The First Record of a Lungfish (Dipnoi, Sarcopterygii) in the Famennian Deposits (Upper Devonian) of the Tver Oblast

Abstract

A new dipnoan genus and species Anchidipterus dariae Krupina, gen. et sp. nov. (Dipteridae) is described based on a lower jaw specimen from the Famennian (Upper Devonian) of the Bilovo locality (Russia, Tver oblast, Toropets district). This taxon is characterized by the short and broad mandibular symphysis, the rostrolateral orientation of the mesial ridge of the prearticular tooth plates and the significant divergence angle of their ridges. The platysymphyseal construction of the lower jaw in Anchidipterus in combination with relatively small and widely spaced tooth plates suggest that this fish fed on poorly armored or soft-bodied, inactive invertebrates and occupied the niche of an unspecialized omnivore in the trophic structure of the community.

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ISSN 0031-0301, Paleontological Journal, 2019, Vol. 53, No. 6, pp. 636–646. © Pleiades Publishing, Ltd., 2019.
Russian Text © The Author(s), 2019, published in Paleontologicheskii Zhurnal, 2019, No. 6, pp. 79–90.
The First Record of a Lungfish (Dipnoi, Sarcopterygii)
in the Famennian Deposits (Upper Devonian) of the Tver Oblast
O. A. Lebedeva, *, N. I. Krupinab, **, and V. V. Linkev ichc, ***
aBorissiak Paleontological Institute, Russian Academy of Sciences, Moscow, 117647 Russia
bEarth Science Museum, Moscow State University, Moscow, 119234 Russia
cShimkevich Andreapol District Local History Museum, Andreapol, 172800 Russia
*e-mail: elops12@yandex.ru
**e-mail: n.krupina@mail.ru
***e-mail: linkevichvalerijj@rambler.ru
Received November 8, 2018; revised December 27, 2018; accepted March 29, 2019
Abstract—A new dipnoan genus and species Anchidipterus dariae Krupina, gen. et sp. nov. (Dipteridae) is
described based on a lower jaw specimen from the Famennian (Upper Devonian) of the Bilovo locality (Rus-
sia, Tver oblast, Toropets district). This taxon is characterized by the short and broad mandibular symphysis,
the rostrolateral orientation of the mesial ridge of the prearticular tooth plates and the significant divergence
angle of their ridges. The platysymphyseal construction of the lower jaw in Anchidipterus in combination with
relatively small and widely spaced tooth plates suggest that this fish fed on poorly armored or soft-bodied,
inactive invertebrates and occupied the niche of an unspecialized omnivore in the trophic structure of the
community.
Keywords: Upper Devonian, Tver oblast, Dipnoi, lower jaw, Anchidipterus dariae, hyoid pumping, lower jaw
symphysis, omnivore
DOI: 10.1134/S0031030119050058
INTRODUCTION
Lungfishes, whether sclerophagous, omnivorous or
even carnivorous, played an important role in the tro-
phic chains of the vertebrate communities in the
Devonian. However, their gracile skull and, most
often, the weak ossification of the bones making it up,
meant that dipnoan fossils are mostly represented by
the sturdy, isolated tooth plates. Each new find of even
a fragment of a skull, especially when associated with
tooth plates, contains new information on the mor-
phology of the fish, as well as its ration and its position
within the trophic chains of fossil communities.
The Bilovo Locality is one of the few Famennian
localities in the Eastern part of the Main Devonian
Field. It is rich in both invertebrate, as well as diverse
vertebrate fossils. Fish fossils were first described,
from two similar sections on the left bank (near the vil-
lage of Bilovo) and the right bank (close to the Bilovo
farm) of the Maly Tuder River (the tributary of the
Kunya River, in the Lovat River basin), by B.P. Mar-
kovsky (Geolkom, the Geological Committee) in 1929
and 1930, and later, in 1930 and 1931, by an expedition
of the Devonian lithological crew of the Leningrad
Geological Prospecting Trust led by R.F. Hecker
(these are stored in the collections of the Borissiak
Paleontological Institute, PIN).
In the article by R.F. Hecker and M.F. Filippova
(1935), D.V. Obruchev gave the following identifica-
tions of the fishes from the “composite” Bilovo area sec-
tion: Bothriolepis n. sp., Bothriolepis sp., Coccosteus sp.,
Holoptychius flemingi Agassiz, 1839, Holoptychius sp.,
Osteolepis n. sp. It was not until 1958 that a special
paleoichthyological field crew led by Obruchev visited
Bilovo and collected some antiarch and osteolepiform
fossils.
E.I. Vorobyeva (1977) described the otico-occipital
block of the osteolepiform rhipidistian Megapomus
heckeri Vorobyeva, 1977 from these collections. The
label mentions that the specimen was discovered by
Hecker in 1930 in layer 4 (according to the description
in Hecker et al. 1935, p. 75). E. Lukševičs (2001)
described a new antiarch species Bothriolepis heckeri
Lukševičs, 2001, based on the fossils from the same
collection and from the same layer. No further finds
were made in the twentieth century.
It is regular field work (since 2011), led by the
members of the E.E. Shimkevich Museum of the
Andreapol district (KMA) that drew the attention of
paleoichthyologists to this locality, monitoring several
bank exposures of small tributaries of the Lovat River
in the Andreapol and Toropets districts of the Tver

PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
THE FIRST RECORD OF A LUNGFISH (DIPNOI, SARCOPTERYGII) 637
oblast. The main goal of this fieldwork has been to col-
lect Devonian vertebrate and invertebrate fossils.
In the collection from the Bilovo locality stored in
KMA, S.V. Moloshnikov (Moscow State University
Museum of Earth Science) and V.V. Linkevich (KMA)
identified the following fossil vertebrates: Bothriolepis
heckeri Lukševičs, 2001, Bothriolepis sp., Dunkleoste-
oidea indet., Holoptychius sp., Osteolepididae indet.,
Dipteridae indet. (Moloshnikov, Linkevich 2017a, b).
Two new antiarch finds are described in these two
papers; the species Bothriolepis heckeri is assigned to
the previously established genus Livnolepis Molosh-
nikov, 2008.
Several tooth plates were found in the Bilovo sec-
tions between 2011 and 2015, and a mandible with well
preserved tooth plates was found in 2016. This latter
fossil was discovered by D.G. Bondar, a worker at the
Toropets Biological Station Chisty Les (Tver oblast).
This mandible, described below, is assigned to a
new genus and species Anchidipterus dariae Krupina,
gen. et sp. nov. The new taxon is different from the
other members of the family Dipteridae Owen, 1846 in
having a relatively short and wide mandible and a dis-
tinctively-shaped symphyseal region, and in the struc-
ture of tooth plates.
GEOLOGICAL STRUCTURE
OF THE FOSSIL-BEARING DEPOSITS
The Bilovo locality is located in the northwest of
the Tver oblast, near the border with the Novgorod
oblast. The locality comprises at least three sections,
located on the sharp bend of the Maly Tuder River and
upstream from it, near Bilovo village (Fig. 1). The sec-
tion exposes an alternation of sandy, carbonate, and
muddy-sandy units of the Tuder River Formation
(correlated with the Eletsian Regional Stage), the
Bilovo Formation (correlated with the Lebedyanian
Regional Stage), and the lower part of the Lnyanaya
Formation (correlated with the Optukhian Regional
Stage) of the upper Lower to Middle Famenian (Ver-
bitsky et al., 2012).
The Tuder Formation occurs in the southwestern
and eastern parts of the Izborsk–Ilmen Lake struc-
tural zone and is exposed on the pre-Quaternary sur-
face along the western part of its distribution (Ver-
bitsky et al., 2012).
Fig. 1. Geographical location of the Bilovo locality. The main map shows the western part of the Tver oblast, the inset shows the
positions of localities relative to the village of Bilovo. The large star marks the section where the fossil material comes from, small
stars indicate the two other sections.
200 m
30 km
Bilovo
M
a
l
y
T
u
d
e
r
Kholm
Valday Bologoe
Vyshny
Volochyok
Torzhok
Tver oblast
Novgorod
oblast
Torop et s
Andreapol’
Staraya
Torop a Zapadnaya
Dvina Nelidovo Rzhev
Tver
Volga R.
Volga R.
Tvertsa R.
Moscow
Region
Demyansk
Marevo
Kholm Seliger Lake
Ostashkov
Lovat
Maly Tuder
Kunya
Pskov oblast
Bolshoi Tuder
Upper Volga
Reservoir
Western Dvina River
Vyshny Volochyok
Reservoir
Msta R.

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PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
LEBEDEV et al.
The sandstones of the Tuder Formation are uncon-
formably overlain by limestones of the Bilovo Forma-
tion. In the Bilovo section, the lower boundary of this
latter formation is assumed to coincide with the base
of the carbonate unit which downlaps onto the yellow-
ish brown sandstones (Verbitsky et al., 2012). The
Bilovo Formation itself is represented by an alterna-
tion of mottled marls, calcareous clays, light gray and
greenish gray sandy fine-grained limestones.
Considering that there are carbonate layers within
the generally terrigenous Tuder Formation (Sammet,
1973), the stratigraphic interpretation of the Bilovo
section is far from self-evident. Within the section
described by Hecker and Filippova (1935), the bra-
chiopods Cyrtospirifer (Spirifer) cf. lebedjanicus
Nalivkin, 1947 which date the Lebedyanian Regional
Stage, only appear in layer 7. All the carbonate layers
below it must, therefore, be assigned to the Eletsian
Regional Stage, which contradicts the currently
accepted position of the top of the Tuder Formation
based on lithological data. Now, it is already in layer 4
in the lower part of the section that Megapomus heckeri
and Bothriolepis heckeri are found, which were consid-
ered in the previous publications (Vorobyeva, 1977;
Lukševičs, 2001) as yielded from the Bilovo Forma-
tion. The specimen described in this article was found
in talus and may be derived from the fossiliferous beds
of either the Bilovo Formation or the Tuder Forma-
tion and therefore be either Eletsian or Lebedyanian in
age. Further geological studies at the section and fur-
ther fossil collection is necessary in order to resolve
this issue. A Lnyanaya age of the described specimens
is unlikely, because the lithology of the Lnyanaya For-
mation is siliciclastic, rather than carbonate. In any
case, further adjustments to the correlation of these
formations of the Lovat River Basin with the beds of
the Central Devonian Field are necessary, especially
using fossil material.
Identifications of vertebrates from the paleontolog-
ical collection of KMA made by Moloshnikov and
Linkevich (2017a, 2017b) and listed above, have been
refined and detailed based on new collections.
A.O. Ivanov (St. Petersburg State University) reiden-
tified the Dunkleosteoidea indet. fossils as Dunkleos-
teus sp. (pers. comm., 2016). The first author also
revised the collection and recognized the presence of
acanthodes Devononchus (?) sp., bone fragments from
the shield of Bothriolepis sp. and scales of Holoptychius
sp. from the uppermost level, the Lnyanaya River For-
mation (upper Famennian). A clearer and more com-
plete picture of the bed-by-bed taxonomic composi-
tion of fishes can be gleaned by extracting vertebrate
microfossils from old samples tied to Hecker’s section,
comparing them with the recently obtained specimens
and redescribing the stratigraphic type section.
SYSTEMATIC PALEONTOLOGY
SUBCLASS SARCOPTERYGII
Order Dipnoiformes
Family Dipteridae Owen, 1846
Genus Anchidipterus Krupina, gen. nov.
E t y m o l o g y. From Latinized Greek anchi (sim-
ilar, close to) and the genus Dipterus.
Type species. Anchidipterus dariae Krupina,
sp. nov.
D i a g n o s i s. The length of the symphyseal lam-
ina of the mandible is half its width and half the width
of the symphyseal median depression. The divergence
angle of the mandibular rami is approximately 60°.
The apex of the prearticular tooth plate oriented dor-
sally. The full angle formed by the plates is 120°, the
divergence angle of the mesial-lateral rows is 110°. The
mesial ridge of the plate is short, reaching mesially the
posterior angle of the dental, oriented rostrolaterally.
Species composition. Type species.
C o m p a r i s o n. N.I. Krupina (2004) included
the following genera in the family Dipteridae Owen,
1846: Dipterus Sedgwick et Murchison, 1828, Rhi-
nodipterus Gross, 1956, Orlovichthys Krupina, 1980,
Tar achno myl ax Barwick, Campbell et Mark-Kurik,
1997 and, provisionally, Grossipterus Obruchev, 1964.
In the present work, we also include the previously
described genera Harajicadipterus Clement, 2009 and
Sinodipterus Qiao et Zhu, 2009, originally not
assigned to any family by the authors of these genera.
Only for the members of the first three genera is the
structure of the lower jaw known, therefore, it is only
with these that we compare our material.
The new genus is different from Grossipterus
(Krupina, 2004, pl. I, figs. 9, 10), provisionally
assigned to the subfamily Dipterinae, in having tooth
plates of a grinding, rather than crushing type (“Dip-
terus type”).
The angle of convergence between the rami of the
lower jaw in Anchidipterus gen. nov. is close to that
observed in Dipterus, slightly more obtuse than in Rhi-
nodipterus, and much more obtuse than in Orlovich-
thys, which has a greatly elongated dentary. Anchidip-
terus is similar to these species in lacking a symphyseal
junction of prearticular tooth plates, but unlike them,
has a much shorter and wider symphyseal region, iso-
metric tooth plates with a much shorter mesial tooth
row, and also differs in the number of ridges on the
tooth plates as well as their angle of divergence.
Unlike Rhinodipterus, which has a mesial ridge of
the prearticular plate that is located parasagitally and
oriented rostromedially, while the anterior edge of the
ridge does not reach the level of the posterior angle of
the dentary, Anchidipterus gen. nov. has a mesial ridge
that is oriented rostrolaterally, while its anterior end
reaches the level of the posterior angle of the dentary,
but does not reach further rostrally.

PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
THE FIRST RECORD OF A LUNGFISH (DIPNOI, SARCOPTERYGII) 639
The angle of divergence of the rows of prearticular
tooth plates in Anchidipterus is approximately the same
as the one observed in Dipterus and is close to the angle
in Rhinodipterus. The apex of the tooth plate is visible
dorsally, whereas in members of the genus Dipterus
and Rhinodipterus, the apex is strongly turned ven-
tromesially and is not visible in dorsal view. It is possi-
ble that this character is not a genus-level (or species-
level) character, but rather reflects the juvenile devel-
opmental stage of the studied specimen.
Anchidipterus dariae Krupina, sp. nov.
E t y m o l o g y. After Daria Bondar, who discov-
ered the specimen.
H o l o t y p e. KMA/4213, incomplete lower jaw
(without the articular region); Russia, Tver oblast,
Toropets district, right bank of the Maly Tuder River,
near the Bilovo farm; Upper Devonian, lower–middle
Famennian; possibly, the Tuder Formation or the
Bilovo Formation.
D e s c r i p t i o n (Figs. 2; 3a; 4; 5c; 6c). Lower jaw
wide, massive, with rami converging at an angle of
about 60° (Figs. 2a, 2c; 3a). This angle is close to that
observed in Dipterus (60°) (Jarvik, 1967) (Fig. 3b),
somewhat more obtuse than in Rhinodipterus (50°)
(Jarvik, 1967) (Fig. 3c), and much more obtuse than
in the long-snouted Orlovichthys (40°) (Krupina,
1980; Krupina et al., 2001) (Fig. 3d). Considering the
condition of the well-developed teeth, recognizable
from the earliest generations, in rows on tooth plates,
and also considering the absence of wear either on the
teeth or the apical part of the plates, the lower jaw
must have belonged to a juvenile individual. The artic-
ular ends of both rami are broken immediately poste-
rior to the posterior margins of the tooth plates, so the
measurements of the length of the rami (17 mm) and
the width of their divergence at the level of the poste-
rior margin of the tooth plates (20 mm) refer only to
the preserved part. The infradentaries are fused with-
out sutures (Figs. 2c, 2e) and the relationship of the
splenial and the postsplenial with the surangular can-
not be determined. The median depression for the
anterior portion of the hypobranchial apparatus is
wide, its length being more than twice its width.
The Meckelian cartilage (Mc, Figs. 2a–2d) is
weakly ossified. The length of the symphyseal lamina
of the Meckelian cartilage (slmc) is approximately half
its width. This plate is exposed dorsally due to under-
ossification and/or incomplete preservation of the
anterior (symphyseal) plates of the prearticular (psl,
Fig. 2a) that lined it in life. In addition to this region,
the Meckelian cartilage is exposed on the mesial sur-
face of the jaw, between the mesial margin of the infra-
dentaries and the ventral margin of the prearticular;
the exposed area runs in a wide swath, pinching out
rostrally, up to the junction of the bony elements at the
posterior end of the symphyseal lamina (Fig. 2d). This
surface served for the attachment of the intermandib-
ular musculature (Miles, 1977; Bemis, 1986). The left
ramus has a narrow and elongated, posterodorsally-
anteroventrally obliquely oriented fenestra inside the
anteroventral process of the prearticular, which also
exposes the Meckelian cartilage; this fenestra is absent
on the right ramus. On the outer surface of the jaw, the
Meckelian cartilage is exposed on the lateral wall of a
notch-shaped, deep and elongated adductor fossa,
which runs anteriorly to the level of the third ridge of
the tooth plate (af, Figs. 2a, 2b, 2e, 2f). R. Miles
(1977) termed this structure, along with its rostral pro-
longation, the suprameckelian fossa in Chirodipterus
australis Miles, 1977; Krupina et al. (2001) called it the
Meckelian pit in Orlovichthys limnatis Krupina, 1980.
In this work, we use E. Jarvik’s (1967) term, the
adductor fossa, because Jarvik established the homol-
ogy of this structure based on the study of mandibular
musculature attachment in the modern Neoceratodus,
which allows for morphological comparison.
The lateral wall of the adductor fossa is entirely
formed by the infradentaries. This is visible on the ver-
tical broken surface of the articular region of the man-
dible after slight polishing (id, Fig. 4a). Ventrally, the
floor of the adductor fossa is formed by the pocket
between the external plate of the infradentaries (idvl)
and their separate longitudinal lateral plate. The dor-
sal margin of the vertical plate of the infradentary ele-
ments, while it does not make contact anteriorly with
the lateral margin of the prearticular, exposes a short
region of the Meckelian cartilage, which runs from the
posterior edge of the anterior sulcus to the anterior
edge of the adductor fossa (Figs. 2e, 2f). Visible on the
polished surface of the broken end of the left ramus,
inside the matrix filling the Meckelian vacuity, are
weakly formed areas of endochondral ossification
(mco, Fig. 4a).
The sutures between the dentary and the neighbor-
ing bones, except the prearticular, cannot be dis-
cerned, and neither can the transit of the mandibular
sensory canal. The mesial regions of the oral sensory
canal are marked by a few large pores at the posterolat-
eral angles of the dentary (oc) and by one or two well
developed rows of pores on the dorsal (oral) surface of
the dentary but are absent on the medial part of the
ventral surface (Figs. 2a–2d). In the symphyseal
region of the dorsal surface, the pore rows are inter-
rupted over a short distance, being divided by the sym-
physeal tubercle. Caudal (lingual) to this tubercle, the
margin of the dentary forms a symmetrical narrow
notch (mi) which may have hosted a small unpaired
adsymphyseal as in Chirodipterus australis (Miles,
1977) or Ch. wildungensis Säve-Söderbergh, 1952 (Jar-
vik, 1967), although in the last of the two species this
structure is somewhat separated from the posterior
margin of the dentary. In the juvenile stages of the
development of Neoceratodus, there is a small
unpaired bone MdY in the same location, carrying
one or two teeth (Jarvik, 1967).

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LEBEDEV et al.
Fig. 2. Anchidipterus dariae Krupina, gen. et sp. nov., holotype KMA/4213, incomplete lower jaw: in dorsal view (a, b), in ventral
view (c, d), in left lateral view (e, f). The arrow on (e) is oriented rostrally. Abbreviations: (af) adductor fossa; (antf) anterior sulcus
delimiting the posterior margin of the dentary; (dp) tooth plate; (idvl) vertical infradental lamina; (ip) horizontal infradentary
lamina; (jd) denticles on the dentary; (lp) labial pit; (Mc) Meckelian cartilage; mi medial notch of the dentary; (mlPra) mesial
laminae of the prearticular; (oc) external foramina of the terminal branches of the oral sensory canal; (Pra) prearticular with
prearticular tooth plates; psl anterior (symphyseal) laminae of the prearticular; (rd) area of the tooth plate formed by reparative
dentine; (slmc) symphyseal lamina of the Meckelian cartilage. Scale 10 mm.
(a) (b)
(c) (d)
oc
oc
jd
mi
slmc
antf
psl Mc
Mc
Mc
Pra
Pra
af
af
lp
lp
ip
ip
rd
dp
dp mlPra
sym
idvl
(e)(f)

PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
THE FIRST RECORD OF A LUNGFISH (DIPNOI, SARCOPTERYGII) 641
On either side of the notch on the lingual surface of
the dentary, there are short rows of 4–6 small rounded
tubercle-like denticles (jd), which are also described in
the same location in Dipterus oervigi Gross, 1964
(Gross, 1964), D. valenciennesi Sedgwick et Murchi-
son, 1828 (Jarvik, 1967) and Orlovichthys limnatis
(Krupina et al., 2001), as well as in the modern Neoc-
eratodus at the hatchling stage (Jarvik, 1967; Kemp,
1995). These may be homologous to the denticles on
the “labial” (dental) tooth plates described in the
hatchling of Andreyevichthys epitomus Krupina, 1987
(Krupina, 1992; Krupina and Reisz, 1999; p. 106,
text-figs. 2A, 4B).
The lingual margin of the dentary (Figs. 2a, 2b) juts
out over the anterior sulcus (antf) which separates it
from the anterodorsal margin of the mesial plates of the
prearticular reconstructed on illustration on the left side
(Fig. 2b). Posteromesial to the pointed posterior pro-
cesses of the dentary, the ossification of the Meckelian
cartilage is exposed on the floor of the sulcus.
The labioventral margin of the dentary fuses with
the infradentaries without any trace of suture
(Figs. 2c–2f). The splenials and postsplenials, fused
without suture, underlie the ventral side of the Meck-
elian cartilage as a single, cosmine-covered horizontal
infradentary plate (ip) covered by large pores, and also
form a common lateral vertical plate (idvl, Fig. 2f),
which caudally forms the lateral wall of the adductor
fossa. Whether it lines the labial pit (lp) in the rostral
region of the skull, is difficult to determine visually.
The prearticulars (Pra) are formed by dorsal lami-
nae carrying tooth plates (dp) which are moderately
displaced posteriorly (compared to Chirodipteridae
and Holodontidae) and by anterior mesial laminae
which partly line the interior surface of the ramus
(mlPra, Figs. 2c, 2d; 4a). The symphyseal parts of the
mesial plates of the prearticular are broken completely
on the right ramus, and considerably broken on the left
ramus, so that it can only be approximately estimated
how far anteriorly these reached and how they lined
the dorsal surface of the symphyseal lamina of the
Meckelian cartilage (Figs. 2a, 2b).
Prearticular tooth plates (Fig. 4b) are wide. Their
width is 8 mm, length is 4 mm. The plates carry six
rows of denticles, four of which start at the apex, and
two start at the level of the third row of each plate. The
full angle formed by the plates is 120°, the angle of row
divergence is approximately 110°. The latter is broadly
equivalent to the one observed in Dipterus valencien-
nesi (Jarvik, 1967) and is close to that in Rhinodipterus
secans Gross, 1956 (Gross, 1956). The apex is distinct,
and is located opposite to the beginning of the first
row, well visible in dorsal view.
Each of the rows counts six teeth, which increase in
size labially. The grooves between the rows are deep
and distinct, beginning immediately at the apex of the
plate. The deepest, widest and longest are the grooves
between the first and the second and between the sec-
ond and the third rows. The longest row is the first
(mesial) one, 6 mm long. The second row is 0.75 of the
first row, the third to fourth rows are 0.625, the fifth is
0.5, and the last, the sixth row, is 0.3775. The mesial
row is oriented rostrolaterally, its anterior end only
reaching the level of the posterior angle of the dentary,
but is separated from it by a groove (Figs. 2a, 2b),
unlike in Rhinodipterus ulrichi Ørvig, 1961 (Jarvik,
1967) (mr) and in Rh. kimberleyensis Clement, 2012
(Clement, 2012) in which the mesial tooth row is
located parasagittally and oriented rostromedially, and
the anterior denticle of the ridge does not reach this
level (Figs. 3a, 3c). Dipterus valenciennesi (Jarvik,
1967) has the anterior ridge running far forward ros-
trally and is separated from the dentary by a wide sul-
cus (Fig. 3b).
Adjacent to the base of the mesial and posterome-
sial edges of the tooth plates is a somewhat narrow
field formed by separate “blisters” composed both of
“cosmine” tissue with large pores and of smooth tissue
(rd, Figs. 2c, 2d). The “blisters” are irregular in shape,
sometimes overlapping each other, with irregular mar-
Fig. 3. Divergence angles of the mandibular rami and the orientation of the first (mesial) tooth row of the prearticular tooth plates
in various Dipteridae: (a) Anchidipterus dariae Krupina, gen. et sp. nov., posterior regions of the mandibular rami reconstructed;
(b) Dipterus valenciennesi Sedgwick et Murchison, 1828; (c) Rhinodipterus ulrichi Ørvig, 1961; (d) Orlovichthys limnatis Krupina,
1980, posterior region of the right mandibular ramus reconstructed [(b, c) redrawn from E. Jarvik (1967); (d) after Krupina
(1980)]. Abbreviation: (mr) first (mesial) tooth row of the prearticular tooth plate.
(a) (b) (c) (d)
60°
mr
60°
mr
50°
mr
40°
mr

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PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
LEBEDEV et al.
gins. This morphology suggests that tissue would have
been alternatively resorbed and redeposited in such
areas. Similar tissue, also adjacent to the tooth plates,
was described by E. White (1965) and R. Denison
(1974) in Dipterus valenciennesi. C. Campbell and
R. Barwick (1998), who described such tissue in Ado-
lolopas moyasmithiae Campbell et Barwick, 1998,
called it “reparative dentine”. Unlike regular cosmine,
this tissue lacks a system of horizontal canals beneath
the “Hautzahnparkett” (den Blaauwen et al., 2005).
S i z e i n m m. Length of the preserved part of the
rami: 17.
Material. The holotype only.
DISCUSSION
In addition to giving the morphological description
of the newly discovered fossil material and erecting a
new taxon, this article will try to identify the trophic
role of the dipnoans within the Bilovo vertebrate com-
munity. In order to answer this latter question, we shall
try to determine the most likely mode of food process-
ing by Anchidipterus.
Devonian dipnoans had two fundamentally differ-
ent structural types of tooth systems. The first type
included fish with vast fields consisting of a shagreen
of denticles, which would be shed and replaced, lining
the bones of the walls of the oral cavity. The second
type included dipnoans which had upper and lower
jaw bones carrying tooth plates (Campbell, Barwick,
1983, 1990). These structural types of the tooth appa-
ratus ref lect differences in the mode of food process-
ing: either simple grasping and holding with the subse-
quent swallowing without processing by tooth ele-
ments (the first type), or crushing (second type)
(Schultze, 1992). The genus Fleurantia is intermediate
between the two (Graham-Smith and Westoll, 1937;
Bystrow, 1944, Smith et al., 1987), having both sparse
dentine denticles on the pterygoids and teeth weakly
organized in rows.
In dipnoans of the second type, complete fusion of
the rami of the lower jaw at the symphysis combined
with the particular structure of the glenoid, prevented
rotation of the rami and only allowed vertical occlu-
sion of the upper and lower plates in adduction, as
shown by W. Bemis (1986) for modern lepidosirens
which have a similar structure of the jaws. Such struc-
Fig. 4. Anchidipterus dariae Krupina, gen. et sp. nov., holotype KMA/4213: (a) schematic representation of the vertical section
through the left ramus of the mandible at the level of the posterior edge of the tooth plate along a natural break; (b) right preartic-
ular tooth plate. Abbreviations: (dp) tooth plates; (id) infradentaries; (idvl) vertical infradentary lamina; (Mc) Meckelian cartilage;
(mco) region of endochondral ossification inside the Meckelian cartilage; (mlPra) mesial laminae of the prearticular;
(Pra) prearticular. Scale 3 mm.
(b)(a)
dp
Mc
Pra
idvl
id
mco
mlPra

PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
THE FIRST RECORD OF A LUNGFISH (DIPNOI, SARCOPTERYGII) 643
ture only allowed the food object to be vertically com-
pressed but not ground or crushed.
The second type can be, in its turn, subdivided into
two functional morphological groups (Fig. 5): 1. Dip-
noans with tooth plates of the crushing type which
make contact anteriorly in the symphyseal plane; the
plates are large relative to the length of the jaw (mem-
bers of the families Dipnorhynchidae, Chirodipteri-
dae, Holodontidae), and 2. Dipnoans with plates that
are small relative to general size, and which do not
come close to reaching the symphysis (e.g. family Dip-
teridae). In the second group, only the anterior lamina
(process) of the prearticular bone can reach the sym-
physeal region, but not its tooth plate.
The first group is characterized by rami that are
shortened relative to the interglenoid distance
(Fig. 5a). The interglenoid width (igw) is greater than
the total jaw length (l) and is greater than or equal to
the length of its ramus (l'). The length of the plates (lp)
can be greater than half the length of the ramus. The
geometrical center of the prearticular plates (pc) is
located in the anterior half of the ramus length. As a
result, and in spite of the general shortening of the jaw,
the lever arm (ll) turns out to be quite long, which
reduces the force exerted on the food object compared
to what it could be with a posterior location of the geo-
metric center of the plate.
This imbalance can be compensated by the general
shortening of the jaws. The shortening of the jaws for
increase in the force applied to the food object in jaw
adduction results in medial occlusion of the prearticu-
lar tooth plates in the symphyseal region. The tight
contact of the opposing mandibular plates was
reflected in the variously developed fusion of the
upper jaw plates, which assured the strengthening of
the palate not only by the pterygoids, but also by the
thick layer of dentine of the tooth plates themselves.
This increased the effectiveness of sclerophagy. On the
other hand, the medial occlusion of the mandibular
plates, as in chirodipterids (Fig. 5a), which had plates
occupying the larger part of the mouth f loor, nar-
rowed and shortened the medial space for the location
of the basihyal and of the chondroid “tongue” of con-
nective tissue supported by this skeletal element.
In the second group (Figs. 5b, 5c), the interglenoid
width is equal or smaller than both the total length of
the jaws and the length of the rami. The length of the
tooth plate is significantly smaller than half the length
of the ramus that carries it. The geometrical center of
the prearticular plates is located at the middle of the
ramus length, or even slightly behind it. In spite of the
relatively long rami, the lever arm turns out to be rela-
tively shorter, compared to the first group, and the
force exerted on the food object is accordingly greater
than it would be if the geometrical center was located
more rostrally.
As shown by W. Bemis and G. Lauder (Bemis,
Lauder, 1986) for modern dipnoans, the hypobran-
chial apparatus acts during the processing of the food
object by vertical back-and-forth motions which
pump water through the mouth. This mechanism was
called by the authors the “hyoid pump”. The flow of
water created by this “pump” during “mastication”
moves the bolus inside the oral cavity and even par-
tially outside the oral cavity. The similarity in the mor-
phology of the visceral apparatus of the modern and
fossil dipnoans suggests that our knowledge of its
function in the modern dipnoans can be tentatively
extended to the fossil ones.
Each of the structures described above has its own
functional morphological advantages and disadvan-
tages. The reduction in the area of the “tongue” and
the shortening of the anterior part of the jaw in the
Devonian dipnoans of the first group (Fig. 6a) with
medially fused tooth plates reduced the surface area of
the hyoid pump, and therefore resulted in a reduced
amplitude of the hydraulic intraoral pressure and a
reduced ability to manipulate the food bolus. It is, of
Fig. 5. Interrelations of the total length of the mandibles, length of the mandibular rami, interglenoid width and lever arm of the
tooth plate acting on a food object: (a) Chirodipterus australis Miles, 1977; (b) Rhinodipterus ulrichi Ørvig, 1961; (c) Anchidipterus
dariae Krupina, gen. et sp. nov. Posterior regions of the mandibular rami, the total length of the mandibles, the length of the man-
dibular rami and interglenoid width of Anchidipterus dariae Krupina, gen. et sp. nov. are reconstructed [(a) after Miles (1977);
(b) after Jarvik (1967)]. Abbreviations: (igw) interglenoid width; (l) length of the mandibles; (l') length of the mandibular rami;
(ll) lever arm of the force acting on the food object; (lp) length of the prearticular tooth plates; (pc) geometrical center of the
prearticular tooth plates.
(a) (b) (c)
igw igw igw
l 'l 'l '
ll
ll ll
lp
lp lp
pc pc
pc
ll l

644
PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
LEBEDEV et al.
course, also possible that no manipulations of this
kind occurred in this group of Devonian dipnoans,
since most of the mouth floor was occupied by the
tooth plates, so that there would have been no need to
move the food object for finer disintegration; i.e., the
size of the prey had to be comparable to the size of the
total area of the tooth plates in each jaw.
The dipterids have a small plate area, so that the space
between them, occupied by the “tongue”, is proportion-
ally greater than in the first group (Figs. 6b–6e).
The surface area of the “piston” of the hyoid pump
(more effective compared to the first group) made
possible the capture of the food object into the oral
cavity by water suction and also its further manipula-
tion. The linear size of the prey could exceed the sur-
face area of the tooth plates themselves, and food pro-
cessing could occur in stages by moving the food bolus
inside the oral cavity and beyond it, as observed in the
modern Protopterus and Lepidosiren (Bemis, Lauder,
1986).
The functional significance of the labial folds in the
modern dipnoans has been described by Bemis (1986),
who showed that these soft-tissue structures deter-
mine the size and the shape of the oral opening, which
is important in the suction-type mode of prey capture.
In the modern dipnoans, bones of the anterior part of
the snout are absent, so that the chondroid, connec-
tive-tissue lips form not only the lateral, but also the
dorsal and the ventral limits of the mouth. In Devo-
nian dipnoans, these were formed by the bones of the
upper and lower jaws. It is likely that the muscles and
the connective tissue of the labial folds, which were
attached on the labial pit of the mandible posterolat-
eral to the symphysis in the Devonian dipnoans,
delimited the mouth laterally and therefore regulated
the inflow opening of the hyoid pump. The ratios of
the width and length of the symphyseal lamina in the
second group vary greatly (Figs. 6a–6e; figs. 7a – 7c).
The width determined the size of the ventral margin of
the oral opening. In Devonian dipnoans we distin-
guish stenosymphyseal and platysymphyseal configu-
rations of the symphyseal lamina. The stenosymphy-
seal type of structure indicates a smaller oral opening,
while the platysymphyseal type indicates a larger oral
opening. The new genus and species Anchidipterus
dariae gen. et sp. nov. undoubtedly belongs to the
platysymphyseal type (Figs. 6c; 7a), whereas Dipterus
(Figs. 6b; 7b) and Rhinodipterus (Fig. 6c) belong to the
stenosymphyseal type. Unexpectedly, Orlovichthys
(Figs. 6e; 7c) falls in the platysymphyseal group,
despite having elongated jaws and a narrow oral open-
ing; this is due to its relatively short symphyseal lam-
ina. By Bernoulli’s law, the increased flow of water in
stenosymphyseal forms (which allowed them to draw
in the food object more effectively) was accompanied
by reduced pressure within the flow (which reduced
the power of suction). The stenosymphyseal mouth
was therefore better adapted for capturing the smaller
but faster-swimming objects, such as the small arthro-
pods. The oral opening in platysymphyseal forms was
suited for swallowing larger but less mobile prey.
The length of the symphyseal lamina could also
have been correlated with the shape of the food object.
A short symphysis may have been sufficient for grip-
ping long, worm-like objects, which could be held
across at any point along their length (Fig. 7a),
whereas the elongated symphysis was more effective
for gripping shorter but more isometric objects which
had to be held with a larger, often spoon-shaped, con-
tact area (Figs. 7b, 7c).
In the second group, the length of the mandible
rami anterior to the anterior edge of the tooth plates
could reach considerable values (e.g., in Rhinodipterus
kimberleyensis: Clement, 2012, text-figs. 3a, 3c). The
elongation of the upper and lower jaws created an
additional tool to capture and retain the food object,
which acted in a tweezer-like manner. The effective-
ness of the grip for such a “tweezer” must have been
increased by the small denticles on the smooth, cos-
mine-covered surfaces of the upper and the lower jaws
(jd), known, for instance, in Anchidipterus dariae gen.
et sp. nov. (Fig. 7a), Dipterus oervigi (Gross, 1964),
D. valenciennesi (Jarvik, 1967), Orlovichthys limnatis
(Krupina et al., 2001) (Fig. 7c) and in the hatchling of
Andreyevichthys epitomus (Krupina, 1992; Krupina
and Reisz, 1999; Krupina, 2004). The elongated jaws
were also suitable for digging the bottom deposits in
search of small, shallow-burrowing prey.
Fig. 6. Reconstructed surface area of “hyoid pump piston” (in gray) and the configuration of the symphyseal lamina of the man-
dibles in various Devonian dipnoans (stenosymphyseal and platysymphyseal types); cross diagrams show the ratio between mouth
width and the length of the symphyseal lamina: (a, b, d) stenosymphyseal type, (c, e) platysymphyseal type: (a) Chirodipterus aus-
tralis Miles, 1977; (b) Dipterus valenciennesi Sedgwick et Murchison, 1828; (c) Anchidipterus dariae Krupina, gen. et sp. nov.;
(d) Rhinodipterus ulrichi Ørvig, 1961; (e) Orlovichthys limnatis Krupina, 1980 [(a) after Miles (1977); (b, d) after Jarvik (1967);
(e) after Krupina (1980)].
(a) (b) (c) (d) (e)

PALEONTOLOGICAL JOURNAL Vol. 53 No. 6 2019
THE FIRST RECORD OF A LUNGFISH (DIPNOI, SARCOPTERYGII) 645
The combination of such characters as the platy-
symphyseal structure of the mouth, the lower-speed,
higher-power hyoid pump, tooth plates adapted to
grinding and pinching, not crushing of the food bolus
all suggest that Anchidipterus of the Bilovo basin fed on
weakly-armoured or soft-bodied, slow-moving, rela-
tively large prey. The prey that would fit this descrip-
tion may have included various worms, small inarticu-
late brachiopods, thin-shelled mollusks (or mollusks
completely lacking a shell) and small arthropods. All
of these fossil animals are known from the Bilovo
assemblage, save for the worms, which can be assumed
to have been present in any basin. Anchidipterus, there-
fore, likely occupied the niche of unspecialized omni-
vores within the trophic structure of the community
they inhabited.
CONCLUSIONS
The Bilovo locality is one of the few Famennian
localities in the eastern half of the Main Devonian
Field (MDF). It is rich in both invertebrate and
diverse vertebrate fossil finds. The first dipnoan
described from the Famennian deposits of the Main
Devonian Field, which we assigned to the family Dip-
teridae Owen, 1846, Anchidipterus dariae Krupina,
gen. et sp. nov., is characterized by a short and wide
symphyseal region of the lower jaw, a rostrolateral ori-
entation of the mesial tooth rows of the tooth plates,
and their large divergence angle.
Devonian dipnoans with tooth plates are divided
into two functional morphological groups. The first
includes sclerophagous forms with relatively short jaws
and large, closely set or medially occluding tooth
plates. The second includes mostly omnivores with
relatively small, laterally and posteriorly displaced
tooth plates. In the first group, the tight contact of the
large opposing mandibular plates increased the effec-
tiveness of sclerophagy. In the second, the interman-
dibular space, occupied by the “tongue”, was relatively
larger. The surface area of the “piston” of the hyoid
pump provided capability for a more active capture of
the fast-moving food objects into the oral cavity and
significant capability for manipulating the food bolus.
The width of the mandibular symphysis in the sec-
ond group determined the size of the oral opening. We
recognize stenosymphyseal and platysymphyseal
types of the structure of the symphyseal lamina. The
stenosymphyseal mouth was better adapted to the cap-
ture of the smaller but faster swimming prey. The
platysymphyseal oral opening was adapted to the cap-
ture of larger but slower moving food objects. It is the
second group that the species described here, Anchidip-
terus dariae Krupina, gen. et sp. nov, belongs to.
The length of the symphyseal lamina could have
been correlated with the shape of the food object.
Elongate, worm-like objects can be gripped with just a
short symphysis, whereas a longer symphysis was more
effective in gripping shorter, but isometric prey.
Platysymphyseal structure of the lower jaw, com-
bined with relatively small, widely set tooth plates,
suggest that Anchidipterus of the Bilovo basin preyed
on weakly armoured or soft-bodied invertebrates.
Within the trophic structure of the community,
Anchidipterus may have occupied the niche of
unspecialized omnivores.
ACKNOWLEDGMENTS
The authors thank D.G. Bondar, the member of the
Toropets Biological Station Chisty Les (Tver oblast), who
found the specimen described in this article and presented
it to the A.A. Shimkevich Museum in Andreapol. We thank
A.O. Ivanov for reviewing the article which helped to sig-
nificantly improve it. The photos were made by S.V. Bagirov
at the Borissiak Paleontological Institute of the Russian
Academy of Sciences.
FUNDING
The research was done as part of the Basic Research
Program of the Presidium of the Russian Academy of Sci-
ences No. 17 “The Evolution of the Organic World. The
Role and Influence of Planetary Processes” under the proj-
ect heading “Ecological restructuring of vertebrate com-
munities during the periods of major ecosystem crises in the
Late Paleozoic and Early Mesozoic.”
Fig. 7. Possible modes of capturing food objects by various dipterid dipnoans: (a) capture of an elongated object using a short
symphysis in Anchidipterus; (b, c) capture of an isometric object using a large contact area of the elongated symphysis: (b) Dipterus
(from Jarvik, 1967), (c) Orlovichthys (from Krupina, 1980). Effectiveness of grip was increased by mandibular denticles on the
oral surface of the lower jaw. Abbreviation: (jd) mandibular denticles.
(a) (b) (c)
jd
jd

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LEBEDEV et al.
REFERENCES
Bemis, W.E., Feeding systems of living Dipnoi: anatomy
and function, The Biology and Evolution of Lungfishes, Bemis,
W.E., Buggren, W.W., and Kemp, N.E., Eds., J. Morphol.
1986, Centennial Suppl., pp. 249–275.
Bemis, W.E. and Lauder, G.V., Morphology and function
of the feeding apparatus of the lungfish, Lepidosiren para-
doxa (Dipnoi), J. Morphol. 1986, vol. 187, no. 1, pp. 81–
108.
Blaauwen, J.L., den, Barwick, R.E., and Campbell, K.S.W.,
Structure and function of the tooth plates of the Devonian
lungfish Dipterus valenciennesi from Caithness and the Or-
kney Islands, Rec. West. Austral. Mus., 2005, vol. 23, pp. 91–
113.
Bystrow, A.P., On the dentition of Fleurantia denticulate,
Dokl. Akad. Nauk SSSR, 1944, vol. 44, pp. 31–32.
Campbell, K.S.W. and Barwick, R.E., Early evolution of
dipnoan dentitions and a new genus Speonesydrion, Mem.
Assoc. Australas. Pa1aeonto1, 1983, vol. 1, pp. 17–49.
Campbell, K.S.W. and Barwick, R.E., Paleozoic dipnoan
phylogeny: functional complexes and evolution without
parsimony, Paleobiology, 199 0, vol. 16, pp. 143–169.
Campbell, K.S.W. and Barwick, R.E., A new tooth-plated
dipnoan from the Upper Devonian Gogo Formation and its
relationships, Mem. Queensl. Mus., 1998, vol. 42, no. 2,
pp. 403–437.
Clement, A.M., A new species of long-snouted lungfish
from the Late Devonian of Australia, and its functional and
biogeographical implications, Palaeontology, 2012, vol. 55,
pp. 51–71.
Denison, R.H., The structure and evolution of teeth in
lungfishes, Fieldiana, Geol., 1974, vol. 33, pp. 31–58.
Graham-Smith. W. and Westoll, T.S., On a new long-head-
ed dipnoan fish from the Upper Devonian of Scaumenac
Bay, P.Q., Canada, Trans. R. Soc. Edinburgh, 1937, vol. 59,
pp. 241–266.
Gross, W., Über Crossopterygier und Dipnoer aus dem
baltischen Oberdevon im Zusammenhang einer vergle-
ichenden Untersuchung des Porenkanalsystems paläo-
zoischer Agnathen und Fische, Kungl. Svenska Vetenskap-
sakad. Handl. Fjärde Ser., 1956, vol. 5, no. 6, pp. 3–140.
Gross, W., Über die Randzähne des Mundes, die Ethmoid-
alregion des Schädels und die Unterkiefersymphyse von
Dipterus oervigi n. sp., Paläontol. Z., 1964, vol. 38, nos. 1–2,
pp. 7–25.
Hecker, R.F., VII. Section exposed along the Lovat River
and its tributaries, Bolshoi Tuder River, Maly Tuder River,
Kunya River, and Smota River, Otlozheniia Glavnogo devon-
skogo polia, Chasti. V–VII. (Deposits of the Main Devonian
Field, Parts 5–7), Tr. Leningr. Geol.-Gidro-Geodez.
Tresta, vol. 9, Leningrad, 1935.
Jarvik, E., On the structure of the lower jaw in dipnoans:
with a description of an early Devonian dipnoan from Can-
ada, Melanognathus canadensis gen. et sp. nov., J. Linn. Soc.
(Zool.). 1967, vol. 47, no. 311, pp. 155–183.
Kemp, A., Marginal tooth bearing bones in the lower jaw of
the Recent Australian lungfish, Neoceratodus forsteri (Oste-
ichthyes: Dipnoi), J. Morphol., 1995, vol. 225, pp. 345–355.
Krupina, N.I., A new dipnoan species from the Famennian
of the Central Devonian Field, Paleontol. J., 1980, vol. 3,
pp. 140–143.
Krupina, N.I., Some data on the ontogeny of Devonian
dipnoans, Academia, 1992, vol. 1, pp. 215–222.
Krupina, N.I. and Reisz, R.R., Reconstruction of the den-
tition in hatchlings of Andreyevichthys epitomus, a Late
Famennian dipnoan from Russia, Modern Geol., 1999,
vol. 24, pp. 99–108.
Krupina, N.I., Reisz, R.R., and Scott, D., The skull and
tooth system of Orlovichthys limnatis, a Late Devonian dip-
noan from Russia, Can. J. Earth Sci., 2001, vol. 38, no. 9,
pp. 1301–1311.
Krupina, N.I., Subclass Dipnoi. Lungfishes, in Iskopaemye
pozvonochnye Rossii i sopredel’nykh stran. Beschelyustnye i
drevnie ryby (Fossil Vertebrates of Russia and Neighboring
Countries. Agnathans and Primitive Fishes), Novitskaya, L.I.,
Ed., Moscow: GEOS, 2004, pp. 373–422.
Lukševičs, E., Bothriolepid antiarchs (Vertebrata, Placo-
dermi) from the Devonian of the north-western part of the
East European Platform, Geodiversitas, 2001, vol. 23, no. 4,
pp. 489–609.
Miles, R.S., Dipnoan (lungfish) skulls and the relationships
of the group: a study based on new species from the Devo-
nian of Australia, Zool. J. Linn. Soc., 1977, vol. 61, pp. 1–
328.
Moloshnikov, S.V. and Linkevich, V.V., New data on the
Late Devonian ichthyofauna of the Tver oblast (Bilovo,
Maly Tuder River), Integrativnaya paleontologiya: perspek-
tivy razvitiya dlya geologicheskikh tselei. Mater. 63 sess. Pale-
ontol. ob-va (S.-Peterburg, 3–7 aprelya 2017 g.) (Integrative
Paleontology: Prospective Geological Applications. Proc.
63rd Sess. Paleontol. Soc.: St. Petersburg, April 3–7, 2017),
St. Petersburg: Vseross. Nauchno-Issled. Geol. Inst., 2017a,
pp. 196–198.
Moloshnikov, S.V. and Linkevich, V.V., Systematic rela-
tionships of the Famennian antiarchs (Vertebrata, Placoder-
mi) of the Tver oblast, Izvestiya VUZov. Geologiya i razvedka,
2017b, vol. 2, pp. 8–14.
Sammet, E.Yu., The eastern part of the Main Devonian Field,
Stratigrafiya SSSR. Devonskaya sistema (Stratigraphy of the
USSR. The Devonian System), Nalivkin, D.V. , Eds., Mos-
cow: Nedra, 1973, vol. 1, pp. 90–100.
Schultze, H.-P., A new long-headed dipnoan (Osteichthyes)
from the Middle Devonian of Iowa, USA, J. Vert. Paleontol.,
1992, vol. 12, no. 1, pp. 42–58.
Smith, M.M., Smithson, T.R., and Campbell, K.S.W., The
relationships of Uronemus: a Carboniferous dipnoan with
highly modified tooth plates, Phil. Trans. R. Soc. B. Biol.
Sci., 1987, vol. 317, pp. 299–327.
Verbitsky, V.R., Verbitsky, I.V., Vasilyeva, O.V., et al., Gosu-
darstvennaia geologicheskaia karta Rossiiskoi Federatsii.
Masshtab 1 : 1000000 (tretye pokolenie). Seriya Tsentral’no-
Evropeiskaia. Listy O-35 – Pskov, (N-35), O-36 – Sankt-
Petersburg. Ob’iasnitel’naia zapiska (National Geological
Map of the Russian Federation. Scale 1: 1000000. Central
European Series. Sheets O-35 Pskov, (N-35), O-36 St. Pe-
tersburg. Descriptive Notes), St.-Petersburg: Cartographic
Factory VSEGEI, 2012.
Vorobyeva, E.I., Morfologiia i osobennosti evolutsii kiste-
perykh ryb (Morphology and Patterns of Evolution in Cros-
sopterygian Fishes), Tr. Paleontol. Inst. Akad. Nauk SSSR,
vol. 163, Moscow: Nauka, 1977.
White, E.I., The head of Dipterus valenciennesi Sedgwick &
Murchison, Bull. Brit. Mus. (Natur. Hist.) Geol., 1965,
vol. 11, pp. 1–45.
Translated by D. Ponomarenko