A new species of Archaeoryctes from the Middle Paleocene of China and the phylogenetic diversification of Didymoconidae

Abstract

Didymoconidae are an enigmatic group of Asian endemic insectivorous mammals. We describe the new didymoconid species Archaeoryctes wangi sp. nov. from the Upper Member of the Wanghudun Formation (Middle Paleocene). This new species from the Qianshan Basin (Anhui Province, China) forms an interesting geographical intermediate between A. notialis from South China and A. borealis and A. euryalis from the Mongolian Plateau. To better understand the origin and evolutionary diversification of Didymoconidae, we performed a cladistic and stratocladistic study of the Didymoconidae and various outgroups. This study of dental material did not resolve the higher level affinities of Didymoconidae, but confirms the validity of the family and its distinctiveness from the morphologically similar Sarcodontidae. Moreover, our results corroborate the current didymoconid classification with the distinction of three subfamilies: “Ardynictinae”, Kennatheriinae and Didymoconinae; “Ardynictinae” are a paraphyletic stemgroup for the two other subfamilies. Our results suggest three distinct didymoconid radiations: (1) primitive ardynictines appeared in South China from the start of the Nongshanian; their evolution continues on the Mongolian Plateau with (2) the radiation of more evolved ardynictines and kennatheriines at the start of the Middle Eocene Arshantan and (3) the origin of didymoconines at the start of the Late Eocene Ergilian.

Full text

GEOLOGICA BELGICA (2013) 16/4: 245-253
A new species of Archaeoryctes from the Middle Paleocene of China and the
phylogenetic diversication of Didymoconidae
Pieter MISSIAEN
1,2
, Floréal SOLÉ
2
, Eric DE BAST
2
, Jian YANG
3
, Cheng-Sen LI
3
& Thierry SMITH
2
1
Research Unit Palaeontology, Ghent University, Krijgslaan 281, S8, B-9000 Ghent, Belgium.
2
O.D. Earth and Histrory of Life, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B-1000 Brussels, Belgium.
E-mail: oreal.sole@naturalsciences.be, eric.debast@naturalsciences.be, thierry.smith@naturalsciences.be
3
State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing
100093, P.R. China. E-mail: yangjian001@gmail.com, lics@ibcas.ac.cn
ABSTRACT. Didymoconidae are an enigmatic group of Asian endemic insectivorous mammals. We describe the new didymoconid
species Archaeoryctes wangi sp. nov. from the Upper Member of the Wanghudun Formation (Middle Paleocene). This new species
from the Qianshan Basin (Anhui Province, China) forms an interesting geographical intermediate between A. notialis from South
China and A. borealis and A. euryalis from the Mongolian Plateau. To better understand the origin and evolutionary diversication of
Didymoconidae, we performed a cladistic and stratocladistic study of the Didymoconidae and various outgroups. This study of dental
material did not resolve the higher level afnities of Didymoconidae, but conrms the validity of the family and its distinctiveness from
the morphologically similar Sarcodontidae. Moreover, our results corroborate the current didymoconid classication with the distinction
of three subfamilies: “Ardynictinae”, Kennatheriinae and Didymoconinae; “Ardynictinae” are a paraphyletic stemgroup for the two
other subfamilies. Our results suggest three distinct didymoconid radiations: (1) primitive ardynictines appeared in South China from
the start of the Nongshanian; their evolution continues on the Mongolian Plateau with (2) the radiation of more evolved ardynictines and
kennatheriines at the start of the Middle Eocene Arshantan and (3) the origin of didymoconines at the start of the Late Eocene Ergilian.
KEYWORDS: Ardynictinae, Sarcodontidae, Qianshan Basin, Asia, Evolution, Stratocladistics
1. Introduction
Didymoconidae are a poorly known, enigmatic group of
insectivorous mammals, which are strictly endemic to Asia
(Lopatin, 2006). They appear at the start of the Nongshanian
Asian Land Mammal Age (ALMA, early Middle Paleocene) and
persist until the Tabenbulakian ALMA (Late Oligocene) (Wang
et al., 2007; Missiaen, 2011). The specialized Oligocene genus
Didymoconus was originally referred to Carnivora (Matthew and
Granger, 1924), and based on similarities of older, more primitive
didymoconids with North American the family has also been
linked to Mesonychidae and Wyolestidae (Gingerich, 1981).
Based on more recent studies of cranial morphology (Meng et al.,
1994; Lopatin, 2001), Didymoconidae are now generally thought
Figure 1. Geographic location of the Qianshan Basin and other principal didymoconid sites. Map of East Asia (modied from Missiaen, 2011).
Hexangular marks show localities of Ardynictinae with list of taxa present, diamond indicates Kennatheriinae, and circles indicate Didymoconinae.
Squares indicate location of Hunanictis and Mongolotherium not formally assigned to a specic subfamily here.

246 P. Missiaen, F. solé, e. De Bast, J. Yang, C.-s. li, & t. sMith
to be related to various primitive insectivorous taxa, but overall
their suprafamilial afnities remain unclear. Similarly, recent
discoveries have led to the recognition of three didymoconid
subfamilies, Didymoconinae, Ardynictinae and Kennatheriinae
(Lopatin 1997, 2006). Specic details of this classication vary
however and the corresponding evolutionary scenarios have
never been formally analyzed (Tong, 1997; Lopatin, 1997, 2006).
Here we describe a new, well preserved and nearly complete lower
jaw of the primitive didymoconid Archaeoryctes from the early
Nongshanian ALMA of the Qianshan Basin of Anhui Province,
China (Fig. 1), and identify it as the new species Archaeoryctes
wangi sp. nov. Additionally, we perform the rst cladistic and
stratocladistic study of Didymoconidae and potentially related
taxa based on dental morphology in order to better understand the
supra- and infrafamilial afnities and the evolutionary history of
Asian Paleogene Didymoconidae.
2. Systematic paleontology
Family Didymoconidae Kretzoi, 1943
Sub-family “Ardynictinae” Lopatin, 1997
Genus Archaeoryctes Zheng, 1979
Type species: Archaeoryctes notialis Zheng, 1979
Included species: Archaeoryctes borealis Meng, 1990;
Archaeoryctes euryalis Lopatin, 2001; Archaeoryctes wangi sp.
nov.
Distribution: Nongshanian (Middle Paleocene) to Arshantan
(Middle Eocene) Asian Land Mammal Age of China and
Mongolia
Archaeoryctes wangi nov. sp.
(Fig. 2-3, Table 1)
Type and only specimen: IBCAS QS003, an associated left and
right dentary, with C and P
4
-M
2
in place on both sides.
Type locality and Horizon: Zhongjialaowu (coordinates: E
116°30’14.83”, N 30°35’18.50”, altitude 46m ), Qianshan County,
Anhui Province, Upper Member of the Wanghudun Formation;
Middle Paleocene, Asiostylops interval zone of Nongshanian
Asian Land Mammal Age (following Missiaen, 2011).
Etymology: In honour of Dr. Wang Yuanqing (IVPP, Beijing)
who extensively studied the fossiliferous deposits in the
Qianshan Basin and who was the rst to report the presence of
Archaeoryctes there.
Diagnosis: Species of Archaeoryctes characterized by a relatively
narrow trigonids with high, pointed protoconid and metaconid
and by a relatively strong entoconid. Similar in size to A.
notialis but differing by a deeper dentary and relatively smaller
M
2
. Smaller in size than A. euryalis and larger than A. borealis,
further differing from A. borealis by the shallower dentary, by
the higher, more gracile P
4
protoconid, and by the lower cristid
obliqua on P
4
-M
2
.
Description: The two dentaries are relatively short and deep
(length: 58 mm, depth below M
1
: 10 mm). The symphysis is
long, robust, and extends below the anterior root of P
3
. The thin
coronoid crest is vertical and high, and delimits a large, shallow
masseteric fossa. The round mandibular condyle is laterally short
and positioned at about the same height as the teeth. The angular
process is slightly medially deected. The right dentary has three
mental foramina (below P
2
, between P
2
and P
3
, and below the
Figure 2. Dental morphology of Archaeoryctes wangi sp. nov. Holotype specimen IBCAS QS003 from the Nongshanian Upper Member of the
Wanghudun Formation in the Qianshan Basin, Anhui Province, P.R. China in occlusal (A) and anterior (B) view, left dentary in lingual (C) and labial (D)
view, and right dentary in lingual (E) and labial (F) view.
Table 1. Tooth dimensions of the holotype specimen of Archaeoryctes
wangi sp. nov. (x) = measurement estimated from roots or partially
erupted teeth. Abbreviations: L = Length; W = Width.

PhYlogenY oF DiDYMoConiDae 247
P
4
trigonid), whereas the left dentary has an additional foramen
below P
3
. The mandibular foramen is wide and low.
The area for the incisors, in front of the canine, is very
small and suggests the presence of one or two small incisors on
each side. The canine is large and curved postero-dorsally, with
a massive root. Both dentaries suggest the presence of three
premolariform and two molariform teeth. The rst premolariform
tooth is single-rooted, the second one is two-rooted, and the third
one is erupting. The last molariform tooth has a narrower talonid
and more posteriorly placed hypoconulid than the preceding
tooth, and the molar dentition therefore seems to be complete.
This reduced dental formula, with only three premolars and
two molars and with P
4
as the last tooth to erupt, is typical for
Didymoconidae, to which the specimen described here is referred.
Because in this group the DP
2
is not replaced (Lopatin, 2006; p.
308), these postcanine loci are here identied as P
2
(= DP
2
), P
3
, P
4
(in eruption), M
1
and M
2
.
P
2
and P
3
are missing on both sides of the specimen. Based on
the alveoli, the P
2
seems to be larger posteriorly than anteriorly.
On both sides P
4
is erupting, and we can only observe the
presence of a distinctly pointed protoconid, and of a narrow,
unbasined talonid with single high talonid cusp (= hypoconid?).
No metaconid is present on P
4
. The two molars show a high,
lingually open trigonid. The protoconid and metaconid are the
two largest cusps with the protoconid higher than the metaconid.
The paraconid is much lower and shorter. The talonid on M
1
is
slightly narrower than the trigonid. The hypoconid, hypoconulid
and entoconid are well individualized and unfused, forming a
curved arc. The hypoconid is clearly the largest talonid cusp, while
the hypoconulid is somewhat higher and more posteriorly placed
than the entoconid. The cristid obliqua is obliquely oriented and
the talonid basin is open lingually due to the posterior position
of the entoconid and the short entocristid, which does not reach
the metaconid. On M
2
, the paraconid is lower and the talonid is
longer and narrower than on M
1
, with a more posteriorly located
hypoconulid.
Comparison: Specimen IBCAS QS003 differs from most other
Asian early Paleogene “insectivores” by the absence of M
3
,
a feature typical of the Sarcodontidae and Didymoconidae
(Lopatin, 2006, Missiaen and Smith, 2008). This new specimen
from Qianshan differs from all Sarcodontidae by the small
and reduced incisors, by the loss of the rst premolar, by the
complete absence of P
4
metaconid, and the absence of carnassial
specialization of the molars. The specimen is however clearly
similar to Didymoconidae by these characters, as well as by the
highly placed rst mental foramen, by the diastemata surrounding
P
2
, and by the molars with a low paraconid, a high protoconid and
metaconid, and a lingually open talonid basin.
The most recent classication of didymoconids involves three
subfamilies, kennatheriines, ardynictines, and didymoconines, of
which only the two rst are recorded in the Paleocene (Lopatin,
2006). Specimen IBCAS QS003 clearly resembles ardynictines
by the simple, single-rooted P
2
, by the P
4
without metaconid
and only a single talonid cusp, and by molars with a distinct,
labiolingually oriented cristid obliqua, and a posteromedially
placed hypoconulid. Contrastingly, kennatheriines and
didymoconines are characterized by at least partially molarized
last premolars, and by talonids where the hypoconulid is lingually
displaced against the entoconid or where all cusps form a straight
transverse line.
Within ardynictines, the new specimen only matches the
genus Archaeoryctes, based on the completely unmolarized
P
4
, and the molars with a low paraconid and relatively low
protoconid and metaconid. Three species of Archaeoryctes have
been so far described, the contemporaneous A. notialis from the
Chijiang Formation in Jiangxi Province (Zheng, 1979), the Late
Paleocene A. euryalis from the Zhigden Member of the Naran
Bulak Formation in Mongolia (Lopatin, 2001) and A. borealis
from the Middle Eocene Arshanto Formation in Inner Mongolia
(Meng, 1990). The new specimen described here resembles
A. notialis but differs by the deeper jaw and by the relatively
smaller M
2
that is similar
in size to M
1
in A. wangi than in A.
notialis. It differs from A. borealis by the much larger size, by
the lower dentary, by the higher, more gracile P
4
protoconid,
and by the lower cristid obliqua on P
4
-M
2
. It differs from A.
notialis and A. borealis by lower molars with a narrower molar
trigonid and less robust protoconid and metaconid and a stronger
entoconid. Archaeoryctes euryalis is only known from a skull
with the upper dentition found in the Gashatan of Naran Bulak
and can therefore not be morphologically compared with the
new Nongshanian lower jaw from the Qianshan Basin described
here. However, because P
4
-M
2
in A. euryalis are over 15 percent
larger than their counterparts in the A. wangi, and because of the
considerable temporal and geographical distance between them,
it seems unlikely that both specimens represent the same species.
We can therefore conclude that specimen IBCAS QS003
represents a new, previously unknown species of Archaeoryctes,
for which we propose the new name Archaeoryctes wangi. The
new material constitutes the oldest and best preserved lower jaw
of the genus Archaeoryctes, and formally indicates its presence in
the early Nongshanian of the Qianshan Basin
3. Phylogenetic analysis
3.1 Cladistic analysis
In order to better understand the origin and evolutionary
diversication of Didymoconidae, we built a cladistic data matrix
for all didymoconid genera plus a number of relevant outgroup
taxa. Because Zalambdalestidae, Leptictidae and insectivores all
have been cited as potential relatives of didymoconids (Szalay
and McKenna, 1971; Meng et al., 1994; McKenna and Bell, 1997;
Lopatin, 2001), Zalambdalestes (Zalambdalestidae), Leptacodon
and Praolestes (Nyctitheriidae), and Gypsonictops (Leptictida)
were included. These specic taxa were chosen based on the
availability of well-preserved specimens and their basal position
within their respective groups.
In our analysis, we additionally included the sarcodontids
Carnilestes, Prosarcodon and Sarcodon. This Asian early
Figure 3. Dental morphology of Archaeoryctes wangi sp. nov. Detail
of the left cheek tooth portion of the holotype specimen IBCAS QS003
from the Nongshanian Upper Member of the Wanghudun Formation in
the Qianshan Basin, Anhui Province, P.R. China in occlusal (A) labial
(B), and lingual (C) view.

248 P. Missiaen, F. solé, e. De Bast, J. Yang, C.-s. li, & t. sMith
Paleogene family of insectivorous mammals is also characterized
by the reduction of their molar dentition (Missiaen and Smith,
2008). No explicit statements have been made about a link
between both families, but Wanolestes was originally described
as a sarcodontid (Huang and Zheng, 2002) and is now considered
a didymoconid (Lopatin, 2006). This analysis therefore also
serves as a test of the distinctiveness and interrelationships of
Sarcodontidae and Didymoconidae.
Finally, we added Prokennalestes as the outgroup for the
analysis, originally resulting in a total of 22 taxa, of which 21
ingroup taxa and 14 didymoconids.
The cladistic matrix contains 48 morphological, mostly
dental, characters (See Appendix). All characters were newly
created based on their potential to discriminate between
didymoconids, between sarcodontids and between the ve
ingroup families. Diagnostic characters mentioned in available
literature were maximally incorporated, most notably those used
by Lopatin (2006) to diagnose didymoconids and sarcodontids,
but only robust, clearly visible and informative characters were
retained. Cladistic analyses were run in PAUP 4.0b10 (Swofford
2003) using default settings, with all multistate characters treated
as ordered.
3.2 Stratocladistic analysis
Didymoconidae have a long, and potentially revealing
stratigraphic distribution, with supposedly primitive genera
occurring earlier than more derived forms (Lopatin, 2006).
The stratigraphic distribution of all taxa was determined from
the available literature and placed in a recent Asian mammal
biochronological framework (Tsubamoto et al., 2004; Wang et
al., 1998, 2007; Missiaen, 2011). Most signicantly, this showed
that the primitive didymoconids Zeuchterium and Wanolestes
are Nongshanian in age (Table 2), rather than Shanghuan and
Gashatan respectively (Missiaen, 2011). This information was
subsequently converted into a stratigraphic character for analysis,
resulting in a total of 12 character states for the stratigraphic
character (See Appendix, char 49). All of the stratigraphic
stages differ by their faunal content and match the criteria for
stratigraphic subdivisions as discussed by Alroy (2002), making
this subdivision in 12 states appropriate or even conservative.
We expanded the classical cladistic approach with a
stratocladistic study, an analytical method aiming to improve
taxonomic resolution by also incorporating stratigraphic data.
Stratocladistics further differ from traditional cladistics by
also considering potential ancestor-descendant relationships,
attempting to reconstruct phylogenetic trees, rather than
cladograms which strictly speaking are only “hierarchies based
Figure 4. Strict consensus trees of cladistic analysis. A. Full analysis, resulting in 2673 MPTs. B. Analysis excluding Mongoloryctes and Hunanictis,
resulting in 90 MPTs. Percentages indicate bootstrap support values higher than 50% for clades, numbers indicate Bremer support values.
Table 2. Summary
table of analysed taxa.
Biochronology following
Tsubamoto et al. (2004)
and Missiaen (2011).
# char.: Number of
morphological characters
scored on a total of 48.

PhYlogenY oF DiDYMoConiDae 249
on homology hypotheses” (Bloch et al., 2001, Brochu, 2001;
Marcot & Fox, 2008). Stratocladistic analyses were run in
StrataPhy 0.3.5a (Marcot & Fox, 2008) using default settings,
with all multistate characters except the stratigraphic character
treated as ordered.
3.3 Results and discussion
The initial cladistic analysis of the complete morphological
data set resulted in a total of 2673 Most Parsimonious Trees
(MPTs) of 132 steps, and a poorly resolved consensus tree (Fig.
4A). Unsurprisingly, the afnities of the Eocene didymoconid
Mongoloryctes known only from a single isolated M
1
(Van Valen,
1966; Lopatin, 2006) are completely unresolved in the analysis.
The strict consensus tree does group all other didymoconid
genera in a monophyletic clade, but fails to provide any further
information on their internal relationships.
A detailed analysis of these cladistic results indicated that
the high number of MPTs was primarily caused by the inclusion
of Mongoloryctes and Hunanictis, for which only 9 and 11
morphological characters could be scored respectively, on a
total of 48 morphological characters. These taxa act as unstable
Figure 5. Strict consensus trees of phylogenetic analyses also incorporating stratigraphic data. A. Strict consensus of the 27 MPTs from Fig. 4B that are
stratigraphically most parsimonious. Circles indicate unambiguous synapomorphies. Open circles indicating homoplasious characters and lled circles
indicating unique synapomorphies. Bold type indicates synapomorphies identically present in Fig. 4B. B. Strict consensus of 4 optimal stratocladistic
trees, showing temporal distribution. Hatching indicates periods where genera were supposedly present but have not been recorded. Length of biochrons
is not to scale, timing of evolutionary events is approximate.

250 P. Missiaen, F. solé, e. De Bast, J. Yang, C.-s. li, & t. sMith
wildcards due to a combination of missing data and character
conicts (Kearney and Clark, 2003), and their removal from the
analysis reduces the number of MPTs from 2673 to 90 MPTs of
130 steps. The corresponding strict consensus tree (Fig. 4B) is
better resolved and more robust. Most signicantly, the consensus
tree groups Archaeoryctes, Zeuctherium, Wanolestes, Ardynictis
and Jiajianictis together in a monophyletic clade, similar to
the didymoconid subfamily Ardynictinae proposed by previous
authors (Tong, 1997; Lopatin, 2006).
A better resolved didymoconid cladogram could be obtained
by additionally removing Jiajianictis and Tshotgoria, for which
only 14 characters were scored, or by considering less strict
consensus techniques. Both solutions however represent poor
answers to missing data problems in phylogenetic analyses
(Kearney and Clark, 2003). Instead, given the potentially
signicant stratigraphic distribution of didymoconids, we added
these stratigraphic data to our analysis as a simple, ordered
character. Of the 90 equally parsimonious morphological trees
from gure 3B, 27 trees are stratigraphically shorter than the
others, with a total of 141 steps. These same 27 trees are also the
most parsimonious results of a new, direct analysis containing
the stratigraphic character from the onset. Their strict consensus
(Fig. 5A) suggests that the “Ardynictinae” form a paraphyletic
stemgroup that gave rise to two monophyletic subfamilies, the
Kennatheriinae and Didymoconinae.
The same data were also analysed using the dedicated
stratocladistic StrataPhy software (Marcot and Fox, 2008),
resulting in 2 optimal topologies and 4 optimal trees. The
stratocladistic consensus solution (Fig. 5B) mainly differs from
Figure 5A in the rooting of the didymoconid family and the relative
position of the most basal didymoconid genera. Otherwise, both
are highly similar, suggesting that the older “Ardynictinae” form
a stemgroup that after the end of the early Eocene gave rise to the
more derived Kennatheriinae and Didymoconinae.
All analyses unambiguously include Wanolestes within
Didymoconidae and clearly discriminate between Sarcodontidae
(Carnilestes, Prosarcodon and Sarcodon) and Didymoconidae
(Figs 4 and 5). These results therefore support the inclusion
of Wanolestes in Didymoconidae and underline the validity of
Didymoconidae as a monophyletic natural group (Lopatin, 2006).
Didymoconids are morphologically characterized by a long
jaw symphysis, by a reduction of the lower incisors, by large
canines and the loss of P
1
/
1
and M
3
/
3
, by relatively simple anterior
premolars mostly lacking a P
3
parastyle and a P
3
paraconid, by
a P
4
with distinct metacone, by upper molars without distinct
conules and by lower molars with a simplied talonid structure
and posteriorly placed entoconid, leading to lingually open
talonid basin. These analyses are generally consistent with
existing subdivisions of Didymoconidae into ardynictines,
kennatheriines and didymoconines (Tong, 1997; Lopatin, 2006).
Primitive ardynictines are characterized by a single rooted P
2
,
and by a premolariform P
4
with a small to absent metaconid
and single talonid cusp. More evolved forms have a reduced
number of lower incisors, generally a more stronger P
3
metacone,
relatively larger last premolars with more distinct metaconid
and more complex talonid, and a more longitudinally oriented
cristid obliqua on the molars. Kennatheriinae are characterized
by a P
4
with three talonid cusps, and a molar hypoconulid that is
lingually displaced and closely appressed against the entoconid.
Didymoconinae on the other hand are diagnosed by a two-rooted
P
2
, by a P
4
with two or three talonid cusps, and molar talonids
with cusps arranged in a straight transverse line.
The main novelties in this phylogenetic study are the explicit
notion that the subfamily Ardynictinae is not a monophyletic clade
but a paraphyletic stem group and the newly proposed afnities
for Zeuctherium and Khaichinula. Lopatin (2006) identied
Zeuctherium as a kennatheriine based on the reduced molar styles.
Zeuctherium however resembles ardynictines, and Archaeoryctes
in particular, by the more molarized P
3
and the stronger hypocone
and hypocone shelf on the molars and is therefore referred to the
ardynictine stemgroup here. The poorly known Khaichinula has
previously been referred to Didymoconinae (Lopatin, 2006), but
is placed here in the Kennatheriinae based on the molariform,
tricuspid P
4
talonid that we consider typical of kennatheriines and
not of didymoconines.
4. Conclusions
Specimen IBCAS QS003 represents a new, previously unknown
species of Archaeoryctes, described here with the name
Archaeoryctes wangi. This conrms the presence of the genus
in the Nongshanian of the Qianshan Basin already alluded to
by Wang et al. (1998), and forms a geographical intermediate
between A. notialis from South China and A. borealis and A.
euryalis from the Mongolian Plateau.
The discovery of this well preserved specimen makes that both
the upper and lower dentition of Archaeoryctes is now relatively
well known, and we performed a morphologic, cladistic and
stratocladistic study of the dental morphology of Didymoconidae
and potentially relevant taxa. Our results unambiguously
conrm the validity and distinctiveness of Didymoconidae from
Sarcodontidae, but we could not unambiguously identify the
higher level afnities of the family based on dental information
alone. This study generally corroborates the current didymoconid
classication of Lopatin (2006) with the distinction of three
didymoconid subfamilies, “Ardynictinae”, Kennatheriinae and
Didymoconinae, although we show that “Ardynictinae” are a
paraphyletic stemgroup for the two other subfamilies. From an
evolutionary point of view, our results suggest three distinct
didymoconid radiations, with an ardynictine stemgroup evolving
in South China from the start of the Nongshanian. At the end of the
Nongshanian, didymoconids disappear from southern and central
China, but continue to thrive in the Mongolian Plateau with
the radiation of more evolved ardynictines and Kennatheriinae
at the start of the Middle Eocene Arshantan and the origin of
Didymoconinae at the start of the Late Eocene Ergilian.
5. Acknowledgements
We thank Li Ya and Zhang Qian-qian (IBCAS), and Nathalie
Van Hoey and Richard Smith (RBINS) for assistance during the
eldwork. D. Nagel (Institut für Paläontologie, Universität Wien)
and A.V. Lopatin (Paleontological Institute, Russian Academy
of Sciences) provided access to reference literature. We thank
A.V. Lopatin and M. Morlo for their very quick reviews of the
manuscript and for providing constructive remarks. PM is a
postdoctoral fellow of the Research Foundation Flanders (FWO
Vlaanderen). Financial support for this research was further
provided by the Belgian Federal Science Policy Ofce (doctoral
fellowship to E.D., and research project MO/36/020 to T.S.). This
paper is a contribution to China International S&T Cooperation
Project supported by the Chinese Ministry of Science and
Technology (2009DFA32210 to C.L.) and bilateral Cooperation
project supported by the Belgian Federal Science Policy Ofce
(BL/36/C54 to T.S.).
6. References
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Manuscript received 09.09.2013, accepted in revised form
27.09.2013, available online 10.10.2013

252 P. Missiaen, F. solé, e. De Bast, J. Yang, C.-s. li, & t. sMith
Characters
1. P
1
/
1
:
0. Present
1. Absent
2. P
2
/
2
:
0. Present
1. Absent
3. P
x
/
x
(sensu Cifelli 2000):
0. Present
Five premolars
1. Absent
Four premolars or less
4. M
3
/
3
:
0. Present
1. Absent
5. Lower jaw symphysis:
0. Short, not extending beyond the anterior border of
P
3
1. Long, extending beyond the anterior border of P
3
6. Mental foramen near P
2
:
0. Located distinctly higher than the foramen near P
4
1. Located at the same height as the foramen near P
4
or lower
7. Dentary:
0. Shallow (dentary height below M
1
< 2x paracristid
height on M
1
)
1. Deep (dentary height below m M
1
> 2x paracristid
height on M
1
)
8. Angular process:
0. Not deected medially
1. Deected medially
9. Lower incisors:
0. Four
1. Three
2. Two
Reference material used for comparison
Prokennalestes. Publications: Kielan-Jaworowska & Dashzeveg, 1989;
Sigogneau-Russell et al., 1992
Gypsonictops. Publications: Simpson, 1927, 1951; Clemens, 1973
Zalambdalestes. Specimens: ZPAL MgM I/43; Publications: Kielan-
Jaworowska, 1968; Kielan-Jaworowska & Tromov, 1981; Wible et al
2004
Carnilestes. Publications: Wang & Zhai, 1995
Prosarcodon. Publications: McKenna et al, 1984; Lopatin & Kondrashov,
2004
Sarcodon. Specimens: IVPP V11134.1, IVPP V11134.2; Publications:
Matthew & Granger, 1925; Matthew et al, 1929; Szalay & McKenna,
1971; Meng et al, 1998; Huang, 2003; Lopatin & Kondrashov, 2004
Leptacodon. Publications: Matthew & Granger, 1921; Simpson, 1935;
McKenna, 1968; Rose, 1981; Smith, 1996
Praolestes. Publications: Matthew et al., 1929; Szalay & McKenna,
1971 ; Kondrashov et al, 2004 ; Lopatin, 2006
Archaeoryctes. Specimens: Q003; IVPP5036; Publications: Zheng, 1979;
Lopatin, 2001; Meng 1990
Wanolestes. Publications: Huang & Zheng, 2002
Hunanictis. Publications: Li et al 1979; Meng et al 1994
Jiajianictis. Publications: Tong, 1997
Ardynictis. Publications: Matthew & Granger, 1925; Tong, 1997; Lopatin,
2003
Mongoloryctes. Publications: Matthew & Granger, 1925; Van Valen, 1966
Zeuctherium. Publications: Tang & Yan, 1976
Kennatherium. Publications: Mellet & Szalay, 1968; Lopatin, 2006
Erlikotherium. Publications: Lopatin, 2006
Khaichinula. Publications: Lopatin, 2006
Ergilictis. Publications: Lopatin, 1997
Didymoconus. Publications: Matthew & Granger, 1924; Mellet & Szalay,
1968; Lopatin, 1997; Wang et al, 2001. Morlo & Nagel, 2002
Archaeomangus. Publications: Lopatin, 1997
Tshotgoria. Publications: Lopatin, 1997
Appendix 1

PhYlogenY oF DiDYMoConiDae 253
3. One
4. Zero, lower incisors absent
10. Canine size:
0. Small, canine root smaller than that the roots of P
2
1. Large and massive, canine root larger than that the
roots of P
2
11. Diastema before P
2
:
0. Absent or indistinct
1. Clearly present
12. P
2
:
0. Two-rooted
1. Single-rooted
13. Diastema between P
2
and P
3
:
0. Absent or indistinct
1. Clearly present
14. Paraconid on P
3
:
0. Present
1. Absent
15. Metaconid on P
4
:
0. Absent
1. Poorly developed or indistinct
2. Present and clearly developed
16. Talonid on P
4
:
0. One cusp
1. Two cusps
2. Three cusps
17. P
4
and M
1
length:
0. P
4
shorter than M
1
(P
4
L/M
1
L<90%)
1. P
4
similar in length to M
1
(90%< P
4
L/M
1
L<110%)
2. P
4
longer than M
1
( P
4
L/M
1
L>110%)
18. M
1
and M
2
length:
0. M
2
shorter than M
1
(M
2
L/ M
1
L<90%)
1. M
2
similar in length to M
1
(90%<M
2
L/ M
1
L<110%)
2. M
2
longer than M
1
(M
2
L/ M
1
L>110%)
19. M
2
and M
3
length:
0. M
3
shorter than M
2
(M
3
L/M
2
L<90%)
1. M
3
similar in length to M
2
(90%<M
3
L/M
2
L<110%)
2. M
3
longer than M
2
(M
3
L/M
2
L>110%)
20. M
1
shape in occlusal view:
0. Trigonid wider than talonid
1. Trigonid narrower than talonid
21. Lower molar trigonid:
0. Low
1. High, at least twice as high as the talonid
22. Lower molar paraconid:
0. Low
1. High and enlarged, paraconid cusp distinctly
higher than the talonid cusps
23. Lower molar metaconid:
0. Similar in height to the protoconid
1. Distinctly lower than the protoconid
24. Orientation of cristid obliqua on M
1-2
:
0. Oblique, running anteriorly and lingually from the
hypoconid
1. Longitudinal, running essentially anteriorly from
the hypoconid
25. M
1
entoconid:
0. Present and distinct, similar to the hypoconid
1. Reduced, distinctly smaller than the hypoconid
2. Absent
26. M
1
hypoconulid:
0. Present
1. Indistinct or absent
27. M
1
hypoconulid:
0. Medially placed
1. Lingual, closely appressed to the entoconid
28. M
1
talonid cusps:
0. Forming a curved arc
1. Linearly arranged, all three cusp forming a straight,
transversal line
29. M
1
talonid basin:
0. Closed, with premetacristid reaching the trigonid
back wall
1. Open
30. M
2
talonid:
0. Longer than M
1
talonid
1. Shorter than M
1
talonid
31. Upper incisors:
0. Three
1. Two
32. P
2
:
0. Two-rooted
1. Single-rooted
33. Parastyle on P
3
:
0. Present
1. Absent
34. Metacone on P
3
:
0. Absent
1. Incipiently present
2. Distinctly present
35. P
3
protocone:
0. Absent
1. A small cusp
2. A distinct cusp, its base approaching the size of
that of the paracone
36. Metacone on P
4
:
0. Absent
1. Present
37. P
4
hypocone region:
0. Talon shelf and hypocone absent
1. Talon shelf and hypocone weakly developed
2. Talon shelf and hypocone developed
38. M
1
Shape:
0. Not transversely elongated (Centrocrista-
Protocone distance/Paracone-Metacone distance
<150%)
1. Transversely elongated (Centrocrista-Protocone
distance/Paracone-Metacone distance >150%)
39. Stylar shelf on molars:
0. Wide
1. Narrow, a mere ridge
40. Molar parastyle and metastyle:
0. Distinct
1. Reduced
41. Preparacrista and postmetacrista on M
1
:
0. Equivalent in development
1. Postmetacrista better developed than preparacrista
2. Postmetacrista strongly developed, preparacrista
reduced
42. Paracone-metacone on M
1
:
0. Well-separated
1. Poorly separated to partially fused
2. Strongly fused
43. Upper molar trigon basin:
0. Conules absent
1. Only conules present
2. Conules and conule wings present
44. Precingulum on M
1
:
0. Absent
1. Present
45. Talon shelf on M
1
:
0. Absent
1. Present as a narrow ridge
2. Present and extending far postero-lingually
46. Hypocone on M
1
:
0. Absent
1. Present
47. Jugal:
0. Developed
1. Reduced
48. Contact between the palatine and lacrimal inside the orbit:
0. Present
1. Absent
49. Statigraphic range:
0. E Cretaceous
1. L Cret
2. Shanghuan
3. Nongshanian - Asiostylops zone
4. Nongshanian - Bothriostylops zone
5. Gashatan
6. Bumbanian
7. Irdinmanhan
8. Sharamurunian+Ulangochian
9. Ergilian
10. Hsandgolian
11. Tabenbulakia