more distant, and becoming gradually subdued; approximating and quite closely arranged as they approach the mouth; in the apical portion often appearing as simple undulations of the’ surface. The entire surface is covered by fine crowded longitudinal striae, which mark both the annulations and the interspaces, but which are not visible to the naked eye. Length from three to six mm. usually under four mm. '
Description: From numerous flattened, weathered specimens, in dolomitic limestone (suite 1612) .
Elongate V-shaped; central depressed fracture; axis straight; originally sub-cylindrical near aperture, very gradually tapering to a sharp or slightly bulbiform apex; length usually 2 to 7 mm.; width distorted due to flattening.
Annulations variable in spacing, usually more closely spaced and weaker or absent near apex and aperture, but stronger near mid¬ length; rounded, symmetrical in profile; average of 4 annulations per mm.
Longitudinal striations closely packed, vague or absent near apex, stronger near aperture; transverse striations may replace annulations near apertures of large specimens but are otherwise absent.
Internal structures not well known; apex infilled by calcite; wall thin, unilayered, constant in thickness.
64
Measurements: Variation in size of figured specimens
1612 A-D:
Length: 3 to 8 mm.
Width: Distorted due to flattening.
Types: Figured Specimen 1612D is the best preserved specimen but is slightly larger than normal.
Horizon and Locality: Eids formation. Middle Devonian; Locality 5, Stuart Bay area, on Cut-through Creek, Bathurst Island, Canada.
Remarks: The figured specimens show a slightly greater variation in length than indicated by Hall for the New York Marcellus and Lower Hamilton specimens. Tentacuiites gracilistriatus Hall is also found in the Ramparts formation near Norman Wells, Northwest Territories. Cooper et al. (1942) correlated the Marcellus formation of New York with the Ramparts formation of the Norman Wells area and gave an age of lower Middle Devonian.
Occurrence of T. gracilistriatus in the Arctic Islands indicates the great area over which this species was distributed. However its stratigraphic range is relatively unrestricted since it occurs in the basal Fort Creek shales, which immediately overlie the Ramparts formation in the Norman Wells area, and possibly conspecific specimens occur in the 'Lower Dark Limestone and Shale" in the Yukon Territory .
Tentacuiites gracilistriatus Hall, n. var. 1593 B Plate 4, figs. 10-12
Description: From numerous specimens on a single block of argillaceous
limestone (suite 1593).
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65
Shell medium to large for species; conical; sub-cylindrical near aperture, tapering more rapidly near apex to a slightly bulbous point; axis straight, cross section circular; length 3 to 6 mm., width at aperture 0.4 to 0.9 mm.
Transverse annulations prominent; last 3 or 4 near aperture closely spaced, remainder widely and sub-equally spaced except toward apex where they gradually become more closely spaced, less prominent, and eventually are absent; annulation profile rounded, asymmetrical, slightly steeper slope on apical side; total annulations 15 to 25;
3 to 4 in space of 1 ram. near aperture.
Longitudinal striations crowded especially in interannular area; indistinct, cover whole shell but obscure near apex; transverse striations absent.
Aperture open, unconstricted, circular; internal mould strongly annulated; apex solid, infilled with calcite; body cavity open, non- septate; interpenetrating cones absent; shell wall uni¬ layered, constant in thickness, approximately 0.04 mm. thick; annu¬ lations result from rhythmical flexure of whole wall rather than thickening of wall layers at annulations; orientation of calcite com¬ posing wall constant, cleavages always make 30 degree angle with wall, regardless of angle wall makes with cone axis.
Measurements: From one complete figured specimen, 1593B.
Length 5.0 mm.
Width at aperture 0.7 mm.
Types: Figured Specimens 1593A-C; 1593B is typical.
Horizon and Locality: Upper R.amparts limestone. Middle ? Devonian; Locality 8, Many Beaver River, 65° 27* N . ,
132° 05 ' W., Northwest Territories.
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Remarks: The distinctive features of T. gracilistriatus n. var. 1593B are the closer spacing of annulations near the apex and aperture, and the wide equal spacing of annulations near mid¬ length. Tentaculites gracilistriatus n. var. 1593B is more regularly and strongly annulated than T. gracilistriatus Hall, (s.s.)
Tentaculites gracilistriatus Hall, n. var. 1593D Plate 4, figs. 9, 13-15
Description: From numerous specimens in two blocks of argillaceous limestone (suites 1593, 1596) .
Shell small; aciculate conical; axis straight; apex slightly bulbous; cross section circular; length usually 2 to 4 mm., width at aperture 0.5 to 0.75 mm.
Transverse annulations high, narrow, quite widely and regularly spaced; profile acute, asymmetrical, steeper slope on apical side of each annulations; gradual decrease in height, spacing and asymmetry of annulations near apex; short segment near apex may be unannulated; total annulations approximately 17; 4 to 5 in space
of 1 mm. near aperture.
Longitudinal striations closely spaced, crowded in inter- annular areas, continuous over whole shell but obscure near apex; transverse striations absent.
Aperture circular, unconstricted; internal mould strongly reflects external annulations; apex solid, infilled with transparent calcite; non-septate; interpenetrating cones absent; shell wall thin, approximately 0.02 mm. thick, nearly constant in thickness throughout length, composed of one layer with faint lamellae parallel to external
surface .
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Measurements: From one typical specimen, 1593D.
Length 3.0 mm.
Width at aperture 0.65 mm.
Types: Figured Specimens 1593D, 1596A-C; 1593D is
considered typical.
Horizon and Locality: Figured Specimen 1593D, "Upper Ramparts limestone". Middle ? Devonian; Locality 8,
Many Beaver River, 65° 27* N. , 132° 05* W., North¬ west Territories.
Figured Specimens 1596A-C, Lower Fort Creek shale,
Upper Devonian; Locality 6, Carcajou River, 64° 50' N., 126° 50' W., Northwest Territories.
Remarks: Tentaculites gracilistriatus n. var. 1593D has an un- annulated apex and thus differs from the closest related specimen,
T. gracilistriatus Hall, 1879, pi. 31A, fig. 44. It is distinguished from other varieties of T. gracilistriatus by its sharp evenly spaced transverse annulations.
Tentaculites gracilistriatus Hall, n. var. 1593D?
Plate 4, fig. 16
Description: From one partially flattened specimen (suite 1598).
Minute; conical; axis straight; tapering to a blunt slightly bulbous apex; cross section avoid due to flattening.
Transverse annulations quite regularly spaced, become visible 0.5 mm. from apex, gradually increase in strength and spacing adorally annulations medium in height, acute to sub-rounded in profile, asymmetrical, steeper slope on apical side of each annulation; 4 annulations occur in 1 mm. near apex; average
spacing for whole shell 4 per mm.; total annulations 18.
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68
Longitudinal striations barely visible, closely spaced,
continuous over complete length; transverse striations absent.
Apex appears solid; other internal structures unknown;
shell surface rough, slightly granular.
Measurements: Length: 3.0 mm.
Width at aperture: 0.65 mm.
Types: Figured Specimen 1598.
Horizon and Locality: Lower Hay River shale, 435' from top. Upper Devonian; Locality 3c, Frobisher 5-B Well, from interval lOS'-llS’, 60° 42' N., 115° 52* W., Hay River, Northwest Territories.
Remarks: The similarity of T. gracilistriatus n. var. 1593D? to T. gracilistriatus n. var. 1593D is striking. The former however has a slightly greater rate of expansion and lower, more obtuse and irregularly spaced annulations.
If T. gracilistriatus n. var. 1593D? from the Hay River shale is conspecific with T. gracilistriatus Hall then this fauna may extend into the Upper Devonian. Lenz (1959, p. 86a) has placed the Hay River shale of the Great Slave Lake area completely within the Frasnian (lower Upper Devonian).
Tentaculites gracilistriatus Hall, n. var. 1593E Plate 4, fig. 8
Description: From a single slightly flattened specimen in a block of argillaceous, limestone; associated with T. gracilistriatus n. var. 1593B and D in the same block (suite 1593) .
Shell small; elongate conical; tapering gradually to a
blunt, non-bulbous apex; axis straight; cross section circular in
unflattened portion.
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.
69
Transverse annulations absent near apex, become visible at 1/3 distance to aperture, gradually increase in strength and spacing towards mid-length, become lower and more closely spaced near aperture; annulations low, variable in thickness, rounded, symmetrical in profile; total annulations 13, approximately 7 per mm.
Longitudinal striations cover whole shell, distinct, un¬ crowded, continuous; transverse striations absent.
Aperture elliptical due to flattening; shell wall thin; interpenetrations absent; apex solid.
Measurements: Length 2.5 mm.
Width at aperture 0.3 mm.
Types: Figured Specimen 15S3E.
Horizon and Locality: "Upper Ramparts limestone". Middle ? Devonian; Locality 8, Many Beaver River, 65° 27' N.,
132° 05' W., Northwest Territories.
Remarks: Tentaculites gracilistriatus Hall, n. var. 1593E is distinguished from other varieties of T. gracilistriatus by its lower, rounded, and more closely spaced annulations which are absent near the apex. It has a greater rate of expansion, and more rounded and closely spaced annulations than T. gracilistriatus Hall (s.s.)
Tentaculites gracilistriatus Hall, n. var. 1594 Plate 4, fig. 7
Description: From a single external mould impressed into a bituminous
shale (suite 1594) .
Minute; stubby conical; tapering irregularly to a sharp point; axis straight; cross section elliptical due to compression.
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Transverse annulations cover apertural 2/3 of shell, absent in apical 1/3; annulations begin abruptly, equal in strength and spacing, acute in profile, symmetrical; 5 annulations per mm., total annulations 10; at point where annulations begin there is a very apparent rapid increase in rate of expansion for space of 2 annulations, then return to same rate of expansion as in unannulated portion.
Closely spaced longitudinal striations cover whole shell, stronger in annulated portion, crowded and faint in unannulated portion; transverse striations absent.
Internal characteristics unknown, probably thin walled; median depressed fracture extending from aperture to apex results from crushing.
Measurements: Length: 3.0 mm.
Width at aperture 0.8 mm.
Types: Figured Specimen 1594.
Horizon and Locality: "Upper Ramparts limestone". Middle ? Devonian; Locality 8, Many Beaver River, 65° 27' N.,
132° 05' W., Northwest Territories.
Remarks: Numerous other specimens identified as T.
gracilistriatus n. var. 1594 were preserved as crushed external moulds, too damaged for illustration.
The variety resembles T. gracilistriatus Hall 1879, pi. 31A, fig. 41, but has a greater number of annulations and a larger apical angle .
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71
Tentaculites sp., ex. gr. T. gracilistriatus Hall Plate 1, figs. 5-17
Description: From many complete and incomplete specimens in a single
block of dark argillaceous limestone,, almost wholly composed of Tentaculites sp. and Styliolina (suite 1546). The former illustrates a wide range of variability; characteristics common to all specimens are:
1. Trausverse annulations
2. Longitudinal striations
3. Conical shape with a straight axis
4. Circular cross section
5. Blunt or slightly bulbous apex
6. Thin shell wall
Often partially flattened near aperture; length 2.0 to 8.0 mm.; width at aperture 0.4 to 1.4 mm.
Annulations extremely variable in spacing, prominence, shape and distribution; generally low, sub-acute, asymmetrical in profile, steeper slope on apical side; usually annulations gradually increase in height and spacing away from apex, but commonly in large specimens annulations become lower and more closely spaced near aperture; orad extremity may be unannulated or only gently undulating; annulations consistently perpendicular to cone axis; total annulations 5 to 35.
Longitudinal striations not visible to naked eye, variable in characteristics when highly magnified; cover whole shell, closely spaced near aperture, more widely spaced near apex, increase by inter¬ calation, new appearances concentrated on apertural slopes of annu¬ lations; crowding of striations near aperture results from cone be¬ coming sub-cylindrical while new striations are still appearing; generally larger shells have closer striation spacing; striations may node slightly on annulation crest; occasional transverse inter- annular striations or growth irregularities.
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Aperture circular, non-operculate, unconstricted; internal mould shows strong reflection of external annulations; body cavity open, non-septate; apex infilled with white calcite; interpenetrating cones absent; shell wall thin 0.03 to 0.04 mm., with 3? layers, a thicker middle layer of whitish calcite, and thin external and internal dark organic? films occasionally preserved.
Measurements: From largest and smallest figured specimens which are complete.
Figured Specimen 1546A: Length 6.9 mm.
Width at aperture 1.3 mm.
Figured Specimen 154-6J: Length 3.8 mm.
Width at aperture 0.6 mm.
Types: Figured Specimens 1546A-M.
Horizon and Locality: "Lower Dark Limestone and Shale",
Lower Devonian ?; Locality 23, Ogilvie River, 65° 32' N., 138° 31 5 W., Yukon Territory.
Remarks: The extreme variability of Tentaculites sp., ex. gr. T. gracilistriatus in a single sample might suggest an even wider range of variation geographically and stratigraphically . Until more detailed study determines if the variations have stratigraphic sig¬ nificance, division into a number of varieties would be of little value.
Tentaculites n. sp. 1602 Plate 6, figs. 3, 10-12
Description: From numerous specimens in two separate collections
(suites 1601, 1602) .
Minute; slender; elongate conical; gradually tapering to a blunt or slightly bulbous apex; axis straight or slightly curved; cross section circular; length 1 to 5 mm., usually less than 3; width at aperture 0.25 to 0.75 mm.
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- Transverse annulations very closely spaced especially near
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apex, adorally increasing slightly in spacing and height; annulations low, slightly irregular in height near aperture, very acute, approxi¬ mately symmetrical in profile; spacing near aperture about 14 per mm., near apex about 23 per mm.; average for shell about 17 per mm.; total annulations 30 to 50.
Longitudinal striations vague, fine, visibly only on better preserved specimens; transverse striations absent.
Aperture circular, open, unconstricted; internal mould strongly reflecting annulations; shell non-septate, infilled with calcite for 1/4 to 3/4 distance to aperture, infilling extends further towards aperture along walls than in centre of cone; interpenetrating cones absent; shell wall very thin, unilayered, dark grey, constant in thickness throughout.
Measurements: From figured specimen 1602A which is typical.
Length: 2.50 mm.
Width at aperture 0.55 mm.
Types: Figured Specimens 1601, 1602A-C; 1602A is considered
typical of the species.
Horizon and Locality: Figured specimens 1602A-C from Eleutherokomma hamiltoni zone (see Crickmay, 1957) of Beaverhill Lake formation, Lower Upper Devonian;
Locality 3b, Swan Hills Alberta, from Home Regent Swan Hills 10-13 Well, Lsd. 10, Sec. 13, Twp. 67, Rge. 10,
W.5 Mer. at 8116 feet.
Figured Specimen 1601 from lower Beaverhill Lake formation. Lower Upper Devonian; Locality 3a, Iosegun Alberta, from California Standard Iosegun 12-5 Well, Lsd. 12, Sec. 5,
Twp. 63, Rge. 19, W.5 Mer. at 10,162 feet.
Remarks: This species is quite distinctive and appears characteristic
of the Beaverhill Lake formation. Diagnostic features are its minute
size, very acute closely spaced annulations and unilayered wall structure.
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74
Tentaculites n. sp« 420, cf. T. acuarites Richt Plate 1, figs. 1-4
cf. Tentaculites acuarites Richt. Zittel, 1913, Textbook of Pal.,
Vol. 1, p. 571, fig. 1073c.
Description: From numerous flattened specimens in collections from 3 localities (suites 420, 421, 1545) .
Originally cone shaped; sub-cylindrical near aperture; tapering more rapidly near apex to an uncrushed bulbous point; axis straight; length 2 to 7 mm.; width at aperture (crushed)
0.35 to 1.7 mm.
Transverse annulations cover whole surface; sub-equally spaced, generally becoming slightly more closely spaced near apex; annulations low, abruptly raised, very acute, symmetrical in profile; average spacing 6 to 10 per mm.; total annulations 30 to 60 depending on length.
Longitudinal striations not visible to naked eye, con¬ tinuous from apex to aperture, low, crowded near apex, increasing only very slightly in spacing adorally; 20 to 25 present in width of crushed shell, in circumference approximately 50.
Internal mould sharply annulated; septa absent; apex infilled with white calcite for short distance towards aperture; interpenetrating cones rare; wall unilayered, dark grey, very thin, constant in thickness throughout length.
Measurements: From the best preserved figured specimen
420A .
Length: 4.7 mm.
Width at aperture (crushed) 1.12 mm.
A graphical plot of annulations per mm. vs. rate of cone expansion for six specimens is shown on fig. 4, p.
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• . •
75
Types: Figured specimens 420A, B, 421, 1545; 420A
shows typical characteristics of species, but is slightly larger than normal.
Horizon and Locality: Figured specimens 420A, B, 421,
Silurian, formation indefinite and 1545 "Lower Dark Limestone and Shale , Lower Devonian?
Figured Specimens 420A, B, Locality 14, Wind River,
65° 14' N., 136° 10' W., Yukon Territory; figured specimens 421, 1545, Locality 22, Ogilvie River,
66° 24' N., 136° 52* W., Yukon Territory.
Remarks: The established range of T. n. sp. 420 is from Lower Silurian to Middle Silurian. In suite 420 it is associated with Monograptus and in 423 (specimens not illustrated) with Monograptus sp. A Lenz. The latter is of Lower Silurian age. (Lenz, 1956, p. lOd) . In suite 427 from the Peel River, Yukon Territory (specimens not illus¬ trated) T. n. sp. 420 is associated with Monograptus sp., cf. M* jaculum, which is of Middle Silurian age. (Lenz, 1956, p. lOd) . (In the same suites 420, 423, 427, T. n. sp. 420 and Monograptus are associated with Styliolina, indicating the latter's occurrence in strata as old as Lower Silurian) .
Tentaculites sp., aff. T. n. sp. 420 Plate 1, fig. 20
cf. Tentaculites fragilis Fenton and Fenton, 1924, Univ. Mich. Pub., Hackberry Stage of the Upper Devonian, p. 193, pi. 33, fig. 11.
Description: From numerous specimens in a compact limestone, preserved
mostly as internal moulds (suite 1557).
Elongate conical; sub -cylindrical near aperture; tapering
gradually to a blunt heart shaped bulb; axis straight; cross section
originally circular; shell ovoid or flattened in preservation; length
2 to 7 mm., width at aperture (crushed) 0.3 to 1.6 mm.
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Transverse annulations quite regularly and closely spaced over whole shell, slightly more crowded near apex, sharp crested, symmetrical in profile, moderate in height, slightly lower near apex, absent on bulbous apex; total annulations 15 to 45; average spacing 7 per mm.
Longitudinal striations invisible to naked eye, cover com¬ plete cone exterior; low, closely spaced, faintly visible on internal moulds o
Aperture open; internal mould strongly reflects external annulations; apex solid, calcite infilled; interpenetrating cones absent; body cavity non-septate; shell wall fragile, very thin, constant in thickness throughout, approximately 0.02 mm.
Measurements :
Length: 3.7 mm.
Width at aperture 0.60 mm.
Types: Figured Specimen 1557.
Horizon and Locality: "Lower Dark Limestone and Shale",
Lower Devonian ?; Locality 21, East Porcupine River,
65° 35' N., 1383 44* W., Yukon Territory.
Remarks: There is a remarkable resemblance between T. sp.,
aff. T. n. sp. 420 and T. fragllis Fenton and Fenton, from the Hackberry Stage of the Upper Devonian, except that the former is longitudinally striated while the latter is transversely striated.
When found in compact limestones, thin walled specimens such as T. sp., aff. T. n. sp. 420 are often preserved as internal moulds, easily mistaken for the true external shell surface. Figured specimen 1557, pi. 1, fig. 20 is an internal mould.
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77
Tentaculites n. sp . 1599, aff. T* mackenziensis Kindle
Plate 4, figs. 17, 18
aff. Tentaculites mackenziensis Kindle, 1919, Geol. Surv. Can.,
Mus. Bull., no. 29, series no. 36, p. 6, pi. 1, fig. 11.
aff. Tentaculites mackenziensis Kindle. Warren & Stelck, 1956, Geol. Assoc. Can. Spec. Pap. no. 1, pi. 15, fig. 11.
Description: From numerous flattened specimens on one piece of
black shale, (suite (1599) .
Minute, originally elongate conical, tapering to sharp
point, axis straight, cross section ovoid due to flattening;
length 1 to 3 mm., width distorted by crushing.
Transverse annulations cover complete surface; generally
low, but variable in strength, very closely spaced, sharp crested
in profile, symmetrical, grouped into a continuous sequence of 1
strong annulation followed by 1 or 2 weak annulations; sequence
not so evident near apex or aperture where annulations more closely
spaced and sub-equal in height; total annulations 40 to 60;
average spacing 19 per mm.
Longitudinal and transverse striations absent.
Internal structures unknown; apex solid, uncrushed for
approximately 1/2 mm. orad of apex; probably thin walled.
Measurements: From figured specimen 1599A.
Length: 3.0 mm.
Width: 0.70 mm.
Types: Figured Specimens 1599A, B.
Horizon and Locality: Perdrix formation. Upper Devonian; Locality 3d, label reads "Jasper Alberta, immediately above Disaster Point." The exact location of Disaster Point could not be found on maps of the Jasper area.
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78
Remarks: The rapid rate of expansion in the figured specimens is mostly a result of cone flattening. Tentaculites mackenziensis was originally described from the Upper Devonian Simpson shale of the Upper Mackenzie River Valley. Illustrations indicate that T. mackenziensis has annulations of equal strength throughout, with approximately 20 annulations per mm. for shells of 5 mm. length. Thus T. n. sp . 1599 has the same annulation spacing but is shorter. Possibly this is due to breakage near the aperture.
Tentaculites ? sp.
Plate 1, fig. 19
Description: From a single figured specimen (suite 1546 0).
Shell elongate conical; gradually tapering to a sharp or slightly bulbous apex; axis straight; cross section slightly ovoid.
Annulations widely spaced transverse undulations, almost indistinguishable near apex and aperture, gradually becoming higher and more widely spaced towards mid-length; profile broadly rounded, symmetrical; total undulations approximately 10.
Longitudinal striations very distinct when magnified but invisible to naked eye; uncrowded, evenly spaced near aperture, crowded and finer near apex, individual striations continuous over complete length; approximately 30 over shell circumference.
Aperture open, unconstricted; internal mould gently un¬ dulating; apex solid, infilled with calcite to approximately mid¬ length and a little further along walls; non-septate; inter¬ penetrating cones absent; shell wall thin, 0.03 mm., thickness
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79
constant throughout,, apparently composed of 3 layers where preser¬ vation is good: a thick central white layer 0.02 mm., and thin external and internal, black organic ? layers 0.005 mm.
Measurements:
Length: 5.4 mm.
Width at aperture 0.80 mm.
Types: Figured Specimen 1546-0.
Horizon and Locality: "Lower Dark Limestone and Shale" of Yukon Territory, Lower Devonian ?; Locality 23,
Ogilvie River, 65° 23' N., 138° 31' W., Yukon Territory.
Remarks: This specimen is intermediate between Tentaculites
and Styliolina . It is placed with the former because of the gentle transverse undulations. Although Styliolina may be transversely striated it does not have transverse undulations.
Genus STYLIOLINA Karpinsky 1884 Styliolina sp., cf. _§. f issurella (Hall)
Plate 4, figs. 3,4
cf. Styliola f issurella Hall, 1879, Nat. Hist, of N.Y., Pal., N.Y. Geol. Surv., Vol. 5, pt. 2, p. 178, pi. 31A, figs. 23,24.
cf. Styliolina fissurella (Hall). Shimer and Shrock, 1947, Index Fossils of North America, p. 526, pi. 215, fig. 53.
Description: From two flattened specimens preserved in a bituminous
shale (suites 1595A, B) .
Small, elongate conical, slightly flattened producing a median depressed fracture; axis straight, apex pointed or very slightly bulbous, apical angle low, apex uncrushed; length 2 to
4.5 mm.
Transverse annulations absent.
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80
Longitudinal striations obscure, broadly spaced, low, visible only near aperture; vague transverse striations corres¬ ponding to indistinct colour bands of white, grey, and dark grey calcite, bands irregular in width and variable in colour sequence.
Measurements: From one specimen which is typical.
Figured Specimen 1595B. Length: 4.1 mm.
Width at aperture distorted due to flattening.
Typed: Figured Specimens 1595A, B.
Horizon and Locality: Label reads "Middle Ramparts shale", Middle ? Devonian; Locality 10, Snake River, 65° 27' N., 132° 05' W., Yukon Territory.
Remarks: Suite 1595 consists of several chips on which the
brachiopods Lingula cf . spatulata and Martlnia richardsoni are asso¬ ciated with jS. sp., cf. _S. fissurella . Lingula cf. spatulata is found in the basal part of the Waterways formation in the Waterways area, and also in the basal part of the Beaverhill Lake formation in Northwestern Alberta, (Koch, 1959, p. 13, fig. 4). Styliolina sp., cf. S> fissurella is present in all three areas: Waterways, Northwestern Alberta, and Yukon Territory. However, this does not necessarily imply a correlation of the Ramparts with the Waterways formation and Beaver¬ hill Lake formation, since Lingula cf. spatulata and Styliolina cf. fissurella are both long ranging species.
Styliolina fissurella var. strigata (Hall)?
Plate 1, fig. 18
? Styliola fissurella var. strigata Hall, 1879, Nat. Hist, of N.Y., Pal., N.Y. Geol . Surv., Vol. 5, pt. 2, p. 178, pi. 31A, figs. 31,32.
Description: From a single specimen preserved in an argillaceous
limestone (suite 1546N) .
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81
Shell minute, stubby conical; axis straight; apex blunt or slightly bulbous.
Transverse annulations and striations absent; longitudinal striations distinct, uncrowded near aperture, becoming faint and very crowded near apex.
Aperture circular, open; apex solid, infilled with calcite, non-septate; shell wall thin; internal mould smooth, external mould rarely preserved.
Measurements:
Length: 1.5 mm. (incomplete)
Width at aperture 0.28 mm.
Types: Figured Specimen 1546N.
Horizon and Locality: "Lower Dark Limestone and Shale , Lower Devonian ?; Locality 23, Ogilvie River, 65° 23’
N., 138° 31' W., Yukon Territory.
Remarks: Distinctive features of Styliolina f issurella var. strigata (Hall) are the very clear, prominent longitudinal striations, and its very minute size. The type specimens are from the lower Middle Devonian Marcellus shale of New York which could be suggestive of a younger age for the "Lower Dark Limestone and Shale Unit" or else that S. f issurella var. strigata ranges into the Lower Devonian.
Styliolina f issurella var. intermittens (Hall)?
Plate 4, figs. 1,2,5, 6
? Styliola f issurella var. intermittens Hall, 1879, Nat. Hist, of N.Y., Pal., N.Y. Geol. Surv., Vol. 5, pt . 2, p. 181, pi. 31, figs. 11-17.
Description: From numerous specimens in a block of argillaceous lime¬
stone (suites 1593F-I) .
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82
Straight, conical, cross section circular, expands quite rapidly from a slightly bulbous apex; length 1 to 5 mm., width 0.2 to 0.6 mm.
Longitudinal striations cover whole shell, extremely fine,
more closely packed near aperture, increase by intercalation, new
appearances concentrated at vague transverse growth lines.
Aperture circular, open; apex solid, infilled with calcite
internal mould smooth, non- septate, interpenetrating cones absent;
shell wall thin, unilayered, almost constant in thickness.
Measurements: From figured specimen 1593G which is
slightly larger than typical.
Length: 4.0 mm.
Width at aperture 0.47 mm.
Types: Figured Specimens 1593F-I.
i.
Horizon and Locality: "Upper Ramparts limestone". Middle ? Devonian; Locality 8, Many Beaver River, 65° 27' N.,
132o 05' W., Northwest Territories.
Remarks: Associated with _S. f issurella var. intermittens
(Hall)? is an apparently smooth Styliolina sp . and Tentaculites cf.
gracilistriatus. The same association occurs in the Genesee and
Marcellus shales of New York (Hall, 1879, p. 182,183).
Styliolina sp . ?
Plate 6, figs. 1,2
? Styliola f issurella (Hall) 1879, Nat. Hist, of N.Y., Pal., N.Y.
Geol . Surv., Vol . 5, pt. 2, p. 178, pi. 31A, figs. 1-30.
Description: From numerous aligned specimens weathered out on a
block of limestone (suite 1573) .
Small, conical, axis straight, cross section circular,
expands gradually from pointed or slightly bulbous apex.
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83
Vague transverse growth lines occasionally visible; fine, closely spaced longitudinal striations on well preserved specimens, become closely packed and obscure near apex.
Aperture circular, open; internal mould smooth; apex solid, calcite infilled; transverse septa probably not present, but textural differences in infilling along length gives septate appearance; interpenetrating cones absent; wall multilayered in larger specimens; thin black layers of constant thickness alternate with grey layers of variable thickness, up to 8 individual layers; smaller specimens have fewer layers; total wall thickness 0.03 to 0.09 mm.
Measurements: From figured specimen 1573A which is typical .
Length: 3.0 mm.
Width at aperture 0.46 mm.
Types: Figured Specimen 1573A.
Horizon and Locality: "Middle ? Devonian''; Locality 9, Mountain front east of Snake River, Yukon Territory.
The shell of Styliolina sp.? is multilayered and solid even towards the aperture. It is not known whether Styliolina sp. (s.l.) possesses a multilayered wall but its common occurrence in flattened condition suggests that it may not. For this reason there is some doubt whether _S. sp.? actually belongs in the genus Styliolina . Its multilayered wall structure gives the impression of a series of nested cones, and in this respect is similar to Polylopia billingsi (Safford) (Clark, 1925).
* s
CHAPTER V
84
CONCLUSIONS
Tentaculitids range from Lower Ordovician to middle Upper Devonian but were relatively rare until Silurian time. Because of insufficient study their use in correlation is only broad at present, however they are potentially valuable as zonal fossils, particularly those of delicate skeletal structure which may have been pelagic. Preservation in a wide variety of lithologies suggests that tentaculitids are essentially useless as environmental indicators.
There are two distinct kinds of tentaculitids, for the pur¬ poses of this thesis termed Forma A and Forma B. The former are larger^ thick walled, sturdy, and complexly structured, while the latter are smaller, thin walled, fragile and simply structured. Mature specimens of Forma A commonly contain one or more interpenetrating cones, internally becoming progressively more delicate. The cone sequence is interpreted to indicate exterior migration of mature animals, which then may have enveloped the skeleton, carried it as a tail guard, or abandoned it.
Tentaculitids probably belong in the Mollusca, being most closely related to the Cephalopoda. Representatives of the latter are analagous to tentaculitids in elongate orthoconic shape, similar external ornament, transversely septate interior, bulbous protoconch, and multi¬ layered shell structure. Within the Cephalopoda, tentaculitids are considered very similar to primitive orthoconic nautiloids, and possibly they are an ancestral belemnite stock.
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.
BIBLIOGRAPHY
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'
-
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.11 7 . i.,' ,1 I
-
}
.1 J
• ^
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.j* . ' ; :J. ...... : . . fo<
/
. «*,
88
_ (1950): Succession of Devonian Faunas in Western Canada;
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89
EXPLANATION OF PLATE 1
Figures 1-3 Silurian, formation indefinite; Figures 4-20 "Lower Dark Limestone and Shale", Lower Devonian?
|
Figs. 1-4: |
Tentaculites n. sp. 420, cf. T. acuarites Richt (p.74). |
|
1. |
Crushed, longitudinal strictions indistinct; figured specimen 420A, (X17) . |
|
2. |
Crushed; figured specimen 4203, (X17) . |
|
3. |
Partially crushed, retouched; figured specimen 421, (X17) . |
|
4. |
Partially crushed internal mould, apically incomplete, retouched; figured specimen 1545, (X17) . |
Figs. 5-17: Tentaculites sp., ex. gr . T. gr acilistriatus Hall (p. 71).
|
5. |
Longitudinal polished section, apically incomplete, thin walls, obtuse annulations, retouched; figured specimen 1546A, (Xll) . |
|
6-17. |
Morphocline series; figured specimens 1546B-M respectively; 10, 11, 17 - strong longitudinal striations; 13, 14, 15 - annulated internal moulds; 8, 9, 10 - crowed weaker annulations near aperture; 6, 7 - obscure closely packed longitudinal striations; all specimens (Xll) . |
|
Fig. 18: |
Styliolina fissurella var. strigata (Hall)? (p.80 )• » |
18. Apex partially concealed, longitudinal striations
|
indistinct; figured specimen 1546N, (Xll). |
|
|
Fig. 19: |
Tentaculites sp.? (p.78 ). |
|
19. |
Strong longitudinal striations, gentle transverse undulations; figured specimen 1546 Q, (X17) . |
|
Fig. 20: |
Tentaculites sp., aff. T. n. sp. 420 (p.75 ). |
|
20. |
Internal mould apically incomplete, figured specimen 1557, (X17) . |
PLATE I
91
EXPLANATION OF PLATE 2
Figures 1-6, 8-11 Hume formation, Middle Devonian; Figure 7, Nahanni formation, Middle Devonian.
Figs. 1,2,5,6,11: Tentaculites n. sp. 1588 (p. 48)
1. Large specimen, widely spaced annulations of variable strength; figured specimen 1588C, (Xll) .
2. Figured specimen 1588A, (Xll).
5. Longitudinal polished section, no interpenetrations, annulation profile acute near apex, obtuse near aperture; figured specimen 1588B, (X8) .
6o Longitudinal polished section through specimen
1588A (Fig. 2), both interpenetrating and external cone septate; a - incomplete wall at aperture; b - internal dark grey layer; c - septa; (X8) .
11. Oblique polished section, juvenile specimen,
annulations acute, internal wall absent at aperture; figured specimen 1588D, (X8) .
Figs. 3,4:
Fig. 7:
Tentaculites n. sp. ? 1590 (p. 51)
3. Large, weathered; figured specimen 1590A, (Xll).
4. Figured specimens 1590Bi}2 left to right; aciculate conical with acute annulations; (Xll).
Tentaculites sp., aff. T. n. sp. 1588 (p. 50)
7. Semi-noded profile, retouched; figured specimen 1586, (Xll).
Figs. 8-10: Tentaculites n. sp. 1587 (p. 47)
8. Longitudinal external view, each fourth annulation slightly higher, apex obscured; figured specimen 1587A, (Xll)
9. Irregular distribution of coarse annulations; figured specimen 1587B, (Xll)
10. Oblique section, three transverse septa; figured specimen 1587C, (XL1).
J
PLATE 2
93
EXPLANATION OF PLATE 3
Figures 1-9 Hamilton formation, Middle Devonian.
Figs. 1-9: Tentaculites n. sp. 1591 (p. 53)
1. Bedding plane covered with complete and fragmented
specimens, partially current aligned; figured specimen 1591, (X4) .
2. Longitudinal polished section, apically incomplete, single interpenetrating cone; figured specimen 1591A, (X8) .
3. Fragmented apertural extremity of large cone, irregular annulation spacing, transverse striations; figured specimen 1591B, (X17) .
4. Transverse polished section; a - slightly oblique, single interpenetration; b - larger interpenetration; figured specimen 1591C, (X8) .
5. Longitudinal polished section of apertural extremity;
c - external grey layer, thin; d - middle whitish layer, thick; e - internal dark grey layer, absent at aperture, discontinuous ly deposited; g - vague transverse partition; h - delicate internal cone; i - interannular striations; figured specimen 1591D, (X17) .
6. Apical extremity of figure 7; f - thickened internal wall, abundant transverse septa; figured specimen 1591E, (X17) .
7. Longitudinal polished section, large interpenetrating cone, fragment of interpenetrating cone near aperture; figured specimen 1591E, (X8) .
8,9. Complete cones; 8- irregular annulation spacing near
aperture; 9- regular spacing; figured specimens 1591F,
G respectively, (X8) .
PLATE 3
95
/
EXPLANATION OF PLATE 4
Figures 1-12 Ramparts formation, Middle Devonian?; Figures 13-15 Fort Greek formation. Figure 16 Hay River shale, Figures 17, 18 Perdrix formation, all Upper Devonian „
|
Figs. 1,2, 5, 6: |
Styliolina fissurella var. intermittens (Hall)? (p.8l) |
|
1. |
Faint longitudinal striations, closely packed; apex incomplete; figured specimen 1593F, (X17) . |
|
2. |
Larger specimen, striations faint; figured specimen 1593G, (X17). |
|
5. |
Longitudinal thin section; cleavage lines emanating from axial line and passing obliquely backwards through internal calcite and shell wall; figured specimen 1593H, (X17) . |
|
6. |
Longitudinal thin section, constant wall thickness, apically incomplete; figured specimen 15931, (X17) . |
|
Figs. 3,4: |
Styliolina sp., cf. S. fissurella (Hall) (p. 79) |
|
3,4. -» * |
Crushed specimens with central depressed fractures; figured specimens 1595A,B respectively, (Xll) . |
|
Fig. 7 : |
Tentaculites gracilistriatus Hall, n. var. 1594 (p.69) |
|
7. |
Central depressed fracture, unannulated apical portion, external mould; figured specimen 1594, (X17) . \ |
|
Fig. 8: |
Tentaculites gracilistriatus Hall, n. var. 1593E, (p*68) |
|
8. |
Closely spaced annulations, vague longitudinal striations, distorted by crushing; figured specimen 1593E, (Xll). |
|
Figs. 9,13-15: |
Tentaculites gracilistriatus Hall, n. var. 1593D (p.66) |
|
9. |
Transverse annulations sharp, equally spaced; figured specimen 1593D, (Xll). |
PLATE 4
-I
97
Explanation of Plate 4 (cont'd)
13,14. Transverse annulations sharp, longitudinal striations
|
vague, apical extremity smooth; figured specimens 1596A,B respectively, (Xll) . |
|
|
15. |
Longitudinal thin section, complete wall flexure, apically incomplete; figured specimen 1596C, (Xll). |
|
Figs. 10 - 12: |
Tentaculites gracilistriatus Hall, n. var. 1593B (p.64) |
|
10. |
Crowded annulations near aperture, longitudinal striations not visible; figured specimen 1593A (Xll). |
|
11. |
Large, widely spaced annulations, crowded near aperture, longitudinal striations indistinct; figured specimen 1593B, (Xll). |
|
12. |
Longitudinal thin section, complete wall flexure, annulations absent extremely close to apex; figured specimen 1593C, (Xll) . |
|
Fig. 16: |
Tentaculites gracilistriatus Hall, n. var. 1593D? (p. 67) |
|
16. |
Annulations regularly spaced, sharp, apex slightly bulbous; figured specimen 1598, (Xll). |
|
Figs. 17,18: |
Tentaculites n. sp. 1599, aff T. mackenziensis Kindle (p. 77) |
17,18.
Each second or third annulation slightly higher, flattened external moulds; figured specimens 1599A,B respectively, (X17) .
98
EXPLANATION OF PLATE 5
Figures 1-23 Ireton formation, Upper Devonian
Figs. 1-23: Tentaculites n. sp„ 1600 (p.55)
1-12. Morphocline series, figured specimens 1600 A-L respectively;
gradational variation of external features from large with noded profile, to small with unnoded profile; all specimens (Xll).
13. Longitudinal polished section through figure 2; a - inter¬ penetrating cones; b - variation in wall thickness at nodes and internodes; c - transverse septa; figured specimen 1600B, camera lucida drawing, (X13) .
14. Longitudinal polished section, two interpenetrating cones, interior cone barely visible; transmitted light, crossed nicols ; figured specimen 1600 M, (X17) .
15. Longitudinal polished section, apical extremity of semi¬ transparent cone; d - septum; & - thickened wall orad of last septum; figured specimen 1600N, (X55) .
16. Portion of large cone; f - transverse striations on apertural slope of coarse annulations; figured specimen 1600-0, camera lucida drawing, (X25) .
17. Transverse polished section, near aperture of large cone; g - external whitish layer of outside cone; h - internal amber coloured layer of outside cone; i - external layer of interpenetrating cone; j - internal layer of inter¬ penetrating cone; external layers have radiate fibrous structure, barely visible; figured specimen 1600P, camera lucida drawing, (X25) .
18. Average specimen, slight node near aperture; figured specimen 1600Q, (X17) .
19. Longitudinal polished section, small specimen, pyritized wall, no interpenetrations; figured specimen 1600R, (X17) .
20. Longitudinal polished section, large, slightly noded specimen, no interpenetrations; figured specimen 1600S, (X17) .
PLATE 5
100
Explanation of Plate 5 (cont'd)
21,22. External and internal views of same specimens; k - apparent depositional continuity between external and interpenetrating cone; note two or more? interpenetrating cones very tightly packed, separate wall layers indistinguishable; aperture of (innermost) interpenetrating cone extends orad of external cone aperture; figured specimen 1600T, (X17) .
23. Freak, anomalously long and spindly, unnoded profile; figured specimen 1600U, (X17) .
101
EXPLANATION OF PLATE 6
>
Figures 1-3 "Lower Dark Limestone and Shale", Lower Devonian?;
Figures 13-16 Eids formation, Middle Devonian; Figures 3,10-12 Beaverhill Lake formation and Figures 4-9 Imperial formation, both Upper Devonian.
|
Figs. 1,2: |
Styliolina sp.? (p. 82 ) |
|
1. |
Bedding plane completely covered with partially flattened specimens, current aligned, apices point upstream; figured specimen 1573, (X8) . |
|
2 „ |
Longitudinal polished section; e - multilayered wall, only faintly visible; transverse "partitions" due to infilling; figured specimen 1573A, (X17) . |
|
Figs. 3,10-12: |
Tentaculites n. sp. 1602 (p. 72) |
|
3. |
Transverse annulations very closely spaced, sharp crested, apex obscured; figured specimen 1601, (X17) . |
|
10,11. |
Polished sections, minute crenulations representing annulations, only faintly visible; figured specimens 1602B,C respectively, (Xll) . |
|
12. |
Poorly preserved, transverse annulations faintly visible; figured specimen 1602A, (Xll) . |
|
Figs. 4-6, 8, 9: |
Tentaculites n. sp. 1614 (p. 61) |
|
4. |
Longitudinal polished section, large specimen, aperturally incomplete; figured specimen 1614A, (Xll). |
|
5. |
Longitudinal polished section; a - external wall; b - internal wall deposit; c - septum; d - clear calcite infilling; aperture incomplete?, retouched; figured specimen 1614B, (Xll). |
|
6 . |
Longitudinal polished section, apically incomplete specimen wholly infilled by matrix and containing a small, reversely oriented internal cone; figured specimen 1614C, (X17) . |
|
8,9. |
Juvenile specimens, non-septate, apices infilled with translucent calcite; figured specimens 1614C,D respectively, (Xll) |
PLATE 6
Explanation of Plate 6 (cont'd)
Fig. 7 : Tentaculites n. sp. 1600 (p. 55)
7. Weathered, noded profile, apically incomplete;
|
figured specimen 1615, (Xll) . |
|
|
Figs. 13-16: |
Tentaculites gracilistriatus Hall (p. 62) |
|
13. |
Small, flattened, unannulated sharp apex, retouched; figured specimen 1612A, (X17) |
|
14-16. |
Larger, all badly weathered, central depressed fracture due to flattening; annulations obtuse, absent near apex, longitudinal striations only faintly visible; figured specimens 1612B-D respectively, (Xll) . |
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