The Largest Asiatic Amphechinus (Erinaceidae, Insectivora, Mammalia) from the Oligocene of Mongolia

Abstract

A lower jaw fragment of a new hedgehog species, Amphechinus gigas sp. nov., from the Oligocene Shand-Gol Formation of Mongolia is described. This species is substantially larger than A. rectus, A. akespensis and other known Amphechinus species from Asia and comparable in size to the European species A. robustus, A. ginsburgi, and A. intermedius. Regarding the length of the lower cheek tooth row, A. gigas is comparable to Recent Erinaceus europaeus; however, the much deeper and more massive horizontal ramus of the dentary shows that A. gigas is larger than the latter.

Full text

302
Paleontological Journal, Vol. 36, No. 3, 2002, pp. 302–306. Translated from Paleontologicheskii Zhurnal, No. 3, 2002, pp. 75–80.
Original Russian Text Copyright © 2002 by Lopatin.
English Translation Copyright © 2002 by
åÄIä “Nauka
/Interperiodica” (Russia).
INTRODUCTION
Amphechinus
belongs to the earliest genera of the
subfamily Erinaceinae. This genus was widespread in
the Oligocene and Miocene of Eurasia and occurred in
the Miocene of North America and Africa (Gureev,
1979; Gould, 1995). The following six species were
described from Asia: Oligocene
A. rectus
(Matthew et
Granger, 1924),
A. kansuensis
(Bohlin, 1942), and
A. minimus
(Bohlin, 1942) from China and Mongolia;
Early Miocene
A. akespensis
Lopatin, 1999 and
A. microdus
Lopatin, 1999 from Kazakhstan; and Early
Miocene
A. bohlini
Bi, 2000 from China (Matthew and
Granger, 1924; Bohlin, 1942; Trofimov, 1960; Mellett,
1968; Sulimski, 1970; Huang, 1984; Lopatin, 1999; Bi,
2000).
A. minimus
and
A. microdus
are small, i.e., com-
parable in size to living
Sorex araneus
L.
A. kansuensis
and
A. bohlini
are somewhat larger.
A. rectus
and
A. akespensis
are only slightly smaller than
Erinaceus
europaeus
L. Late Oligocene
A. arvernensis
(Blain-
ville, 1839) and Early Miocene
A. edvardsi
(Filhol,
1879) from Europe are of approximately the same size.
Certain European species of
Amphechinus
, i.e., Oli-
gocene
A. robustus
(Lavocat, 1951); Middle Miocene
A. ginsburgi
Baudelot, 1972; and
A. intermedius
(Gail-
lard, 1899) are as large as Recent
Erinaceus europaeus.
Postpalerinaceus vireti
(Crusafont Pairo et Villalta, 1947)
from the Pliocene of Spain is larger than all the above-
listed species. Crusafont Pairo and Villalta (1947) and
Gould (1995) assigned
P. vireti
to the genus
Amphechi-
nus
(=
Palaeoerinaceus, Palerinaceus
), whereas Gureev
(1979) assigned it to a particular subgenus of the genus
Erinaceus
.
The present study describes a new species of the
genus
Amphechinus
from the Lower Oligocene of
Mongolia. Regarding the tooth measurements, the new
species is comparable to
A. robustus, A. ginsburgi,
A. intermedius, Postpalerinaceus vireti
, and
Erinaceus
europaeus
; at the same time, its lower jaw is substan-
tially larger and more massive than those of the listed
species. The fragmentary lower jaw of the new species
was found together with
A. rectus
and
A.
cf.
kansuensis.
The Largest Asiatic
Amphechinus
(Erinaceidae, Insectivora,
Mammalia) from the Oligocene of Mongolia
A. V. Lopatin
Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997 Russia
e-mail: alopat@paleo.ru
Received October 26, 2000
Abstract
—A lower jaw fragment of a new hedgehog species,
Amphechinus gigas
sp. nov., from the Oligocene
Shand-Gol Formation of Mongolia is described. This species is substantially larger than
A. rectus, A. akespensis
,
and other known
Amphechinus
species from Asia and comparable in size to the European species
A. robustus,
A. ginsburgi
, and
A. intermedius.
Regarding the length of the lower cheek tooth row,
A. gigas
is comparable to
Recent
Erinaceus europaeus
; however, the much deeper and more massive horizontal ramus of the dentary
shows that
A. gigas
is larger than the latter.
(a)
(b)
(c)
10 mm0
Fig. 1.
Amphechinus gigas
sp. nov., holotype PIN,
no. 4567/14, fragmentary right dentary containing P
4
–M
2
:
(a) labial, (b) occlusal, and (c) lingual views.

PALEONTOLOGICAL JOURNAL
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No. 3
2002
THE LARGEST ASIATIC
AMPHECHINUS
(ERINACEIDAE, INSECTIVORA, MAMMALIA) 303
The material comes from the Shand-Gol Formation.
The specimens were found in a bed located 10–15 m
above a basalt layer in the eastern slope of the Khunuk
Valley, opposite to the Menkhen-Teg locality in the Val-
ley of Lakes (collected by E.V. Devyatkin and I.G. Liskun,
1972). The material on
A. rectus
from several Shand-
Gol localities (Ulan-Khurekh 1, collected by V.Yu. Reshe-
tov in 1979; Tsagan-Obo 3 and Elste-Turamne-Ar, col-
lected by E.K. Sytchevskaya in 1993 and 1995) and
specimen PIN, no. 475/1200 from the Tatal-Gol local-
ity, described by Trofimov (1960), were used for com-
parison.
The following abbreviations are used in this paper:
(PIN) Paleontological Institute of the Russian Academy
of Sciences, Moscow, and (IVPP) Institute of Verte-
brate Paleontology and Paleoanthropology, Beijing.
SYSTEMATIC PALEONTOLOGY
Family Erinaceidae Fischer, 1817
Subfamily Erinaceinae Fischer, 1817
Tribe Amphechinini Gureev, 1979
Genus
Amphechinus
Aymard, 1850
Amphechinus gigas
Lopatin, sp. nov.
Amphechinus
cf.
rectus
: Huang, 1984, p. 308, pl. I, fig. 12.
Etymology. From the Greek
gigas
(giant).
Holotype. PIN, no. 4567/14, fragmentary right
dentary containing P
4
–M
2
; Mongolia, Khunuk locality;
Lower Oligocene, Shand-Gol Formation.
Description (Figs. 1, 2, and 3a). A large hedge-
hog, P
4
–M
3
is approximately 15 mm long, and M
1
–M
3
is approximately 12 mm long. The horizontal ramus of
the lower jaw is deep and massive. The large mental
foramen is on a level with the posterior root of P
4
. The
I
2
is stout. Judging by the preserved alveoli, the canine
was larger than the anterior premolar.
P
4
has a weakly developed posterior cingulid. The
paraconid is somewhat higher than the protoconid. The
protoconid is noticeably posteriorly inclined. Meta-
conid is absent, the lingual wall of the protoconid is
almost straight, flat, and only slightly inflated at the
base. The talonid is very short but broad, broader than
the trigonid.
M
1
is large and long, the trigonid is more than two-
thirds as long as the entire M
1
. The labial cingulid is
well developed and broad, the postcingulid is
extremely weak. The paraconid is large and massive.
The paralophid is long and has a weak notch. The pro-
toconid is substantially more massive and higher than
the metaconid. The metalophid notch looks like a small
depression between the apices of the protoconid and the
metaconid. The metastylid is undeveloped. The talonid
is substantially shorter than the trigonid, but it is of the
same width. The entoconid is higher than the hypo-
conid, strongly longitudinally compressed, and extends
anteriorly to form a relatively high and straight entoc-
ristid, which encloses lingually the talonid basin. The
cristid oblique connects the hypoconid to the middle of
the posterior base of the protoconid. The metalophid
and the posterolophid curve posteriorly; the entocristid
and the cristid oblique extend almost in parallel to the
longitudinal tooth axis.
M
2
is almost 1.5 times shorter than M
1
. The trigonid
is slightly broader and 1.7 times longer than the talonid.
M
2
is similar to M
1
in structural pattern, but differs in
certain features, i.e., the paralophid is shortened, the
metaconid is reduced to a lesser extent, and the meta-
stylid looks like a weak projection.
M
3
is represented by the anterior root located in the
alveolus and by the anterior wall of the alveolus of the
posterior root. Judging from the arrangement and mea-
surements of these structures, M
3
was at most half as
long as M
2
.
Measurements, mm. Holotype: length of P
4
–M
2
is 12.6; length of M
1
–M
2
, 9.7; length
×
width: (P
4
) 3.2
×
2.1; (M
1
) 5.8
×
3.1 (trigonid, 4.0
×
3.1; talonid, 1.8
×
3.1); and (M
2
) 4.0
×
2.75 (trigonid, 2.5
×
2.75; talonid,
1.5
×
2.45); dentary depth at P
4
and M
1
, 8.0; at M
2
, 8.2;
and at M
3
, 7.7; dentary thickness at P
4
, 4.9; at M
1
, 4.3;
and at M
2
, 4.2.
Comparison.
A. gigas
sp. nov. differs from all
known species of the genus by very large measure-
ments (table) and extremely massive lower jaw. In
(a)
(b)
05 mm
Fig. 2.
Amphechinus gigas
sp. nov., holotype PIN,
no. 4567/14, fragmentary right dentary containing P
4
–M
2
:
(a) labial, (b) occlusal, and (c) lingual views.
(c)

304
PALEONTOLOGICAL JOURNAL
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No. 3
2002
LOPATIN
addition, it differs from the majority of species by the
structure of P
4
(in which the paraconid is higher than
the protoconid and metaconid is absent) and by the
presence of double-rooted M
3
. The new species differs
from the most similar species from Asia (
A. rectus
and
A. akespensis) by the absence of metaconid on P4 and
certain structural details of the lower molars, in partic-
ular, weak postcingulids of M1 and M2 and the absence
of metastylid on M1.
Remarks. Judging from the measurements
(5.9 mm long and 3.3 mm wide) and structure, the
large M1 (specimen IVPP, no. V7340) from the Ulan-
tatal locality of China, which was initially determined
as A. cf. rectus (Huang, 1984), actually belongs to
A. gigas.
Occurrence. Lower Oligocene of Mongolia and
China.
Material. Holotype.
DISCUSSION
The Recent Erinaceidae are divisible into three
groups by measurements: small, in which the body is
10–15 cm long and the skull is 30–40 mm long;
medium-sized, the body is 15–30 cm long, the skull is
41–63 mm long; and large forms, the body is 31–45 cm
long and the skull is 60–87 mm long. The first group
comprises the shrew-hedgehogs Hylomys (including
Neotetracus and Neohylomys) and Podogymnura, the
second comprises the true hedgehogs Hemiechinus,
Paraechinus, and Erinaceus (including Atelerix and
Mesechinus), and the third includes the gymnura Echi-
nosorex gymnurus. The largest member of true hedge-
hogs (Erinaceinae) is the European hedgehog Erina-
ceus europaeus (Gureev, 1979), the body of which is
19.5–30 cm long, and the skull is 43–63 mm long.
Extinct hedgehogs include certain giant insecti-
vores. In particular, the skull of Deinogalerix koenig-
swaldi Freudenthal, 1972 from the Late Miocene of
Italy (Gargano) is 210–223 mm long (Freudenthal, 1972).
Judging from the reconstructed skeleton, the body of
this shrew-hedgehog was approximately 60–70 cm
long. Quite apparently, this is an exception accounted
for by the insular giantism (Guérin, 1997); in general,
extinct hedgehogs that are comparable in size to Erina-
ceus europaeus should be regarded as large erinaceids.
Only a small number of such forms occurred in the Oli-
gocene and Miocene of Eurasia; these were mainly the
Measurements of teeth and lower jaws of large-sized hedgehog species (Amphechinus, Postpalerinaceus, and Erinaceus)
Species Reference P4–M3P4–M2M1–M3M1–M2P4M1M2M2/M1
Jaw depth
under
P4–M1
A. rectus Huang, 1984 – – 7.5–8.1 – 1.4–2.5 3.7–4.4 2.4–3.2 0.62–0.74 3.9–5.1
PIN,
no. 475/1200 11.5 9.9 9.0 7.3 2.6 4.4 3.3 0.75 6.6
PIN,
no. 4567/12 about
12.0 about
10.0 9.7 7.5 – 4.7 3.3 0.70 6.6
A. akes-
pensis Lopatin, 1999 – 10.5 – – 2.8 4.7–4.8 3.5 0.73 6.5
A. arver-
nensis Baudelot, 1972 11.2 – 9.0 – 2.4 4.4 3.4 0.79 6.03
Ziegler, 1998 ––––2.62–2.98 3.93–4.38 2.9–3.54 0.74–0.81 4.05–5.25
A. edwardsi Baudelot, 1972 11.2 – 9.0 – 2.8 4.4 3.2 0.75 5.7–6.0
Ziegler, 1990 – – – – 2.6–3.15 4.01–5.0 3.32–3.61 – –
A. gigas holotype about
15.0 12.6 about
12.0 9.7 3.2 5.8 4.0 0.69 8.0
Huang, 1984 – – – – – 5.9 – – –
A. robustus Lavocat, 1951 – 12.0 10.0–11.0 9.0 2.7 4.95 3.9 0.79 6.1
Ziegler, 1990 – – – – 2.75 – 3.53 – –
Ziegler, 1998 – – – – 4.11–4.35 5.4–6.2 4.17–4.8 0.77 6.0–6.9
A. gins-
burgi Baudelot, 1972 14.6–14.9 – 11.3–11.5 – 3.2–3.47 5.2–5.34 4.38 0.82 6.2–7.0
A. inter-
medius Baudelot, 1972 15.0 – 11.5 – 3.8 5.5 4.5 0.86 7.0
P. vireti Baudelot, 1972 – – – – 3.52–3.84 5.52–6.04 4.6–5.3 0.85 7.2
E. europaeus collection PIN 15.0–15.3 12.7–13.5 12.3–12.4 10.0–10.3 3.5 5.5–5.9 4.5–4.9 0.81–0.83 5.4–5.9

PALEONTOLOGICAL JOURNAL Vol. 36 No. 3 2002
THE LARGEST ASIATIC AMPHECHINUS (ERINACEIDAE, INSECTIVORA, MAMMALIA) 305
above-mentioned species of the genus Amphechinus.
Certain members of the Brachyericinae also reach rela-
tively large sizes; in particular, the skull of Late Oli-
gocene Metexallerix gaolanshanensis Qiu et Gu, 1988
from China is approximately 50 mm long (Qiu and Gu,
1988).
The table shows the tooth measurements of large-
sized species of Amphechinus and proper hedgehogs.
The teeth of Amphechinus are relatively small and the
horizontal ramus of the lower jaw is relatively deeper
and more massive than those of Erinaceus (Fig. 3);
therefore, it is impossible to perform direct compari-
sons of sizes between the members of these genera.
Based on the ratios between the lengths of the lower
tooth row (table), lower jaw, and skull in certain
European species of the genus Amphechinus (the skulls
of A. arvernensis and A. edwardsi are approximately
35 mm long), it is possible to estimate the measure-
ments of the species from Asia as follows: the skulls of
A. minimus and A. microdus are approximately 20 mm
long, those of A. kansuensis and A. bohlini are about
25 mm long, those of A. rectus and A. akespensis are
about 30–45 mm long, and those of A. gigas are about
55–60 mm long.
To date, the following species of the family Erina-
ceidae have been found in the Shand-Gol Fauna of
Mongolia and northern China: Tupaiodon morrisi and
Zaraalestes minutus (Tupaiodontinae); Exallerix hsan-
dagolensis (Brachyericinae); and Palaeoscaptor acri-
dens, Amphechinus rectus, and A. cf. minimus (Erinace-
inae) (Matthew and Granger, 1924; Trofimov, 1960;
McKenna and Holton, 1967; Mellett, 1968; Sulimski,
1970; Huang, 1984). Taking into account the prelimi-
nary study of the Oligocene Erinaceidae from Mongo-
lia stored at the PIN, the number of Amphechinus spe-
cies recorded in the Shand-Gol Fauna increases by
four; these are A. cf. minimus, A. cf. kansuensis, A. rec-
tus, and A. gigas. These species are well distinguished
from each other not only by the dental structure but also
by the measurements. This fact is evidence of adaptive
radiation of Oligocene Amphechinus and explains the
presence of a large number of sympatric species of the
same genus in Central Asia. As far as is known (Bohlin,
1942; Bendukidze, 1993; Lopatin, 1999; Meng et al.,
1999; Bi, 2000), the differentiation in size of the
Amphechinus species remained in Asia at the end of the
Late Oligocene (A. minimus, A. kansuensis, and A. cf.
rectus) and early in the Miocene (A. microdus, A. bohlini,
and A. akespensis); however, the species comparable in
size to A. gigas have not been recorded in the deposits
of this age.
ACKNOWLEDGMENTS
This study was supported by the Russian Founda-
tion for Basic Research, project nos. 98-04-49089,
99-04-48636, and 00-15-97754.
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