A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function

Abstract

Abstract Lebedev, O.A. 2009. A new specimen of Helicoprion Karpinsky, 1899 from Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position and function. —Acta Zoologica (Stockholm) 90 (Suppl. 1): 171–182 A new Helicoprion bessonowi Karpinsky, 1899 (Chondrichthyes, Eugeneodontiformes) specimen from the Artinskian of Kazakhstan is described. This is the southernmost occurrence of this species in the Cisurals area. Its presence suggests a biogeographical link for this species between the Cisurals and Japan. Residue obtained from chemical preparation of the sample included numerous scales and several teeth, which are tentatively assigned to Helicoprion. This assumption is based upon morphological similarity of the scales to those known in other eugeneodontiforms. Campodus-like teeth might be part of the lateral dentition of Helicoprion. A new reconstruction of the interaction of the lower tooth whorl with the upper jaw dentition is suggested and its function is discussed. It is proposed that there was no symphysial whorl in the upper jaw but its role was played by a rigid cover formed by a series of small teeth at the palatoquadrates. Microscopic study of the tooth crown surface revealed scratch marks, which might have resulted from pressing the food object against the upper jaw. Using extant odontocetans as an ecological model led to a conclusion that helicoprionids most likely fed on cephalopods and to some extent on fish. This assumption is based upon the concentration of functional dentition in the area of the lower jaw symphysis in both groups of animals.

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Acta Zoologica
(Stockholm)
90
(Suppl. 1): 171–182 (May 2009) doi: 10.1111/j.1463-6395.2008.00353.x
© 2009 The Author
Journal compilation © 2009 The Royal Swedish Academy of Sciences
171
Abstract
Lebedev, O.A. 2009. A new specimen of
Helicoprion
Karpinsky, 1899 from
Kazakhstanian Cisurals and a new reconstruction of its tooth whorl position
and function. —
Acta Zoologica
(Stockholm)
90
(Suppl. 1): 171–182
A new
Helicoprion bessonowi
Karpinsky, 1899 (Chondrichthyes, Eugeneodonti-
formes) specimen from the Artinskian of Kazakhstan is described. This is the
southernmost occurrence of this species in the Cisurals area. Its presence
suggests a biogeographical link for this species between the Cisurals and Japan.
Residue obtained from chemical preparation of the sample included numerous
scales and several teeth, which are tentatively assigned to
Helicoprion
. This
assumption is based upon morphological similarity of the scales to those
known in other eugeneodontiforms.
Campodus
-like teeth might be part of the
lateral dentition of
Helicoprion
. A new reconstruction of the interaction of the
lower tooth whorl with the upper jaw dentition is suggested and its function is
discussed. It is proposed that there was no symphysial whorl in the upper jaw
but its role was played by a rigid cover formed by a series of small teeth at the
palatoquadrates. Microscopic study of the tooth crown surface revealed scratch
marks, which might have resulted from pressing the food object against the
upper jaw. Using extant odontocetans as an ecological model led to a conclusion
that helicoprionids most likely fed on cephalopods and to some extent on fish.
This assumption is based upon the concentration of functional dentition in the
area of the lower jaw symphysis in both groups of animals.
Oleg A. Lebedev, Palaeontological Institute of the Russian Academy of Sciences,
Profsoyuznaya St. 123, Moscow, 117997, Russia.
E-mail: olebed@paleo.ru
Blackwell Publishing Ltd
A new specimen of
Helicoprion
Karpinsky, 1899 from
Kazakhstanian Cisurals and a new reconstruction of its tooth
whorl position and function
O. A. Lebedev
Palaeontological Institute of the Russian
Academy of Sciences, Profsoyuznaya St.
123, Moscow, 117997, Russia
Keywords:
Lower Permian, Artinskian,
Helicoprion
,
dentition
Accepted for publication:
18 June 2008
Introduction
Enigmatic
Helicoprion
fossils comprise rows of up to 135–180
tooth crowns set upon a common base that is coiled into a flat
bilaterally symmetric whorl attaining 35– 40 cm in diameter.
The smaller (older) tooth crowns are situated inside the whorl.
The first whorls were found at the end of the 19th century in
the Divya Gora quarry by the town of Krasnoufimsk (Perm
Government, currently Sverdlovsk Region) (Karpinsky
1899a,b). Since then, numerous findings of these strange
tooth complexes became almost globally known within a
wide stratigraphic range, spanning from the Sakmarian to
the Kungurian (Late Permian).
The oldest coiled helicoprionid fish find in Russia is an
incomplete whorl of
Shaktauites seywi
Tchuvashov, 2001
from the Sakmarian of Shakh-Tau quarry close to Sterlitamak
(Bashkortostan, Cisurals: Tchuvashov 2001). This genus
shows a smaller degree of coiling and fewer teeth than in
Helicoprion
. The oldest members of the latter genus were
described from the Wolfcampian of Texas (Kelly and Zangerl
1976) and from the erratic boulder from California, which is
dated as Asselian-Artinskian (Bendix-Almgreen 1966).
During the Artinskian,
Helicoprion
was widely distributed
(Fig. 1). Apart from the Cisurals, it is known from Spitsbergen
(Nassichuk 1971), Canada and the United States (Nassichuk
1971; Chorn 1978; Zangerl 1981), Mexico (Sour-Tovar

A new specimen of
Helicoprion
Karpinsky
•
Lebedev Acta Zoologica
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(Suppl. 1): 171–182 (May 2009)
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Journal compilation © 2009 The Royal Swedish Academy of Sciences
et
al
. 2000), Japan (Yabe 1903), Laos (Hoffet 1933), China
(Chen
et
al
. 2007), Australia (Teichert 1940) and possibly
Iran (Obruchev 1964). The youngest
Helicoprion
find comes
from the Lower Kungurian of the Perm Region (Tchuvashov
2001). Several finds of
Sinohelicoprion
(Liu and Chang 1963;
Zhang 1979; Liu and Wang 1994), including the latest one
from the Changxingian of Hunan province (Lei 1983) and
Hunanohelicoprion
(Liu 1994; Cheng
et
al
. 2004) including
the youngest species from the Maokuo of the Guizhou prov-
ince (Cheng
et
al
. 2004), are known from China. Therefore,
helicoprionids were globally distributed apart from the
southwest margins of Gondwana. This may be the result of
supposed glaciation preventing their spreading to this region
during the Early Permian. These huge sharks possibly inhabited
the oceanic basins and entered the shallow-water seas only
temporarily, for example during spawning seasons.
The present finding represents the southernmost
occurrence of
Helicoprion bessonowi
Karpinsky, 1899 in the
early Permian Cisurals basin (Fig. 1). The new locality of
H. bessonowi
Karpinsky, 1899 is situated at the junction of
the Uralian Strait with the northern coast of Tethys, providing
a biogeographic connection to the occurrence of this species
in Japan as well as evidence of a Tethys–Panthalassa link
between Asian and Euramerican helicoprionids.
Materials and Methods
A new
H. bessonowi
Karpinsky, 1899 (specimen PIN 1988/38,
Fig. 2) was found by Ruzhentsev in Kazakhstan (Aktyubinsk
Region, Aktasty locality; Lower Permian, Artinskian, Aktasty
Substage). The specimen consists of two almost half-volutions,
the larger one from the youngest, external coil and the smaller
one from the inner coil adjoining it. Both were embedded in
a piece of organoclastic limestone. The external face of the
specimen was badly damaged. To expose the unbroken internal
surface of the whorl the sample was treated with 10% acetic
acid solution. The residue obtained comprised numerous
diverse microremains, including scales and teeth. The associated
fish microremains included a variety of other chondrichthyan
teeth like those of
Cobelodus obliquus
Ivanov, 2005 (Fig. 4K–M),
Stethacanthus
sp. (Fig. 4N–P) and scales of Actinopterygii indet.
(Fig. 4Q). These will be described elsewhere. Microremains
were examined by scanning electron microscopy.
Systematic palaeontology
Order Eugeneodontiformes Zangerl, 1981
Family Helicoprionidae Karpinsky, 1911
Referred genera
Apart from the type genus,
Agassizodus
St John and Worthen,
1875;
Parahelicoprion
Karpinsky, 1924;
Campyloprion
East-
man, 1902;
Sarcoprion
Nielsen, 1952;
Toxoprion
Hay, 1909;
Sinohelicoprion
Liu and Chang, 1963;
Hunanohelicoprion
Liu,
1994 and
Shaktauites
Tchuvashov, 2001.
Diagnosis (emended after Obruchev 1964)
Large marine eugeneodontiforms in which the jaw symphysis
was armed with an arched or spiral dental complex composed
of the conjoint base and a set of separate tooth crowns
compressed laterally. Lateral crown sides form symmetric
processes extended rostrally (spurs), whereas the bases
(where seen) extend caudally. Lateral teeth organized into
numerous series, up to 25 elements in each. The base of the
tooth whorl rests upon an unpaired spiral basimandibular
rod-like cartilage fusing with the Meckelian cartilages.
Remarks
The family Helicoprionidae was created by Karpinsky as
early as 1911, but apart from the Russian palaeoichthyologists
this systematic unit was accepted only by Teichert (1940)
and Bendix-Almgreen (1966). Most western researchers
(for example Chorn 1978) included this genus into the
Edestidae until Zangerl (1981) erected the Agassizodontidae
to include genera related to
Helicoprion
Karpinsky, 1899. He
noted partial correspondence of the Agassizodontidae to
Helicoprionidae but did not explain the reasons for erecting
Fig. 1—Distribution of Helicoprionidae
during the Lower Permian. 1. Middle Urals
(Russia), 2. Kazakhstan, 3. Spitsbergen,
4. Canadian Arctic Archipelago, 5. British
Columbia, 6. Alberta, 7. Idaho, 8. Nevada,
9. Texas, 10. Mexico, 11. Laos, 12. Tibet
(China), 13. Guizhou (China), 14. Hunan
(China), 15. Hubei (China), 16. Zhejian
(China), 17. Japan, 18. Western Australia,
19. Iran (?). Palaeogeographical map after
Ziegler et al. (1997), modified.

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a new family name. As the Helicoprionidae Karpinsky
(1911) have priority over Agassizodontidae the former family
name is supported here.
Helicoprion
Karpinsky (1899a)
Diagnosis
(
emended after
Obruchev 1964 and Zangerl 1981)
High and narrow symphysial part of the Meckelian cartilage
forms a case enclosing most of the older part of the spiral.
Symphysial dentition forms a whorl, which may consist of up
to three coils and bear up to 180 tooth crowns. Crown cutting
edges smooth or denticulated. Lateral processes of crowns
(spurs) attain the level of the vertical axis of the preceding or
the next before the preceding tooth crown rostrally. Teeth
consist of osteodentine and the crowns are coated with
enameloid. Palatoquadrates are lined with the series of small
‘
Campodus
’-like teeth.
Type species
Helicoprion bessonowi
Karpinsky (1899a).
Geographical distribution and age
Apart from the type species from the Artinskian of Cisurals
(Russia), Kazakhstan and Japan, the following species
are known:
Helicoprion sierrensis
Wheeler, 1939 (Asselian-
Artinskian, glacial boulder, California);
H. nevadensis
Wheeler,
1939 (Artinskian, Nevada);
H. ferrieri
(Hay, 1907) and
H.
ergasaminon
Bendix-Almgreen, 1966 (Phosphoria Formation,
Roadian; Idaho);
H. svalis
Siedlecki, 1970 (Artinskian-
Ufimian; Spitsbergen);
H. davisii
(Woodward, 1886) (?
Kungurian-Ufimian; Western Australia);
H. mexicanus
Müllerried, 1945 (Leonardian, Mexico). Poorly preserved
H. karpinskii
Obruchev, 1953 specimen comes from pre-
sumably Kungurian of Cisurals.
Helicoprion bessonowi
Karpinsky (1899a) (Figs 2 and 3)
Helicoprion bessonowi
: Karpinsky (1899a; p. 20, text-figs 18–
57, pls. 1–3, 4, figs 1–11); Karpinsky (1899b; p. 25, text-
figs 18–22 and 36–57); Karpinsky (1911; p. 1105, text-
fig. 2); Obruchev (1964; pl. 3, fig. 1, text-figs 32–33);
Zangerl (1981; p. 86, text-fig. 98I).
Type specimen
Lectotype – tooth whorl in the Central Research Geological
Museum (TsNIGR, Russia, St.-Petersburg) 1/1865, Russia,
Sverdlovsk Region, Krasnoufimsk District, a quarry 3 km to
the west from Krasnoufimsk; Lower Permian, Artinskian,
Fig. 2—Two fragments of the tooth whorl PIN 1988/38, Kazakhstan, Aktyubinsk Region, left bank of the Aktasty River, Aktasty locality;
Lower Permian, Artinskian, Aktasty Substage. Scale bar = 3 cm.

A new specimen of
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Karpinsky
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(Suppl. 1): 171–182 (May 2009)
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Journal compilation © 2009 The Royal Swedish Academy of Sciences
Sarga Regional Stage, Divya Formation. The lectotype was
indicated by Obruchev (1964).
Material
Incomplete tooth whorl PIN 1769/6, type locality and horizon
(Karpinsky 1915); PIN 1988/38, two fragments of the same
tooth whorl, Kazakhstan, Aktyubinsk Region, left bank of
the Aktasty River, Aktasty locality, Aktasty Substage.
Species diagnosis
The apical crown angle is 45
°
. Crenulated cusps are simple,
wider than deeper. The depth of the paired ledge of the basal
side of the complex base does not exceed one-fifteenth of the
total coil depth.
Remarks
Neither Karpinsky nor other authors created the diagnosis
for the
H. bessonowi
Karpinsky, 1899, so the one given above
is compiled anew.
Geographical distribution and age
Cisurals and Japan; Lower Permian, Artinskian.
Description
The youngest, external coil bears 26 crowns and broken
crown bases, the older smaller coil has 24 completely and
imperfectly preserved tooth crowns. Estimated quantity of
the crowns per volution is 44– 45, which would make about
130–140 for the complete whorl.
Crown size increases significantly by the whorl. Namely, in
the larger coil in which no completely preserved crowns are
present, the length of the crown base at the level of the maximal
anterior embayment increases approximately 1.5 times from
the anteriormost to the posteriormost elements. In the smaller
coil both total crown length (including the crown base) and
the length of the projecting part of the crown increase 1.4
times caudad. In tooth whorls of comparable size from the
type locality PIN 1769/6 (Fig. 8A) the corresponding ratios
are 1.3 and 1.2, which are very similar.
The crown edges are crenulated from both anterior and
posterior sides. Crenulating cusps are wider than deep and bear
one or two vertical incisions from the external margin (Fig. 3).
The crown bases are short; forwards they reach the radial
axis of only the preceding tooth and this feature persists
throughout the extent of both described volutions (Figs 2
and 3). However, in PIN 1769/6 this characteristic is different.
While in the innermost whorl the crown bases are similarly
short, the larger second one shows crown bases attaining the
posterior edge of the element before the preceding one and
in the largest, third one the crown bases attain the radial axis
of this segment crown or even its anterior edge.
Another distinction of PIN 1988/38 from PIN 1769/6 is
the large space between the crown bases. While in the latter
specimen the crown bases are closely spaced, in the former
they are widely set apart (Fig. 3); the maximum width of the
space almost reaches the width of the crown base itself. In the
lectotype TsNIGR 1/1865 the width of this space varies,
increasing posteriorly, that is from the centre outward. With
careful chemical preparation it may be seen that both the
anterior and the posterior margins of the spur in PIN 1988/
38 bear acute enameloid crests prolonging those of the
protruding part of the crown. Adjoining parts of the base are
lined with numerous large vascular canal openings. At the
base of the crown spurs all along the external coil fragment
there is a large vascular canal impression giving off radial
branches, which enter spaces between the crown bases. In
contrast to PIN 1769/6 and the lectotype TsNIGR 1/1865 in
PIN 1988/38 the basal tips of the crown bases do not reach
the basal edge of the coil base; this free surface occupies
about a third of the coil base depth. The basal groove surface
in the inner coil is almost smooth; in the external one it is
sculptured with longitudinally directed rugosity.
? Helicoprion bessonowi
Karpinsky (1899a) (
Campodus
sp.)
(Fig. 4A,B)
Description
Two teeth of this type were found in the residue. In PIN
1988/47 the base is almost completely destroyed; only its
lingual wall perforated with very large numerous nutrient
foramina is partly preserved. The labial side of the crown
forms labial buttresses of which the one supporting the central
tubercle is the largest. The central tubercle is compressed
Fig. 3—Enlarged part of the older (inner) volution of the tooth whorl
PIN 1988/38. Scale bar = 0.5 cm.

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transversely and extends to the lingual side of the crown more
than to the labial one. Two pairs of lateral tubercles bear a
low, but acute sagittal ridge, often giving off small branches.
At the central tubercle the sagittal ridge is interrupted by
a transverse crest. Short crests fill the space between the
branching ornament of the main system of ridges. This specimen
is morphologically indistinguishable from the one figured by
Karpinsky (1904), but is much smaller.
Remarks
Remains associated with the
Helicoprion
tooth whorls are
very rare. Karpinsky (1904) presented an unassociated
Campodus
sp. tooth originating from the same locality from
where an imprint of the whorl was known. He suggested, and
later Nielsen (1952) supported the suggestion by analogy
with
Sarcoprion
, that this tooth belonged to
Helicoprion
lateral
dentition. Bendix-Almgreen (1966) described minute
rectangular or rhombic teeth disposed in rows in the
Helico-
prion ferrieri
specimen of the anterior part of the head. Both
upper and lower jaws in
Sarcoprion
(Nielsen 1932, 1952)
bear numerous rows of
Campodus
-like teeth. It is highly
probable that the tooth PIN 1988/47 was a part of
Helicoprion
lateral dentition.
? Helicoprion bessonowi
Karpinsky (1899a) (Figs 4C–J and
5M–P)
Description
Numerous scales extracted from the rock sample are uniformly
built, although they show a great variety of individual appearance.
Generally a high coronal part is mounted upon a shallow
rounded, oval or irregularly rounded base forming a narrow
brim around the crown footing. The basal surface is concave,
irregular and bears numerous vascular pores (Fig. 4H).
Fig. 4—Microremains obtained from the
rock sample, which contained the tooth
whorl PIN 1988/38. —A and B. ?
Helicoprion bessonowi Karpinsky, 1899
(Campodus sp.), tooth PIN 1988/47.
—
A. Occlusal view from the lingual side;
—
B. occlusal view from the labial side.
—
C–J. Scales presumably belonging to
Helicoprion bessonowi Karpinsky, 1899.
—
C, D. Specimen PIN 1988/48;
—
C. lateral coronal view; —D. lateral view.
—
E, F. Specimen PIN 1988/49; —E. lateral
coronal view; —F. coronal view.
—
G–I. Specimen PIN 1988/50; —G. lateral
view; —H. same view, base enlarged;
—
I. magnified view of the vertical ridge
showing serration. —J. Specimen PIN
1988/51, lateral view. —K–M. Cobelodus
obliquus Ivanov, 2005, tooth PIN 1988/52;
—
K. labiocoronally; —L. lingually;
—
M. coronally. —N–P. Stethacanthus sp.,
tooth PIN 1988/53; —N. coronally;
—
O. labiocoronally; —P. lingually.
—
Q. Actinopterygii indet. scale PIN 1988/
54. Scale bars—A, B, E, F = 1 mm;
C, D, G, H, J, N–Q = 0.3 mm,
K–M = 0.1 mm and I = 0.01 mm.

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Monodontode or polyodontode crowns are sculptured by
rough vertical ridges, which tend to become finer and bifurcate
basally. The ridge margins are serrated (Fig. 4I). In poly-
odontode scales individual conical odontodes fuse with their
bases and basal parts of their walls, but their apical parts
remain independent (Fig. 4C–F). In monodontode scales a
slender cusp occupies a small area in the middle of the wide
flat base (Fig. 4J).
Remarks
Scales were never found in association with Helicoprion
whorls, even with the best-preserved specimens of H. ferrieri
(Hay 1907). Bendix-Almgreen (1966), who described this
material in detail, noted that this was probably because of the
absence of scales at the snout. However, in Sarcoprion,
another member of the Helicoprionidae, Nielsen (1932,
1952) figured the lateral part of the symphysial region lined
with scales possessing flattened polygonal crowns (Fig. 5A).
Presumably ‘edestid’ scales from the Upper Permian of East
Greenland (possibly belonging to Fadenia or Sarcoprion)
were described by Stensïo (1962) (Fig. 5B– H). In eugeneo-
dontiform caseodontid Ornithoprion from the Pennsylvanian
of Indiana, USA (Zangerl 1966) scales are known (Fig. 5I –L).
Taking into account manifestation of these skeletal elements
in related members of the order, one cannot exclude the
possibility of their presence in Helicoprion.
Morphologically, scales in Ornithoprion, East Greenland
‘edestids’ and those described above are very closely built
(Fig. 5). All of them demonstrate a flat or somewhat concave
base rounded in the plan view and generally following the
crown outline. The neck is better expressed in the elements
consisting of a smaller number of odontodes (Fig. 5F,G,I,K,O).
The crown is formed by a differing amount of odontodes
fused at their sides. Individual odontode apices are expressed
to varying degrees, being rounded in Ornithoprion (Fig. 5I– L)
and Greenland ‘edestids’ (Fig. 5B–H), pointed in the
Helicoprion bessonowi scales (Fig. 5M–O) and flat (not
unlikely because of lifetime abrasion) in Sarcoprion
(Fig. 5A). This general morphological similarity between
scales in the edestiforms mentioned above does not make
improbable the attribution of the materials from Kazakhstan
to Helicoprion.
An alternative suggestion is the attribution of these elements
to other fish, for example symmoriiforms Cobelodus and
Stethacanthus. However, their skin is naked except for modified
scales along the lateral line canal (e.g. Zangerl 1981), so
scales described above might belong to either an unknown
fish of which there are no other remains in the collection,
or to Helicoprion, which is easier to assume. The second
interpretation seems more parsimonious and is accepted
here.
Discussion
Various authors suggested several hypotheses on the position
of the Helicoprion tooth whorl and its function. Russian workers
(Karpinsky 1899a,b; Obruchev 1953, 1964; Tchuvashov
Fig. 5—Comparison of morphological scale patterns in various eugeneodontiforms. —A. Scales at the lateral side of the lower jaw symphysis
in Sarcoprion edax Nielsen, 1952 (large elements on top of the figure are basal parts of the tooth whorl crowns); B–H. ‘edestid’ scales from
the Upper Permian of East Greenland; —I–L. scales in Ornithoprion hertwigi Zangerl, 1966, all in vertical cross-section; M–P. scales
presumably belonging to Helicoprion bessonowi Karpinsky, 1899. —M. Specimen PIN 1988/51; —N. specimen PIN 1988/48; —O. specimen
PIN 1988/50; —P. specimen PIN 1988/49. —A, C, E, P. coronally; —B, D, F, G, H, M–O. laterally. —A. redrawn from Nielsen (1952);
—B–H. redrawn from Stensïo (1962); —I–L. from Zangerl (1966), modified. Not to scale.

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2001) placed the whorl at the upper jaw and this reconstruc-
tion remained in textbooks for decades (Fig. 6). Karpinsky
(1911, 1915) suggested that the whorl might be enclosed in
the cartilage, but his first earlier graphic reconstruction did
not show this (Fig. 6A). Obruchev (1953) reconstructed the
whorl with the symphysial cartilage filling the space between
the coils. His idea was based upon the presence of prismatic
cartilage patches remaining there after preparation (Fig. 6B).
It is not improbable that some of the whorls were preserved
in association with cartilage enclosing them but it was later
removed by careless preparation.
Bendix-Almgreen (1966), on the basis of uniquely pre-
served materials from the Phosphoria Formation (Idaho)
clearly stated that the Helicoprion whorls were set at the lower
jaw symphysis, rested upon an unpaired basimandibular
cartilage and were enclosed, apart from the youngest part of
the external coil, into a cartilaginous case formed by the
symphysial part of the Meckelian cartilages. Regretfully, he
reconstructed only this anteriormost part of the lower jaw
and did not demonstrate its position with respect to the upper
jaws and rostrum. The first author to publish the reconstruction
of the tooth whorl at the lower jaw in the whole fish was Long
(1995) (Fig. 7A). Janvier (1996) also placed the whorl at the
lower jaw and enclosed half of it within a reconstructed
cartilaginous case (Fig. 7B). However, the latter author was
following the structure of the lower and upper jaws of the
related long-snouted genus Sarcoprion. Janvier displayed the
anterior part of the external coil exposed out of the mouth
cavity, representing the rostral and ethmoidal parts of the
skull as being very low and hypothesized that the whorl
rested between ‘two similar series of upper teeth’. On the
contrary, Bendix-Almgreen (1966) concluded that ‘... no
similar organ was developed in the upper jaw’.
Apart from Sarcoprion, whorls in both the lower and the
upper jaws within Eugeneodontiformes are known only in
Fadenia crenulata Nielsen, 1932 (Bendix-Almgreen 1975),
Edestus heinrichi Newberry and Worthen, 1870 (Zangerl
1981) and Edestus mirus Hay, 1912 (Nielsen 1952). In the
last two forms, the position of these elements with respect to
each other is either unknown or dubious. Superposition of
the Fadenia lower jaw to the upper one suggests that the
former was somewhat shifted caudally, so that occlusion of
the anterior lower jaw elements possibly occurred with the
posterior upper jaw elements. Moreover, in Sarcoprion and
Fadenia symphysial elements are much wider and, respec-
tively, lower, more robust than in Helicoprion, which makes
food processing between whorls conceivable, in contrast to
the last genus in which dental crowns are very high, strongly
compressed laterally and would hardly resist lateral force
which would inevitably arise from interaction with the upper
jaw symphysial antagonist. Taking into account dozens,
maybe hundreds, of Helicoprion tooth whorls found in the
world, not a single ‘upper jaw’ specimen was ever described.
No upper jaw element was found in the best-preserved specimen
Fig. 6—Early reconstructions of Helicoprion.
—
A. The first reconstruction performed
by A. P. Karpinsky (1899a);
—
B. reconstruction by Obruchev (1953).
Fig. 7—Recent reconstructions of
Helicoprion whorl position. —A. The fir st
head reconstruction in which the whorl is
placed at the lower jaw; —B. whorl position
based upon helicoprionid Sarcoprion.
—
A. Redrawn from Long (1995);
—
B. after Janvier (1996), modified.

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© 2009 The Author
178 Journal compilation © 2009 The Royal Swedish Academy of Sciences
(Idaho no. 4) of Helicoprion ferrieri (Hay, 1907), presenting
an almost complete anterior part of the head (Bendix-
Almgreen 1966).
Contra Janvier (1996) and following Bendix-Almgreen
(1966) opinion it is also suggested that dental antagonists for
the lower jaw whorl might have been made of a rigid cover
formed by a series of very small and thin teeth on the palato-
quadrates (Fig. 8). Such a coating is known in Helicoprion
ferrieri (Hay 1907) (Bendix-Almgreen 1966) and members
of related families within Eugeneodontiformes, for example
Sarcoprion, Caseodus, Bobbodus and others (Zangerl 1981).
The median palatal cavity housed the functional part of the
whorl while the mouth was closed, like paired palatal cavities
housed parasymphysial whorls in onychodontiform fish
Onychodus (Andrews et al. 2006). These palatal rows of tiny
(in comparison to the whorl crowns) teeth might act together
as chain armour to provide semi-rigid support for the food
object while it was pressed by the lower jaw dentition against
it and at the same time protected the palate.
The hypotheses on the Helicoprion mode of feeding evolved
almost in parallel with reconstructing process. Karpinsky
(1899a,b, 1911) suggested that the whorl was used as a
weapon of attack used to fight other large fish. Long (1995)
compared its function to the rostrum in the extant saw-fish
Pristis that enters the compact fish or cephalopod school and
kills prey with the help of abrupt horizontal movements of
the anterior part of the body.
Obruchev (1953) and Tchuvashov (2001) despite placing
the whorl on the upper jaw proposed its usage as ploughing
out benthic invertebrates. Bendix-Almgreen (1966) noted
lifetime abrasion in Helicoprion ergasaminon, but did not
attempt to interpret it. In general for the Helicoprion whorl he
suggested cutting and tearing function ‘in combination with
the rows of small upper jaw teeth’.
Checking the hypothesis on the whorl function led to
examination of the tooth crown surfaces. This revealed
scratch traces over several of the best-preserved crowns in
PIN 1769/6 (Fig. 9). Almost all scratch marks are directed
radially to the tooth whorl centre that shows that the biting
force was applied between the jaws. This fact rejects the
‘ploughing’ hypothesis because in this case wear traces
should be directed tangentially to the tooth whorl. Thus, the
whorl might be used for grasping prey or tearing off large
pieces by pressing the food object against the upper jaw.
Serration of the crown edges facilitated cutting soft tissues.
It is suggested that helicoprionids preyed mostly on soft-bodied
cephalopods or soft parts of shelled ones, possibly partly on
fish. Scratches might result from incidental contact with a
hard object, such as a shell edge.
For reconstruction of trophic behaviour modes in large
Palaeozoic chondrichthyans, odontocetans are suggested
here as a morphonutritiological model. These whales are
similar to edestids and helicoprionids by their large size and
pelagic habitat. Extant odontocetans feed on fish and cepha-
lopods. Examples from this group facilitate reconstruction of
functioning of the dentition in helicoprionids (Fig. 10).
In the recent ichthyoteuthophagous Physeter (Yablokov
et al. 1972) teeth are found only in the lower jaw and their
antagonist is a thick and hard integument lining the palate
(Fig. 10A). There are several genera within the odontocetans
(for example, Grampus, Kogia, Ziphius) (Fig. 10B,C) in which
teeth are absent or almost absent at the upper jaw and strongly
reduced in number at the lower one, being concentrated
close to the symphysis (Yablokov et al. 1972). According to
the nutritiological classification suggested for cetaceans by
Tomilin (1954) and supported by Yablokov et al. (1972) these
mammals belong to ichthyoteuthophagous or teuthophagous
predators. Cited authors claimed that the fewer teeth are
present at the lower jaw the larger percentage in their diet is
constituted by cephalopods. Presumably, this type of dentition
suits best catching and processing of these food objects.
It is therefore not impossible that helicoprionids and edestids
occupied the same ecological niche in the Lower Permian
pelagic basins as extant ichthyoteuthophagous and teutho-
phagous cetaceans (Fig. 10D–F).
Based upon this similarity and taking into account inter-
relationships of Helicoprion to other eugeneodontiforms a new
reconstruction of the animal in its environment is suggested
(Fig. 11). In all three eugeneodontiforms known by more or
Fig. 8—Suggested reconstruction of Helicoprion tooth whorl and its
relation to hypothesized upper jaw and the snout. Arrow shows
growth direction of the tooth whorl. Abbreviations: bm,
basimandibular cartilage; fpw, functional part of the whorl; ld,
lateral dentition; M. cart, Meckelian cartilage; nft, newly forming
teeth; r. cart, rostral cartilage; stw, symphysial tooth whorl. Lower
jaw symphysis and rostrum reconstruction based upon Bendix-
Almgreen (1966).

Acta Zoologica (Stockholm) 90 (Suppl. 1): 171–182 (May 2009) Lebedev •A new specimen of Helicoprion Karpinsky
© 2009 The Author
Journal compilation © 2009 The Royal Swedish Academy of Sciences 179
Fig. 9—Symphysial lower jaw tooth whorl
Helicoprion bessonowi Karpinsky, 1899, PIN
1769/6. —A. Overall view; —B. enlarged
area showing subradial scratch marks,
graphically emphasized. Scale bars
—
A. = 2 cm; —B. = 0.5 cm. —A. Whitened
with ammonium chloride,
—
B. natural view.
Fig. 10—Comparison of helicoprionid and
edestid dentitions (to the right) to those of
extant cetaceans (to the left) demonstrating
shortening of the tooth rows towards the
symphysis. In cetaceans this phenomenon
results from the transition from
ichthyoteuthophagy to teuthophagy.
Shortening of the working part of the tooth
whorls in edestids and helicoprionids may
demonstrate their transfer to teuthophagy.
—
A. Ichthyoteuthophagous Physeter;
—
B. teuthophagous Kogia;
—
C. teuthophagous Grampus; —D. edestid
Sarcoprion; —E. edestid Edestodus mirus;
—
F. Helicoprion. Not to scale; —A. after
Yablokov et al. 1972; —D. after Nielsen
1952; —E. after Obruchev 1953, all
modified.

A new specimen of Helicoprion Karpinsky •Lebedev Acta Zoologica (Stockholm) 90 (Suppl. 1): 171–182 (May 2009)
© 2009 The Author
180 Journal compilation © 2009 The Royal Swedish Academy of Sciences
less complete skeletons (Caseodus, Romerodus and Fadenia:
Zangerl, 1981) the body is fusiform, the caudal fin is equilobate
and strongly forked, suggesting outstanding swimming
abilities, as should be also the case in Helicoprion. Only one
dorsal fin appears to be present. Neither anal nor pelvic fins
are reconstructed by analogy with its closest eugeneodon-
tiform relatives.
Spectators encountering the Helicoprion tooth whorls are
always impressed by their large size. However, no attempts
to guess the total length of the body were ever made by
palaeoichthyologists. It is suggested here to use data on the
whorl size for at least very rough calculation of this parameter.
If the whorl diameter is roughly equal to the length of the lower
jaw symphysis, it may be used for an approximate estimation
of the skull length. Using this standard, and suggesting ‘normal’
fish body proportions (that is not too much elongated eel-
like or shortened) in Helicoprion, the body length should be
around five times the head length, that would give us very
rough estimate of the body length. Thus, basing upon illu-
strations in Zangerl (1981), in Romerodus the symphysis length
makes about 25% of the skull length, in Caseodus about 28%
and in Fadenia about 40%. This range of proportions is likely
to be close to the meaning in Helicoprion. The largest known
whorl diameter is 0.4 m (Tchuvashov 2001), which would
correspond to a 1.0–1.6 m skull length and, correspondingly
to a 5–8 m body length, which is comparable to the length of
the largest modern sharks. Certainly, this estimate is very rough
and is based upon assumptions, which cannot currently be
checked.
Conclusions
– A new find of Helicoprion bessonowi Karpinsky, 1899
enlarges the distribution of these fish to the South Urals
area, which corresponded during the Permian to the
northern coast of Tethys, providing a biogeographical
connection to the occurrence of this species in Japan
through the Uralian Strait.
– Simple monodontode and complex polyodontode scales
found in the rock sample probably belong to Helicoprion
Fig. 11—New Helicoprion reconstruction.

Acta Zoologica (Stockholm) 90 (Suppl. 1): 171–182 (May 2009) Lebedev •A new specimen of Helicoprion Karpinsky
© 2009 The Author
Journal compilation © 2009 The Royal Swedish Academy of Sciences 181
based upon morphological similarity to those known in
other eugeneodontiforms. Campodus-like teeth might be
a part of Helicoprion lateral dentition.
– A new reconstruction of the symphysial tooth whorl
contact with the snout and upper jaw structures and
whorl function is proposed and the whorl function is
discussed. The younger third of the last coil is thought to
enter a median palatal cavity. It is proposed that there
were no analogous whorl antagonists in the upper jaw but
its role was played by rigid cover formed by series of small
teeth on the palatoquadrates.
– Microscopic study of the tooth surfaces revealed scratch
marks which might have resulted from pressing of the food
object against the upper jaw, rather than from ploughing
bottom sediment in search for soft invertebrates as was
suggested by earlier authors.
– Using extant odontocetans as a morphonutritiological
model leads to a conclusion that helicoprionids most
likely fed on cephalopods and to some extent on fish. This
assumption is based upon concentration of dentition at
the lower jaw symphysis in both groups of animals.
Acknowledgements
The author would like to express his sincere gratitude to
Prof. Janvier (MNHN, Paris, France) and other colleagues –
palaeoichthyologists – for encouraging this study and for pro-
viding valuable comments during his report in Uppsala
(Sweden) in August 2007. Important notes and advice during
manuscript preparation were supplied by anonymous referees,
to whom the author is greatly indebted.
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