[p. 83]
ON SOME EARLY TRIASSIC PECTINACEA (BIVALVIA) FROM THE
EASTERN PRE-CAUCASUS AND MANGYSHLAK
V. A. Gavrilova*
Information is presented on the range of bivalves of superfamily Pectinacea, discovered in Lower Triassic
deposits of the Eastern Pre-Caucasus and Mangyshlak, as well as descriptions of eight species: Eumorphotis telleri,
E. multiformis, Leptochondria minima, L. bittneri, L. (?) dagestana sp. nov., Ornithopecten temirbabensis,
Palaeontolium microtis and Entolioides ussuricus, and also illustration of one taxon, Claraia cf. punjabiensis is
given.
Ammonoids have the greatest value for the biostratigraphic partition of the Lower
Triassic in the regions being studied. At that, in Mangyshlak in sections of the Tyururpinskiy
Series, uncovered and revealed along the core of deep drill holes, the currently most detailed
sequence of changes of complexes of late Dzhelamian [Olenekian?] ammonoids are seen,
allowing the distinguishing of five biostrata [7].1 One should emphasize that here marine Upper
Dzhelamian sediments lie under and are covered by red-colored and terrigenous formations
without ammonoids.
In the Eastern Pre-Caucasus, Triassic sediments have been established only as a result of
deep drilling for oil and gas. In a stratigraphic chart of 1979, the Kultayskaya and
Dem’yanovskaya Svitas are included in the Dzhelamian stage [8]. According to the complexes
of ammonoids observed in them, the former is assigned to the Lower Dzhelamian substage, and
the latter to the Upper Dzhelamian. However, poor preservation of the rock material and weak
paleontological description do not allow accomplishing a more detailed partition of the Upper
Dzhelamian according to ammonoids in this region.
In frequency and preservation, especially in the core of the drill hole, they are far
inferior in numbers to bivalves. The presence of the latter is as well an important index of a
definite facies environment which allows them to be used for reconstructing the conditions of
sedimentation. Many species of bivalves had entered into stratigraphic charts of western Central
Asia and the Eastern Pre-Caucasus at all only on the basis of preliminary paleontological
identifications. Until now, Early Triassic bivalves of the southern regions of SNG remain very
poorly studied.
Our article is devoted to the results of research of Pectinacea, most widely distributed in
in Dzhelamian sediments of the Eastern Pre-Caucasus and Mangyshlak. The collections of T. V.
Babicheva (Central Asian Expedition of IGiRGI) 1982, 1984 and those of the author in 1978–
1980 and 1984 are used in this work.
The description of Pectinacea given below was done first and is a supplement to the
*
Original citation: Gavrilova, V. A. 1995. O nekotorykh rannetriasovykh pektinatseiakh predkavkaz’ia i
mangyshlaka. Bulletin of the Moscow Society of Naturalists, Geological Series 70(5):83–97. Translated by
Rosanne D’Aprile Johnson, Smithsonian Institution, 2004. Scanned and edited by Abree Murch and Matthew
Carrano, 2014.
1
The author accepts division of the Lower Triassic into Induan and Dzhelamian stages [9].
paleontological description of the Parsymurunskaya, Uzen’skaya, and Tartalinskaya Svitas of
Mangyshlak, and is its [p. 84] paleontological foundation for Dem’yanovskaya Svita of the
Eastern Pre-Caucasus [2, 6, 7, 8].
The monographic study of Dzhelamian complexes of Pectinacea of the regions being
examined allowed establishing their systematic composition and stratigraphic range. Three
families are represented here: Pterinopectinidae Newell, 1938, Aviculopectinidae Meek et
Hayden, 1864 and Entoliidae Korobkov, 1960. The first family is represented by six taxa:
Claraia aurita (Hauer), Claraia orbicularis dagestanica Gavr. subsp. nov., Claraia
stavropolica Gavr. sp. nov., Cl. australasiatica kumschokensis Gavr. subsp. nov., Cl. aff.
tridentina (Bittn.), Cl. cf. punjabiensis (Witt.), examined in a separate article. Only a photo
illustration of the species Cl. cf. punjabiensis (Witt.) is given for comparison in this work. The
following species are assigned to Aviculopectinidae: Eumorphotis telleri (Bittn.), E.
multiformis (Bittn.), Leptochondria minima (Kipar.), L. bittneri (Kipar.), L. (?) dagestanica
Gavr. sp. n., and Ornithopecten temirbabensis Kipar. Only two species of Entoliidae have been
studied: Palaeoentolium microtis (Witt.) and Entolioides ussuricus (Bittn.). The oldest
representative of Pectinacea is endemic species Ornithopecten temirbabensis Kipar., remains of
which have been discovered in the cores of many drill holes in the territory of YuzhnoMangyshlak depression. Finds of it coincide with variegated clay siltstones and calciferous
argillites of the Upper Parsymurunskaya Svita, traced through areas in the Zheltybay-Uzen’,
Zhazgurla, and Aksu-Kendyrlik zones of lithofacies. Because it lies directly under formations
of the Uzen’skaya Svita with Late Dzhelamian ammonoids in all sections, its geological age is
conditionally accepted as Early Dzhelamian.
The rest of the Pectinacea species were discovered together with remains of ammonoids.
Analysis of species composition of studied Pectinacea demonstrated that five species are
common to those of southern Primor’ye, established earlier by A. Bittner and L. D. Kiparisova in
Dzhelamian sediments but at a lower stratigraphic level (Meekoceras layers–Owenites zone):
Leptochondria minima Kiparisova, L. bittneri Kiparisova, Entolioides ussuricus (Bittner),
Palaeoentolium microtis (Witt.) and Eumorphotis multiformis (Bittner). Finds of the species
mentioned in Upper Dzhelamian sediments of Mangyshlak and the Eastern Pre-Caucasus could
be evidence of either their broader stratigraphic range as a whole, or of migration from Primor’ye
to regions to the west.
With descriptions of studied Pectinacea species, terminology previously suggested by N.
I. Kurushin [3] is used.
The collection is kept in the F. N. Chernyshev Central Research Geology Museum in St.
Petersburg under No. 12682.
Superfamily Pectinacea Rafinesque, 1815
Family Aviculopectinidae Meek et Hayden, 1864
Subfamily Aviculopectininae Meek et Hayden, 1864
Genus Eumorphotis Bittner, 1901
Eumorphotis telleri (Bittner, 1899)
Pl. 1, Fig. 4
Pseudomonotis telleri: Bittner, 1899a, p. 710, pl. 15, figs. 11–15; 1901a, p. 568, pl. 22, figs. 1–5; Frech,
1909, p. 22, pl. 2, figs. 3, 4;
Pseudomonotis (Eumorphotis) telleri: Ogilvie-Gordon, 1927, p. 20, pl. 1, figs. 6a–b; Kiparisova, 1947, pl.
14, fig. 5;
Eumorphotis telleri: Ichikawa, 1958, p. 154, pl. 22, figs. 11–13.
The lectotype is described in A. Bittner’s work [11, pl. 15, fig. 13]. Alps, Yugoslavia,
Lower Triassic, Upper Werfenian strata.
D e s c r i p t i o n . Shell is average size (up to 30.5 mm in height and up to 25 mm in
length), oval, slightly prosocline, inequilateral, strongly elongate in height. Hinge is straight,
long, somewhat less than the overall shell length. Apical angle is 82°.
Left valve is strongly convex, the maximum convexity being found in the upper half of
its height. The beak is massive, turning slightly forward, hanging like a vulture over the hinge
and being approximately one third of the overall valve length distant from anterior margin.
Anterior slope of beak is steep, but the posterior and lower are more gently sloping. Anterior
auricle is triangular, slightly convex and separated from main field of the valve by a rather deep
groove. Posterior auricle is set apart by a gently sloping bend, is flat and larger than anterior.
Surface of valve is covered with weak and irregular concentric growth marks.
D i m e n s i o n s (mm):
Spec. No.
4/12 682
H
30.5
L
24.6
H/L
1.23
Hinge Length
23.8
Hinge Length/L
0.96
Convexity
10.6
Convexity/H
0.30
C o m p a r i s o n . The examined specimen differs from the most closely related species,
Eumorphotis iwanovi (Bittner) [1, p. 8, pl. 1, figs. 1–9] from Lower Triassic beds of YuzhnoUssuriyskiy Kray by having valves more elongate in height, a massive beak, turned forward, by
greater difference in dimensions of auricles and by the absence of radial ribs.
R a n g e . Lower Triassic of Darvaz, Hungary, Yugoslavia; Upper Dzhelamian of
Mangyshlak.
M a t e r i a l . Single steinkern of left valve of satisfactory preservation.
Eumorphotis multiformis (Bittner, 1899)
Pl. 1, figs. 2, 3
Pseudomonotis multiformis: Bittner, 1899, p. 10, pl. 2, figs. 15–22;
Pseudomonotis (Eumorphotis) multiformis: Spath, 1935, p. 74, pl. 22, fig. 8; Kiparisova, 1947, p. 97, pl.
15, figs. 1–9; 1954, p. 10, pl. 1, figs 11–13;
Eumorphotis multiformis: Kiparisova, 1938, p. 224, pl. 2, figs. 4, 9, 12; pl. 3, figs. 2–4; Ciriacks, 1963, p.
77, pl. 15, figs. 13–15; Nakazawa, 1971, p. 117, pl. 23, figs. 7–12; Chen, 1976, p. 184, pl. 30, figs. 34–35; Yin
Hongfu et Ho Yuanliang, 1979, pl. 14, fig. 3;
Eumorphotis multiformis var. regularaecosta: Kiparisova, 1938, p. 227, pl. 2, figs 10–11;

82°
Eumorphotis multiformis var. rara: Kiparisova, 1938, p. 227, pl. 3, fig. 1;
Eumorphotis multiformis var. rudaecosta: Kiparisova, 1938, p. 226, pl. 2, figs. 5 & 14;
Eumorphotis multiformis regularaecosta: Ciriacks, 1963, p. 77, pl. 15, fig. 14; Chen, 1976, p. 185, pl. 30,
fig. 29
Eumorphotis multiformis rudaecosta: Okuneva, 1976, p. 28, pl. 1, figs. 1, 3; Chen, 1976, p. 185, pl. 30, fig.
33.
The lectotype is illustrated in Bittner’s work [1, pl. 2, fig. 21]. No. 45/221, TsNIG Museum.
Yuzhno, Ussuriyskiy Kray, Shamara River, Lower Triassic.
D e s c r i p t i o n . Shell is of average size (up to 39.5 mm in height and 31.5 in length),
slightly prosocline, oval, elongate in height,
[p. 86]
[p.
87] not
equilateral. Beak strongly protrudes beyond the long straight hinge, visibly close to anterior margin.
Apical angle is equal to 88 - 90°.
Left valve is strongly convex with maximum convexity in upper half of its height. Anterior
auricle is close to right-angled, convex and set well apart from main field of valve by a narrow
groove. Larger, slightly separated auricle, flat, elongate in length, pointed. { sic }
Entire surface of the valve, including auricles, is covered with radial ribs of three-four orders,
varying in nature of arrangement, length and prominence. Thus, in the Dagestan specimen (Ill. 1, fig.
2), the coarsest ribbing, situated in a three-order system, is visible. Ribs of the first and second orders
differ slightly in length and prominence, and ribs of the third order are substantially finer and have
an irregular arrangement: on the anterior half of valve surface, interspaces of ribs of first and second
orders are developed in twos, but in the posterior margin, they {are developed} either singly or are
absent altogether.
In the largest outer steinkern of the left valve, without an anterior auricle with ragged surface
in the part around the beak (Ill. 1, fig. 3), the radial sculpture is regularly situated and is slightly
distinguishable in prominence of ribs of four orders.
Distinct concentric, but irregular growth lines are developed as well on valves, as a result of
the intersection with which, ribs acquire unevenness or serration. On the auricles, growth lines bend,
turned toward the beak with convexity.
Pl. 1. Fig. 1. Claraia cf. punjabiensis (Wittenburg, 1909). Spec. No. 11/2682, a – left valve, x1.5; b –view from
beak side, x2. Mangyshlak, southwestern slope of Kumshoky Mountain, outcrop 2, layer 7, sample 2–7–78f/80.
Upper Dzhelamian, Tartalinskaya Svita. Collections of V. A. Gavrilova, 1980. Figs. 2–3. Eumorphotis multiformis
(Bittner, 1899). 2 – Specimen No. 2/12682, left valve, xl. Dagestan, Darginskaya area, drill hole 2, 4126–4116 m
depth. Upper Dzhelamian, Dem’yanovskaya Svita. Collections of V. A. Gavrilova, 1984; 3 – Specimen No.
3/12682, left valve, x1. Mangyshlak, southwestern slope of Kumshoky Mountain, outcrop 2, layer 8, specimen 2–8–
79f/80. Upper Dzhelamian, Tartalinskaya Svita, Collections of V .A. Gavrilova, 1980. Fig. 4. Eumorphotis telleri
(Bittner, 1899) Specimen No. 4/12682, left valve, x1. Mangyshlak, north slope of Karatauchik Range, region of
Dollapa Well, outcrop 3, sample 3–11f/79. Upper Dzhelamian, Tartalinskaya Svita. Collections of V. A. Gavrilova,
1979. Figs. 5, 6. Leptochondria minima (Kiparisova, 1938), 5 – Specimen No. 5/12682, 5a – left valve, x4; 5b – the
same, x5; 6 – Specimen No. 6/12682, 6a – left valve, x4; 6b – the same, x5. Mangyshlak, northern slope of
Karatauchik Range, Dollapa Well region, outcrop 3, sample 3–24f/79. Upper Dzhelamian, Tartalinskaya Svita.
Collections of V. A. Gavrilova, 1979. Figs. 7, 8. Leptochondria bittneri (Kiparisova, 1938). 7 – Specimen No.
7112682, left valve, x3. Mangyshlak, southwestern slope of Kumshoky Mountain, outcrop 2, layer 8, sample 2–8–
79f/80. Collections of V. A. Gavrilova, 1980. 8 – Specimen No. 8/12682, right valve, x2. Northern slope of
Karatauchik Range, Dollapa Well region, outcrop 3, sample 3–16f/79. Upper Dzhelamian, Tartalinskaya Svita.
Collections of V. A. Gavrilova, 1979. Figs. 9, 10. Leptochondria (?) dagestanica Gavrilova, sp. nov. 9 – Specimen
no. 9/12682, left valve, x1. Mangyshlak, northern slope of Karatauchik Range, region of Dollapa Well, outcrop 3,
sample 3–16f/79. Upper Dzhelamian, Tartalinskaya Svita. Collections of V. A. Gavrilova, 1979. 10 – holotype No.
10/12682, 10a – left valve, x1; 10b – the same; x2.5. Dagestan, Solonchakovaya area, drill hole 47, 4470–4465 m
depth. Upper Dzhelamian, Dem’yanskaya Svita. Collections of V . A. Gavrilova, 1984. Figs. 11, 12. Ornithopecten
temirbabensis Kiparisova, 1980. 11 – Specimen No. 11/12682, left valve, x5. Southern Mangyshlak, Zhilandy area,
drill hole 4, 3944–3937 m depth. 12 – Specimen No. 12/12682, impression of right valve, x5. Tasbulat area, drill
hole 26, 3642–3633 m depth. Lower Dzhelamian, Parsymurunskaya Svita. Collections of T. V. Babicheva, 1982,
1984.
[p. 88]
D i m e n s i o n s (mm):
Spec. No.
23/12 682
2/12 682
3/12 682
H
L
19.2 18.l
35.4 27.2
39.5 31.5
H/L Hinge Length Hinge Length/L
1.06
17.3
0.95
1.30
–
–
1.25
–
–
Convexity
7.8
6.4
12.l
Convexity/H
0.40
0.18
0.31

88°
–
90°
C o m p a r i s o n a n d r e m a r k s . The collection of syntypes of species
Eumorphotis multiformis (Bittner), which was the basis of study for its designation and the first
description carried out by A. Bittner [1], contains 6 left valves. I suggest the largest left valve of
these, with slightly damaged auricles, be the lectotype; it has an exceptionally a well-preserved
sculptured surface, the most typical for the species being examined.
The specimens studied differ from the species Eumorphotis telleri (Bittner) described
above in having large dimensions, smaller apical angle and by the presence of radial ribbing.
It is distinguished from Eumorphotis iwanovi [1, p. 8, pl. 1, figs. 1-9], described by A.
Bittner from Lower Triassic of Yuzhno-Ussuriyskiy Kray, by smaller size of valves elongate in
height and multi-order system of radial ribbing, which covers the entire surface of the shell.
R a n g e . Lower Dzhelamian of Yuzhnoye Primor’ye, Khabarovskiy Kray; upper
Dzhelamian of Dagestan and Mangyshlak; Lower Triassic of Greenland, U.S., China, and Japan.
M a t e r i a l . One impression and three steinkerns of left valves in various states of
preservation from three localities.
Genus Leptochondria Bittner, 1891
Leptochondria minima (Kiparisova, 1938)
Pl. 1, Figs. 5, 6
Pecten (Leptochondria?) ex. aff. albertii: Bittner, 1899, p. 6, pl. 2, figs 1,2, 4–10;
Pecten (Velopecten) minimus: Kiparisova, 1938, p. 246, pl. 4, figs. 10, 12; pl. 5, figs. 4–6; 1947, p. 113, pl.
21, figs. 3, 6. 9, 10; 1954, p. 12, pl. 3, figs. 3–7;
Pecten (Velopecten) minimus var. reticulatus: Kiparisova , I 938, p. 247, pl. 5, figs. 1–2;
Pecten (Velopecten) minimus var. laevis: Kiparisova, 1938, p. 247, pl. 5, fig. 3;
Leptochondria minima: Nakazawa, 1971, p. 119, pl. 23, figs. 13 &14 ; Chen, 1976, p. 159, pl. 29, figs. 1–3;
Yin Hongfu et Ho Yuanliang, 1979, pl. 14, fig. 6.
Holotype is illustrated in L. D. Kiparisova’s work [4, pl. 5, fig. 5]. No 42/10909, TsNIG
Museum. Ussuriyskiy Kray, Russkiy Island, Karpinskaya Bay; Lower Triassic.
D e s c r i p t i o n . Left valves are small (up to 10 mm in height and length), close to
round in outline, almost equilateral. Beaks are small, central, slightly protruding beyond the
straight hinge. Apical angle is equal to 100-109°. Valve is convex with auricles slightly
delimited. Anterior auricle is substantially larger than posterior and is set apart from overall
surface of valve by a weak depression. It is slightly convex, and when joining the anterior
margin, has an almost right-angled outline. The posterior auricle, in no way separated from the
valve surface, gradually is joined to the posterior margin at an obtuse angle.
Valve surface is covered with numerous radial thread-like, straight and densely situated
riblets of one order, strongly pronounced with the aid of a magnifying glass. In some specimen
[p. 89] they are more bold, and in others, they are flatter. Five mm from the beak, the number of
riblets reaches 60–70. On the valve, concentric, regularly situated, more feebly marked, fine
growth lines and irregular, coarse folds are developed as well; in some specimens, 11–14 such
folds are observed. At the intersection with them, the riblets bend and the surface of the valve
acquires a concentrically undulating nature. Auricles are covered with radial striae and threadlike growth lines.
D i m e n s i o n s (mm):
Spec. No.
5/12 682
6/12 682
H
8.5
9.6
L
8.7
10.0
H/L
0.98
0.96
Hinge Length Hinge Length/L
4.9
0.56
0.68
6.8

100°
109°
C o m p a r i s o n . The Mangyshlak specimens are very closely related to shells of
Leptochondria bittneri [4, p. 243, figs. 5–9, 11, 13] from the Lower Triassic of Ussuriyskiy
Kray, being distinguished from the latter by smaller size and more feeble and simple radial
sculpture on the left valve.
From Leptochondria albertii [3, p. 90, pl. 17, figs. 3–8] from Anisian deposits of
northern Central Siberia, it differs not only by substantially smaller dimensions, but also by
more convex left valve, as well as by thread-like radial sculpture.
R a n g e . Lower Dzhelamian: Ussuriyskiy Kray; Upper Dzhelamian; Mangyshlak;
Lower Triassic: China, Japan.
M a t e r i a l . Three steinkerns and five impressions of left valves in varying states of
preservation from two localities.
Leptochondria bittneri (Kiparisova, 1938)
Pl. 1, Figs. 7, 8
Pseudomonotis cf. multiformis: Bittner, 1899, p. 10, pl. 2, figs. 11–14;
Pecten (Velopecten) bittneri: Kiparisova, 1938, p. 243, pl. 4, figs. 5–9, 11, 13; 1947, p. 113, pl. 21, figs. 4,
5, 7, 8;
Leptochondria cf. bittneri: Chen, 1976, pl. 29, fig. 4.
Holotype is illustrated in L. D. Kiparisova’s work [4, pl. 4, fig. 11]. No. 38/10909,
TsNIG Museum. Ussuriyskiy Kray, Russkiy Island, Lower Triassic.
D e s c r i p t i o n . Shells are small (up to 14 mm in height and 13 mm long), from
rounded to slightly elongate in height, almost equilateral. Beaks are small, central, protruding
slightly over the straight hinge. Apical angle is equal to 105-116°.
Left valve is uniformly convex with slightly delimited auricles. Anterior auricle is
slightly larger than the posterior one and separated from the overall field of the valve by an
outlining groove. Auricles are slightly convex and joined to the anterior and posterior margins at
almost identical obtuse angles. Valve surface is covered with fine radial riblets of several orders,
concentric growth lines and nicks. At that, several variations in the manner of arrangement of
radial riblets on the valves are visible. Between two ribs of the first order, a single rib of the
second order proceeds from the beak to the lower margin. Riblets of the third order appear at a
distance equal to approximately 1/3 of height from the beak. One more riblet of the fourth order
is wedged in from the middle of the valve height, but they are not visible in every rib interspace.
Ribs of the first two orders are coarser and more bold, which, in their prominence are visibly
distinguished [p. 90] from each other, and the ribs of the third and fourth orders are more
smoothed out {softened} and fine, almost identical in prominence. At 5 mm from the beak, the
number of ribs reaches 50–55. The concentric sculpture is represented by thread-like growth
lines and disorderly nicks. Sometimes, where intersecting with the latter, the radial ribs break
down and acquire a somewhat displaced new direction. Auricles are covered with more strongly
pronounced concentric growth lines and scarcely visible radial striae.
The right valve is slightly convex, not equilateral in outline, with attenuated anterior
margin. Anterior auricle is set apart from the main valve field by a groove, which replaces a
deep byssal notch. Radial sculpture is more feeble and simpler than in the left valve.
D i m e n s i o n s (mm):
Spec. No.
7/12 682
8/12 682
24/12 682
l. v.
r. v.
l. v.
H
L
H/L
Hinge length
Hinge length/L
11.6
13.l
13.7
11.8
12.5
12.1
0.98
1.04
1.13
7.1
7.6
6.9
0.60
0.60
0.57

116°
110°
105°
C o m p a r i s o n . From Leptochondria albertii [3, p. 90, pl. 17, figs. 3–8], from the
Anisian of northern Central Siberia, the species being described differs by having smaller
dimensions, more complicated differentiated radial ribbing and larger apical angle.
R a n g e . Lower Triassic: China; Lower Dzhelamian of Ussuriyskyi Kray; Upper
Dzhelamian: Mangyshlak.
M a t e r i a l . Two steinkerns of left valves and one inner steinkern of a right valve of
satisfactory preservation from two localities.
Leptochondria (?) dagestanica2 Gavrilova, sp. nov.
Pl. l , Figs. 9, 10
Holotype No. 10/12682, TsNIG Museum. Eastern Pre-Caucasus, Dagestan,
Solonchakovaya area, drill hole 47, 4465–4470 m depth. Lower Triassic, upper Dzhelamian
substage, Dem’yanovskaya Svita.
D e s c r i p t i o n . Shell is of average dimensions (up to 25 mm in height), of oval
outlines, elongate in height, acline or slightly prosocline. Apical angle is equal to 82–90°.
Left valve is from slightly to moderately convex, the greatest convexity being found on
its anterior and central parts . Beak is small, subcentral and does not protrude over the straight
hinge. Auricles are sharply delimited from the overall valve field. The anterior slightly convex
auricle is triangular with acute (78°) or right external angle. Posterior flat auricle is smaller than
the anterior, obtuse-angled one (116°).
2
From the locality of the holotype in the territory of Dagestan.
Surface of valve is covered with fine straight radial riblets of two orders. There are
around 45 riblets in all with riblets of the second order arising irregularly within the interspaces.
The strongly pronounced primary ribs have a triangular section and the rib interspaces
substantially exceed them in thickness . Ribs of the second order are smoothed out and shorter
than the primary ones, and in the rib interspaces, they occupy a marginal position. In the
posterior margin of the valve, radial riblets of two orders are more densely [p. 91] situated and
become almost identical in prominence. Fine concentric growth lines, which become more
prominent on the anterior and posterior margins, are developed as well on the valve. The auricles
are covered with sparse radial striae and densely situated, thread-like growth lines.
On the inner steinkern, sculpture appears to be somewhat smoothed out.
D i m e n s i o n s (mm):
Spec. No.
10/12 682
9/12 682
H
19.5
24.8
L
15.2
-
H/L
1.28
-
Hinge length
8.1
-
Hinge length/L
0.53
-

82°
90°
C o m p a r i s o n a n d r e m a r k s . Difficulties arose upon identification of the form
being examined with establishing the genus to which it belongs. In the shape and sculpture of the
auricles, sharply set apart from the main field of the left valve by straight grooves, as well as in
the acute-angled or right apical angle, the specimens examined are similar to shells which are
usually attributed to genus Chlamys, which is distinguished by somewhat smaller differences in
dimensions of anterior and posterior auricles, by the absence of unevenness on the ribs and
complicated cellular sculpture of the rib interspaces.
With the almost equilateral, weakly convex left valve with subcentral beak and simpler
radial sculpture, the Dagestan specimens are close to shells of genus Leptochondria. However,
one should note, that round or oval shell shape with poorly separated auricles, almost identical in
size and the obtuse apical angle, is characteristic of the majority of ancient forms of this genus
from the Early and partially from Middle Triassic. Only in the younger (Late Triassic)
representatives of genus Leptochondria are auricles sharply separated from the overall valve
field.
Because only left valves are represented in the available collection of specimens being
described, and these were discovered together with remains of other pectinids and late
Dzhelamian ammonoids, and representatives of genus Chlamys have a higher stratigraphic range
in Triassic sediments, then very conditionally, I assign them to genus Leptochondria. It is
possible that in the future, this species will be assigned to a new genus, but for now this question
is difficult because of the lack of paleontological material.
The greatest similarity of the species being described is to Leptochondria pervulgata
[10, p. 248, pl. 30, figs. 2–4] from Anisian sediments of Italy, which is distinguished by a higher
and more equilateral valve with finer radial ribbing, as well as by sculptured auricles.
Some similarity is observed with Pecten venustulus [12, p. 55, pl. 6, fig. 9], which as well
is assigned to genus Leptochondria and is known from Carnian Stage of Bakony (Hungary).
However, the species being described differs in the left valve being less convex, and having
auricles more sharply separated and radial ribs of two orders.
From Chlamys (Praechlamys) subalternicostata [10, p. 345, pl. 46, figs. 1–3] from the
Carnian Stage of the Southern Alps, the specimens studied are distinguished by smaller size,
absence of sinus in anterior auricle, fewer radial ribs and more weakly sculptured auricles.
R a n g e . Upper Dzhelamian: Eastern Pre-Caucasus and Mangyshlak. [p. 92]
M a t e r i a l . A single outer steinkern of a left valve and its impression in satisfactory
condition, and a single inner steinkern of a left valve, lacking posterior part and an auricle from
two localities.
Genus Ornithopecten Cox, 1962
Ornithopecten temirbabensis Kiparisova, 1980
Pl. 1, Figs. 11, 12
Ornithopecten temirbabensis: Kiparisova, 1980, p. 151, pl. 35, figs. 7, 8.
The holotype is illustrated in L. D. Kiparisova’s work [5, pl. 35, fig. 7]. No. 3/11012,
TsNIG Museum, South Mangyshlak, Temirbaba area, drill hole 1, 3784–3791 m depth; Lower
Triassic, Dolnapinskaya Svita.
D e s c r i p t i o n . Shell is small (up to 6–6.5 mm in height and 7 mm in length), slightly
elongate, inequivalved, not equilateral, with hinge equal to or somewhat exceeding the overall
length of the shell. Apical angle is equal to 114–120°.
Left valve is moderately convex. Beak is small, displaced forward, and, being set apart at
1/3 of length from anterior margin, does not protrude beyond the straight hinge. The anterior
auricle is large, slightly convex, separated by the steep anterior slope of the valve. The surface of
the valve is covered with numerous fine, straight radial riblets of two-three orders, which when
approaching the lower margin equalize in thickness. At the lower margin, their number reaches
50–55. Concentric, thread-like growth lines are developed as well and also wrinkles situated
irregularly, which become more sharply defined on crossing the auricle.
Right valve is compressed, with a small swelling in the area of the beak, and is flat in the
lower part. Beak is small, feebly marked. The narrow and long anterior auricle is in the shape of
an acute-angled triangle, sharply delimited from the anterior margin of the valve by a deep
groove which ends in a small hollow. At the groove it is convex, but when approaching the
hinge, it flattens out. Sculpture of the valve is the same as on the left. The posterior auricles of
both valves are somewhat more poorly separated, wing-like, with a small hollow on the posterior
margin. Besides the wrinkles, feebly marked radial striae are visible on the auricles.
In the inner steinkern, sculpture is noticeably smoothed out.
D i m e n s i o n s (mm):
Spec. No.
12/12 682
11/12 682
H
4.0
5.0
L
5.8
6.6
H/L
0.69
0.76
Hinge Length
6.3
6.9
Hinge Length/L
1.09
1.04
DPCh*
2.2
2.5
DPCh/L*
0.38
0.38

120°
114°
C o m p a r i s o n . When comparing with the type species of genus Ornithopecten, 0.
bosniae (Bittner) [13, p. 592, pl. 26/9, figs. 16, 17], described from the Anisian deposits of
Yugoslavia, a great similarity is not visible, because the Mangyshlak species differs substantially
by having smaller shell size, with more distinctly separated auricles, with larger anterior auricle
of the right valve, which is the shape of an acute-angled triangle and delimited from the main
field of the valve by a deep groove, by having narrow posterior wing-like auricles of both valves
*
Translator’s note: These mysterious initials occurred in an earlier publication I translated. Here, I think they
may refer to “length of anterior portion” and “length of anterior portion/[overall] length.”
with small hollow on posterior margin, being covered with visible concentric wrinkles, and the
finer radial sculpture being identical on both valves.
[p. 93] From species O. schlosseri (Bittner) in the description and illustration of A.
Allasinaz [10, p. 264, pl. 32, figs. 6, 7] from Anisian deposits of Yugoslavia, the specimens
being described are distinguished not only by smaller dimensions, but also by a more eccentric
and blunt, non-protruding beak, different shape of the more sharply separated auricles and
different type of sculpture.
R a n g e . Lower Dzhelamian: Mangyshlak.
M a t e r i a l . A single impression of right valve and three steinkerns of left valves in
various states of preservation from four localities.
Family Entoliidae Korobkov, 1960
Genus Palaeoentolium Romanov, 1985
Palaeoentolium microtis (Wittenberg, 1908)
Pl. 2, Figs. 1–6
Pecten discites var. microtis: Bittner, 1899, p. 2, pl. 1, figs. 12–18; Bittner, 1901, p. 90, pl. 9, figs. 43–54;
Pecten discites mut. microtis: Frech, 1904, p. 34, pl. 1 fig. 4;
Pecten microtis: Wittenberg, 1908, p. 20, pl. 2, figs. 9–11; Ogilvie-Gordon, 1927, p. 24, pl. 2, fig. l 7a, b.
Pecten (Entolium) microtis: Kiparisova, 1954, p. 11, pl. 2, figs. 3, 4;
Entolium microtis: Kiparisova, 1938, p. 250;
Entolium discites microtis: Chen, 1976, p. 208, pl. 34, figs. 12, 13;
Palaeoentolium microtis: Romanov, 1985, p. 35.
The lectotype is illustrated in A. Bittner’s work [1, pl. 1, fig. 13]. No.1/221, TsNIG
Museum. Yuzhno-Ussuriyskiy Kray, Russkiy Island, Ayaks Bay, Lower Triassic.
D e s c r i p t i o n . Shells of average dimensions (up to 28 mm in height and 27 mm in
length), from round to elongate in height, sometimes slightly oblique, equivalved, equilateral,
and from slightly to moderately convex. Beaks are small, slightly pointed, central and not
protruding beyond the straight hinge, which takes up approximately one third of shell length.
Small auricles well separated are almost equal, symmetrical, and do not protrude above the
hinge. The anterior auricle is close to right-angled in outline, but the posterior is strongly
oblique and obtuse-angled.
The surface of the valves is covered with fine, numerous concentric growth lines and
coarser small folds, more strongly developed in the lower half of the shell. Sometimes, weak
radial sculpture is visible, expressed by straight striae. The auricles are covered with thread-like
growth lines. On the inner surface of the valves, auricular crura and lateral bolsters [resilial
teeth] are well developed.
D i m e n s i o n s (mm):
Spec. No.
19/12 682
H
10.7
L
10.3
H/L
1.03
Hinge margin
3.4
Hinge margin/L
0.33

115°
20/12 682
21/12 682
22/12 682
23/12 682
24112 682
25/12 682
26/12 682
11.5
11.6
14.l
19.4
22.2
23.7
27.9
9.7
9.8
14.7
17.l
18.6
23.1
26.5
1.18
1.18
0.95
1.13
1.19
1.02
1.05
4.2
3.3
4.3
4.8
5.1
6.7
–
0.43
0.33
0.29
0.24
0.27
0.29
–
92°
98°
116°
118°
104°
108°
112°
V a r i a b i l i t y . Outlines of the shells appear to range from round to elongate in height
(H/L varies from 0.95 to 1.18). Valve convexity varies from slight to moderate. The prominence
and nature of the arrangement of the concentric folds are susceptible to a degree of variability:
[p. 94]
[p. 95] they vary from coarse wrinkles to less coarse, fine growth lines. In some specimens,
they are not numerous and are more strongly developed in the lower half of the shell, while in
others, they are more feebly marked and are situated at approximately equal interspaces along
the entire height of the valve, and in a third of them, they are completely invisible. The apical
angle varies from 92 to 118°.
C o m p a r i s o n . The shells being described differ from the most closely related
species, Palaeoentolium discites (Schloth.), illustrated by A. Allasinaz [10, p. 284, pl. 35, fig.
8, 9] from the Anisian of Italy, by having shorter hinge, small auricles, and greater apical angle,
and more sharply pronounced concentric sculpture.
The examined specimens differ from P. hallense (Woehrmann) [10, p. 287, pl. 36, figs.
1–4] from the Carnian of the Alps (Northern Tyrol) by having smaller shells, shorter hinge, and
by the presence of coarse concentric folds.
R a n g e . Lower Triassic: Spitzbergen, Austria, Hungary, China, and Primorskiy Kray;
Upper Dzhelamian: Dagestan, Mangyshlak.
M a t e r i a l . 15 steinkerns and impressions of odd pieces of valves in various states of
preservation from two localities.
Genus Entolioides Allasinaz, 1972
Entolioides ussuricus (Bittner, 1899)
Pl. 2, Figs. 7–10
Pecten ussuricus: Bittner, 1899, p. 4 pl. 1, fig. 11;
Pecten sichoticus: Bittner, 1899, p. 4, pl. 11, fig. 10;
Pecten (Aequipecten) ussuricus: Kiparisova, 1938, p. 251, pl. IV, figs. 14–16;
Pecten (Eupecten) ussuricus: Kiparisova, 1947, p. 109, pl. XX, figs. 10–13; 1954, p. 12, pl. III, figs. 1,2;
"Pecten" ussuricus: Nakazawa, 1961, pl. 12, figs. 10–12.
Holotype is illustrated in A. Bittner’s work [1, pl. I, fig. 11]. Spec. No. 5/221, TsNIG
Museum. Ussuriyskiy Kray, Russkiy Island, Paris Bay; Lower Triassic.
Description. The shell is of average size (up to 34.5 mm in height and 37 mm in
length), from round to slightly elongate, not equilateral, inequivalved. The apical angle is equal
to 105–120°.
Left valve is moderately convex. Its middle section is the most convex, but the lateral
ones are recessed, and only at the boundary with the auricles
Pl. 2. Figs 1–6. Palaeoentolium microtis (Wittenburg, 1908). 1 – Spec. No. 13/12682, steinkern of left valve, x3; 2
– Spec. No. 14/12682, steinkern of left valve, x1; 3 – Specimen No. 15/12682, steinkern of left valve, x1. Dagestan,
Darginskaya area, drill hole 2, 4077–4072 m depth. 4 – Specimen No. 16/12682, left valve, x2, 4126–4116 m
depth. 5 – Sample No. 17/12682, a – steinkern of left valve, x1, b – the same, x3; 4077–4072 m depth. Upper
Dzhelamian, Dem’yanovskaya Svita. Collections of V. A. Gavrilova, 1984. 6 – Spec. No. 18/12682, a – steinkern
of left valve, x3; b – its impression, x3. Mangyshlak, northern slope of Karatauchik Range, region of Dollapa Well,
outcrop 2, Sample 2–198f/75. Upper Dzhelamian, Tartalinskaya Svita. Collections of V. A. Gavrilova, 1975. Figs.
7–10. Entolioides ussuricus (Bittner, 1899). 7 – Specimen No. 19/12682, steinkern of right valve, x2; Mangyshlak,
northern slope of Karatauchik Range, region of Dollapa Well, outcrop 3, sample 3– 16f/79; 8 – Spec. No.
20/12682, a – steinkern of left valve, x2; b – its impression, x2, outcrop 3, sample 3–15f/79; 9 – Specimen No.
21/12682, steinkern of left valve, x2; outcrop 3, sample 3–10f/79. Upper Dzhelamian, Tartalinskaya Svita.
Collections of V. A. Gavrilova, 1979. 10 – Specimen No. 22/12682, steinkern of left valve, x1. Dagestan, Stepnaya
area, drill hole 24, 4950–4940 m depth. Upper Dzhelamian, Dem’yanovskaya Svita. Collections of V. A.
Gavrilova, 1984.
[p. 96] are small swellings observed again. The anterior swelling is narrower and longer than the
posterior one. The beak is subcentral, small, slightly pointed, not protruding over the straight
and long hinge. The surface of the inner steinkerns is represented by radial ribs, feebly marked
in relief, which proceed straight from the beak to the lower margin, slightly thickening and
keeping the rib interspaces wider than they are themselves. Fine, concentric growth lines and
irregularly situated wrinkles are developed as well as radial ribbing. Flat and smooth obtuse
auricles with rounded apices are distinctly delimited from the main valve field and do not
protrude beyond the hinge. Under the anterior auricle, there is a shallow byssal groove.
Impressions of short auricular and hinge crura are visible on the surface of the inner steinkern.
The right valve is less convex than the left. The sculpture is represented by fine
concentric growth lines. Sometimes, scarcely visible radial striation along the anterior margin
can be seen on the surface of the valve. On the inner surface of the steinkern, long and narrow
lateral bolsters, which proceed for some distance from the anterior and posterior margins are
very visible.
D i m e n s i o n s (mm):
Spec. No.
15/12 682
16/12 682
17/12 682
18/12 682
l. v.
l. v.
r. v.
r. v.
H
L
11.9
17.3
17.8
34.l
12.7
17.6
19.1
37.0
H/L
0.93
0.98
0.93
0.92
Hinge Length
5.7
8.8
8.0
Hinge Length/L
–
–
0.44
0.50
0.41

105°
113°
110°
120°
V a r i a b i l i t y . Variations in the shell outline, from rounded to slightly elongate,
appear (H/L varies from 0.92 to 0.98). The apical angle varies from 105 to 120°.
C o m p a r i s o n . From most closely related species Pecten kokeni Wittenburg [14, p.
7, pl. 2, figs. 3, 4], which probably is ascribed to genus Entolioides and is known from Lower
Triassic sediments from the Salt [River] Range, the species being described differs in having a
flat right valve and finer radial sculpture on the left valve.
From species Entolioides zitteli (Woehrmann et Koken), illustrated by A. Allasinaz [10,
p. 300, pl. 38, figs 4, 5; pl. 39, figs. 1–6] from the Carnian of Lombardy, the Mangyshlak
specimens are distinguished by elongate shell shape, large apical angle and different type of
sculpture on both valves.
R a n g e . Lower Triassic: Ussuriyskiy Kray and Japan; Upper Dzhelamian:
Mangyshlak and Dagestan.
M a t e r i a l . One impression and four inner steinkerns of broken valves from two
localities. Remains of a fine layer of shell has been preserved on one steinkern.
LITERATURE CITED
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triasovykh otlozhenii Iuzhno-Ussuriyskogo kraya]//Tr. Geol. komiteta, vol. 7, no. 4, pp. 1–35.
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Sciences]. Ser. geol. no. 4, pp. 151–157.
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197–311.
[Page 97]
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Venetien//Jahrb. Geol. Reichsanst. Wien, vol. 52, no. 3/4, pp. 495–643.
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Lamellibranchiata des Stid-Ussuri-Gebiets//N. Jahrb. Mineral. Geol. Palaont. vol. 1, pp. 6–13.
VSEGEI,
Saint Petersburg
Submitted for publication
19.04.94