Article A new species of Peltephilidae (Mammalia: Xenarthra: Cingulata) from the late Miocene (Chasicoan SALMA) of Argentina

Abstract

A new species of Peltephilidae (Mammalia, Xenarthra, Cingulata) (early Eocene–late Miocene) is described here. The new taxon is based on three specimens collected from the margins of Arroyo Chasicó, Buenos Aires Province, (Argenti-na), which correspond to the Arroyo Chasicó Formation (late Miocene, Chasicoan SALMA). The new species is charac-terized by osteoderms with a very rough exposed surface showing high longitudinal and well developed crests (two lateral and one central) with deep and ample valleys among them. The new taxon is the only " relictual " xenarthran cingulate of the Santacrucian Age (late early Miocene) to be registered for the last time in the Chasicoan SALMA (late Miocene), and represents the youngest record of the family Peltephilidae.

Full text

Accepted by M. Weksler: 16 May 2012; published: 28 Jun. 2012
ZOOTAXA
ISSN 1175-5326 (print edition)
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Copyright © 2012 · Magnolia Press
Zootaxa 3359: 55–64 (2012)
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55
A new species of Peltephilidae (Mammalia: Xenarthra: Cingulata) from the late
Miocene (Chasicoan SALMA) of Argentina
LAUREANO R. GONZÁLEZ-RUIZ1,3, GUSTAVO J. SCILLATO-YANÉ2,3,
CECILIA M. KRMPOTIC2,3 & ALFREDO A. CARLINI2,3
1Laboratorio de Investigaciones en Evolución y Biodiversidad (LIEB), Universidad Nacional de la Patagonia “San Juan Bosco” sede
Esquel (UNPSJB), Ruta Nacional 259, km 16.5, 9200, Esquel, Chubut, Argentina. E-mail: gonzalezlaureano@yahoo.com.ar
2División de Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo de La Plata, Paseo del Bosque s/n, 1900 La Plata,
Argentina. E-mail: scillato@fcnym.unlp.edu.ar , ckrmpotic_pv@museo.fcnym.unlp.edu.ar, acarlini@fcnym.unlp.edu.ar
3CONICET
Abstract
A new species of Peltephilidae (Mammalia, Xenarthra, Cingulata) (early Eocene–late Miocene) is described here. The
new taxon is based on three specimens collected from the margins of Arroyo Chasicó, Buenos Aires Province, (Argenti-
na), which correspond to the Arroyo Chasicó Formation (late Miocene, Chasicoan SALMA). The new species is charac-
terized by osteoderms with a very rough exposed surface showing high longitudinal and well developed crests (two lateral
and one central) with deep and ample valleys among them. The new taxon is the only “relictual” xenarthran cingulate of
the Santacrucian Age (late early Miocene) to be registered for the last time in the Chasicoan SALMA (late Miocene), and
represents the youngest record of the family Peltephilidae.
Key words: Xenarthra, Peltephilidae, Miocene, Chasicoan SALMA, Argentina
Introduction
The Peltephilidae (Xenarthra, Cingulata) are a peculiar group of fossil mammals known since the late XIX century
(Ameghino 1887) and characterized by a short and broad rostrum, high skull, short jaw, completely fused and
expanded mandibular symphysis, teeth with chisel-like occlusal surfaces forming a complete series without
diastema, U-shaped dental arcade, dental formula 7/7, and the presence of a pair of osteoderms on the nasals and
maxillaries forming recurved “horns” (Ameghino, 1891, 1894; Scott, 1903). Like all cingulates, they have a dorsal
carapace of osteoderms regionalized in a cephalic shield, a dorsal shield, and a caudal sheath (Engelmann, 1985).
Peltephilines were traditionally regarded as specialized carnivores (Hoffstetter, 1958), but recent analyses
(Vizcaíno & Fariña, 1994, 1997; Vizcaíno, 2009) proposed an alternative view for peltephilines as having fed on
moderately tough items, although animalivory cannot be excluded as a dietary habit, which might have included
plant material of underground origin in addition to carrion.
The Peltephilidae are registered exclusively in South America and are recorded from the Paleogene (early
Eocene, Riochican SALMA; Scillato-Yané, 1986; Carlini et al., 2005, 2010) to the Neogene (late Miocene, Chasi-
coan SALMA; Pascual, 1965). The last detailed systematic revision of the group dates from the 1930s (Bordas,
1936, 1938). According to the catalogue of Mones (1986), there are five genera (Peltephilus Ameghino, Peltecoe-
lus Ameghino, Anantiosodon Ameghino, Epipeltephilus Ameghino, and Parapeltecoelus Bordas) and 17 species of
Peltephilidae formally nominated, of which 12 were considered valid by Scillato-Yané (1980). In addition, two
undescribed species are referred in the literature (Barrio et al., 1984; Croft et al., 2009).
The presence of Chasicoan Peltephilidae is known since Cabrera and Kraglievich (1931) mentioned materials
of Peltephilus or an allied genus from Arroyo Chasicó, Buenos Aires Province (Figure 1). Later on, those speci-
mens, as well as newly collected material, were assigned to Epipeltephilus by Kraglievich (1934), Pascual (1965),
and Cattoi (1966), sometimes with a doubtful specific identification.

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Scillato-Yané (1979) identified three specimens of peltephilids from the Chasicoan and described one of them
briefly. This author assigned all the specimens to Peltephilidae incertae sedis, because previous identifications
were not based on empiric evidence and because they were not clearly assigned to any of the known genera. Later
on, Scillato-Yané (1982), in his unpublished PhD dissertation, recognized a new genus and species of Peltephilidae
based on same three specimens; unfortunately, this description remains unpublished.
After studying the specimens identified by Scillato-Yané (1979, 1982), as well as a new specimen collected
during recent field work in Arroyo Chasicó, we have concluded that the material represents a new species of
Epipeltephilus. This new species, exclusive to the Chasicoan fauna, is the youngest record of the family Peltephili-
dae.
FIGURE 1. Geographic location of the type locality Arroyo Chasicó, Buenos Aires Province, Argentina.
Material and methods
Characteristics of osteoderms of the cephalic shield, dorsal shield, and caudal sheath of cingulates have tradition-
ally been used in the diagnosis and description of the different genera and species. In fact, most taxonomic studies
on fossil armadillos are based on different patterns of ornamentation and morphology of the osteoderms from the
carapace (Ameghino, 1889; Yepes, 1928; Hoffstetter, 1958; Paula Couto, 1979; Scillato-Yané, 1982; Wetzel, 1982;
Carlini et al., 2009, 2010). The terminology here used to describe the osteoderms follows Croft et al. (2007), Krm-
potic et al. (2009), and Carlini et al. (2009).
We follow the higher level taxonomic arrangement of McKenna and Bell (1997), as well as the catalogues of
Scillato-Yané (1980) and Mones (1986) for the species of Peltephilidae considered valid, and the preliminary list-
ing offered by González (2010a, b). The geochronologic scheme follows Flynn and Swisher (1995). We examined
specimens from the following institutions: MACN: Museo Argentino de Ciencias Naturales “Bernardino Rivada-
via”, Buenos Aires, Argentina; MACN A: Colección Nacional Ameghino, Museo Argentino de Ciencias Naturales
“Bernardino Rivadavia”, Buenos Aires; MLP: División Paleontología de Vertebrados, Facultad de Ciencias Natu-
rales y Museo, Universidad de La Plata, La Plata, Argentina; MMP: Museo Municipal de Ciencias Naturales de
Mar del Plata “Lorenzo Scaglia”, Mar del Plata, Argentina.
For comparative purposes, the following specimens were studied: Peltephilus strepens Ameghino 1887
(MACN A 771; MLP 55-XII-13-132; MLP 67-VIII-13-2; MLP 69-IX-9-18); Peltephilus pumilus Ameghino 1887
(MACN A 866-870; MLP 67-XI-13-1a3); Peltephilus giganteus Ameghino 1894 (MACN A 4891-4900, type);
Peltephilus ferox Ameghino 1891 (MACN A 4901, type; MACN A-7784-7798); Peltephilus nanus Ameghino
1898 (MACN A 7958-7959, type); Peltephilus depressus Ameghino 1897 (MACN A 12016, type); Peltephilus

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granosus Ameghino 1902 (MACN A 12019, type); Peltephilus protervus Ameghino 1897 (MACN A 12020, type);
Peltephilus depressus Ameghino 1897 (MACN A 12016, type); Anantiosodon rarus Ameghino 1891 (MACN A
5119, type); Peltecoelus praelucens Ameghino 1902 (MACN A 12022, type); Parapeltecoelus pattersoni Bordas
1938 (MACN 11946, type); Epipeltephilus recurvus Ameghino 1904 (MACN A 11641, type); Epipeltephilus
recurvus? (MLP 16-2; MLP 69-XII-19-5; MLP 69-XII-19-9; MLP 91-IX-7-14).
Results
Most of the species of Peltephilidae (E. recurvus, Peltephilus nanus, P. giganteus, P. protervus, P. depressus, P.
granosus, Peltecoelus praelucens) are known by few osteoderms (< 10), while Peltephilus pumilus and P. strepens
are known by a few more osteoderms (< 100). If we consider that extant “armadillos” have between 600–1000
osteoderms (Vizcaíno y Bargo, 1993; González, 2010a), we conclude that carapaces of Peltephilidae are still poorly
known. Thus, the knowledge of the carapace of Peltephilidae is based on the genus Peltephilus, which is repre-
sented by more complete specimens (Scott, 1903). The cephalic shield is formed by 19–21 large osteoderms that
are placed following a pattern: three large hexagonal osteoderms in the middle line, the posterior one being the
larger, and seven polygonal osteoderms on each side. In front of the middle line there are two large “horn-like”
osteoderms on the nasals and maxilars. There were possibly two additional anterior osteoderms (Ameghino, 1894;
Scott, 1903). The osteoderms from the caudal sheath are still unknown.
Epipeltephilus is a monotypic taxon (E. recurvus) and the holotype (MACN A 11641) comes from Lago
Blanco (=Laguna Blanca) Chubut Province (Río Mayo Formation, “Mayoan” SALAMA). The type is formed only
by a portion of the skull and one hemi-mandible. There are four groups of osteoderms from other Mayoan localities
assigned to Epipeltephilus recurvus: MLP 16-2 and MLP 69-XII-19-9, from Río Huemules; MLP 69-XII-19-5
from Río Genguel; and MLP 91-IX-7-14 from Cerro Guenguel (see González, 2010a). Another mention of
?Epipeltephilus from Río Senguer (Kraglievich, 1930; Bondesio et al., 1980) is a misidentification, and the osteo-
derms belongs to Proeutatus sp. (MLP 16-5) (see González, 2010a).
The allocation of this new species within Epipeltephilus is based on the characters of the osteoderms surface of
the dorsal carapace, principally the combination of roughness of the exposed surface and the development of ele-
vated longitudinal crests. Given the absence of a phylogenetic analysis of the Peltephilidae the diagnosis of the spe-
cies of this family are based almost exclusively on qualitative characters of the osteoderms (see González, 2010a).
Systematic Paleontology
Xenarthra Cope 1889
Cingulata Illiger 1811
Dasypodoidea Gray 1821
Peltephilidae Ameghino 1894
Epipeltephilus Ameghino 1904
Type specie. Epipeltephilus recurvus Ameghino 1904.
Included species. The type species and the species described below.
Diagnosis (emended from Ameghino, 1904 and González, 2010a). Skull larger and posteriorly wider and shal-
lower than Peltephilus and Parapeltecoelus, and with the temporal and parietals extended laterally. Sagittal and
occipital crests less developed than Peltephilus. The mandibular ramus is larger than that of Peltephilus and with
vertically implanted molariforms, which are anteriorly inclined in Peltephilus. The upper molariforms (as well the
lower in Peltephilus) are sub-elliptical, whereas they are prismatic-triangular in Peltephilus and Parapeltecoelus.
The last upper molariform is similar in shape to other of the same series unlike Peltephilus and Parapeltecoelus
which have very small last molariforms. The osteoderms of the dorsal carapace of Epipeltephilus are rougher and
with more elevated and developed crests than Peltecoelus and Peltephilus.

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Epipeltephilus kanti new species
(Figures 2–3A)
Etymology. “kanti” in honor of the Prussian philosopher Emmanuel Kant (1724–1804), brilliant creator of the crit-
icism and precursor of the modern scientific philosophy.
Holotype. MLP 92-XI-19-7, three fixed osteoderms of the dorsal shield (Figure 2 A–C).
Geographic and stratigraphic occurrence of the holotype. Arroyo Chasicó (38°37´06.10´´S,
62°59´14.53´´W), Buenos Aires Province, Vivero Member, Arroyo Chasicó Formation, Chasicoan SALMA. Mate-
rial collected during a field trip organized by the Facultad de Ciencias Naturales y Museo de La Plata (Argentina)
and Duke University (USA).
FIGURE 2. Osteoderms of Epipeltephilus kanti: A–C, Holotype (MLP 92-XI-19-7); D–G, Referred material, D–G (MLP 28-
X-11-66), H (MMP 339-M). Scale Bar: 5 cm.
Referred material. MLP 28-X-11-66, three complete, fixed osteoderms and an additional fragment of the dor-
sal shield (Figure 2 D–G); MLP 60-VI-18-3, one molariform and osteoderms of an indeterminate region of the dor-
sal shield; MMP 339-M, one movable osteoderm of the dorsal shield (Figure 2 H). All specimens were collected in
the Vivero Member, Arroyo Chasicó Formation (Figure 1).
Differential diagnosis. Osteoderms larger than those of Peltephilus nanus and Peltephilus pumilus, and simi-
lar in size to those of Epipeltephilus recurvus, Peltecoelus praelucens, and the other species of Peltephilus. Longi-
tudinal crests (two lateral and one central) are higher and more developed than in Epipeltephilus recurvus,
Peltephilus giganteus, Peltephilus pumilus, Peltephilus strepens and Peltephilus protervus. These crest are absent
in Peltecoelus praelucens, Peltephilus depressus, Peltephilus granosus and Peltephilus nanus. Exposed surface of
the osteoderms roughed like Epipeltephilus recurvus much more than the species of Peltephilus and Peltecoelus
praelucens.

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Comparative description. Molariform. Scillato-Yané (1982) described the molariform MLP 60-VI-18-31 as
very small and lower because the main wear pit is located externally, as in Peltephilus according to Scott (1903),
and it would correspond to the third or fourth molariform of the left dental series. It is broken in its base and the
preserved part measures 7.6 mm of maximum antero-posterior diameter, and 3.5 mm of maximum cross-sectional
diameter.
According to Scillato-Yané (1982) the molariform section is subtriangular, less compressed than in Anantio-
sodon, whereas in Epipeltephilus (E. recurvus) teeth are subeliptic. In addition, Vizcaíno and Fariña (1997: 81)
remarked that the molariforms of Peltephilus are “chiefly triangular in section and slenderly built”. Lower molari-
forms of Peltecoelus and Parapeltecoelus are not known.
Osteoderms of the dorsal shield. Shape and size. The known osteoderms of Epipeltephilus kanti are rectan-
gular or quadrangular (Figure 2 A–H). They cover a large range of sizes (Table 1), indicating that osteoderms from
different regions of the dorsal shield are represented; also, that the size variation of the osteoderms was probably
remarkable at intraspecific level, depending on the regions of the dorsal shield, as it happens in Eutatus (Burmeis-
ter, 1883; Scillato-Yané, 1982).
In relation to other species of Peltephilidae, the osteoderms of Epipeltephilus kanti are larger than those of
Peltephilus nanus, and generally larger than those of Peltephilus pumilus, but within the range of variation of the
remaining species of Peltephilus, as well as Epipeltephilus recurvus and Peltecoelus praelucens (Table 1).
TABLE 1. Measurements of osteoderms and their associated foramina (mm).
Foramina. Osteoderms of Epipeltephilus kanti generally have one or two big oval foramina, which can be
associated to glandular cisterns (Scillato-Yané, 1979; Croft et al., 2007). In the case of Epipeltephilus kanti, the
largest foramina correspond to the largest osteoderms (Figure 2 A–H, 3A). In some osteoderms, there is a smaller
foramen between and over the previous ones; this character is mentioned by Croft et al. (2007) for the osteoderms
of a specimen of cf. Peltephilus sp. One movable osteoderm of Epipeltephilus kanti has a third big foramina under-
neath the two bigger (Figure 2 H).
Much variation has been documented for the number of osteoderm foramina in different species of Peltephili-
1. : * We searched this specimen several times in the MLP collections with Dr. Marcelo Reguero (Collection Manager) and
with Dr. Scillato-Yané (who originally described it in 1982) but we could not find it. Unfortunately, the molariform is lost
in the Museum and the illustrations given by Scillato-Yané (1982: plate 1, figura 4) do not have enough resolution for com-
parisons.
Taxon Osteoderm
type Osteoderm surface Foramina
Width
(min-max) Length
(min-max) Width
(min-max) Length
(min-max)
Epipeltephilus kanti Fixed 12.4–27.1 11.5–29.5 1.4–3.1 1.6–3.5
Movable 16.1 24.6 1.4–1.9 0.8–1.0
Epipeltephilus recurvus?Fixed 12.1–19.0 11.2–22.6 2.0–2.8 2.2.–2.5
Movable 17.6–21.5 22.3–23.9 1.0–1.6 2.1–2.6
Peltephilus strepens Fixed 13.8–21.1 16.4–25.4 1.2–1.5 1.7–1.5
Movable 16.5–19.3 18.6–27.1 0.9–0.9 1.1–1.3
Peltephilus pumilus Fixed 9.1 12.5 1.1–1.5 1.2–1.4
Movable 8.5–11.9 10.2–15.8 0.9–2.5 1.0–2.7
Peltecoelus praelucens Fixed 14.8–23.4 19.3–25.8 3.0 2.4
Peltephilus nanus Fixed 7.7–8.7 5.9–7.2 1.3–1.9 1.2–1.8
Peltephilus protervus Movable 22.3 35.8 2.4 2.6
Peltephilus giganteus Fixed 12.4–13.6 16.0–17.1 1.85–2.2 2.3–2.5
Peltephilus depressus Movable 17.4–19.7 22.5–26.2 1.4–2.1 1.6–1.7
Peltephilus granosus Fixed 14.5–13.0 17.8–23.3 1.8–2.4 2.4–2.8

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dae: Peltephilus strepens has two or four (Ameghino 1887) (Figure 3 F–G); Peltephilus pumilus, P. nanus, P.
giganteus, P. protervus and P. granosus have two (Figure 3 C, D, E, H, J); Peltephilus depressus has two or three;
Ameghino (1897) mentioned four foramina for that species, but the type and assigned material have two or three
(Figure 3 I); Peltecoelus praelucens has three foramina (Ameghino, 1902) (Figure 3 K), and Epipeltephilus recur-
vus has generally four foramina (Croft et al., 2009) (Figure 3 B), although there are also osteoderms with one, two
or three foramina.
Crests. The osteoderms of Epipeltephilus kanti have one middle longitudinal crest and two lateral longitudinal
crests. All of them are elevated, wide and have rough margins, with the subsequent development of deep and ample
valleys among them. The middle longitudinal crest may or may not reach the posterior border while the two laterals
always do. The posterior border is elevated and has rough margins.
Some osteoderms of Epipeltephilus recurvus have a middle longitudinal crest, but unlike Epipeltephilus kanti,
it is a narrow and not high. Peltephilus giganteus has three longitudinal crests, but they are rounded, without rough-
ness and without ample valleys between them (Figure 3 E). Peltephilus protervus has a smooth and well developed
crest, which extends only one half the surface of the osteoderm, being anteriorly wide and disappearing posteriorly
(Ameghino, 1897) (Figure 3 H). A longitudinal crest is developed in Peltephilus strepens (Figure 3 F–G)
(Ameghino, 1887), but it is low instead of marked as in P. giganteus or Epipeltephilus kanti. Some osteoderms
assigned to Peltephilus pumilus have a high and narrow longitudinal middle crest (Ameghino, 1887) (Figure 3C),
whereas in other specimen assigned to this species this crest is absent. The osteoderms of Peltephilus nanus, Pelte-
philus depressus, Peltephilus granosus and Peltecoelus praelucens lack the longitudinal crests (Ameghino, 1897;
Ameghino, 1902) (Figure 3 D, I, J, K).
Surface roughness. The exposed surface of the osteoderms of Epipeltephilus kanti is rougher than any other
Peltephilidae. The osteoderms of Epipeltephilus recurvus are not as rough as in E. kanti. Peltephilus pumilus, P.
nanus, P. giganteus, and P. strepens has osteoderms with similarly rough surfaces (Figure 3 C–G), but rougher than
in Peltephilus protervus, P. depressus, and Peltecoelus praelucens (Figure 3 H, I, K), and less than E. recurvus and
E. kanti (Figure 3 A–B). Although P. granosus has an anterior rough region, Peltephilus protervus and P. granosus
has smooth and punctuate surfaces (Ameghino, 1897, 1902). Finally, although Ameghino (1902) remarks that the
osteoderms of Peltecoelus praelucens are completely smooth, we observed that they are also punctuate.
Geochronology and biostratigraphy. The first fossils from Arroyo Chasicó (Figure 1) were collected by S.
Roth and his assistant B. Eugui around 1915 (Kraglievich, 1934; Pascual, 1961; Bondesio et al., 1980). Cabrera
(1928) and Kraglievich (1934) were the first to mention this locality, followed by works of Reig (1957), Pascual
(1961, 1965), and Pascual et al. (1965).
Kraglievich (1934) recognized the Chasicoan (“Chasicoense”) geologic horizon and assigned a Miocene age
to its fauna, while indicating that: “…esta fauna es casi equivalente a la más antigua de Entre Ríos y su edad puede
considerarse Miocena” (Kraglievich, 1934: 89). Pascual (1961, 1965) and Pascual et al. (1965) defined the Arroyo
Chasicó Formation indicating the existence of outcrops in the headwaters of Arroyo Chasicó and in the cliffs of the
Chasicó lagoon (type area). They also recognized a Chasicoan SALMA on the basis of the presence of “relictual”
mammals from the Santacrucian SALMA and the primitive character of the Pan-Araucanian predominant taxa.
Bondesio et al. (1980) summarized the data on the geology and fossil mammals of the area and divided Arroyo
Chasicó Formation into two Members: the lower Vivero Member and the upper Las Barrancas Member. According
to these authors, these members are related to two different biozones: 1) Biozone of Chasicotherium rothi
Ameghino, which is a local representation of the “Viverense” (lower Chasicoan); and 2) Biozone of Chasicotatus
ameghinoi Scillato-Yané, which represents the “Barranquense” (upper Chasicoan). Both units were deposited dur-
ing the earliest part of the late Miocene (Tonni et al., 1998; Cione et al., 2000). Zárate et al. (2007) conducted a
geologic study of the Chasicoan deposits recognizing different lithofacies and paleosols. This lithofacial adjust-
ment does not fit with the lithostratigraphic division of the Arroyo Chasicó Formation in two members.
In accordance with the more recent biostratigraphic scheme proposed by Verzi et al. (2008), Chasicotatus
ameghinoi was recorded in the Biozones of Chasichimys bonaerense Pascual, Chasichimys scagliai (Pascual), Xen-
odontomys simpsoni Kraglievich and Xenodontomys elongatus (Verzi, Montalvo & Tiranti). For that reason, Verzi
et al. (2008) suggested to change the Biozone of Chasicotatus ameghinoi, since it would be not an exclusive taxon
for that biozone. Finally, Schultz et al. (2004) presented an 40Ar/39Ar age of 9.23 ± 0.09 Ma for Arroyo Chasicó For-
mation, placing the Chasicoan fauna between the Mayoan (ca.10.0–11.8 Ma) and the Huayquerian (6.8–9.0 Ma)
faunas, in the time interval of ca. 9.0–10.0? Ma based on the scheme by Flynn and Swisher (1995).

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FIGURE 3. Osteoderms of Peltephilidae: A, Epipeltephilus kanti (MLP 92-XI-19-7, part of the holotype); B, Epipeltephilus
recurvus? (MLP 91-IX-7-14); C, Peltephilus pumilus (MACN A-866-870); D, Peltephilus nanus (MACN A 7958-7959, part of
the type); E, Peltephilus giganteus (MACN A-4891-4900, part of the type); F-G, Peltephilus strepens (MACN A-771); H,
Peltephilus protervus (MACN A-12020, part of the type); I, Peltephilus depressus (MACN A-12016, part of the type); J, Pelte-
philus granosus (MACN A-12019, part of the type); K, Peltecoelus praelucens (MACN A-12022, part of the type). Scale Bar:
5 cm.
Discussion and conclusions
The Peltephilidae are represented by 12 recognized valid species distributed in 5 genera (Scillato-Yané, 1980),
from which 11 are registered during late Oligocene–early Miocene (ca 28.4–15.97 Ma), and only one, Epipeltephi-
lus recurvus, during the entire middle and late Miocene (ca 15.97–5.33 Ma), specifically for the upper part of the
middle Miocene (Río Mayo Formation, Mayoan SALMA, ?10.0–11.8 Ma). In that context, although peltephilids
for the late Miocene (Arroyo Chasicó Formation, Chasicoan SALMA, 9.0–10.0? Ma) were mentioned and briefly
described, they have never been formally nominated and studied in detail.

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Only the holotype of the new taxon (MLP 92-XI-19-7) has precise stratigraphic information, i.e., that of
Arroyo Chasicó Formation, and was collected in the Vivero Member, lower in the section (in schedula). Bondesio
et al. (1980) mentioned the Peltephilidae only for the Vivero Member, implying that all other known specimens
may come exclusively from this Member.
On the basis of the particular “aggregate” of fossil mammals, Pascual (1965) and Pascual et al. (1965) recog-
nized the Chasicoan SALMA, characterized by “la presencia de mamíferos Pan-santacrucianos y en el carácter
primitivo de sus elementos Pan-araucanianos, que son predominantes” (Pascual et al., 1965: 177). Within these
“santacrucian mammals” recorded up to the Chasicoan, two cingulate xenarthrans are included: the Peltephilidae,
and one Dasypodidae Euphractinae, the genus Vetelia Ameghino (Scillato-Yané, 1986). The latter has been recently
recorded in several Huayquerian localities, slightly younger than the Chasicoan (Esteban & Nasif, 1996; Esteban et
al., 2001; Ciancio et al., 2006; Georgieff et al., 2004; Tonni et al., 1998); therefore, its biocron exceeds the Chasi-
coan SALMA and are no longer considered as the last occurrence of those “relictual” Santacrucian taxa. According
to this, within the Cingulata, the Peltephilidae, with Epipeltephilus kanti, is the only “relictual Santacrucian” taxon
whose last record is the Chasicoan SALMA. In addition, although Ameghino (1906: 482) indicated in a list of taxa
the presence of “?Peltephilus” for its “ Faunas Entrerrianas”, that record was opportunely disestimated by Scil-
lato-Yané (1982: 62), essentially because the material was never described or figured, and has not been found in its
repository (MACN). At the moment, Epipeltephilus kanti sp. nov. is the youngest record of the entire family Pelte-
philidae.
Finally, the presence of Epipeltephilus, Vetelia perforata, and Palaehoplophorini (“Hoplophorinae”) in the
Mayoan and Chasicoan (all absent in the Colloncuran), as well as the absence of Stegotheriini, Proeutatus (Euta-
tini), Stenotatus (Eutatini), Prozaedyus (Euphractini), and Propalaehoplophorinae (all recorded in the Colloncuran)
indicates a closer affinity between the Mayoan and Chasicoan faunas than between the Mayoan and the Collon-
curan ones, according whit the interpretations of Bond (1993) and Vucetich et al. (1993) for native ungulates and
rodents, respectively.
Acknowledgements
The authors wish to thanks M. Reguero (MLP) and S. M. Álvarez (MACN) for allowing us the access to the collec-
tions of fossil mammals under their care. To D. Croft (CWRU School of Medicine) for information about Epipelte-
philus. To A. A. Dondas (MMP) for pictures of the specimen MMP 339-M. M. Tejedor and G. Martin have
contributed with the English translation. To D.A. Croft and D. Perea for their reviews and helpful suggestions. The
research project of the middle Miocene of Patagonia was funded by the National Science Foundation (to R.F. Kay,
Duke University, USA), providing the type of the new species here described. To the FCNYM (for the N-593 and
N-568 to AAC).
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