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An Acad Bras Cienc (2014) 86 (4)
Anais da Academia Brasileira de Ciências (2014) 86(4):
(Annals of the Brazilian Academy of Sciences)
Printed version ISSN 0001-3765 / Online version ISSN 1678-2690
www.scielo.br/aabc
1673-1691
http://dx.doi.org/10.1590/0001-3765201420140455
A new prozostrodontian cynodont (Therapsida) from the Late Triassic Riograndia
Assemblage Zone (Santa Maria Supersequence) of Southern Brazil
MARINA B. SOARES1, AGUSTÍN G. MARTINELLI1 and TÉO V. DE OLIVEIRA2
1Laboratório do Setor de Paleovertebrados, Departamento de Paleontologia e Estratigraa, Instituto de Geociências,
Universidade Federal do Rio Grande do Sul/UFRGS, Av. Bento Gonçalves, 9500, 90540-000 Porto Alegre, RS, Brasil
2Museu de Zoologia, Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana/UEFS,
Av. Transnordestina, s/n, Novo Horizonte, 44036-900 Feira de Santana, BA, Brasil
Manuscript received on September 8, 2014; accepted for publication on October 14, 2014
ABSTRACT
We report here on a new prozostrodontian cynodont, Botucaraitherium belarminoi gen. et sp. nov.,
from the Late Triassic Riograndia Assemblage Zone (AZ) of the Candelária Sequence (Santa Maria
Supersequence), collected in the Botucaraí Hill Site, Candelária Municipality, state of Rio Grande do Sul,
Brazil. The new taxon is based on a single specimen (holotype MMACR-PV-003-T) which includes the
left lower jaw, without postdentary bones, bearing the root of the last incisor, canine and four postcanines
plus one partial crown inside the dentary, not erupted, and two maxillary fragments, one with a broken
canine and another with one postcanine. The features of the lower jaw and lower/upper postcanines
resemble those of the prozostrodontians Prozostrodon brasiliensis from the older Hyperodapedon AZ and
Brasilodon quadrangularis and Brasilitherium riograndensis from the same Riograndia AZ. The inclusion
of Botucaraitherium within a broad phylogenetic analysis, positioned it as a more derived taxon than
tritylodontids, being the sister-taxon of Brasilodon, Brasilitherium plus Mammaliaformes. Although the
new taxon is based on few cranial elements, it represents a additional faunal component of the Triassic
Riograndia AZ of southern Brazil, in which small-sized derived non-mammaliaform cynodonts, closely
related to the origin of mammaliaforms, were ecologically well succeed and taxonomically diverse.
Key words: Cynodontia, Prozostrodontia, Santa Maria Supersequence, Triassic.
Correspondence to: Marina Bento Soares
E-mail: marina.soares@ufrgs.br
INTRODUCTION
The rich fossil tetrapod content from the Middle-
Upper Triassic of southern Brazil is recorded in
beds related to the Santa Maria Supersequence, in
which four recognized faunal tetrapod associations
succeed in time: Dinodontosaurus, Santacruzodon,
Hyperodapedon and Riograndia Assemblage Zones
(AZ) (Soares et al. 2011) (Fig. 1). In all of these
bio stratigraphic unities, whose proposed ages are
based on correlations with Argentinean and
Malagasy faunas (Abdala and Ribeiro 2010),
the non-mammaliaform cynodonts (Therapsida,
Eucynodontia) account for a signicant percentage
of the recorded taxa, taxonomically com prising
the most diverse group. In fact, the diversity of the
derived non-mammaliaform probainognathian
cynodonts, grouped into the Clade Prozostrodontia
(sensu Liu and Olsen 2010), from the Upper Triassic
Candelária Sequence (Santa Maria Supersequence)
of southern Brazil is remarkable when compared to
An Acad Bras Cienc (2014) 86 (4)
1674 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
its global fossil record, based upon poorly preserved
specimens. At least two prozostrodontians are
known from the Hyperodapedon AZ (Bonaparte and
Barberena 2001) and at least ve from the younger
Riograndia AZ (Bonaparte et al. 2001, 2003, 2005,
2010, 2012, Martinelli et al. 2005, Soares et al. 2011).
Recent studies on these taxa have highlighted their
essential contribution to the understanding of the
mammaliaforms origin (Bonaparte et al. 2005, Luo
2007, Abdala 2007, Liu and Olsen 2010, Bonaparte
2012), illustrating the climbing mosaic of characters
developed during the Middle-Late Triassic transition
(Bonaparte et al. 2005, Martinelli and Rougier 2007,
Martinelli and Bonaparte 2011, Bonaparte 2012,
Rodrigues et al. 2012, 2013).
In the late Carnian Hyperodapedon AZ,
the prozostrodontians Therioherpeton cargnini
Bonaparte and Barberena (1975) and Prozostrodon
brasiliensis Bonaparte and Barberena (2001) are
recognized, both displaying several derived features
in the skull and dentition (e.g. lack of prefrontal
and postorbital, constricted root in postcanines)
that positioned them as basal prozostrodontians
(Liu and Olsen 2010). From this AZ, Charruodon
tetracuspidatus Abdala and Ribeiro (2000) and
Trucidocynodon riograndensis Oliveira et al.
(2010) are also known. Charruodon was originally
related to Therioherpeton due to the morphology
of the lower postcanines; nonetheless, based on
the deep and robust lower jaw (unexpected for
Therioherpeton based on its skull), we consider that
the phylogenetic position of Charruodon cannot be
elucidated until new specimens come to light. On the
other hand, Trucidocynodon represents a member of
the Ecteniniidae (Oliveira et al. 2010, Martinez et al.
2013), which is positioned outside, as sister-group of
Prozostrodontia (Martinez et al. 2013).
With regard to the prozostrodontian content, the
early Norian Riograndia AZ includes Riograndia
guaibensis Bonaparte et al. (2001) Irajatherium
hernandezi Martinelli et al. (2005), Brasilodon
quadrangularis, Brasili therium riograndensis
Bonaparte et al. (2003), and Minicynodon
Bonaparte et al. (2010). Riograndia is the most
common cynodont of this AZ, represented
by several exquisitely pre served specimens.
Riograndia is considered as a basal member of
the Tritheledontidae Clade (Bonaparte et al. 2001,
Soares et al. 2011) or a basal Ictidosauria, sister-
taxon of Tritheledontidae (sensu Martinelli et al.
2005, Martinelli and Rougier 2007). Irajatherium
is still poorly represented in comparison to other
cynodonts from this AZ. However, its dentition
resembles that of Chaliminia from the Late
Triassic of Argentina and Pachygenelus from the
Early Jurassic of Africa (Martinelli and Rougier
2007). Hence, Irajatherium is positioned as a basal
Tritheledontidae (Martinelli et al. 2005, Martinelli
and Rougier 2007, Oliveira et al. 2011). Brasilodon,
Brasilitherium (Bonaparte et al. 2003, 2005,
2012), and Minicynodon (Bonaparte et al. 2010,
2012) are relatively well-documented and they are
crucial taxa in cynodont evolution because they
constitute the sister-group of Mammaliaformes
(e.g., Bonaparte et al. 2003, 2005, 2012, Abdala
2007, Martinelli and Rougier 2007, Luo 2007, Liu
and Olsen 2010, Rodrigues et al. 2012, 2013, Ruff
et al. 2014). Bonaparte et al. (2005) created the
Family Brasilodontidae to include Brasilodon and
Brasilitherium, and, subsequently, other taxa were
included in it such as Protheriodon estudianti
(Bonaparte et al. 2006, Bonaparte 2012). Some
authors (e.g., Liu and Olsen 2010) pointed out
that Brasilodon and Brasilitherium are synonym
and also that a monophyletic Brasilodontidae
has not been recovered (e.g., Abdala 2007).
Notwithstanding these issues that are currently
under revision, the impact that the discovery of
the brasilodontids from the Riograndia AZ of
southern Brazil has caused is unprecedented
(Bonaparte et al. 2003, 2005, 2012, Rodrigues et
al. 2012, 2013).
In this contribution, we present a new pro-
zostrodontian cynodont from the Riograndia AZ of
An Acad Bras Cienc (2014) 86 (4)
1675
A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
the Candelária Municipality, state of Rio Grande
do Sul, Brazil. The new taxon is described,
compared and included in a broad phylogenetic
analysis of cynodonts. Although based on a partial
lower jaw and maxillary fragments, the specimen
represents a new taxon of prozostrodontian
with several features shared with Prozostrodon
from the Hyperodapedon AZ and especially
with Brasilodon and Brasilitherium from the
Riograndia AZ. The new specimen contributes
to the understanding of the non-mammaliaform
prozostrodontian diversity.
Fig. 1 - A: Geographical location of the Santa Maria Supersequence (Paraná Basin) in the state of Rio Grande do Sul, Brazil.
B: Chronostratigraphy of the southern Brazilian Triassic, showing the four Assemblage Zones (AZ) based on tetrapods context.
From Horn et al. 2004. Biostratigraphy after Soares et al. 2011. Abbreviations: Any, Anisian; Car, Carnian; Ind, Induan; Lad,
Ladinian; Nor, Norian; Ole, Olenekian; Rha, Rhaetian.
GEOLOGICAL SETTING AND BIOSTRATIGRAPHY
The Upper Triassic Candelária Sequence corres ponds
to a third-order sequence placed in the Santa Maria
Supersequence (sensu Zerfass et al. 2003, Horn et
al. 2014) (Fig. 1). The basal portion of the Sequence
consists of a coarsening-upward succession that begins
with red mudstones interbedded with small-scale
trough cross-bedded sandstone lenses. Rhytmites
and sigmoidal massive to climbing cross-laminated
sandstone bodies are also present (Soares et al. 2011).
This facies association is interpreted as a lacustrine-
deltaic depositional system in a humid climate (Holz
and Scherer 2000, Zerfass et al. 2003). The Candelária
Sequence encompasses the Hyperodapedon AZ
(sensu Abdala et al. 2001), in which the most abundant
components are the rhynchosaur Hyperodapedon
sp. and the traversodontid cynodont Exaeretodon
riograndensis Abdala et al. (2002). Besides the
aforementioned cynodonts (e.g., Trucidocynodon,
Therioherpeton, Charruodon and Prozostrodon), its
dinosaur content also deserves mention (Bittencourt
and Kellner 2009, Langer et al. 1999, Cabreira et al.
2011). This faunal association enables us to correlate
these levels with those of the Ischigualasto Formation
from Argentina, whose basal layer was dated as
An Acad Bras Cienc (2014) 86 (4)
1676 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
230.3-231.4 ± 0.3My (Rogers et al. 1993, Furin
et al. 2006, Martinez et al. 2011). The top of the
Candelária Sequence, where the younger Riograndia
AZ is recognized, has an increased content of
sandstone. The layers occur as narrow, massive
or stratied (horizontal and trough cross bedding)
lenses interpreted as amalgamated sandstone
bodies related to high width/depth ratio channels.
This succession is interpreted as the progressive
replacement of a lacustrine-deltaic by a uvial system
(Rubert and Schultz 2004, Soares et al. 2011). The
Riograndia AZ is characterized by a rich association
of small tetrapods, such as the procolophonid
Soturnia caliodon Cisneros and Schultz (2003),
and the sphenodontid Clevosaurus brasiliensis
Bonaparte and Sues (2006), among others, and
the ve taxa of advanced non-mammaliaform
cynodonts aforementioned (Riograndia, Brasilodon,
Brasilitherium, Irajatherium and Minicynodon).
The dinosaurs are represented by the plateo saurid
Unaysaurus tolentinoi Leal et al. (2003), the
theropod (sensu Langer et al. 2009) Guaibasaurus
candelariensis Bonaparte et al. (1999), and
new specimens with sauropodomorph afnities
(Bittencourt et al. 2013), plus the dinosauriform
Sacisaurus agudoensis Ferigolo and Langer (2007).
Also compose the Riograndia AZ the dicynodont
Jachaleria candelariensis Araújo and Gonzaga
(1980), an indeterminate phytosaur (Kischlat and
Lucas 2003), isolated teeth of archosaurs (Dornelles
1990), and a stereospondyl amphibian (Dias-da-Silva
et al. 2009). This whole fauna occurs in a series of
outcrops mainly located in Candelária and Faxinal do
Soturno municipalities, and the record of Riograndia
guaibensis in at least ve of them, enables their
correlation to the Riograndia AZ (Soares et al. 2011,
Bittencourt et al. 2013). In turn, Riograndia AZ can
be correlated to the fauna from the base of the Los
Colorados Formation of Argentina (Early Norian)
due to the presence of the same dicynodont genera,
Jachaleria (Bonaparte 1971, see also comments in
Martinelli and Rougier 2007).
The Botucaraí Hill Site (sensu Bittencourt et
al. 2013) crops out along the highway BR 287,
Candelária Municipality, state of Rio Grande do
Sul, Brazil (29° 40’ 53” S; 52° 50’ 28” W). This
site is characterized by twelve meters of massive
to laminar mudstones intercalated by centimeter
massive sandstones lenses, followed by a layer of
massive sandstones and another layer of trough
cross bedded sandstone, one meter thick each. The
holotype of the new cynodont was collected at the
same level where several materials of Jachaleria
and some sauropodomorph dinosaur remains were
found (Bittencourt et al. 2013) (Fig. 2).
SYSTEMATIC PALEONTOLOGY
THERAPSIDA Broom, 1905
CYNODONTIA Owen, 1861
EUCYNODONTIA Kemp, 1982
PROBAINOGNATHIA Hopson, 1990
PROZOSTRODONTIA Liu and Olsen, 2010
Botucaraitherium gen. nov.
DIAGNOSIS
Botucaraitherium is diagnosed by the following
association of characters: upper postcanines
with a prominent central cusp (A), with
symmetric mesial and distal edges, two cusps
mesio-lingually (cusp B) and disto-lingually
(cusp C) arranged (being A>>B=C), and two
accessory cuspules in the mesio-labial border
and one cuspule in the disto-labial edge; the
three main upper cusps form a subtle angle
(opposite to the condition of the “reverse
triangle pattern”); lingual surface of the crown
of upper postcanines slightly concave, with a
flexion; lower postcanines with a main large
cusp a on the mesial half of the crown, followed
by cusps c and d decreasing in size posteriorly,
slightly curved backward; main cusp a totally
asymmetrical, with a concave mesial edge and
is about two times taller than the straight distal
An Acad Bras Cienc (2014) 86 (4)
1677
A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
edge; cusps c and d with symmetrical mesial
and distal edges; reduced and basal positioned
cusp b (cusp a>c>d>>b); lower postcanines with
multicuspidated lingual cingulum shelf, with
small mesial cusp e; upper and lower postcanines
with 8-shaped cross-section root; large diastema
between canine and postcanines in adult stage;
postcanine replacement including the loose of
anterior postcanines, addition of new ones at the
rear and substitution of other functional teeth.
TYPE AND ONLY KNOWN SPECIES
Botucaraitherium belarminoi sp. nov.
ETYMOLOGY
Botucarai, in reference to the Botucaraí Hill, which
dominates the landscape of the Candelary City
(state of Rio Grande do Sul) and where there are
several outcrops with Triassic fauna. In one of these
outcrops, Botucaraí Hill Site (sensu Bittencourt et
al. 2013) the holotype was found. Therium, from
the New Latin, that derives from the Greek thērion,
which means “beast”, frequently used in mammals
and close relative forms.
Botucaraitherium belarminoi sp. nov.
HOLOTYPE
MMACR-PV-003-T, left lower jaw, without
postdentary bones, bearing the root of last incisor,
the canine, and four partially preserved postcanines
plus one partial crown inside the dentary (not
erupted), and two left maxillary fragments, one with
a broken canine and the other with one postcanine
and the root of the following two teeth.
DIAGNOSIS
Same as for genus.
Fig. 2 - A: Road map with City of Candelária indicated. B: View of the Botucaraí Hill site, southern margin of BR 287 road, with
the indication of the fossiliferous level. C: Log of the Botucaraí Hill Site.
An Acad Bras Cienc (2014) 86 (4)
1678 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
ETYMOLOGY
belarminoi, named in honor of Mr. Belarmino
Stefanello, a volunteer at the Museu Municipal
Aristides Carlos Rodrigues, who found the fossil.
LOCALITY AND HORIZON
From the Botucaraí Hill Site (sensu Bittencourt et al.
2013) near the level where the dicynodont Jachaleria
(Aráujo and Gonzaga 1980) and dinosaur remains
with sauropodomorph afnities (Bittencourt et al.
2013) were recovered. It is located about 8 kilometers
west of Candelária City, in a roadcut of the route
BR-287, state of Rio Grande do Sul, Brazil (Fig. 2),
Candelária Sequence, Santa Maria Supersequence
(Zerfass et al. 2003, Horn et al. 2014), Riograndia AZ
(Soares et al. 2011), possibly Early Norian (Fig. 1).
DESCRIPTION
The specimen MMACR-PV-003-T is mostly not
well-preserved due to several breakages in the
lower jaw and the maxillary fragments are isolated
(Fig. 3). Only the lower canine, one upper and some
lower postcanines preserve most of their crown.
All the material included in the holotype specimen
was found in association and corresponds to only
one individual.
MAXILLA
The two available portions of maxilla are extremely
fragmented, without much information. Based on
the preserved teeth, they correspond to the left side
of the skull. One of the fragments, which preserves
the left canine, has the external surface anteropos-
teriorly concave, highlighting the prominent canine
root (Fig. 3A). Just posterior to it there is a small
foramen, facing anteriorly. The second fragment
has a complete anterior postcanine and the two
8-shaped roots of the two following ones (described
later) (Fig. 3B). Above the rst broken postcanine
(i.e. the rst root) there is a concavity and subtle
notch which possibly corresponds to a large exit of
the infraorbital branch of the trigeminal nerve.
LOWER JAW
The dentary is only observed in medial view
(Fig. 4). The jaw is anteroposteriorly larger than
any of the known specimens of Brasilodon,
Brasilitherium and Minicynodon from the same
Riograndia AZ, and smaller than Prozostrodon from
the Hyperodapedon AZ. The horizontal ramus is
slender along the anterior half and becomes slightly
deeper at the rear. Therefore, the alveolar level and
the ventral margin of the horizontal ramus are slightly
divergent posteriorly. The mandibular symphysis is
unfused as in prozostrodontians (e.g., Prozostrodon,
Brasilodon, Brasilitherium; Bonaparte and Barberena
2001, Bonaparte et al. 2003, 2005) and has some
longitudinal ridges and a small foramen. The trough
for the postdentary bones is relatively reduced and
runs forward, becoming smaller, parallel to the
ventral edge of the dentary. The dentary seems to be
transversely wide at the angular process; this region
is not well-preserved although its shape seems to
be similar to that of Prozostrodon (UFRGS-PV-
0248-T). Below the alveolar line, the dental lamina is
observed, mainly at the level of the fourth postcanine.
The dentary has a large diastema between canine
and postcanines and the canine base and alveolar
level of the incisor is positioned slightly dorsal to the
alveolar level of the postcanine series (Fig. 4A). This
condition is similar to that observed in Prozostrodon,
Brasilodon, Brasilitherium (Bonaparte and Barberena
2001, Bonaparte et al. 2003, 2005) and other
possibly related forms such as Microconodon and
Dromatherium (Hahn et al. 1994, Sues 2001).
The coronoid process is broad anteroposte riorly
and tall dorsoventrally (Fig. 4A). It rises behind the
pc4 where its base is more transversely broad than
the remaining edge. A clear scar for the coronoid
bone is not observable at this region, possibly due
to the bad preservation. The articular process of the
dentary is broken at the rear, nonetheless it seems
to be well-developed as in other prozostrodontians
(e.g., Prozostrodon, Brasilodon).
An Acad Bras Cienc (2014) 86 (4)
1679
A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
Only the anterior 1/3 portion of the horizontal
ramus of the dentary can be observed in lateral view.
The surface is slightly convex dorso-ventrally and
there are at least two small mental foramina below
and anteriorly to the level of the canine.
UPPER DENTITION
The upper incisors are not preserved. One fragment
of maxilla keeps the left canine which is partially
broken. It is elliptical in cross section, at the base,
twice mesio-distally longer than transversely wide.
The preserved mesial and distal edges are gently
concave, without evidence of a ridge or crenulations
(Fig. 3A). The mesial edge is subtle convex whereas
the distal one is straight to slightly concave. The
upper canine is larger than the lower one.
The other fragment of maxilla preserves one
postcanine and the root of the following two (Fig. 3A).
Unfortunately, there is no contact between both
maxillary fragments, precluding any detail of the
Fig. 3 - Holotype (MMACR-PV-003-T) of Botucaraitherium belarminoi gen. nov. et sp. nov. A: Fragment of left maxilla with
portion of canine in lateral and posterior views. B: Fragment of left maxilla with postcanine in lateral, medial and ventral views.
C: Detail of upper postcanine in labial (lateral) and lingual (medial) views. Scale bars equals 5 mm in A and B and 2 mm in
C. Gray areas indicate broken surfaces. Abbreviations: A-C, refers to name of cusps; Ca, upper canine; cr, constricted root; dac,
distal accessory cuspule; iof, ventral edge of the infraorbital foramen; mac, mesial accessory cuspule; r, root.
An Acad Bras Cienc (2014) 86 (4)
1680 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
rst postcanine and the condition of the diastema.
In addition, the upper postcanine count is unknown
as is the exact position of the preserved postcanine.
The preserved postcanine has the crown as
long as tall, mesio-distally, and about two times
long than wide. The crown is dominated by a
central cusp (A), with symmetric mesial and distal
edges, and two cusps mesio-lingually (cusp B)
and disto-lingually (cusp C; the tip of this cusp is
broken) arranged. Cusps B and C have quite similar
sizes but cusp B is positioned slightly more dorsal
than cusp C. In oclusal view, the three cusps form
a subtle angle, opposite to the condition observed
in mammaliaforms with the reverse triangle pattern
(Crompton and Jenkins 1968). In addition, there are
accessory cingular cuspules on the labial side. On
the mesio-labial corner there are two tiny cuspules
(the more mesial the smallest) which are the most
dorsally positioned cusps of the crown. Hence,
there is some considerable distance between these
cuspules and cusp B. Also, these accessory cuspules
make the mesial width of the crown slightly wider
than the distal width. The disto-labial accessory
cusp is near cusp C, at its dorsal base (Fig. 3C).
In oclusal view the labial surface of the crown is
fairly straight whereas the lingual one is concave,
with a exion. The root of this postcanine is
entirely inside the alveolus, but in labial view, the
beginning of a longitudinal groove can be observed,
constricting the root. The size of the only known
upper postcanine is considerably smaller than the
lower ones, a condition observed in some other
probainognathians (e.g., Prozostrodon, Brasilodon,
Irajatherium, Bonaparte and Barberena 2001,
Bonaparte et al. 2003, 2005, Martinelli et al. 2005).
The upper postcanine pattern of the Botuca-
raitherium is quite different from those of the
tritheledontids (Irajatherium, Chaliminia), in which
there are a mesiodistally compressed and transversely
broad main cusp, with small mesial and distal
cusps (with a labial cingulum in the postcanines of
Pachygenelus; Gow 1980, Martinelli et al. 2005,
Martinelli and Rougier 2007). Botucaraitherium also
differs from Riograndia because the latter taxon has
up to nine cusps mesiodistally aligned without any
cingulum (Bonaparte et al. 2001, Soares et al. 2011).
The upper postcanines of Prozostrodon display four
aligned cusps (A, B, C, D) (Bonaparte and Barberena
2001) without lingual cusps or any cingular cuspules.
Thus, the upper postcanines of Botucaraitherium
differ signicantly from those of Prozostrodon
in having three main cusps (instead of four) plus
accessory labial cingular cuspules (Fig. 5A, B).
The upper postcanine pattern of Botucarai-
therium is more closely related to that of Brasilodon,
Brasilitherium and Minicynodon (Fig. 5A, C)
(Bonaparte et al. 2003, 2005, 2010, 2012) than to any
other prozostrodontian. Regarding the brasilodontids,
its postcanines have a prominent central cusp (A),
one mesial (B) and one distal (C), small accessory
cusps aligned on the lingual side, and one mesial
and one distal small cusp on the labial side, giving
a symmetrical cusp arrangement. This pattern
is consistent in all specimens of Brasilodon and
Minicynodon, but in some specimens referred to
Brasilitherium the distal labial accessory cusp is
placed more posteriorly (Bonaparte et al. 2010,
Martinelli and Bonaparte 2011).
Botucaraitherium is differentiated from brasilo-
dontids by a notoriously more bulbous crown and
two (not one) mesio-labial accessory cusps. These
features have never been observed even in the largest
specimens of the aforementioned brasilodontids.
Therefore, we considered this feature as unique
of Botucaraitherium, since in the large sample of
brasilodontids from the Riograndia AZ, this condition
was never observed.
In addition to the only preserved upper
postcanine, the maxillary fragment preserves the
root of the two following teeth. The roots increase
in size posteriorly and are 8-shaped in cross-section,
in which the longitudinal groove is present in both
labial and lingual sides, with each lobe having its
own root canal.
An Acad Bras Cienc (2014) 86 (4)
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A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
LOWER DENTITION
The number of lower incisors is unknown. The root
of the last incisor is preserved, which is circular in
cross-section. It is next to the canine, indicating
the lack of a diastema. Anteriorly to this root, the
dentary is partially broken off and it is impossible to
deduce the number and size of the other incisors (Fig.
4A). In Brasilodon there are three incisors and based
on its dentary morphology the number of incisors for
Botucaraitherium is likely to be the same.
The canine is broken at the tip (Fig. 4A). It is
sub-circular in cross-section, with the mesial edge
slightly convex and the distal one slightly concave.
On the distal edge there is a thin longitudinal
ridge, without serrations. The enamel covering the
crown is very thin and a large portion of the root
is observed outside the alveolus. There is a large
diastema between the canine and the postcanines.
Along the posteriormost portion of the diastema
there is a mesio-distally oriented sulcus that could
Fig. 4 - Holotype (MMACR-PV-003-T) of Botucaraitherium belarminoi gen. nov. et sp. nov. A: Left lower jaw in medial view.
B and C: detail of the postcanines in medial view. Scale bar equals 10mm in A and 3mm in B. Gray areas indicate broken surfaces.
Abbreviations: a-e, refers to name of cusps; ca, canine; ci, cuspidated cingulum; co, coronoid process of dentary; cr, constricted
root; D, dentary; dl, dental lamina; mg, meckelian groove; npc5, non-erupted postcanine 5; pc, postcanine; s, symphysis.
An Acad Bras Cienc (2014) 86 (4)
1682 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
correspond to closed alveoli of the lost teeth. The
loss of the anterior postcanines and concomitantly
the enlargement of the diastema are a pattern obser-
ved in several taxa, such as some tritylodontids
(e.g., Oligokyphus, Tritylodon; Kemp, 1982)
Brasilodon and Brasilitherium (Martinelli and
Bonaparte 2011), and some early mammaliaforms
(e.g., Sinoconodon; Crompton and Luo 1993, Luo
et al. 2004).
The postcanine series includes ve teeth (Fig 3).
The pc1 consists of a main cusp that was in process
of eruption. Unfortunately, at this region there is a
large breakage that obscures the anatomy of the tooth.
The pc 2-4 are similar in size. Although the crown
of pc2 and pc3 are extremely damaged, they show
similar crown morphology. There is a main large cusp
(a) on the mesial half of the crown, followed by two
cusps (c and d) that decrease in size posteriorly. These
three cusps are slightly posteriorly projected, but not
to the degree of, for example, Chiniquodon (Abdala
and Giannini 2002). The cusps are not bulbous and
constitute the sectorial portion of the crown. Cusp a
is totally asymmetrical with the mesial edge concave
and about two times taller than the straight distal
edge. Cusps c and d have symmetrical mesial and
distal edges. On the mesio-labial edge of the crown,
in a basal position, there is a small cusp b. In the pc2
and pc4 that better preserve the crown morphology,
the cusp size is a>c>d>>b. In the lingual side of the
postcanines there is a well-developed cingulum with a
small mesial cusp e (better observed in pc2), followed
by a series of tiny cuspules that reach the distal margin
of the crown, forming a cingular shelf (Fig. 4B, C).
The posteriormost portion of the pc4 lies
internally to the coronoid process. The postcanine
roots are incipiently bifurcated, with a well-developed
longitudinal groove. Just below the pc4, there is a
main cusp (a) of a non-erupted last postcanine.
The tooth morphology of Botucaraitherium
is reminiscent of Prozostrodon and brasilodontids.
The multicuspidated lingual cingular shelf of
Botucaraitherium is similar to that of Prozostrodon.
In contrast, Brasilodon and Brasilitherium have
less crenulated labial cingulum, and instead there
are more discrete cuspules (cusps e and g) (e.g.,
UFRGS-PV-0603-T). With regard to the main
cusps, the crown is taller in Botucaraitherium than
in Prozostrodon, and in the latter taxon, cusps a, b
and c are more bulbous (less sectorials) with less
contrast in height among them (Fig. 6).
TOOTH REPLACEMENT
The information on a single lower jaw is limited but
a few comments on tooth replacement are possible.
The large diastema posteriorly to the canine and
Fig. 5 - Comparisons of upper postcanines. A: Botucaraitherium
belarminoi gen. nov. et sp. nov (Holotype MMACR-PV-003-T) in
left labial view. B: Prozostrodon brasiliensis (Holotype UFRGS-
PV-0248-T) in left labial view. C: Brasilodon quadrangularis
(Holotype UFRGS-PV-0611-T) in right labial view. Scale bar
equals 1mm.
An Acad Bras Cienc (2014) 86 (4)
1683
A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
the closed mesial alveoli, indicate that the anterior
most postcanines were lost and not replaced. The
anteriormost postcanine (i.e., labeled along the text
as pc1) partially inserted in the alveolus shows that
some teeth of the series were replaced and the last
postcanine (pc5), represented by a non-erupted
tooth, indicates that new teeth were added at the rear.
Among prozostrodontians, some mix of alternate and
sequencial replacement was observed in Brasilodon
and Brasilitherium, being apparently polyphyodonty
taxa (Bonaparte et al. 2003, 2005, Martinelli and
Bonaparte 2011). It should be emphasized that the
sequence of postcanine eruption and the number of
replacement per locus at the non-mammaliaform
prozostrodontians-mammaliaforms boundary is a
matter still poorly understood.
DISCUSSION
Botucaraitherium belarminoi constitutes a new
prozostrodontian cynodont from the Riograndia AZ
of southern Brazil. The holotype represents an adult
individual, larger than any known brasilodontid from
the same AZ. There are no recorded specimens of
Brasilodon and Brasilitherium in the Botucaraí Hill
Site. In turn, these taxa are relatively abundant in the
Sesmaria do Pinhal 1 Site, located about 600 meters
away (Bonaparte et al. 2003, 2005). In addition,
within the Botucaraí region there is a record of
Brasilitherium-like teeth in Sesmaria do Pinhal 3 Site,
located about 1000 meters away from the Botucaraí
Hill Site (Soares et al. 2011, Bittencourt et al. 2013).
The new species is clearly related to prozos-
trodontians, and especially to Brasilodon and
Brasili therium (Bonaparte et al. 2003, 2005), due to
the morphology of the upper and lower postcanines
(see Fig. 5, 6). They can be differentiated by the
presence in Botucaraitherium of a well-developed
multicuspidated lingual cingular shelf in lower
postcanines and more bulbous upper postcanines,
with more than one mesio-labial accessory cuspules.
Fig. 6 - Comparisons of the right posterior lower postcanines in lingual view. A: Botucaraitherium belarminoi gen. nov. et sp.
nov (Holotype MMACR-PV-003-T). B: Brasilitherium riograndensis (UFRGS-PV-0603-T); C: Brasilodon quadrangularis
(UFRGS-PV-0765-T). D: Prozostrodon brasiliensis (Holotype UFRGS-PV-0248-T). Scale bar equals 3 mm.
An Acad Bras Cienc (2014) 86 (4)
1684 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
Its resemblance to Prozostrodon, from the older
Hyperodapedon AZ, is also noteworthy. The lower
dentition of both taxa is quite similar, especially
because of the multicuspidated lingual cingular shelf.
However, the sectorial portion of the postcanines
of Botucaraitherium seems to be less bulbous with
taller main cusps. The upper postcanines have
stronger differences, due to the fact that the teeth
of Prozostrodon are less quadrangular (with the
exception of the last non-erupted postcanine of the
holotype), and with three more developed accessory
cusps in relation to the main cusp.
PHYLOGENETIC ANALYSIS
A parsimony analysis was performed based on 34
taxa and 145 morphological cranial, dental and
postcranial characters (see Appendices 1 and 2),
modied from the matrix presented by Liu and
Olsen (2010). Some characters and codications
were modied (Appendix 1) and two new
terminal taxa (i.e., Brasilitherium riograndensis
and Botucaraitherium belarminoi) were added.
Liu and Olsen (2010) considered Brasilodon and
Brasilitherium as synonyms; therefore, they used
only Brasilodon as a terminal taxon. The proposal
synonymy for these two species is a matter not
clearly understood yet (see for example, Martinelli
and Bonaparte 2011, Bonaparte et al. 2012) and
will be further analyzed. We considered them as
separate taxa in the current analysis.
The data matrix (Appendix 2) was analyzed
using Maximum Parsimony with equally weighted
characters with the computer program TNT 1.1
(Goloboff et al. 2008). All characters were treated
as non-additive. The equally weighted parsimony
analysis was conducted performing a heuristic search
of Wagner trees with 500 random addition sequences,
followed by TBR (Tree Bisection Reconnection), and
saving 20 trees per round, which improve the searches
and ensures to nd all optimal trees.
Our analysis resulted in four most parsimonious
trees of 441 steps, with a consistency index (CI)
Fig. 7 - Strict consensus tree with Bremer index, positioning Botucaraitherium
belarminoi gen. nov. et sp. nov as a derived prozostrodontian.
An Acad Bras Cienc (2014) 86 (4)
1685
A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
of 0.481 and a retention index (RI) of 0.780. The
strict consensus and Bremer index of each node are
shown in Figure 7.
In the four most parsimonious trees obtained, the
af nities of Botucaraitherium with the brasilodontids
are supported. Indeed, Botuca raitherium is positioned
as a more derived taxon than tritylodontids, as the
sister group to the clade composed by Brasilodon
and Brasilitherium plus Mammaliaformes. Despite
the fragmentary aspect of the new taxon, especially
the characters of the dentary and dentition give
support to this relationship.
The presence of Botucaraitherium in the Rio-
grandia AZ (Fig. 8), adding to the already known
brasilo dontids, reinforces the idea that the non-
mammaliaform prozostrodontians enjoyed their greater
representativeness during the Late Triassic in South
America, which outlined the evolutionary scenery
where the most profound anatomical steps related
to the origin of mammaliaforms have taken place.
ACKNOWLEDGMENTS
The authors thank Carlos Nunes Rodrigues, Curator
of the Museu Municipal Aristides Carlos Rodrigues
(Candelária, RS), for permitting the study of the
specimen MMACR-PV-003-T. The authors would also
like to thank Bruno L.D. Horn for providing the Figure
2 and for the Botucaraí Hill Site stratigraphic pro le
(Fig. 3) and Luiz Flávio Lopes for the photographs.
We also thank to Jorge Blanco for the skillful drawing
of Botucaraitherium (Fig. 8). Funds were provided by
the Conselho Nacional de Desenvolvimento Cientí co
e Tecnológico (CNPq nº 304143/2012-0; grants to
MBS and AGM). We are grateful for the comments
of Dr. Guillermo Rougier, Dr. Ricardo Martinez, the
anonymous reviewer and the Editor of AABC, Dr.
Alexander Kellner, which greatly improved the Ms.
INSTITUTIONAL ABBREVIATIONS
MMACR-PV-T, Museu Municipal Aristides Carlos
Rodrigues, (Paleovertebrates, Triassic collection),
Candelária, Rio Grande do Sul, Brazil; UFRGS-
PV-T, Universidade Federal do Rio Grande do Sul
(Paleovertebrates, Triassic collection), Porto Alegre,
Rio Grande do Sul, Brazil.
RESUMO
Nós reportamos aqui um novo cinodonte prozostrodonte,
Botucaraitherium belarminoi gen. et sp. nov., do Triássico
Tardio da Zona de Assembleia (ZA) de Riograndia da
Sequência Candelária (Supersequência Santa Maria),
coletado no a oramento Sítio Botucaraí, no município de
Candelária, Rio Grande do Sul, Brasil. O novo táxon está
baseado em um único espécime (holótipo MMACR-PV-
003-T) o qual inclui a mandíbula esquerda, sem os ossos
pós-dentários, com a raiz do último incisivo preservada,
o canino e quatro dentes pós-caninos, além de uma coroa
parcial, não erupcionada, do quinto pós-canino, e dois
fragmentos maxilares, um com um canino quebrado, e
outro portando apenas um dente pós-canino. As feições
mandibulares e dentárias assemelham-se àquelas dos
cinodontes prozostrodontes Prozostrodon brasiliensis
da ZA de Hyperodapedon, mais antiga, e de Brasilodon
Fig. 8 - Artistic reconstruction of Botucaraitherium belarminoi
gen. et sp. nov., by Jorge Blanco.
An Acad Bras Cienc (2014) 86 (4)
1686 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
quadrangularis e Brasilitherium riograndensis da mesma
ZA de Riograndia. A inclusão de Botucaraitherium em
uma ampla análise logenética posicionou-o como um
táxon mais derivado do que os tritilodontídeos, sendo
o táxon-irmão de Brasilodon, Brasilitherium e mais
Mammaliaformes. Apesar de o novo táxon ser baseado em
poucos elementos cranianos, ele representa um componente
faunístico adicional na ZA de Riograndia do Triássico
sul-brasileiro, na qual os cinodontes não-mamaliaformes
de pequeno tamanho, intimamente relacionados à origem
dos mamíferos, foram ecologicamente bem sucedidos e
taxonomicamente diversos.
Palavras-chave: Cynodontia, Prozostrodontia, Super-
sequência Santa Maria, Triássico.
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An Acad Bras Cienc (2014) 86 (4)
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A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
Appendix 1. Phylogenetic Analysis
Botucaraitherium was included into the phylogenetic framework of Liu and Olsen (2010), which constitutes
the largest matrix of non-mammaliaform cynodonts to date. This matrix is based upon several previous
contributions, including that of Hopson and Barghusen (1986), Rowe (1988), Wible and Hopson (1993),
Lucas and Luo (1993), Luo (1994), Luo and Crompton (1994), Martínez et al. (1996), Hopson and Kitching
(2001), Luo et al. (2002), Bonaparte et al. (2003, 2005), Sidor and Smith (2004), Martinelli et al. (2005),
Abdala (2007), Martinelli and Rougier (2007), and Oliveira et al. (2010).
The data matrix of Liu and Olsen (2010) was modied for the current analysis:
1) CHANGES IN SCORINGS OF TAXA:
Character 01: Prozostrodon changes from 1 to 2 (based on Bonaparte and Barberena 2001). Riograndia
changes from 0 to 1 (based on Bonaparte et al. 2001, Soares et al. 2011)
Character 07: Therioherpeton changes from ? to 1 (based on Bonaparte and Barberana 2001, Oliveira 2006).
Character 11: Brasilodon changes from 1 to 2.
Character 13: Prozostrodon changes from 0 to 1 (based on UFRGS-PV-0248-T; Martinelli et al. 2005,
Martinelli and Rougier 2007).
Character 14: Prozostrodon changes from 1 to 2 (based on UFRGS-PV-0248-T; Martinelli et al. 2005,
Martinelli and Rougier 2007).
Character 19: Riograndia changes from ? to 0 (based on Bonaparte et al. 2001, Soares et al. 2011).
Character 26: Riograndia changes from ? to 0 (based on Soares et al. 2011).
Character 27: Riograndia changes from ? to 1 (based on Bonaparte et al. 2001).
Character 30: Prozostrodon changes from ? to 2.
Character 35: Riograndia changes from 2 to 1. Brasilodon changes from 2 to 1 (based on Bonaparte et al. 2005).
Character 37: Brasilodon changes from ? to 1 (based on Bonaparte et al. 2005).
Character 93: Prozostrodon changes from 0 to 1 (based on UFRGS-PV-0248-T).
Character 96: Exaeretodon and Scalenodon angustifrons change from 1 to 0 (due to change in
character definition).
Character 98: Brasilodon changes from ? to 0.
Character 103: Prozostrodon changes from 0 to 1.
Character 119: Brasilodon changes from 0 to 0+1.
2) CHANGES IN CHARACTER DEFINITION:
Character 37 (modied according to Hopson and Kitching 2001, Martinelli and Rougier 2007: ch. 47):
Length of palatine relative to maxilla in secondary palate: shorter (0); about equal (1); longer (2).
Character 96 (redened): Incisors: all of similar size (0); some incisor large (1).
Character 106 (new state and re-ordered): Upper postcanine roots: single (0); constricted root, with incipient
longitudinal groove (1); divided into two longitudinal aligned roots (2); multiple roots (more than two) (3).
Character 107 (new state and re-ordered): Lower postcanine roots: single (0); constricted root, with
incipient longitudinal groove (1); divided (2).
3) ADDITION OF NEW TAXA:
Brasilitherium riograndensis (Bonaparte et al. 2003, 2005, 2012).
Botucaraitherium belarminoi (this paper).
An Acad Bras Cienc (2014) 86 (4)
1690 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
Appendix 2. Data matrix
Distribution of character-states for the 145 characters based on Liu and Olsen (2010) plus the modication
in Appendix 1, among Procynosuchus delaharpeae as outgroup and 32 ingroup terminal taxa considered in
the analysis.
Procynosuchus delaharpeae
0000000100000000000000000000000000000000000000000000000000000001[01]00000000000000000
000001000000000100010000000--00-0000000000000-00000000000000002
Galesaurus planiceps
010000000000000000100000100001100000000000000000000000000000000000000000000001000010
0000000001100100000010000--00-1000000001100????00??0??0000000
Thrinaxodon liorhinus
01[01]0000000000000000000000000001110000000000000000000000000000000000000001001010000
100000110001100000010000000--00-1000000001100-00000000000?0000?
Platycraniellus elegans
0110000000000000001100000000010110000000??00000000?0000000000000000000101??101000?101
0?0??0001?0?100000000000--0?-0?000??????????????????????????
Cynognathus crateronotus
00000000000000001021002110000011100001011100010100?0000000000000100000111001011011201
011120001101000100010000--00-1001000000111000000110000000000
Diademodon tetragonus
[01]0000000000000001022012111000111100000011100010100000000[01]000000000000000100101111
120101112113110100012001000100100?000100001111000000110000000000
Trirachodon berryi
11100100[01]00000001121011111010011101002011100010100000002100000000000110111020110111
010111211311010001211100020110100101???01111000000????00000000
Sinognathus gracilis
1020?100100000??11010011110?1?1?1010?0011000010100???????00000?000?01101110201101110101
1??113120000002?0?00?201100?0201??????????????????????????
Langbergia modisei
001000000000000001210111110100111010000110000101?0?000?21??0000000001?0?11????101110101
11211311010001200100020110100101?????1????????????????????
Pascualgnathus polanskii
1020?100100000001122012111011?1110100001??000101?0???0?2?00000???0?0??????????[01]0?12010
11??113210000002[12][12]000-110100-12010???1101??0000??1000000000
An Acad Bras Cienc (2014) 86 (4)
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A NEW CYNODONT FROM THE LATE TRIASSIC OF BRAZIL
Luangwa drysdalli
??00?1000?0000010121001111????1110?00001???00101000000?2??00000???0???????????1011201011
??113110100012[12][12]000-202100-12010???110110000???1100000000
Massetognathus pascuali
0111110010000000110101111101121110200001000001010000001211000000000011011102011011[12]
01011??11311021110211000-222100-120100000101101000??1100000000
Exaeretodon argentinus
00111110100000111121012111011211101[01]00010?00010100010002110000000000?101????01101121
1011??113210010102[12][12]000-120100-122100000001101001111100000000
Scalenodon angustifrons
??10?1?0000000??1101012111?????1101?0??1??00010100?0000211000000?000??0?????0?[01]0?12??0
11??113110100012[12][12]000-202100-1201??????????????????????????
Scalenodon hirschoni
???0010?????001?11?????111011211101?0?0?0??00????????????1?000?0?????1??1?0?0?[01]??1???011
??113220001002[12][12]000-222100-1201??????????????????????????
Chiniquodon theotonicus
11101010100000101011000001011[12]11112100011000010100000001000000000000?1?01???11101120
1011120001100000000010000--00-100000??000011010001110000?0000
Lumkuia fuzzi
??1000101000000?00000000010?1201101001010100010010?0000001000000000000001000011011201
000120001100000000010000--00-10000?????001????????????0?????
Ecteninion lunensis
001??0021000002000000000000?1[01]11100002011100010100?10001010000000000110011021110110
01011??00011000001[01]0010000--00-?00000???1??110??0?????0???????
Probainognathus jenseni
0110100210000010010110000101121111100001110001000000001100000000000011001102111021001
011120001100000010000000--00-00110000?000110???0??11000?0000
Therioherpeton cargnini
?????0121?11122?2100??0????????1111???????????????????????????????????????????????????????00
0????????0?0?1100--00-?00000??1?00?????????1111110011
Riograndia guaibensis
0113101211111221?10???0000111201111120110001020000?0000102000010001121102?13????0030111
1??001211001100[12]001100--00-10100??????????????????????????
Pachygenelus monus
20131012111112212100100000011201112120110001020000100001020000101??121102213132020301
111120012210010001000010--00-002001???0001111101??1111111111
An Acad Bras Cienc (2014) 86 (4)
1692 MARINA B. SOARES, AGUSTÍN G. MARTINELLI and TÉO V. DE OLIVEIRA
Prozostrodon brasiliensis
21?010?2????1221?1?????????112?1111?1????????????????????????????????????????????0301111??00
10000000111001100--00-001000???000?????0???1111110000
Botucaraitherium belarminoi
?????0???????????????????????????????????????????????????????????????????????????0???11????01
??????001?001110--01-00?????????????????????????????
Brasilodon quardangularis
[01]000?0121121122120001000?00?1201111102110001021001?0?112220?00111011211022131320?03
01111??0011100001011001110--01-001[01]1??????0111??11????????????
Brasilitherium riograndensis
0000?0121121122120001000000?1201111102110001021011?01112220???11?011211022131320103011
11??0010100001011001110--01-001[01]1????????????11????????1111
Tritylodon longaevus
102-1111110112211102001111011211102122110000110110110102121111011010311022031202003
11111??1132210-22-222-32-2-1100-03221??????210??????1?????1111
Oligokyphus major
[12]??-1111?10112???102010110?1?2?1??21????????110?10110102?211110110003100220312020
0311111??1132110-22-222-32-2-1100-0322111100?2101111??1121111111
Bienotherium yunnanense
102-11111101122111?201?111011211102122110000110110110?02?01111?110?031??22131?02003
11111??1132110-22-222-32-2-1100-03221??????210??11??????111111
Kayentatherium wellesi
102-11111?0112211102011111111201102122110000110110110102121111?110?0311022131202003111
11121132110-22-222-32-2-1100-0322?11100021011?1111121??1111
Adelobasileus cromptoni
???????01121?2????????????????0??????2110001021011?21112210000101110??????????????????????
???????????????0?????0??1??????????????????????????????
Sinoconodon rigneyi
0002?0101121122120001000?01?1211112102110011031011?21112221011101010????????0?302030111
2??2001000001001002210--00-10101??????????????????????????
Morganucodon oehleri
0?02?0101121122120002?0000111111112102110011032011121112220112111111211022132430203011
12122221000001011002210--01-0010111111001111111??1121111111
