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New Early Diverging Cingulate (Xenarthra: Peltephilidae)
from the Late Oligocene of Bolivia and Considerations
Regarding the Origin of Crown Xenarthra
Bruce J. Shockey
Manhattan College, Riverdale, NY 10471 USA;
Peabody Museum of Natural History, Yale University, New Haven, CT 06520-8118 USA;
American Museum of Natural History, New York, NY 10024 USA
—email: bruce.shockey@manhattan.edu
ABSTRACT
Remains of peltephilid cingulates from the late Oligocene (Deseadan, South American Land
Mammal Age) of Salla, Bolivia, are described and organized as two morphs, the larger referred to
a new taxon, Ronwolffia pacifica, and the smaller as indeterminate. A fairly well-preserved cra-
nium serves as the holotype for Ronwolffia pacifica, with referred material consisting of jaws, os-
teoderms, and a partial pelvis. Ronwolffia is recognized by a combination of characters, some of
which are regarded as general placental traits compared to some distinctive features of the well-
known Santacrucian species of Peltephilus. Such generalized traits in Ronwolffia include tenden-
cies for eight (rather than seven) mandibular teeth, unfused mandibular symphysis, incompletely
ossified auditory bulla, and a low occiput and cranial vault. Like those of other peltephilids, the
temporomandibular joint (TMJ) is low, but, unlike typical armadillos and the genotypic Pel-
tephilus strepens, the glenoid fossa forms part of the wall of the external acoustic porus. Similar
crowding of the TMJ and porus is noted in Peltephilus pumilus and Peltephilus ferox.
Terminology related to the classification of xenarthrans is considered. Dasypodoidea Gray,
1821 is herein used for the crown clade that includes armadillos and glyptodonts, with Cingulata
designating the total clade (crown + stem); that is, taxa more closely related to Dasypus than to
any pilosan taxon (sloth or anteater). It is also desirable to clearly discriminate between the crown
and total clade Xenarthra; thus Xenarthra is herein used exclusively for the crown, with the bio-
geographically inspired name, Americatheria, being proposed for the total clade; that is, taxa
more closely related to Dasypus than to any members of Afrotheria or Boreotheria.
KEYWORDS
Cranial anatomy, fossil record, Deseadan, Salla (Bolivia)
Bulletin of the Peabody Museum of Natural History 58(2):371–396, October 2017.
© 2017 Peabody Museum of Natural History, Yale University. All rights reserved. • http://peabody.yale.edu
Introduction
The Cingulata is a curious clade of armored mam-
mals that is represented by just over 20 living
species—a mere relic of its former grandeur
(Gardner 2005; Vizcaíno and Loughry 2008).
Strictly a New World phenomenon, the West
learned of these beasts via Belon du Mans
(1553:467; Figure 1), with Buffon, more than 200
years later, providing a fairly complete account of
the diversity of living species that he based largely
on studies by one Father d’Abbeville (Buffon
1753–1767; English translation by Barr 1797). The
first hint of the spectacular diversity of extinct cin-
gulates came from a discovery by Jesuit mission-
ary Thomas Falkner along the banks of the Río
“Carcarania” (the Río Carcarañá, also known as
the “Tercero”), a tributary of the Paraná about 325
km northwest of Buenos Aires (Falkner 1774).
Falkner described this fossil as a “shell of an ani-
mal ... near three yards over” (Falkner 1774:54–55;
presumably the curvilinear dimension). His
observation of the size of the shell and it being
composed of many “hexagonal bones” (Falkner
1774:55) leaves no doubt that the remains he
found were that of what would later become
known as a glyptodont (Owen 1839). Falkner cor-
rectly recognized the affinity of his extinct beast
with living cingulates, writing, “It seemed in all
respects, except it’s [sic] size, to be the upper part
of the shell of the armadillo” (Falkner 1774:55).
Falkner’s discovery on the Río Carcarañá inspired
Darwin to visit the area, where he too found fos-
sil mammals (Darwin 1840:146–147; note that in
his Voyage of the Beagle, Darwin consistently mis-
spelled Falkner’s name as “Falconer”).
Francisco P. Moreno, during his exploratory
journey of 1876 and 1877 to Patagonia, rediscov-
ered a rich Miocene fauna of southern Patagonia,
the Santacrucian (Moreno 1879, 1882; Brinkman
2003). Moreno’s subsequent founding of the
Museo de La Plata, his leadership there, especially
with the short-lived employment of the Amegh-
ino brothers at La Plata, resulted in Carlos
Ameghino’s discovery of many new fossil mam-
mals, including various cingulates, from the San-
tacrucian Beds, which the elder Florentino
described (Ameghino 1887, 1889). These cingu-
lates from the Santacrucian South American Land
Mammal Age (SALMA) included a couple of gen-
era of armadillos (Prozaedyus and Stenotatus) that
are superficially similar to modern taxa (Scott
1903–1904), as well as a few distinct forms, such
as a somewhat anteater-like dasypodine armadillo
(Stegotherium Ameghino, 1887) and glyptodonts
(e.g., Propalaeohoplophorus Ameghino, 1887), the
latter of which were smaller than the famous
giants of the Pleistocene (Ameghino 1889; Scott
1903–1904; Vizcaíno et al. 2012). The fauna also
contained distinctive, armadillo-like osteoderms
of two size ranges, the larger described as Pel-
tephilus strepens Ameghino, 1887 and the smaller,
P. p u m il u s Ameghino, 1887 (pumilus means
dwarf). On subsequent discovery of the skulls
referred to these taxa, as well as that of P. f e r o x
Ameghino, 1891, Ameghino concluded that these
animals differed so much from typical armadillos
that he placed them in a separate group, the Pel-
tephilidae Ameghino, 1894.
Peltephilids are peculiar, armadillo-like,
extinct mammals that have beveled “slicing” teeth,
short muzzles, low temporomandibular joint
(TMJ), and distinctive bony armor over their
skulls, the anterior of which form horn-like struc-
tures. These anatomical features so excited
Ameghino that he characterized the animal as a
“ferocious beast” that was “carnivorous like a tiger
and armed with horns, like a rhino—it is some-
thing the most vivid imagination could never con-
jure” (translation of Ameghino 1904:22; the
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
372
FIGURE 1. Tatu from the New World. An early image of a cingulate from a drawing of a taxidermy specimen
(Belon 1553:467).
original reading, “un peludo feroz y carnicero
como un tigre y armado de cuernos como un
rinoceronte, es algo que no hubiera podido inven-
tar la imaginación más vivaz”).But it seems
Ameghino underestimated his own power of
imagination, for less excitable spirits (e.g., Viz-
caíno and Fariña 1997) have since reduced pel-
tephilids from carnivorous, tiger-rhino monsters
to more conventional, armadillo-like animals (i.e.,
digging herbivores), though carnivory, to some
degree, has long been considered as a possibility
for peltephilids (e.g., Scott 1903–1904; Hoffstetter
1958; Scillato-Yané 1977; Vizcaíno and Fariña
1997). Still, despite revolutions in the philosophy
and the science of paleontology (e.g., cladistics,
improved comparative anatomy, molecular sys-
tematics), Ameghino’s concept of the Peltephili-
dae as a distinct clade, separate from armadillos
and glyptodonts, remains a preferred phylogenetic
hypothesis (Gaudin and Wible 2006; Billet et al.
2011; Vizcaíno et al. 2012; Mitchell et al. 2016),
though affinities with “euphractine” armadillos
has also been considered (Englemann 1985; Pat-
terson et al. 1989).
Fossils referred to the Peltephilidae range
from the early Eocene (Scillato-Yané 1986;
Oliveira and Bergqvist 1998; Carlini et al. 2010)
to the late Miocene (e.g., Bordas 1936; González-
Ruiz et al. 2012), but they are still only well known
in the Miocene, especially in the Santacrucian
SALMA. Exceptionally, three species referred to
the Santacrucian Peltephilus, as well as the Col-
huehuapian Parapeltecoelus Bordas, 1938, are
known from fairly complete skulls (Ameghino
1894; Scott 1903–1904; Bordas 1936; Vizcaíno
et al. 2012; see also Materials and Methods). Until
relatively recently, pre-Miocene peltephilids had
only been known from a few isolated osteoderms.
However, Shockey and Anaya (2008) documented
jaws and pedal elements, as well as osteoderms, of
peltephilids from the late Oligocene (Deseadan)
of Salla, Bolivia, and Kearney and Shockey (2008)
reported and briefly described the skull of a then
unnamed peltephilid of Salla. These remains,
along with additional specimens from Salla, are
the basis of this present study.
The purpose of this work is to provide
anatomical descriptions of peltephilid remains
from Salla, especially that of the cranium (YPM
VPPU 020700) that serves as the holotype of the
new taxon, Ronwolffia pacifica. Unassociated jaws,
osteoderms, and a partial pelvis are described and
tentatively referred to this new taxon. Distinctly
smaller osteoderms and an associated partial hind
limb are also described and are characterized as
an indeterminate species. Phylogenetic definitions
are given for relevant clades and the justification
for proposed new terminology is provided (see
Discussion).
Materials and Methods
Specimens Examined
The primary study specimen is YPM VPPU
020700 (Figures 3, 5A, 7F), a nearly complete cra-
nium from Salla, Bolivia, in the Division of
Vertebrate Paleontology Princeton University
Collection at the Yale Peabody Museum of Nat-
ural History, Yale University (YPM VPPU), New
Haven, Connecticut, USA. This specimen serves
as the holotype of Ronwolffia pacifica, new taxon,
and reflects a preference for the use of cranial
material, rather than osteoderms, for taxonomic
and phylogenetic studies of cingulates.
Additional peltephilid specimens of Salla were
examined in the Yale Peabody Museum’s Salla
holdings, as well as at the Florida Museum of
Natural History, University of Florida (UF),
Gainesville, Florida, USA, and the Salla collection
Muséum National d’Histoire Naturelle (MNHN-F
SAL), Paris, France. Those examined for this study
are listed in the “Referred specimens” section of
the description of Ronwolffia pacifica and under
the “Referred indeterminate specimens” heading.
Salla peltephilids were compared to those of
the Santacrucian SALMA in the Yale Peabody
Museum vertebrate paleontology holdings and the
American Museum of Natural History (AMNH),
New York, New York, USA, and with published
information, especially Scott (1903–1904) and Pat-
terson et al. (1989). Bordas (1938) was used to
compare cranial material of Salla with that of Para-
peltecoelus Bordas, 1938. Salla peltephilids were
also compared to extant dasypodoideans, includ-
ing Dasypus, Euphractus, Tolypeutes, and Pri-
odontes (specimens in the Yale Peabody Museum
mammal collection and the American Museum of
Natural History), as well as published descriptions
of these dasypodoidean taxa (Patterson et al. 1989;
Wible and Gaudin 2004; Gaudin and Wible 2006).
Three study casts of skulls of peltephilids
from the Ameghino collection were frequently
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 373
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
374
FIGURE 2. Classification and phylogeny of Americatheria (new clade name). The classification for the Americathe-
ria used in the text is given above the cladogram. The analysis of Mitchell et al. (2016, fig. 2) forms the basis of this
cladogram (indicated with stems shown with bold lines). Modifications are illustrated with dashed lines. The tree
was modified to show the Chlamyphorinae (Chlamyphorus) as part of an unresolved trisomy formed by it, the
Glyptodontinae, and Tolypeutinae to represent the conflicting results between the two analyses of Mitchell et al.
(2016, figs. 1 and 2). Subgroups of Chlamyphoridae are labeled A, Euphractinae, B, Glyptodontinae, C,
Chlamyphorinae, and D, Tolypeutinae. Taxa included in the figure but not in Mitchell et al. (2016) include Ron-
wolffia (position inferred by membership in Peltephilidae) and the extant pilosan genera (Choloepus, Cyclopes,
and Myrmecophaga; relationships based on Delsuc et al. 2004). Glyptatelus was given to illustrate the time constraint
for the origins of glyptodonts. Ages of origins given (excepting those for Americatheria and Cingulata) are derived
from Gibb et al. (2016). The origination age of Americatheria is estimated from Springer et al. (2003), Delsuc et al.
(2004), and Foley et al. (2016). That given for the origin of Cingulata is constrained by the presence of cingulates
in the late Paleocene–early Eocene Itaboraí fauna (Oliveira and Bergqvist 1998).
consulted. These were acquired by the American
Museum in 1908 through an exchange with the
Museo Argentino de Ciencias Naturales (Flo-
rentino Ameghino was director of the museum
at that time). AMNH 14506 is a cast of the spec-
imen that seems to represent the specimen on
which of Peltephilus ferox Ameghino, 1891 was
based (here regarded as the holotype, though
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 375
A
D
•closed anterior
dental arcade
•small incisive
foramina
?carotid
foramen
glenoid
fossa
bulla
hypoglossal
foramena
foramen
magnum
condyle
“mastoid” regio
n
of squamosal
external
acoustic
porus
jugular
foramen
infraorbital
foramen
3 cm
E
glenoid
fossa
e.a.p.
C
YPM VPPU 021147
YPM VPPU 020700
YPM VPPU 020700
B
YPM VPPU 021147
F
foramen
ovale
foramen for
Eustachian tube
inferior petrosal sinus?
internal carotid canal?
YPM VPPU 020700
glenoid
fossa
lateral frontal
dipoic foramen
foramen
ovale
FIGURE 3. Cranial material of Ronwolffia pacifica, new taxon. A–E. Holotype cranium, YPM VPPU 020700].
A. Right lateral view. B. Posterior view. C. Ventral view. D. Line drawing of ventral view. E. Dorsal view. F.
Referred specimen, YPM VPPU 021147, tip of rostrum, in ventral and dorsal views (left and right, respectively).
D represents a hypothetical reconstruction of the skull, based on the holotype and YPM VPPU 021147, recon-
structed as if there were no overlap, implying a count of eight upper teeth to complement the eight lower teeth
that occur in mandibles YPM VPPU 021143 and UF 93587 (Figure 6). Abbreviations: e.a.p., external acoustic
porus. The scale bar at F applies to all.
Ameghino did not specifically identify a type).
The measures given by Ameghino in defining P.
ferox (total length 11 cm, palatal length 5 cm,
and tooth row length 39 mm) agree with those of
homologous regions of the AMNH 14506 cast,
which looks very much like the drawing of the P.
ferox skull provided by Ameghino (1894, fig. 66).
AMNH 14491 (Figure 7G) is a cast of a skull
with much of its cranial shield referred to P. fe r ox .
It is essentially identical to the specimen figured
by Ameghino (1897, fig. 86; 1904:22, fig. 12), and
also by Scott (1903–1904, pl. 15, fig. 1) (but see
Vizcaíno and Fariña 1997 for alternate interpre-
tation). The correspondence that came with the
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
376
A
B
CD
2 cm
Fr
Fr
Pa
Fr
Pa
(Na)
Mx
Fr
frontal
inflation
YPM VPPU 021145
YPM VPPU 021144
infraorbital nerve
lateral frontal
dipoic foramen
dorsal frontal
dipoic foramena
FIGURE 4. Partial cranium of Ronwolffia pacifica new taxon. Referred specimen, YPM VPPU 021144, a damaged
rostrum, and YPM VPPU 021145, the dorsal portion of brain case, likely of a single individual. A. Dorsal. B. Right
lateral. C. Posterior. D. Ventral view of palate. At B, the frontoparietal suture is highlighted by a dashed black line,
and a dashed white line in the rostrum indicates the route of the infraorbital nerve via the sinuous groove of
infraorbital canal. Abbreviations: Fr, frontal; Mx, maxilla; (Na), nasal (missing, but outlined by Fr and Mx); Pa,
parietal. Scale bar applies to all.
cast from Ameghino (found in the AMNH
archives by Susan Bell) indicates that he regarded
it as a cast of the “tipo” of P. f e ro x . However it
cannot be the holotype, as this specimen seems
to have been found some time after P. f e r o x
Ameghino, 1891 had been described. This cast
is almost certainly of the specimen that Amegh-
ino referred to in the figure legend of Ameghino
(1894, fig. 66), where he noted it as having been
recently discovered and as being a perfect
(“absolument parfaits”) specimen that included
its cranial shield. This specimen had been found
after the manuscript of Ameghino (1894) was in
its advanced stages and already included the
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 377
FIGURE 5. Comparative anatomy of peltephilid auditory regions. A–Aⴖⴖ.Ronwolffia pacifica, YPM VPPU 020700.
Right auditory region is shown in ventrolaterial view (A), ventral view (A⬘), and ventrolateral view (A⬙) of left
auditory region, reversed to facilitate comparison. B–Bⴕⴕ.Peltephilus pumilus, YPM VPPU 015391. Right auditory
region in lateral (B) and ventral views (B⬘). C. Peltephilus strepens, AMNH 014502, in ventral view. Abbreviations:
e.a.p., external acoustic porus; xs, cross section. Photographs at different scales to facilitate comparison.
drawing given in fig. 66 (this drawing seems to
have been that of the original basis for P. f e r o x
[noted above, represented by AMNH 14506]).
The third cast, AMNH 14502 (Figure 5C), is of a
cranium that Ameghino indicated in his corre-
spondence as being of P. strepens. This cast is of
a nearly complete skull, missing only the zygo-
matic arch, glenoid, and auditory region of the
right side. This cast (AMNH 14502) seems to be
of the same specimen that Bordas figured as
“Peltephilus ferox” (Bordas 1938, fig. 2). How-
ever, since it is larger than the two specimens
identified by Ameghino as P. f e r ox (Table 1;
Ameghino 1891 had diagnosed P. fe rox as being
smaller than P. strepens and much larger than P.
pumilus), it is here regarded as, indeed, being a
cast of P. strepens, as denoted in Ameghino’s
correspondence.
Phylogenetic Evaluation
The phylogeny of Billet et al. (2011) (based largely
on the work of Gaudin and Wible 2006) was used
to estimate the phylogenetic context of Ronwolffia.
The discussion of peltephilid character polarities
(like that of Gaudin and Wible 2006) includes ref-
erences to generalized therian mammals (e.g.,
Didelphis virginiana, Atelerix algirus, and the
extinct Leptictis; see Gaudin and Wible 2006). The
phylogeny of Mitchell et al. (2016, fig. 2) served as
the backbone of Figure 2, which is given in order
to provide a general context for Xenarthra, its
major subgroups, and putative stem taxa.
Anatomical Nomenclature
Wible and Gaudin (2006) served as a model for
anatomical terminology of the cranium. For con-
venience sake, and due to a question of precise con-
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
378
TABLE 1. Cranial measures of selected peltephilids. Cranial measures of Ronwolffia pacifica and American Museum
of Natural History study casts compared with those of Bordas (1938). The cast indicated as being of Peltephilus
strepens (AMNH 14502) is very similar in appearance to that of Bordas (1938, fig. 2), which he indicated was of
P. fe r ox . The measures taken from AMNH 14502 are likewise similar to the data of Bordas for “P. fe r ox ”. As t he s e
data are somewhat greater than those given for P. f er o x , AMNH 14502 is herein regarded as indeed that of
P. strepens. Numbers in parentheses indicate estimates that are based on nearly complete but damaged features
or data taken from casts.
Dental Width of
Catalog Maximum series Palate internal Greatest
Taxon number length length length orbit width
Ronwolffia pacificaaYPM VPPU (118) — (55) 34 78
020700
Ronwolffia pacifica YPM VPPU (110) (35) — — —
021144–021145
Parapeltecoelus
pattersoni a, b 150 47 55 37 70
“Peltephilus ferox” b
cf. Peltephilus strepens 131 37 56 45 (76)
Peltephilus strepens AMNH 14502 (130) (38) (56) (33) —
(cast)
Peltephilus feroxaAMNH 14506 (112) (37) (54) (30) (69)
(cast)
Peltephilus feroxcAMNH 14506 (117) — — — (77)
(cast)
Peltephilus pumilus b105 35 49 36 66
Peltephilus pumilus YPM VPPU 92.0 29.4 45.5 30 —
015391
Peltephilus pumilus AMNH 9524 (82) — — — 53
a Holotype.
b Data from Bordas (1938).
c See Ameghino 1897, fig. 86.
tact, the common term TMJ (temporomandibular
joint) is used in the discussion of the jaw joint.
As the general placental homologues of pel-
tephilid tooth loci are unknown, the teeth are sim-
ply referred to as “molariforms” (“Mf” for the
upper series and “mf” for the lowers). The nota-
tion of the lowers follows Shockey and Anaya
(2008), in which the teeth of the jaws having seven
teeth are identified as mf 1–7, but those with eight
as mf 0–7, implying that the most mesial, diminu-
tive tooth (⫽mf 0) as that which is absent in Pel-
tephilus spp. and individuals of Ronwolffia that
have just seven lower teeth (Figure 6; and see
Shockey and Anaya 2008 for discussion).
González-Ruiz et al. (2013) was the standard
for nomenclature regarding osteoderms. It was,
however, necessary to discriminate between “pri-
mary” and “secondary” foramina of the osteo-
derms of the carapace, as many of the peltephilid
osteoderms of Salla have distinctive foramina that
are smaller than the primary foramina (⫽simply
the foramen or foramina of González-Ruiz et al.
2013), but much larger than the many minute
nutrient foramina or pores.
Geochronology
The geochronology discussed in the text follows
that of Flynn and Swisher (1995) with more spe-
cific references to stratigraphy given by Kay et al.
(1998) for Salla in particular.
Systematic Paleontology
Americatheria
New Clade Name
Definition. Americatheria is the total clade (sensu de Queiroz
2007) of the crown clade Xenarthra Cope, 1889 (phylogenetic
definition below) to include stem taxa more closely related to
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 379
2 cm
mf 0
mf 1
mf 2
mf 5 mf 5
mf 2
BB’
B”
C
C’
mf 1
mf 1
A
A’
mf 7
YPM VPPU 021143
UF 93587 UF 93586
YPM VPPU 021143
FIGURE 6. Peltephilid jaws of Salla. A. Mandible of Ronwolffia pacifica, YPM VPPU 021143, in occlusial view (A)
and in lateral view (A⬘, reversed). B, C. Mandible, UF 93587 and UF 93586, cf. Ronwolffia pacifica, each in dor-
sal and lateral views. Note fused mandiblular symphysis in A, but unfused in B and C. Eight teeth occur in A and
B, but C has only seven. Notation (where the first tooth of A and B is mf 0, followed by mf 1–7) is based on the
dental homologies suggested by Shockey and Anaya (2008). Abbreviations: mf, lower “molariform” teeth.
crown xenarthrans than they are to members of Afrotheria or
Boreotheria.
Etymology. The prefix “America” is in regard to South America
(the continent to which the name originally applied) in recog-
nition that this continent was an important region for the evo-
lution of the crown Xenarthra. It is also given to honor Amerigo
Vespucci (1454–1512) as an unrecognized herald of the science
of biogeography for his early observations and deductions
regarding the distinctiveness of South America’s flora and fauna,
his foresight that South America was indeed a continent based
on the many species he encountered (Ober 1909; Boorstein
1983), and for his courage to clearly state the heretical implica-
tions of that great biodiversity (i.e., “We s a w m ore w i l d
animals...than could ever have entered the ark of Noah,” English
translation from Ober 1909:98–99).
Synonyms. “Xenarthra” (sensu lato; e.g. Madsen et al. 2001;
Murphy et al. 2001; Delsuc et al. 2016, and many others).
Composition. Crown Xenarthra (Cingulata and Pilosa) plus
stem members, of which none are confidently identified. The
poorly known Seymour Island “sloth” (Vizcaíno and Scillato-
Yané 1995) (Eocene Antarctica) may pertain to the stem, as it
cannot be confidently referred to either the Pilosa or Cingulata
(MacPhee and Reguero 2010). Palaeanodonts and gond-
wanatheres have been considered as possible stem xenarthrans
(Simpson 1945; Scillato-Yané and Pascual 1985), but such has
been disputed (e.g., Goin et al. 2012; Gaudin et al. 2009). Other
hypothesized sister groups of Xenarthra, such as Tubulidentata
and Pholidota, have been excluded in recent analyses, in which
the Tubulidentata (e.g., aardvarks) were found to be members of
the Afrotheria and the Pholidota (pangolins) as members of
Boreotheria, sister to the Carnivora (Madsen et al. 2001; Mur-
phy et al. 2001; Weddell et al. 2001).
Xenarthra Cope, 1889
(sensu stricto, to represent the crown clade)
Definition. Xenarthra is the clade that includes Dasypus, Brady-
pus, and Tam a n d u a, the most recent common ancestor of these
taxa, and all of the descendants of that common ancestor.
Cingulata Illiger, 1811
(the total clade Dasypodoidea Gray, 1821)
Definition. Cingulata is the total clade of the crown clade Dasy-
podoidea and is defined as taxa that are more closely related to
members of dasypodoidean xenarthrans (e.g., Dasypus, Euphra-
tus, Tol y p e u tes, Chlamyphorus) than the y are to any members of
the Pilosa (e.g., Bradypus, Ta m a n dua).
Peltephilidae Ameghino, 1894
Definition. Cingulates that are more closely related to species
of Peltephilus than to Dasypus, Euphractus, Tol y p e u t es, or
Chlamyphorus. Though the preferred hypothesis is that the
Peltephilidae are not members of the crown clade Dasy-
podoidea, this “family” definition is proposed as thus to allow
for the possibility that the Peltephilidae are members of the
crown.
Included genera. Undoubted members of the Peltephilidae
include species of Parapeltecoelus Bordas, 1938; Peltephilus
Ameghino, 1887; Peltecoelus Ameghino, 1902; Anantiosodon
Ameghino, 1891; and Epipeltephilus Ameghino, 1904 (Bordas
1938; McKenna and Bell 1997; González-Ruiz et al. 2012), plus
the new taxon described below, Ronwolffia pacifica. Species of
Machlydotherium have also been considered to be members of,
or sister to, the Peltephilidae (Wolf 2007; González-Ruiz et al.
2012).
Distribution and age. Peltephilids are known only from South
America. Undoubted taxa occurred from the late Oligocene,
Deseadan SALMA (Ameghino 1897) to late Miocene, Chasi-
coan SALMA (González-Ruiz et al. 2012). If Machlydotherium
pertains to the Peltephilidae, then the clade originated by the
early Eocene (Scillato-Yané 1986; Oliveira and Bergqvist 1998;
Carlini et al. 2010).
Ronwolffia pacifica
New Taxon
Figures 3, 4, 5A, 6, 7A, B, and F, 8A–C, 9,
and Table 1
Synonyms. Peltephilus, Hoffstetter 1968; “cf. Pel tephilus sp.”, Mac-
Fadden et al. 1985; “Unnamed genus, cf. Peltephilus,” Sh oc ke y
and Anaya 2008; “unnamed taxon” and “Deseadan taxon,” Kear-
ney and Shockey 2008.
Etymology.The name, Ronwolffia, is given as a tribute to the late
Ronald Wolff, formerly of the Department of Zoology, Univer-
sity of Florida (UF), Gainsville, Florida, USA to honor his pio-
neering work at Salla, to recognize his considerable service as
undergraduate advisor at UF, and as a much belated note of grat-
itude from this present student for Dr. Wolff ’s guidance as com-
parative anatomy instructor and as a thesis advisor. The
combination, Ronwolffia pacifica, is to suggest the dual nature to
which peltephilids have been regarded: wolf-like predators and
“peaceful” (pacific) herbivores.
Diagnosis. Short-faced, flat-headed cingulate of moderate size;
cranium about as broad as that of the large, extant tolypeutine
dasypodoidean Priodontes maximus, but total skull length much
shorter; TMJ with lateral and ventral placement of the glenoid
fossa from the post-zygomatic root, contributing to anteroven-
tral wall of the external acoustic porus; anterior upper dentition
continuous, incisive foramen small, number of upper teeth
unknown—apparently seven, but possibly eight, or variable (as
occurs in the dentary); number of lower teeth varies between
seven and eight; mandibular symphysis variably fused or
unfused, suggestive of dentary fusion occurring later in Ron-
wolffia than in other known peltephilids or not occurring at all
in a portion of the population.
Differs from the early Miocene Parapeltecoelus pattersoni
Bordas, 1938 by its relatively longer palate (shorter posterior cra-
nium), smaller size, and anterior dental arcade being arched
rather than having a blunt, semicircular form.
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New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 381
FIGURE 7. Peltephilid cranial appendages. A–E. Nasal, horn-like osteoderms. A. YPM VPPU 021149, right lat-
eral view of right nasal osteoderm. B. YPM VPPU 021148, left lateral view of left nasal osteoderm. C. YPM
VPPU 004251, left lateral view of left nasal osteoderm. D. MNHN-F SAL 236, left lateral view of nasal osteoderm
still attached to anterior left fragment of the snout. E. MNHN-F SAL 655, left lateral view of left nasal osteo-
derm. F. Right lateral views of YPM VPPU 020700 holotype cranium, YPM VPPU 021143, referred mandible,
and YPM VPPU 021149, referred nasal osteoderm, reconstructed as if they are of a single individual. G. AMNH
14506, a cast of skull and mandibles of Peltephilus ferox; see also Ameghino (1897, fig. 86, 1904, fig. 12).
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
382
AB
C
1234
UF 93586
567
123
456
UF 93515
Articulating
surface
Secondary
foramina
Primary
foramina
12
4
D
ilium
E
osteoderm
1 cm
3
YPM VPPU 023661
FIGURE 8. Peltephilid osteoderms of Salla. A. Schematic drawing of osteoderm (enlarged, based on C2) to illus-
trate and define features discussed in text. B. Right lateral view of YPM VPPU 023661 illustrating the form of a
dorsolateral osteoderm and its proximity to the extreme end of the right ilium. C. UF 93586, six associated osteo-
derms referred to Ronwolffia pacifica. D. Five miscellaneous peltephilid osteoderms of the YPM VPPU collec-
tion, not associated, but the two of D4 are bound together, presumably representing their contact in life. E. UF
93515, six associated osteoderms found with a partial hind limb (Figure 10). The osteoderms of B and C are
referred to Ronwolffia pacifica. That of D3 may also pertain to this species, but the others are regarded here as
indeterminate species. Scale bar applies to all, except A, which is enlarged to denote details (see also Table 2).
Similar size as the Santacrucian Peltephilus f erox Ameghino,
1891, cranial vault flatter (not domed), tendency for dentaries to
be unfused at symphysis or fuse later in development and ten-
dency to have eight lower teeth.
Similar to the Santacrucian Peltephilus pumilus by the gle-
noid forming a component of the acoustic porus, but differs by
its larger size, flatter cranial vault, ontogenetically later fusion of
symphysis of mandible (or variability of presence of ossification
of symphysis), and the variable presence of eight, rather than
just seven teeth, in each dentary.
Smaller than Peltephilus strepens and differing by narrower
nasals, smaller sagittal crest, absence of notch in nuchal crest,
and distinctive lateroventral TMJ with glenoid at anteroventral
surface of the external acoustic porus.
Differs from Anantio sodon spp. by its much greater size and
greater number of teeth.
Distribution. Known only from Salla, Bolivia; late Oligocene. The
holotype of Ronwolffia pacifica was collected from a locality at
Salla that Leonardo Branisa (Bolivian geologist and Princeton
grantee) designated as V-5 during his first expedition to Salla
(unpublished letter from Branisa to Glenn Jepsen, dated 17 July
1964, in the Yale Peabody Division of Vertebrate Paleontology
archives; Shockey and Anaya in prep.). Branisa himself did not
visit V-5 at the time, but defined it based on the collection made
by his crewmember, Alberto Elier, as a quebrada (gorge or
canyon) between Tapial Pampa and Calaboza Pata. The precise
stratigraphic level of V-5 is unknown, but was likely in the upper
regions, above the Principle Guide (Unit 4), because Elier was
apparently prospecting relatively near Branisa, who was work-
ing in Tapial Pampa at that time. So, the type probably came from
either Unit 5 or Unit 6, above the Principle Guide Level, as did all
of the referred specimens of R. pacifica that have stratigraphic
data (see Referred Specimens, below). Several referred speci-
mens, however, lack stratigraphic control; thus, it is presently only
suggestive to consider the possibility that this taxon was limited
to these upper horizons, above the Principle Guide (sensu Villar-
roel and Marshal 1982; MacFadden et al. 1985; Kay et al. 1998).
Peltephilid remains of smaller individuals occur in Unit 3, below
the Principle Guide, but these may pertain to a smaller species
and are thus noted in a separate section below.
Holotype. YPM VPPU 020700, damaged but nearly complete
cranium, including most of the rostrum and most of posterior
cranium, including the basicranium. It is missing only the ante-
rior extreme of the rostrum (missing two to three anterior teeth),
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 383
TABLE 2. Individual size variations of osteoderms. Lengths (anteroposterior dimensions) and widths (transverse
dimensions) of osteoderms that were collected in close physical proximity for two individuals. Those of the larger
individual (UF 93586, C1–6) are referred to Ronwolffia pacifica, new taxon, and those of the smaller (UF 93515,
E1–6) to an indeterminate taxon. The numbering of individual osteoderms are from the specimens in Figure 8C,
E. Statistical summary include means, standard deviations (SD), coefficient of variations (CV), and ranges.
Specimen Length Width Form
UF 93586
C1 19.2 14.0 Mobile
C2 22.4 14.5 Mobile
C3 20.3 13.5 Mobile
C4 19.8 14.4 Indeterminate
C5 21.2 16.3 Fixed
C6 19.2 15.1 Fixed
Mean 20.6 14.5
SD 1.25 1.06
CV 0.06 0.07
Range 19.2–22.4 13.5–16.3
UF 93515
E1 13.3 9.0 Mobile
E2 17.1 11.0 Mobile
E3 15.2 8.2 Mobile
E4 15.1 10.3 Mobile
E5 13.1 8.7 Mobile
E6 12.7 9.3 Fixed
Mean 14.4 9.4
SD 1.69 1.05
CV 0.12 0.11
Range 13.1–17.1 8.2–11.0
the lateral portion of the left glenoid fossa, and both zygomatic
arches.
Referred specimens. Material referred to the Ronwolffia paci-
fica include the following: YPM VPPU 021144 (Figure 4
[right]; Branisa field number 17582), rostrum with damaged
maxillae containing right Mf 2–7 and alveolus for Mf 1, left
Mf 3–7, and anterior orbital region missing the root of zygo-
matic arch and missing the nasals, apparently associated with
and probably the same individual as YPM VPPU 021145;
YPM VPPU 021145 (Figure 4 [left]; Branisa field number
17581), a partial cranial vault, preserving much of the pari-
etals and a fraction of the occiput, (no precise locality infor-
mation); YPM VPPU 021147 (Figure 3F, Branisa field
number 17670), anterior region of the snout (which does not
match the missing portion of the holotype) preserving nasal
aperture, first three teeth of each side, anterior palate with
incisive foramina, anterior part of nasal bone and maxilla/pre-
maxilla (border indeterminate); YPM VPPU 021143 (Figure
6A), left and right dentaries with eight teeth in each jaw,
solidly fused at the symphysis, missing the ascending rami
and the posterior horizontal rami; UF 93587 (Figure 6B), left
dentary with eight teeth (some damaged) from the Upper
White (Unit 6) of Tapial Pampa; UF 93586 (Figure 6C), left
dentary with seven teeth and associated with osteoderms,
from the Upper White (Unit 6) of Tapial Pampa; YPM VPPU
021149 (Figure 7A, Branisa field number 5266), horn-like cra-
nial osteoderm; YPM VPPU 021148 (Figure 7B, Branisa field
number 5265), horn-like cranial osteoderm; UF 93586, asso-
ciated osteoderms, mostly fragmentary (Figure 8A, C); YPM
VPPU 023661 and MNHN-F SAL 242 (Figure 9; Branisa field
number 14613), these two specimens, in two collections, are
matching halves of a partial pelvis of a single individual,
bound by matrix, that contains three and one-half lumbar ver-
tebrae, a sacral vertebrae, and associated osteoderms.
Description.
General cranial characteristics. Though clearly armadillo-like
in many respects, the skull of Ronwolffia, like those of species
of the Santacrucian Peltephilus, has several traits that are dis-
tinct from those of dasypodoidean cingulates. These include a
short rostrum, closed anterior dental arcade, distinctly low
TMJ with an intimate glenoid-external acoustic porus rela-
tionship, mandible deepest at the symphysis, and with modi-
fied horn-like cephalic osteoderms (Figures 3–7). In profile
(Figure 3A), Ronwolffia appears somewhat flat-headed, com-
pared with Peltephilus spp., lacking the distinctive domed cra-
nial vault over the braincase of P. p um il u s and P. f er ox (Scott
1903–1904, pl. 16, fig. 3; Ameghino 1894, fig. 66). The poste-
rior cranium of Ronwolffia is as broad as that of the extant Pri-
odontes maximus, but, owing to the short rostrum, the total
skull length is much less than that of P. maximus.
Nasal-facial region. The tip of rostrum of the holotype is miss-
ing and there is severe puncture damage in the nasal-frontal
region. YPM VPPU 021147 preserves the anterior halves of the
nasals (Figure 3F) and, though the nasals are completely miss-
ing on YPM VPPU 021144, the maxillae and frontals define its
general outline, indicating a somewhat hourglass form (Figure
4A). As indicated by YPM VPPU 021144, the frontal-nasal
suture is transverse and fairly short (Figure 4A). Anterior to a
slight constriction, the nasals increase their widths so that they
dominate the dorsal surface at the tip of the snout. In addition
to the increased breadth of the nasal at the tip of the rostrum,
they extend anteriorly, beyond the external nasal aperture
(Figure 3F).
The premaxillary-maxillary suture is not visible in either
the facial or palatal regions, so the anterior extent of the facial
process of the maxilla cannot be determined. The maxillary-
frontal suture (visible on YPM VPPU 021144, see Figure 4A)
initially follows the same transverse line as the nasofrontal
suture, but makes an anterior turn to descend along the ante-
rior portion of the anterior zygomatic root. The zygomatic facial
process of the maxillae seems to only form the anteroventral
portion of the anterior zygomatic root, the base of which proj-
ect laterally from a point overlying the last molariform (Figure
3). The maxillary face of the zygomatic root is pierced by a mod-
erately large infraorbital foramen. Associated with this foramen
(conspicuous on the left side of the holotype) is a groove within
the face of the maxilla, presumably related to the route of the
infraorbital nerve, a major branch of cranial nerve V2, and ves-
sels that pass through the intraorbital canal (Figure 4B; Gaudin
and Wible 2006). The dorsal component of the maxilla dimin-
ishes in size as it extends toward the tip of the rostrum. Break-
age on both the holotype and YPM VPPU 021147 occur where
the maxilla and premaxilla might have met (as suggested by
reconstruction in Figure 3D), but this is far from certain.
A pair of swellings occurs on the dorsal surface of the
frontals above the anterior region of the orbits, a feature that Bil-
let et al. (2011) noted as generally occurring in dasypodoideans,
excepting Dasypus spp. The anterior regions of these frontal
inflations are damaged, but the posterior portions are fairly con-
spicuous (Figure 4A, B). Breakage of YPM VPPU 021144
through frontals provides a cross-sectional view that shows a
sinus within the maxillary bone that is related to the inflations.
Two foramina are generally associated with each swelling (Fig-
ures 2A and 4A, B) and were likely traversed by dipoic veins.
But whereas dipoic foramena are generally limited to the dorsal
surface in armadillos (e.g., Euphractus, see Wible and Gaudin
2004, fig. 1A), both the holotype and referred specimen YPM
VPPU 021144 have a lateral foramen communicating with the
sinus (Figures 3A and 4B). Between the paired swellings lies a
shallow fossa. The frontals extend to the level of the post-orbital
constriction, where it forms its suture with the parietals (high-
lighted in Figure 4B). This suture is transverse in dorsal view,
but projects posteriorly in lateral view.
Palate. The gently curved convex, lateral tooth rows, along with
the more sharply arched anterior dental arcade, define a nearly
oval palate. Two minute, but sharply defined, incisive foramina
occur at the most anterior end of the palate (YPM VPPU
021147), between the first pair of teeth (Figure 3D, F). The lon-
gitudinal dimensions of these foramina are only about 1.5 mm,
but each has an associated shallow, posterior groove of about 3
mm in length. The suture separating the left and right halves of
the palatal process of the premaxilla are clearly visible on YPM
VPPU 021147 (Figure 3F) where it undulates between the tiny
incisive foramina but follows a straighter course beyond the level
of the second tooth.
There are no visible sutures on the holotype to define either
the anterior or posterior extremes of the palatal face of the max-
illa (i.e., no visible suture where the maxilla meets the premax-
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
384
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 385
MNHN-F SAL 242
MNHN-F SAL 242
MNHN-F SAL 242 = B#14613
epiphysis
missing
lumbrosacral
joint
YPM VPPU 023661
YPM VPPU 023661
anterior
ilium
iii iii
iv iii
iii
iv
zygopophysis
(broken)
YPM VPPU 023661
ilium
ilium
ilium
AB
C
D
2 cm
FIGURE 9. Pelvic region of a peltephilid of Salla (cf. Ronwolffia pacifica). Both the Yale Peabody Museum of Nat-
ural History and Muséum National d’Histoire Naturelle specimens of the pelvic region are from a single individ-
ual. A. Distal view of YPM VPPU 023661 showing parts of the distal lumbar vertebra, zygopophysis fragment,
and broken dorsal osteoderms (i, ii, iii, and iv) suspended in the matrix. B. Anterior view of MNHN-F SAL 242,
showing the osteoderms that match those of Ai–iv. C. Left lateral views of YPM VPPU 023661 and MNHN-F
SAL 242, digitally joined to approximate their anatomical positions in life. D. Ventral views of YPM VPPU 023661
and MNHN-F SAL 242, also digitally joined. The tag shown in the callout at C (“Salla 41613”) is the field num-
ber, written in Leonardo Branisa’s hand. Scale bar at D applies to all.
illa or the palatine). The palate is widest at the level of the penul-
timate tooth, then diminishes its width a little until it reaches
the base of the pterygoid, of which only part of the left side is
preserved (Figure 3C, D). The distal portion of the palatines sug-
gests a U-shaped internal nasal aperture, but the area is too dam-
aged to be certain.
In addition to the damaged posterior palatines, much of
the posterior rostrum throughout the region of the post-orbital
constriction is badly damaged. It seems that the specimen had
been collected as two reasonably solid parts (rostrum plus pos-
terior cranium) and was glued together along the relatively
undamaged dorsal surface, which retained faithful contacts for
reconstruction.
Orbital region and cranial vault. The posterior root of the zygo-
matic sits lower on the skull than the anterior (Figure 3). This
anterior root is obliquely joined to the face of the skull such that
the base arises at the level of the last tooth, but the dorsal extreme
lies above the penultimate tooth. The dorsal portion of the root
is mostly composed of the jugal, but the maxilla forms much of
the ventral surface and anterior face. Breakage obscures any
facial component of the lacrimals.
The postorbital constriction is fairly broad. Damage at ven-
tral region of the constriction is too extreme to provide any trust-
worthy information regarding the foramina of the alisphenoids.
As in Peltephilu s spp., the parietals are relatively large. That
of Ronwolffia is flatter than those of Peltephilus and also has a
smaller sagittal crest. The nuchal crests are thick and rugose, like
those of P. strepens and P. f er o x. However, unlike these two San-
tacrucian taxa, which have a gap in the crests, those of Ronwolf-
fia run continuously to the mastoid region, which forms the
posterior component of the laterally placed external acoustic
porus.
Glenoid fossa, auditory region, and basicranium. The most strik-
ing feature of the skull of Ronwolffia is the low glenoid fossa and,
especially, its intimate association with the external acoustic
porus. Whereas the TMJ of most dasypodoideans (senso lato, to
include glyptodonts) is conspicuously higher than the level of
the maxillary tooth row (see Serrano-Fochs et al. 2015), that of
Ronwolffia (and all other known peltephilids) is at the same level
as the dentitions. The glenoid fossa is oval with its long axis being
imperfectly transverse, directed somewhat obliquely, about 65°,
to the long axis of the skull, with the lateral extreme being a lit-
tle more anterior than the medial. This form is in sharp contrast
to that of the glenoid fossae of Peltephilus spp. in which the lat-
eral extreme is in a more posterior position than the medial (e.g.,
P. p u mi lu s; Patterson et al. 1989, fig. 14). There is no apparent
postglenoid process, but the body of the glenoid fossa forms the
anterior wall of the external acoustic porus—it appears as thus
on the reasonably well preserved right side (Figure 5A⬘), but is
better observed on the left, where part of the glenoid articular
surface is broken and reveals the cross section that shows this
relationship (see Figure 5A⬙).
The tympanic element at the base of the external acoustic
porus seems to form a short tube that is imperfectly aligned with
the porus and extends ventrally to form a loose attachment with
auditory bulla. The caveat here, however, is that there a discon-
tinuity between the tubular component and the bullar compo-
nents (Figure 5A), suggesting that the tubular meatus and
auditory bulla are of separate centers of ossification (likely ecto-
and entotympanic). Thus, the interpretation here of the compo-
sition of the elements of the external acoustic porus of Ronwolf-
fia is as follows: the anteroventral portion is formed by the
glenoid region of the distinct process of the squamosal; the dor-
sal and posterior components are also squamosal; and the ven-
tral portion is the ectotympanic, which also forms at least the
lateral portion of the tubular meatus. A similar form occurs in
Peltephilus pumilus, YPM VPPU 015391. See Discussion for the
alternative interpretations of this region in Peltephilus spp. by
Ameghino (1897), Scott (1903–1904), and Patterson et al. (1989).
The auditory bulla of Ronwolffia is relatively shorter and
blunter than those known in Peltephilus spp. The anterolateral
region lays close to the glenoid fossa, separated only by a narrow
and undulating Glaserian fissure, the pathway for the chorda
tympanic nerve for entry into the lateral region of the bulla (Fig-
ure 5A⬘). The Glaserian fissure of Ronwolffia differs from those
of Peltephilus pumilus and P. strepens by this sinuous form; this
fissure is fairly straight in P. pu mi lu s and P. strepens (Figure 5B,
C). An opening at the anterior apex of the bulla is likely for the
Eustachian tube (Figure 3D; see also Patterson et al. 1989, fig.
14). Just anterior to this opening, medial to the glenoid fossa,
lies the foramen ovale, which is best preserved on the left side of
the holotype of Ronwolffia (Figure 3C). The diminutive piriform
foramen noted by Patterson et al. 1989 as being just medial to the
Eustachian foramen in Peltephilus, was not located in Ronwolf-
fia. A small but conspicuous foramen piercing the lateral face of
the bulla, just medial to the Glaserian fissure, does not have a
homologue in Peltephilu s (Patterson et al. 1989). It may represent
a carotid foramen. Unlike the bulla of P. p u m il us , the median
wall does not seem to be firmly attached to the basioccipital. The
jugular (posterior lacerate) foramen lies just posteromedial to
the bulla. It is circular and fairly large. Posteromedial to the jugu-
lar foramen is the much smaller hypoglossal foramen (Figures
3D and 5A⬘).
Occiput. Consistent with the low cranial vault of the holotype
skull of Ronwolffia, the occiput is wider than tall (Figure 3B),
whereas occiputs of Peltephilus spp. have dorsoventral dimen-
sions (heights) greater than their widths. In posterior view, there
are no sutures visible to define the outline of individual cranial
elements. The lateral exoccipital area (best preserved on the left
side) seems to overlap the bony element (presumed to be the
posterior exposure of the petrosal) to which it is fused. Amid
this damaged lateral region of the occiput is a remnant of a sul-
cus to suggest an occipital groove.
Mandible. Three peltephilid jaws are known from the Salla col-
lections and these are tentatively referred to Ronwolffia pacifica
(Figure 6). All are similar to those known of Santacrucian spec-
imens of Peltephilu s by way of the deep, robust symphysis (depth
>20% of length) and teeth having rounded ovals to ovular trian-
gles in cross section. The tooth crowns of all the teeth in all
known Salla specimens are broken, so they cannot be evaluated
for the distinctive peltephild characteristic of having beveled
crowns. Also, like jaws of Peltephilus, the angular process (pre-
served on UF 93586) is lower than those of extant armadillos,
lying ventral to the ventral border of the base of the horizontal
ramus. But whereas all of the known Santacrucian peltephilid
jaws have solidly fused symphyses, two of the three jaws of the
Salla peltephilid jaws are unfused (Figure 6). Also, whereas all
known dentaries of Peltephilus spp. have seven teeth, those of
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
386
Salla vary between seven (UF 93586) and eight (YPM VPPU
021143 and UF 93587; Figure 6). No other examples in which a
peltephilid has more than seven teeth in a dentary are presently
known.
Integ ument . There are several osteoderms in Salla collections
referred to the Peltephilidae. They include elements of the
cephalic shield, especially the conical, horn-like nasal elements,
as well as those of the carapace. The most distinctive of these are
the nasal “horns.”
Several of the horn-like, nasal osteoderms are known from
the Yale Peabody Museum, Florida Museum of Natural History,
and Muséum National collections (Figure 7A–E). These are con-
ical with varying degrees of asymmetry, size, sharpness of their
apices, and relative size of the basal “hillock” that flanks the
major cone. For example, the osteoderms shown in Figure 7A
and B are taller, more sharply pointed, and have relatively
smaller hillocks than the two osteoderms of Figure 7D and E.
The osteoderm of Figure 7C is distinctly larger than the rest. The
small osteoderm shown in Figure 7D is still attached to a small,
anterior fragment from the maxillary-premaxillary region of a
small peltephilid.
The dorsoventral dimension of the rostrum of specimen
MNHN-F SAL 236 (Figure 7D) is barely half that of the rostral
region of the holotype. This significantly smaller size suggests that
it may be of a smaller species than Ronwolffia pacifica, an ontoge-
netically younger individual, or it may represent a smaller, more
anterior horn, as reported by Ameghino (1894). The good fit of
cranial osteoderm YPM VPPU 021149 (Figure 7A) with the holo-
type of R. pacifica (Figure 7F) suggests that it and the similarly
sized YPM VPPU 021148 (Figure 7B) are referable to this taxon.
No articulated sections of carapaces of Ronwolffia have
been encountered and no reasonably complete carapaces are
known for any peltephild. A few osteoderms bound by matrix
with a partial pelvis referred to Ronwolffia (YPM VPPU 023661
and MNHN-F SAL 242—the two forming a single specimen;
Figure 9) suggests their general positions in life, though some
postmortem shifting may have occurred. Several dorsal osteo-
derms of this specimen show an alternating oblique orientation
that is here assumed to be due to postmortem deformation, such
as lateral compression (Figure 8A, B). However, especially
because this zigzag pattern persists over 5 cm, the possibility that
it represents the life positions in which the carapace had a sagit-
tal crest and two shallower parasagittal crests, reminiscent of the
crests of alligator snapping turtles (Chelydridae: Macrochelys),
should also be considered.
At the dorsolateral side of the pelvic region, just dorsal and
anterior to the tip of the right ilium, lies an exposed osteoderm
that retains some of its dorsal features (Figure 8B). Its length and
width is 23.5 mm by approx. 15 mm, giving it the greatest
anteroposterior length of any peltephilid osteoderm of Salla
sampled (see Table 2). This osteoderm has four primary foram-
ina that seem to radiate from a shallow, barley palpable, dam-
aged longitudinal central elevation (sensu González-Ruiz et al.
2013). The presence of a longitudinal central elevation is a fea-
ture common on osteoderms of Peltephilus spp., but is other-
wise absent from known peltephilid osteoderms of Salla. The
entire face of this pelvic osteoderm is riddled with many evenly
distributed, minute nutrient foramina.
A variety of loose and isolated dorsal osteoderms of the
carapace have been collected. UF 93586 and UF 93515 are
exceptional as they include associated, disarticulated osteo-
derms, the best preserved of which are shown in Figure 8C and
E, respectively (Table 2). These two clusters of osteoderms are of
distinct sizes (nonoverlapping dimensions, Table 2), suggesting
the possibility that they are of two different species, as inferred
from these and from other remains in collections by Hoffstetter
(1968) and Shockey and Anaya (2008). UF 92586 is the larger,
having osteoderm dimensions that are generally smaller, but
with overlapping ranges, than those given for Peltephilus strepens
(Ameghino 1891; González-Ruiz 2012, tbl. 1). Given that the
cranium of Ronwolffia pacifica is almost as large as that known
for P. strepens (AMNH 14502), it seems most plausible that the
osteoderms of UF 93586 pertain to R. pacifica.
The osteoderms of UF 93586 include both movable ele-
ments (Figures 8A, C1–3) and those that are fixed (Figure
8C5–7; C4 is ambiguous). Both forms are generally rectangular,
having anteroposterior dimensions (lengths) greater than the
transverse (widths), with aspect ratios of the best preserved
osteoderms averaging 1.4 (ranging from 1.27 to 1.54), which is
similar to those of other peltephilids, but is much less than those
generally associated with dasypodoidean armadillos (González-
Ruiz 2012, tbl. 1). All have dorsal surfaces pitted by many minute
nutrient foramina and two to four, often three, large, circular
primary foramina. These primary foramina lay just anterior to
the midsection of the osteoderms and near the narrow, trans-
verse articulation facets in the movable osteoderms and gener-
ally near the anterior extreme in the fixed osteoderms.
Additionally, these osteoder ms tend to have several “secondary”
foramina that lie between the primary foramina and the anterior
articulating surface (Figure 8A). These secondary foramina are
smaller than the primary, but larger than the many nutrient fora-
men that pierce much of the dorsal surfaces of the osteoderms.
These secondary foramina also tend to be ovoid to polygonal, in
contrast to the primary foramena, which tend to be circular. The
dorsal surfaces of these osteoderms lack any longitudinal central
elevation, common in species of Peltephilus and Epipeltephilus
(González-Ruiz 2012).
Pelvic region. YPM VPPU 023661 and MNHN-F SAL 242 are
two portions from a single individual that represents part of the
posterior lumbar region of the vertebral column (the last three
and one-half lumbars) and the anterior half of the pelvis pre-
served in a common matrix of sediments that seems (allowing for
some distortion) to represent a reasonably close approximation
of the relative positions of the bony elements in three dimensions
(Figure 9). These elements seem to represent an ontogenetically
young individual, perhaps a sub-adult, as suggested by the epi-
physes of the vertebral centra being unfused. Considering that at
least Dasypus spp. become sexually mature prior to dental and
osteological maturity (Ciancio et al. 2012), such an interpreta-
tion must be given with caution. Despite the incomplete develop-
ment of the pelvis, the measurable osteoderm (Figure 8B) fused
via matrix with this pelvic specimen is the largest of Salla. The
pelvis is also much larger than the partial pelvis collected by Bar-
num Brown in association with a damaged skull of Peltephilus
pumilus (AMNH 9524) from the Santacrucian Beds.
Though Peltephilus is known to have four lumbar verte-
brae (Scott 1903–1904), the number of lumbar vertebrae of the
Salla peltephilid, cf. Ronwolffia pacifica, is unknown. The cau-
dal three and the caudal half of the most anterior fourth are
present in the YPM VPPU/MNHN-F specimen. The form of
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 387
the centrum of the penultimate lumbar is exposed at the cau-
dal side of YPM VPPU 023661 (Figure 9A). In outline, this
centrum is symmetrically oval, unlike those of most dasy-
podoideans in which the dorsal surface tends to have a cen-
tral concavity and the ventral side being a single convexity (e.g.,
Stegotherium). The cross section of the third to last lumbar
centrum reveals the dorsoventral compression of at least the
intermediate part of that vertebral body.
The last lumbar and first sacral vertebrae seem to share
a common epiphysis between the two (Figure 9D), suggest-
ing that the lumbrosacral joint would fuse later in ontogeny.
The posterior region of the first sacral is bilaterally expanded
toward the ilia where coossification occurs between it, the
ilia, and the third sacral vertebra. The acetabulum is missing,
but the anterior processes of both ilia are preserved. They
are thin and extend to the level of the border of the penulti-
mate lumbar and the one that precedes it as narrow spatu-
late termini. The ilia lack any significant anterior expansion
and do not seem to fuse with any other elements. The
distal extreme of the ilia comes in close proximity to the
osteoderms, but does not form a shelf or even any club-like
thickening at the anterior extreme as generally occurs
in dasypodoidean armadillos and glyptodonts (Scott
1903–1904).
Peltiphilidae sp. indet.
Referred indeterminate peltephilids. The following specimens
are referable to the Peltephilidae, but not readily to Ronwolffia
pacifica. This doubt is based on size differences, with one spec-
imen (YPM VPPU 004251) seeming to be too large and the oth-
ers (UF 93515, MNHN-F SAL 236, MNHN-F SAL 655) too
small: YPM VPPU 004251, large, robust, horn-like cranial
osteoderm (Figure 7C); MNHN-F SAL 236, rostral fragment
with attached right nasal “horn”; MNHN-F SAL 655, left nasal
“horn” collected in 1970 from “Pógho-p-oghoni”, probably the
equivalent to MacFadden’s “Poco Poconi”, which consists mostly
of horizons of the “Red Rodent Zone” of Unit 3 (MacFadden et
al. 1985; Kay et al. 1998); UF 93515, many fragments of smaller
osteoderms, a few of which are reasonably complete (Figure 8E),
associated partial left femur, distal tibia and fibula (fused), and
partial left pes that includes an astragalus, navicular, ecto-
cuneiform, metatarsals II, III, and IV, and a medial and a distal
phalanx from the east side of Calaboza Pata, in the “Red Rodent
Zone” of Unit 3.
Description.
Osteoderms. The osteoderms of UF 93515 (Figure 8E) are smaller
and with nonoverlapping dimensions than those referred to Ron-
wolffia pacifica (Table 2). Also, whereas the osteoderms of R. paci-
fica (i.e., UF 93586; Figure 8C) and the holotype cranium are of
similar size to those of P. strepens, the femur associated with the
small osteoderms is likewise distinctly smaller than the femur
referred to P. strepens (Scott 1903–1904; Vizcaíno and Fariña
1997). The smaller size of UF 93515 is not likely a function of a
young ontogenetic age, since the associated distal tibia-fibula are
firmly fused to one another, a fusion of which does not occur
until late in ontogeny in Peltephilus (Scott 1903–1904).
In addition to being smaller than osteoderms referred to
R. pacifica, the osteoderms of UF 93515 do not have such con-
spicuous secondary foramina as those referred to the Ronwolf-
fia (UF 93586). Half of the samples of UF 93515 (Figure 8E1–3)
have distinctive rugosities that project from the region between
the primary foramina and the anterior articular surface. Like
those of R. pacifica, those of UF 93515 have two to four primary
foramina and have similar aspect ratios.
Hind limb. Several hind limb elements are associated with the
osteoderms noted above (UF 93515). These include a badly
damaged left femur, a right distal tibia-fibula, and a partial right
pes that contains the astragalus, ectocuneiform, metatarsals II,
III, and IV, and medial and distal phalanges of an indeterminate
digit (Figure 10).
The Salla femur is much smaller than that of the Santacru-
cian partial skeleton referred to Peltephilus strepens (Scott
1903–1904, pl. 16, fig. 9). It is missing the proximal end and the
cranial surface at the distal end is badly damaged. Enough of the
shaft is present to indicate its breadth and its roughly rectangu-
lar cross-sectional form, typical of most xenarthrans, but differ-
ent from the femur referred to Peltephilus, cf. P. strepens, which
narrows between the epicondyles and the third trochanter to
more circular cross section (Scott 1903–1904, pl. 16, fig. 9; YPM
VPPU 015390). The third trochanter is of similar relative size
as that of the P. strepens, but is more robust and lies adjacent to
a transverse thickening of the caudal surface of the shaft.
A fragment of the tibia-fibula is sufficient to show that these
two elements were solidly fused, with the tibia having a distinctly
broad transverse dimension associated with its articulation with
the wide trochlea of the astragalus. The observation of Scott
(1903–1904) that the distal tibia and fibula of young individuals
of Peltephilus were unfused and that of older ones were fused
suggests that UF 93515 was likely an adult, thus its small size
was not a function of early ontogenetic development.
The partial pes is similar to that of Peltephilus strepens (Scott
1903–1904), having a broad astragalus with a strongly columnar
trochlea, a thick astragalar neck, and three subequal metatarsals
(II, III, and IV). The ungual phalanx is of blunt triangular form
in dorsal view, being as “hoof-like” as that described by Scott for
cf. P. strepens (Scott 1903–1904:97). The most significant differ-
ence between pes of UF 93515 of Salla and that of cf. P. strepens
(YPM VPPU 015390) is the greater size of that of the Santacru-
cian taxon, cf. P. strepens.
Discussion
Peltephilids of Salla
There may be two species of peltephilid cingulates
at Salla (Hoffstetter 1968; Shockey and Anaya
2008). The smaller morph is known from the
lower sections (Red Rodent Zone of Unit 3) and a
larger, Ronwolffia pacifica, from the upper hori-
zons (Branisella Level of Unit 5, but especially the
Upper White, Unit 6). The stratigraphic docu-
mentation for many specimens, however, is too
incomplete to make any positive statements
regarding the temporal coexistence (or lack
thereof) for these two morphs at Salla. The differ-
ence in sizes is not likely due to ontogeny, as the
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
388
fused distal tibia and fibula associated with the
smaller osteoderms strongly suggest that the indi-
vidual represented was an adult. The lesser-
known smaller morph is left as an indeterminate
species with the hopes that more material will be
discovered to clarify its nature. Features of the
more completely known R. pacifica are discussed
below.
Anatomical Features of Phylogenetic
Significance of Ronwolffia
general characteristics
Ronwolffia pacifica shares the following apomor-
phic features with other members of the Cingu-
lata: flattened osteoderms forming carapace and
head shield; apparent absence of foramen rotun-
dum; Glaserian fissure adjacent to foramen ovale;
incisive foramen confined far anteriorly, appar-
ently within the premaxilla; and external nares
wide and inclined anterioventrally (Gaudin and
Wible 2006). With its short muzzle, closed ante-
rior dental arcade, low TMJ, dermal “horns” of the
carapace, and ossified auditory bulla, Ronwolffia is
confidently referred to the Peltephilidae. In some
regards, Ronwolffia retains some characteristics
that are herein regarded as unspecialized com-
pared to the geologically younger peltephilids,
such as Parapeltecoelus (Colhuehuapian) and Pel-
tephilus spp. (Santacrucian). Such putative ple-
siomorphic traits in Ronwolffia include a lower
occiput, braincase, and rostrum; incompletely
ossified auditory bulla; a tendency for having eight
(rather than seven) teeth in the dentary; and ten-
dency for having unfused (rather than fused) den-
taries at the mandibular symphysis. The polarities
of the tooth count of the dentaries are discussed
below, as is the peculiar nature of the TMJ of
Ronwolffia.
dentary tooth-count
The interpretation above that eight teeth in the
mandible is plesiomorphic compared to seven is
in apparent conflict with the analysis of Gaudin
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 389
FIGURE 10. Hind limb elements of a peltephilid of Salla. UF 93515 contains a left hind limb found in association
with several small peltephilid osteoderms (Figure 8). A. Caudal view of left femur, missing proximal end. B. Cra-
nial view of right fused distal tibia-fibula. C. Dorsal view of partial associated right pes in dorsal view, including
the astragalus, navicular, ectocuneiform, metatarsals II, III, and IV, and medial and distal phalanges of an inde-
terminate digit. Abbreviations: ast, astragalus; ec, ectocuneiform; fib, fibula; Mt, metatarsals; nav, navicular; tib,
tibula. Scale bar applies to all.
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
390
and Wible (2006). They identified the presence of
eight teeth in the mandible as a putative synapo-
morphy for the Dasypodoidea (⫽Node 2 of
Gaudin and Wible 2006, where character changed
from tooth count of seven to eight). This, how-
ever, was given in the context of a folivoran out-
group; i.e., Bradypus, which has only four lower
teeth. The authors were conscious that such an
outgroup might be insensitive to deeper phyloge-
netic context (Gaudin and Wible 2006:160) and
thus referred to three “generalized therian taxa” (a
metatherian opossum, Didelphis, and two eulipo-
typhlans: a hedgehog, Atelerix, and the extinct
Leptictis) to qualitatively consider some problem-
atic character polarities. Doing so gives a broader
context of placental mammals, where 11 teeth of
the dentary are regarded as the hypothetical
ancestral number (e.g., O’Leary 1913). In this con-
text, the eight teeth of Ronwolffia and dasy-
podoideans would not be considered apomorphic
compared to the seven of Peltephilus spp. Thus,
the condition of eight teeth in the jaw of some
individuals of Ronwolffia is tentatively regarded
here as being plesiomorphic compared to the
seven of Peltephilus spp.
temporomandibular joint
A major feature that distinguishes peltephilids
from other cingulates (and xenarthrans in gen-
eral) is their low TMJ. This is manifest by the
mandibular condyles at the level of the tooth rows
(and the associated ventral projection of the angu-
lar process) and the low glenoid fossae of the
squamosal (associated with straight, horizontal
zygomatic arches). Peltephilus strepens seems to
manifest a somewhat conventional low TMJ. That
is, the glenoid fossa occurs at the base of the zygo-
matic process of the squamosal, just anterior to
the auditory bulla and the external acoustic mea-
tus (Figure 5C). However, the TMJ of Ronwolffia
(Figure 5A) as well as those of P. pu m il u s (Figure
5B) and P. f e r ox are remarkable by their intimate
contact with the external acoustic meatus. That is,
the mandibular condyle articulates within the
fossa of bone that also forms the anteroventral
wall of the external acoustic porus. The precise
anatomical structure on which lies the articular
facet for the mandibular condyle has been inter-
preted as being a “reptilian” quadrate for P. f e ro x
(Ameghino 1897, fig. 86 legend), a post glenoid
process of the squamosal (Scott 1903–1904,
regarding a generic Peltephilus, but based on the
diminutive P. pumilus, YPM VPPU 015391), and
(implicitly) the anterior crus of the ectotympanic
(Patterson et al. 1989:33; also regarding that of
YPM VPPU 015391). Breakage of the glenoid on
the left side of the holotype of Ronwolffia (Figure
5A⬙, reversed to show as right) provides a fortu-
itous cross section of the bone on which lies the
mandibular articular facet as well as a cross sec-
tion of the nearby squamosal root of the zygo-
matic. Both features arise from the same element,
demonstrating that the glenoid fossa is indeed
squamosal, but that its opposite surface forms
about 90° of the arc of the anteroventral of the bor-
der of the acoustic porus. This is in contrast to P.
strepen, in which the surface opposite the glenoid
is the dorsal surface of the zygomatic root (as
exemplified in AMNH 14502).
Classification and Nomenclature
The classification and nomenclature used in the
Systematic Paleontology section requires justifica-
tion. To do so, it is it is necessary to consider recent
and significant advances in the knowledge of cingu-
late phylogenies in particular (e.g., Delsuc et al.
2003, 2004, 2016; Gibb et al. 2016; Mitchell et al.
2016) and our understanding of the Xenarthra in
general (e.g., Madsen et al. 2001; Murphy et al.
2001; Waddell et al. 2001; Delsuc et al. 2016). These
changes are of such a nature that they alter basic
concepts to a degree that the common vocabulary
used a decade ago (or less) is now antiquated and
new terminology is required and, thus, proposed.
Revolution, Congruence, and Consensus
The dawn of this new millennium brought forth a
molecular revolution in placental mammal system-
atics (e.g., Madsen et al. 2001; Murphy et al. 2001).
This radical new discipline joined an incremental
flow of knowledge from “old school” comparative
anatomy (Englemann 1985; Wible and Gaudin
2004; Gaudin and Wible 2006) and the two intellec-
tual forces converged to overturn fundamental
views regarding cingulate phylogeny (Delsuc et al.
2004, 2016; Gaudin and Wible 2006; Billet et al.
2011; Gibb et al. 2016; Mitchell et al. 2016). For
example, as recent as the milestone mammalian
classification of McKenna and Bell (1997), it had
been considered natural (i.e., phylogenetically
sound) to classify and to think about the armored
xenarthrans in dichotomous terms; that is, as
either “armadillos” (Dasypodidae, sensu lato) or
glyptodonts (Glyptodontidae or Glyptodontoidea,
the latter to also include the Pamptheriidae; e.g.,
Englemann 1985; Gaudin and Wible 2006). How-
ever, advances in the studies of xenarthrans have
raised significant doubts regarding this view. Such
doubts, arising from the independent perspectives
of both molecules (e.g., Delsuc et al. 2004, 2016;
Gibb et al. 2016; Mitchell et al. 2016) and mor-
phology (Englemann 1985; Gaudin and Wible
2006; Gaudin and McDonald 2008; Billet et al.
2011), have converged toward a consensus where
glyptodonts are now regarded as being nested
among traditional “dasypodids” (armadillos) and
that the deepest division in the crown clade is not
between armadillos and glyptodonts, but betwixt
Dasypus spp. and all other extant armadillo genera,
within which the glyptodonts are nested (Figure 2;
Gibb et al. 2016; Delsuc et al. 2016; Mitchell et al.
2016). Recognizing this phylogenetic gulf between
Dasypus spp. and the remaining extant armadillos
and related extinct glyptodonts (a split thought to
have occurred about 42 million years ago; Figure
2), Gibb et al. (2016) proposed the novel and bio-
logically reasonable classification to limit the previ-
ously inclusive “family”, Dasypodidae Gray, 1821,
to a more exclusive clade that includes only Dasy-
pus Linnaeus, 1758 (“long nose armadillos”) and
related extinct taxa (e.g., Stegotherium), essen-
tially the “Dasypus group” of Patterson et al.
(1989:12). The remaining members of the crown
seem to form a clade that Gibb et al. (2016) pro-
posed to gather under a more inclusive
Chlamyphoridae Gray, 1869 composed of the
Chlamyphorinae Yepes, 1928 (the small “fairy
armadillos” Chlamyphorus and Calyptophractus);
the Tolypeutinae Gray, 1865 (Priodontes, Tolypeutes,
and Cabassous; i.e., the “giant”, “three-banded”,
and “naked-tailed” armadillos, respectively), and
the Euphractinae Winge, 1923 (Euphractus,
Chaetophractus, and Zaedyus; the “six banded”,
“hairy,” and “pichy” armadillos). By inference from
morphological studies (e.g., Gaudin and Wible
2006; Billet et al. 2011), as well as the recent molec-
ular phylogenies of Delsuc et al. (2016) and Mitchell
et al. (2016), the Chlamyphoridae also include the
extinct glyptodonts and pampatheres.
Left ambiguous in the work of Gibb et al.
(2016) is the naming of the clade (the crown
clade) that includes both the Dasypodidae and
Chlamyphoridae. The authors listed both “Dasy-
poda” and “Cingulata” at the stem leading to the
branching of Dasypodidae and Chlamyphoridae
on their first cladogram (Gibb et al. 2016, fig. 1)
and, likewise, they titled the heading of the
armadillo section of the paper, “Armadillos (Cin-
gulata/Dasypoda)” (Gibb et al. 2016:628). Not
considered in their study are extinct clades of
armored xenarthrans that are believed to fall
outside the domain of crown armadillos, such
as the Peltephilidae (Gaudin and Wible 2006;
Billet et al 2011; Mitchell et al. 2016) and likely
other taxa, such as Palaeopeltis Ameghino 1895;
Pseudorophodon Hoffstetter, 1958; and species of
Machlydotherium Ameghino, 1902, as well as
other fossil taxa that are older than the hypothet-
ical origin of crown clade of armadillos (e.g., Itab-
oraian taxa; Oliveira and Bergqvist 1998); an
origin that molecular clock dating suggests as hav-
ing occurred from about 40 to 45 Ma (Delsuc et al.
2004, 2012, 2016; Gibb et al. 2016).
Whereas there are extinct armored xenarthrans
that seem to have diverged prior to the node that
defines the crown clade of armadillos and
glyptodonts, and whereas these extinct taxa have
a long history of being classified as members of
the Cingulata, it is desirable to retain Cingulata to
serve as the name for the total clade (sensu de
Queiroz 2007) of armored xenarthrans that
includes both members of the crown and of the
stem (Figure 2).
Dasypodoidea Gray, 1821 is herein proposed
to designate the crown clade of armadillos; that
is, the group that includes Dasypus, Euphractus,
Chlamyphorus, and Toly p e ut e s plus the last com-
mon ancestor of these taxa and all of the descen-
dants of that ancestor (Figure 2). Despite the
awkwardness of the name (compared to that
of “Dasypoda”, sensu Gibb et al. 2016), Dasy-
podoidea is preferred, since “Dasypoda” had
been used in a much narrower sense (e.g., Engle-
mann 1985) than the intentionally inclusive
Dasypodoidea (McKenna and Bell 1997). Also,
though not prohibited by the International Code
of Zoological Nomenclature, it is desirable to
avoid the use of “Dasypoda” since it is the valid
name for a genus of bees (Hymenoptera: Melli-
tidae: Dasypoda).
Xenarthra—One Name, Two Meanings
The recent advances in studies of the Xenarthra
in general include three major points: (1) the
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 391
“xenarthra” (
=
Xenarthra sensu lato, crown +
stem) represent one of the three major clades of
placental mammals; the other two being the
Afrotheria and Boreotheria, where Boreothe-
ria ⫽Laurasiatheria + Euarchontaglires; (Mur-
phy et al. 2001; Madsen et al. 2001); (2) the
“xenarthra” diverged from Afrotheria and
Boreotheria roughly 100 million years ago
(Springer et al. 2003; Delsuc et al. 2004; Foley et
al. 2016) or, perhaps, even earlier (Nishihara et
al. 2009); and (3) Cingulata and Pilosa diverged
about 65 million years ago (Figure 2; Delsuc et
al. 2004, 2012). Thus, it seems that there was a
significant (more than 35 million years) “ghost”
lineage (sensu Norrell 1992) prior to the evolu-
tion of crown clade Xenarthra (Delsuc et al.
2004, 2012).
Such a ghost lineage can be reasonably
inferred by the recognition of over fifty osteolog-
ical synapomorphies for crown Xenarthra
(Gaudin and McDonald 2008). Such a great many
synapomorphies for a group indicates that many
evolutionary transformations occurred in the
stem (Figure 2). But since no stem members are
known, these evolutionary changes were cryptic,
occurring some time after divergence of the clade
from afrotheres and boreotheres and prior to the
rise of the last common ancestor of pilosans and
cingulates.
Although there is a consensus that the major
clade that includes xenarthrans is of a lineage dis-
tinct from Afrotheria and Boreotheria, there is no
consensus as to the relatedness among these three
groups. All three possibilities have been proposed:
(1) “xenarthra” is sister to a monophyletic Epithe-
ria, where Epitheria ⫽Afrotheria + Boreotheria
(McKenna 1975; Kriegs et al. 2006; O’Leary et al.
2013); (2) Afrotheria is sister to a monophyletic
to Exafroplacentalia, where Exafroplacentalia ⫽
“xenarthra” + Boreotheria (Waddell et al. 1999;
dos Reis et al. 2012); and (3) Boreotheria is sister
to Atlantogenata, where Atlantogenata ⫽
Afrotheria + “xenarthra” (Asher et al. 2009; see
Foley et al. 2016 for recent summary). In any of
these cases the “xenarthra” would be nested
among mammals that had such non-xenarthran
characteristics as well-developed, tribosphenic
molar crowns; dentitions of determinate growth;
higher metabolic rates; vertebrae lacking extra,
“xenarthrous” articulations; no armor; and no
ischio-axial reinforced pelvis (McNab 1980;
Gaudin and McDonald 2008 and references
therein).
The point here is that the early stem members
to the crown clade Xenarthra should have looked
quite different from members of the crown. This
great difference of stem members from the crown
must be considered (or even assumed) in order to
contemplate the origins of the peculiar xenarthrans.
However, it is presently common to use the term
“Xenarthra” for both the crown clade and for the
major group of placental mammals to which the
crown Xenarthra are members (e.g., Madsen et
al. 2001; Murphy et al. 2001). But, it is essential
that the crown and stem be differentiated, per-
haps especially so in such a situation where stem
members should be expected to have morpho-
logical traits very different from members of the
crown. Thus, it is undesirable to use the same
name for both the crown and total clade, as it
obscures the expected differences between
crown and stem.
For clarity and to aid in discriminating
between crown and stem, Xenarthra Cope, 1889 is
herein restricted to crown clade, with the new
name “Americatheria” being proposed to desig-
nate the total clade. This name is given in order to
reflect the biogeographic features of the names of
the other two major placental mammal clades
(Afrotheria and Boreotheria) and to imply the sig-
nificance of South America in the Cenozoic bio-
geography of the Xenarthra (see Systematic
Paleontology; Figure 2).
Precedence for recognizing and naming
higher-level taxonomic groups that are far more
inclusive than the known included taxa is well
established. Tubulidentata Huxley, 1872 is exem-
plary (other mammalian examples include the
Embrithopoda Andrews, 1906 and Dermoptera
Illiger, 1811). Huxley established the ordinal level
Tubulidentata at a time when it was known by a
single species, the aardvark, Orycteropus afer
Saint-Hilaire, 1795. Recognizing such higher-level
groups for phylogenetically isolated clades should
call our attention to significant gaps in the record
of life and arouse our awareness of the gaps that
remain in the greater body of knowledge of life.
Conclusions
Salla, the late Oligocene locality that provided
the oldest known reasonably complete skulls of
Bulletin of the Peabody Museum of Natural History 58(2) • October 2017
392
dasypodoidean armadillos (Billet et al. 2011),
also reveals an instructive skull of an ancient
peltephilid. This cranium provides the basis for
the new taxon, Ronwolffia pacifica. In a context
that includes generalized therians (e.g., Didel-
phis, Atelerix, and Leptictis) and geologically
younger peltephilids, R. pacifica seems to retain
some traits that can be judged to be plesiomor-
phic compared with the Miocene peltephilids.
These include eight (rather than seven)
mandibular teeth, unfused mandibular symph-
ysis, and a relatively low, undomed cranial vault.
The mandibular-dental features, however, vary
in referred specimens of R. pacifica, suggesting
a population in which there was indeed signifi-
cant variation. It is possible that the variation
also included great differences in the sizes of
individuals, but prudence has restrained the
referral of some very small peltephilid remains
of Salla to R. pacifica. These are simply referred
to as belonging to an indeterminate taxon,
which may be R. pacifica or a separate, unnamed
species. A single specimen of very large cranial
“horn” suggests the possibility of an additional,
larger peltephilid species at Salla.
Recent cingulate phylogenetic analyses (e.g.,
Gaudin and Wible 2006; Billet et al. 2011; Mitchell
et al. 2016) suggest that the Peltephilidae diverged
prior to the origin of the monophyletic group that
includes the Dasypodidae (sensu stricto of Gibb
et al. 2016) and Chlamyphoridae (sensu lato of
Gibb et al. 2016 to include glyptodonts). This
dasypodid-chlamyphorid clade represents the
crown, designated herein as the Dasypodoidea,
whereas the Cingulata is regarded as the total
clade that includes the crown Dasypodoidea as
well as stem lineages that diverged before the last
common ancestor of members of the crown
evolved, but are more closely related to Dasypus
than to any pilosan (folivoran or vermilinguan).
The Peltephilidae seems to represent such a stem
member of the Cingulata; that is, lying outside the
crown clade, but being more closely related to
Dasypus spp. or Chlamyphorus spp. than to any
pilosan.
Ever since the term was coined (Cope 1889),
Xenarthra has been used to indicate New World
armadillos, sloths, and anteaters. However, with
the molecular revolution at the turn of this new
millennium, “Xenarthra” sensu lato has been
additionally applied to the newly recognized
major placental clade that is sister to both the
Afrotheria and Boreotheria and eventually gave
rise to the Xenarthra sensu stricto (e.g., Madsen
et al. 2001; Murphy et al. 2001; Delsuc et al. 2016).
It is not only proper, but conceptually necessary, to
discontinue this ambiguous practice. Thus, the
total clade (Xenarthra + stem) is herein named the
Americatheria, with the emphasis that the gap
between the origin of the Americatheria and the
origin of the Xenarthra is great, both in terms of
time (more than 35 million years) and in terms of
morphology. There can be little doubt that early
diverging members of the Americatheria did not
look very much like any of the wonderfully
strange members of the Xenarthra—that “great
horde which has peopled South America since the
Eocene” (Cope 1889:657).
Acknowledgments
This study was greatly facilitated by Chris Norris,
Daniel Brinkman, Marilyn Fox, and Eric Sargis of
the Yale Peabody Museum of Natural History,
who provided access to specimens in the divisions
of Vertebrate Paleontology and Vertebrate Zool-
ogy and helped with specimen curation and
preparation. For their various kindnesses and
access to specimens and library resources under
their care, the author is also grateful to Susan Bell,
Ruth O’Leary, and John Flynn of the American
Museum of Natural History; Guillaume Billet and
Christian de Muizon of the Muséum National
d’Histoire Naturelle, Paris; and Richard Hulbert,
Bruce J. MacFadden, and Jonathan Bloch of the
Florida Museum of Natural History. Critical com-
ments from Kevin de Queiroz of the Smithsonian
National Museum of Natural History and Jacques
Gauthier of the Yale Peabody Museum of Natural
History regarding a related project has improved
this present manuscript. Two anonymous review-
ers as well as Kaori Tsukui of the Massachusetts
Institute of Technology provided helpful critiques
and suggestions. Susan Butts, of Yale University,
and the executive editor of the Bulletin, suggested
means to address some issues raised by the
reviewers. Of course, I am solely responsible for
any problematic issues that may remain in this
work.
Received 1 February 2017; revised and accepted 14
June 2017.
New Early Diverging Cingulate (Xenarthra: Peltephilidae) from Bolivia • Shockey 393
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