Content uploaded by Marcelo A. Reguero
Author content
All content in this area was uploaded by Marcelo A. Reguero on Jul 15, 2014
Content may be subject to copyright.
NEW LATE OLIGOCENE HEGETOTHERIIDAE (MAMMALIA, NOTOUNGULATA)
FROM SALLA, BOLIVIA
MARCELO A. REGUERO
1
and ESPERANZA CERDEÑO
2
1
Departamento Científico de Paleontología de Vertebrados, Museo de La Plata. Paseo del Bosque s/n, B1900 FWA La Plata,
Argentina, regui@fcnym.unlp.edu.ar
2
IANIGLA-CRICYT, Avenida Ruiz Leal s/n, 5500 Mendoza; and Museo de Ciencias Naturales y Antropológicas
“J. C. Moyano”, Parque Gral. San Martín, 5500 Mendoza, Argentina
ABSTRACT—The diverse fauna from Salla, western Bolivia, represents a rare glimpse into the evolutionary history of
Tertiary South American mammals outside of Patagonia (Argentina). The Hegetotheriidae (Notoungulata) from the
Deseadan of Salla are composed of two taxa, a new genus and species and a species of Prohegetotherium.Sallatherium
altiplanense gen. et sp. nov., differs from Prohegetotherium by its very long, thin nasals; more medially placed labial groove
on upper cheek teeth; more reduced I2-I3-C and i3-c separated by diastemata; and much narrower symphysis. The
smaller, more common hegetothere from Salla is identified as Prohegetotherium schiaffinoi; the abundant new material
from Bolivia permits a better characterization of this otherwise poorly known species from Uruguay and Argentina
(Corrientes and Entre Ríos provinces). The Divisaderan Ethegotherium carettei from Argentina is regarded as a junior
synonym of P.schiaffinoi, extending the chronologic range of the genus into the early Oligocene. A revised diagnosis of
the type species of Prohegetotherium,P.sculptum, is provided based on new material. This species is known exclusively
from Argentina.
INTRODUCTION
The Hegetotheriidae (order Notoungulata) is represented dur-
ing the Deseadan age by two subfamilies, the Hegetotheriinae
with two genera, Prohegetotherium and Sallatherium, gen. nov.,
and the Pachyrukhinae with three genera (Reguero, 1999). Pro-
hegetotherium and its type species P.sculptum were originally
described by Ameghino (1897) on two fragmentary maxillae
probably from Cabeza Blanca, Chubut, Argentina. In the origi-
nal description, Ameghino (1897) emphasized the resemblance
with Hegetotherium of the Santacrucian age, but differentiated
Prohegetotherium by its having a labial groove near the anterior
margin of the cheek teeth and a well-developed canine.
MacFadden et al. (1985) noted the presence of two hegetoth-
eres from Salla, Bolivia, and referred to them as Prohegeto-
therium sp. A and B, of large and small size, respectively. While
studying the Deseadan hegetotheres from Argentina, Reguero
(1999) confirmed the presence of two hegetotheres at Salla. The
identification and detailed description of these taxa are the pri-
mary subject of this paper. One is recognized as a new genus and
species, whereas the other is recognized as Prohegetotherium
schiaffinoi, a poorly known species from the Fray Bentos For-
mation in Uruguay (Kraglievich, 1932). Some Argentinean fos-
sils are also referred to this taxon. Based on more complete
material from Patagonia, we provide a revised diagnosis for the
Deseadan species Prohegetotherium sculptum, exclusively re-
corded in Argentina.
We consider the small hegetothere from Salla, as well as the
Divisaderan Ethegotherium carettei, to belong in the genus Pro-
hegetotherium (Reguero, 1999; Reguero and Cerdeño, 2001).
Prohegetotherium is paraphyletic in a recent phylogenetic analy-
sis of the Hegetotheriidae (Castro, 2001). However, the phylo-
genetic analysis of Castro (2001) was preliminary, some charac-
ters were not included, and the nodes have low support. Also,
Castro (2001) only used fragmentary material of P.sculptum and
did not include material from Bolivia. López (2002) regarded E.
carettei as a valid taxon, but he only compared E.carettei with P.
sculptum and Hegetotherium mirabile, and not with specimens
from Salla. Consequently, and also following Bond and López
(1997) and Cerdeño and Contreras (2000), we recognize the fol-
lowing genera in the Hegetotheriinae: Prohegetotherium
Ameghino, from the Divisaderan (early Oligocene, Pascual et
al., 1996) of Argentina and the Deseadan (late Oligocene) of
Bolivia, Uruguay and Argentina; Sallatherium, gen. nov. from
the Deseadan of Bolivia; Hegetotherium Ameghino from the
Colhuehuapian (early Miocene) and Santacrucian (middle Mio-
cene) of Patagonia; and Hemihegetotherium Rovereto (including
Pseudohegetotherium) from the Chasicoan (late Miocene) and
Huayquerian (late Miocene) of Argentina.
Salla is located about 95 km southeast of La Paz, in the Salla-
Luribay Basin, northwestern Bolivia (Fig. 1; Hoffstetter, 1968).
Since its discovery in 1962, many expeditions to Salla have pro-
duced rich samples of mammals considered representative of the
Deseadan South American Land Mammal Age (Hoffstetter,
1969, 1976; Hoffstetter and Lavocat, 1970; Lavocat, 1976; Patter-
son and Wood, 1982; Villarroel and Marshall, 1982; Hoffstetter
and Petter, 1983; Petter and Hoffstetter, 1983; Soria and Hoff-
stetter, 1983; MacFadden and Frailey, 1984; Wolff, 1984, 1985;
Bond, 1991; Vucetich, 1991; Reguero and Cifelli, 1997; Shockey,
1997a, b). Previously considered to be early Oligocene, radio-
metric data suggested a late Oligocene age for the Salla beds
(MacFadden et al., 1985; Naeser et al., 1987; Kay et al., 1998),
between 25 and 29 Ma. Reguero et al. (2003a) stated that the
Salla Fauna best matches that from the upper Oligocene Fray
Bentos Formation (Deseadan) of Uruguay.
MATERIAL AND METHODS
The studied material from Salla derives from the fossil verte-
brate collections of the ACM, Pratt Museum at Amherst Col-
lege, Amherst, Massachusetts, Florida Museum of Natural His-
tory (UF), Gainesville, Florida, USA, and the Museo Nacional
de Historia Natural (MNHN-BOL), La Paz, Bolivia. Argentin-
ean fossils included in this study belong to the Museo de La Plata
(MLP), La Plata, Argentina; the Museo Argentino de Ciencias
Naturales “Bernardino Rivadavia” (MACN), Buenos Aires, Ar-
gentina; PZ-Ctes, PRINGEPA (Programa de Investigación
Geológica y Paleontológica), Corrientes, Argentina; American
Museum of Natural History (AMNH), New York, USA; and
Field Museum of Natural History (FMNH), Chicago, USA. The
Journal of Vertebrate Paleontology 25(3):674–684, September 2005
© 2005 by the Society of Vertebrate Paleontology
674
Uruguayan material is housed at the Museo Nacional de Historia
Natural de Montevideo (MNHN-DP), Uruguay. A detailed list
of specimens is in Appendix 1.
Dental terminology follows Reguero (1999), and for the de-
scription of dental imbrication we follow Villarroel (1974). For
distinguishing contacts between nasal, premaxillary and maxil-
lary bones from typical sutures in other mammals, we use the
term ‘imbrication’sensu Francis (1965). All dimensions are ex-
pressed in millimeters.
Abbreviations—APD/TD, anteroposterior/transversal diam-
eters; D/d, upper/lower deciduous premolars; I/i, upper/lower
incisors; L, length; M/m, upper/lower molars; Ma, Megannum;
P/p, upper/lower premolars; SALMA, South American Land
Mammal Age; W, width.
SYSTEMATIC PALEONTOLOGY
Order NOTOUNGULATA Roth, 1903
Suborder HEGETOTHERIA Simpson, 1945
Family HEGETOTHERIIDAE Ameghino, 1894
Subfamily HEGETOTHERIINAE Ameghino, 1894
SALLATHERIUM, gen. nov.
Prohegetotherium MacFadden et al., 1985:242, fig. 10 (partim);
Reguero, 1999:178, 182–184 (partim), figs. 32, 33
Type and Only Known Species—Sallatherium altiplanense,
sp. nov.
Diagnosis—Hegetotheriinae with nasals especially long and
thin, not enlarged posteriorly. Labial groove on upper cheek
teeth more medially placed than in Prohegetotherium.I1en-
larged, more oval in cross-section and more obliquely implanted
than in Prohegetotherium,Hegetotherium and Hemihegeto-
therium. I2-I3-C more reduced than in Prohegetotherium and
separated by diastemata, contrary to Prohegetotherium and
Hemihegetotherium, which have a closed dental series. P3-M3
with ovoid occlusal outline, different from the more quadrangu-
lar section of other hegetotheriines. Mandible with symphysis
much narrower than in other hegetotheriines. Lower canine ab-
sent, i3 reduced, and a diastema separates i3 and p1. Lower p3
with anterior lobe longer than posterior one, contrary to Prohe-
getotherium and Hemihegetotherium.
Geographic and Chronologic Distribution—Salla, Bolivia
(Fig. 1). Deseadan SALMA, late Oligocene.
Etymology—The generic name Sallatherium refers to the
Salla locality, Bolivia.
SALLATHERIUM ALTIPLANENSE, sp. nov.
Prohegetotherium sp. A: MacFadden et al., 1985:242, fig. 10.
Prohegetotherium sculptum: Reguero, 1999:178, 182–184 (par-
tim), figs. 32, 33.
Holotype—UF 91621, partial skull with right and left com-
plete upper dental series I1-M3, and associated incomplete man-
dible with right i1-3, p1-m3 and left i1-3, p1-m2 (Fig. 2). Col-
lected from the “Estratos de Salla”, Upper Salla Beds, Bolivia by
Mr. Félix Vargas in 1984.
Diagnosis—As for the genus.
Distribution—Salla, Bolivia. Deseadan SALMA, late Oli-
gocene.
Etymology—The name altiplanense refers to the highland Al-
tiplano region of Bolivia.
Referred Specimens—UF 172150, palate with left C, P1-P2
(broken), P3-M1, M2 (broken), M3, and right P3, P4-M3 (bro-
ken), and associated partial left dentary with m1-m3 (broken)
and partial right dentary with p2-p4; UF 172454, left maxilla with
M1 (broken), M2-M3; UF 172406, isolated left M1 or M2; UF
91622, right dentary with p4-m3; UF 91836, right dentary with
p3-m1; and UF 172429, right dentary with p2-m1.
Description and Comparisons
Skull and Mandible—The holotype skull and mandible of Sal-
latherium altiplanense, UF 91621 (Fig. 2), is that of an adult, with
completely fused sutures and substantial tooth wear. The nasals
are especially thin and long, with forward-directed nasal aper-
ture. Rostral and mandibular narrowing is very marked. Premax-
illa and maxilla are higher and flatter than those of P.schiaffinoi.
The nasal imbricates gently on the premaxilla, not to the degree
of in P.schiaffinoi. The infraorbital foramen is small. The lacri-
mal is well developed and slightly larger than in Hegetotherium
mirabile. The anterior zygomatic root is well developed and oc-
cupies the length of M1-M3, as in P.sculptum and H.mirabile.
On the inferior surface of the anterior part of the arch, there is
a small tubercle below the infraorbital foramen. The zygomatic
plate is about 50 percent less developed in width than in H.
mirabile. At the level of the premaxilla, the marked symphyseal
narrowing involves the I1-I3 and C (Fig. 2C). The anterior part
of the palate is narrow (I3-I3 width ⳱14.1 mm; M2-M2 distance
⳱32.3 mm [holotype]; 33.1 mm [UF 172150]). In lateral view
(Fig. 2B), UF 91621 is very similar to H.mirabile (Sinclair, 1909:
4, fig. 1D) with respect to the positions of the I1, C, and P1. The
orbit is relatively smaller than in P.schiaffinoi.
The mandible is high and robust (Fig. 2D). It has more sym-
FIGURE 1. Map of major localities discussed in the text: 1, Salla,
Bolivia, 2,Cañada de Las Mulas, Uruguay, 3, Corrientes, Argentina, 4,
Divisadero Largo, Mendoza, Argentina, and 5, Cabeza Blanca, Chubut,
Argentina.
REGUERO AND CERDEÑO—NEW HEGETOTHERES FROM BOLIVIA 675
physeal narrowing at the level of i1-c (UF 91621, i3-i3 width ⳱
9.8 mm) than P.sculptum. The mental foramen is between p2
and p3.
Upper Dentition—The upper dentition (Fig. 2C) is complete,
but with noteworthy reductions. I1 is enlarged and more oval in
cross-section than those of P.schiaffinoi and H.mirabile. It only
has labial enamel. I2-I3 are caniniform and very reduced. I2-C
are not procumbent. The canine is slightly larger than the I2-I3
and has enamel restricted to the labial surface. Short diastemata
separate the I1-I2-I3-C. P1 is more reduced than in P.sculptum;
it is single-rooted, and practically lacks enamel. P2-P3 have bet-
ter developed parastylar grooves than in H.mirabile. P3-M3 dif-
fer from those of H.mirabile by their more ovoid occlusal outline
(Fig. 3). From P2 to M3, all teeth are covered by a continuous
layer of external cementum. Tooth size increases from P2 to M2,
and they are imbricated. P2 is larger than P1, with discontinuous
enamel on the anterior and posterior faces; the anterior band of
dentine is beveled by wear. P2 is submolariform, while P3-P4 are
molariform with developed parastylar areas. M1 and M2 are very
similar in morphology and size, and have weakly developed
parastyles. P4-M3 display smooth posterolingual grooves. The
M3 is smaller than M2, labiolingually narrow, and has a sinuous
ectoloph. I1 to M3 length in UF 91621 is 62.9 mm.
Lower Dentition—The incisors are very procumbent (Fig.
2E). Both i1 and i2 have only labial enamel. The ratio i1:i2 is less
than 1.5:1. The i3 is more reduced and shorter, and separated by
anterior and posterior diastemata. The p1 is long and narrow,
reduced, single-rooted, and only has labial enamel. The p2 has
two lobes of similar size. The anterior face shows a wide dentine
band. The lingual face is rather straight. The labial groove is
marked, but shallow. The p3 is larger than p2, submolariform,
but smaller than the p4. The anterior lobe is narrower than the
posterior one, which is shorter. Its lingual face is smoothly con-
cave. The labial groove is deeper than in p2. The p4 has more
straight lingual face, and the lobes are more similar, the anterior
one still somewhat narrower, as in the molars (Fig. 2E). The m3
is the longest tooth. It is bilobate, but with the talonid much
longer than the trigonid and its labial face convex.
Tables 1 and 2 show the tooth dimensions of S.altiplanense
compared with those of P.sculptum. They are very similar in
size. The P2 and P3 of S.altiplanense seem to be slightly shorter
than in P.sculptum, but only one specimen of the new taxon is
available for comparison. No postcranial remains have been as-
sociated with the cranial material of S.altiplanense.
FIGURE 3. Occlusal views of right M1 and M3 in Prohegetotherium,
Sallatherium;Hegetotherium, and Hemihegetotherium. Figures at diffe-
rent scales.
FIGURE 2. Holotype of Sallatherium altiplanense, gen. et sp. nov. from Salla, Bolivia, UF 91621. A, occlusal, B, lateral, and C, dorsal views of the
skull. D, lateral, and E, occlusal views of the mandible. Scale bars equal 2 cm.
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 25, NO. 3, 2005676
Genus PROHEGETOTHERIUM Ameghino, 1897
Prohegetotherium Ameghino, 1897:424, figs. 10a, b
Propachyrucos Ameghino, 1897:427 (partim)
?Propachyrucos Kraglievich, 1932:50–51, fig. 3
Ethegotherium Simpson, Minoprio and Patterson, 1962:275,
fig. 18
Type Species—Prohegetotherium sculptum Ameghino, 1897.
Diagnosis—(modified after Reguero, 1999) I1 less hypertro-
phied than Sallatherium,Hegetotherium, and Hemihegeto-
therium. Maxillary root of the zygomatic arch less developed
than in Hegetotherium and Hemihegetotherium. I2 and I3 less
reduced than in Hegetotherium,Sallatherium and Hemihegetoth-
erium. Upper canine developed. M3 with more convex lingual
face and more reduced metastyle than Hegetotherium. Lower
canine reduced (Prohegetotherium sculptum). Lower third molar
with elongated second lobe.
Geographic and Chronologic Distribution—Argentina, Uru-
guay, and Bolivia. Divisaderan (early Oligocene) and Deseadan
(late Oligocene) SALMAs.
PROHEGETOTHERIUM SCHIAFFINOI (Kraglievich, 1932)
Propachyrucos?schiaffinoi Kraglievich, 1932:51, fig. 3.
Prohegetotherium carettei Minoprio, 1947:371–374, figs. 3–5;
Simpson and Minoprio, 1949:21–23, figs. 8–9; Simpson and
Minoprio, 1950:250–251, fig. 3.
Ethegotherium carettei (Minoprio, 1947): Simpson, Minoprio,
and Patterson, 1962:275, fig. 18.
Prohegetotherium sp. B: MacFadden et al., 1985:242, fig. 10.
Prohegetotherium sp.: Álvarez, 1978:256.
Propachyrucos sp.: Álvarez, 1978:257 (partim).
Prohegetotherium sp.: Bond et al., 1998:46–47, fig. 4.
Holotype—MNHN-DP-186, partial left maxilla with P2-M2.
Fray Bentos Formation, Cañada de Las Mulas, Santa Lucía
River, Departamento de Canelones, Uruguay. Deseadan
SALMA.
Holotype of Ethegotherium carettei—MACN 16609, right half
of a skull, very crushed and included in the matrix, and right
dentary fragment with p3-m3. Divisadero Largo, Mendoza, Ar-
gentina. Divisaderan SALMA, early Oligocene. Part of the type,
the ‘cotype’(left half of the skull) is housed uncatalogued at the
Museo de Ciencias Naturales of Córdoba University, Córdoba
Province, Argentina (López, 2002).
Revised Diagnosis—Smaller than Prohegetotherium sculptum
and S.altiplanense, with shorter and wider nasals. I3, c, and p1
more reduced than in P.sculptum. Lower cheek teeth not im-
bricated. Lobes of lower cheek teeth rounded rather than angu-
lar, as in P.sculptum and Hegetotherium. Anterior lobe of p3
TABLE 2. Lower tooth dimensions of Sallatherium altiplanense from Salla (UF), Bolivia, and Prohegetotherium sculptum from Argentina and
Uruguay (P. shumwayi). *From Loomis (1914).
i1 i2 i3
LWLWLW
UF 91621 3.0 2.1 3.3 2.4 3.8 2.1
S. altiplanense
p1 p2 p3 p4 m1 m2 m3
LWLWLWLWLWLW L W
UF 91621 2.6 1.7 4.3 2.5 5.6 4.5 6.5 4.9 7.1 4.9 7.3 4.5 9.7 4.2
UF 91622 ——————7.0 4.1 7.6 4.6 7.7 4.5 9.7 4.4
UF 91836 ————6.7 4.3 8.5 5.0 8.5 4.7 ————
UF 172429 ——5.0 3.2 6.0 4.0 7.0 4.5 8.8 4.3 ————
P. sculptum
MLP59-II-26-108 ————————7.5 3.5 7.5 3.6 9.4 3.4
MLP 61-IV-14-2 ————————5.4 3.5 5.9 3.8 8.0 3.3
MLP 77-VI-1-1 ——3.8 2.6 6.0 4.2 7.3 4.6 7.3 4.6 8.7 4.3 ?8.9 3.8
AMNH 29605 3.2 1.6 6.0 3.0 6.6 3.5 7.0 3.7 7.0 3.8 6.6 3.8 8.2 3.0
AMNH 93 ——————————6.2 3.1 ——
AMNH 312c ——————————7.6 3.7 ?8.0 2.9
AMNH 116421 ————6.2 3.2 6.8 3.3 6.8 3.2 6.3 3.2 8.2 3.2
FMNH P14695 ——6.4 3.3 6.5 4.0 7.6 4.2 8.0 4.5 7.7 4.5 ——
FMNH P14695 ————7.7 3.9 7.7 4.2 7.8 4.3 ————
P. shumwayi* ————6.0 3.2 7.0 3.5 7.0 3.5 ————
TABLE 1. Upper tooth dimensions of Sallatherium altiplanense from Salla (UF), Bolivia, and Prohegetotherium sculptum from Argentina.
I1 I2 I3 C
LWLWLWLW
UF 91621 7.7 2.8 2.4 2.1 2.0 1.8 2.5 2.0
S. altiplanense
P1 P2 P3 P4 M1 M2 M3
LWLW L WLW L WLWLW
UF 91621 4.1 2.2 5.9 4.0 6.1 4.4 7.2 5.4 7.8 5.8 8.0 5.6 7.8 4.6
UF 172454 ———— — ——— — 5.5 8.0 5.4 7.8 4.5
UF 172150 3.2 2.5 —— — ——— — —————
UF 172406 ———— — ———10.7 5.6 ————
P. sculptum
FMNH P13414 ——7.5 3.5 ?8.2 4.6 7.3 4.6 8.3 5.0 8.2 4.8 6.8 3.9
FMNH P14683 ——7.8 3.8 6.3 4.1 —— — —————
FMNH P14695 ——7.5 4.1 — ——— 8.6 5.6 ————
REGUERO AND CERDEÑO—NEW HEGETOTHERES FROM BOLIVIA 677
relatively more elongated than in S.altiplanense. Talonid of m3
without labial groove and with lingual groove fainter than in P.
sculptum.
Geographic and Chronologic Distribution—Uruguay, Fray
Bentos Formation; Bolivia, Salla, “Upper Salla Beds”, and Ar-
gentina, Mendoza, Corrientes, and Entre Ríos provinces (see
Appendix 1). Divisaderan and Deseadan SALMAs, early to late
Oligocene.
Referred Specimens—From Salla, Bolivia: UF 91661, skull
with left I1-I3, C, P1-P3 (broken), P4-M3, right I1-I3, C, P1-P2
(broken), P3-M3, and associated partial mandible with right p1
(root), p2-m3 and left p3-m3; UF 91662, skull with left I1-I3, C,
P1-P3 (broken), P4-M1, right I1, I2 (broken), I3, C-P1 (broken),
P2-M3, and associated symphysis and left p3-m2, m3 (broken);
UF 91312, incomplete palate with right and left M1-M3; UF
91321, associated right m1-m3 and left m2-m3; UF 91350, incom-
plete palate with right and left series with C-P2 (broken), P3-M3;
UF 91623, right maxilla with P4-M3; UF 91624, right maxilla with
P4-M3; UF 91647, incomplete skull with right and left series
P2-M3; UF 91317, right maxilla with P2-M3; UF 91674, left maxi-
lla with M1-M3; UF 91821a, incomplete palate with right I1 (bro-
ken); UF 26952, right maxilla with M1-M3; UF 172445, skull
fragment with left P2-M1, M3, right P3-M3 and associated left
femur and both tibias (proximal fragments); UF 172447, incom-
plete palate with right I1-I3, C, P1(broken), P2-M1, and left I1
(broken), I2, I3-P1 (broken), P2-P4, and incomplete mandible
with right i1-i3, c, p1-p2 (broken), and left i1-i3 (broken), c, p1
(broken), p2-m3; UF 172457, right maxilla with P4-M3; UF
172483, right maxilla with P1 (broken), P2-M3; UF 172129, man-
dible with i1-i2, and i3 (broken), right p2 (broken), p3-m3, and
left p2 (broken), p3-m3, two distal femora; UF 172482, left den-
tary with p1-p3 (broken), p4-m3; UF 91333, left dentary with
p3-m3; UF 26951, left dentary with p4-m2; UF 172502, articu-
lated right tarsus and metatarsus. The specimens UF 26952 (right
maxilla with P3-M3), UF 26918 (left dentary with p4-m3), and
UF 29951 (left dentary with p4-m3) lack stratigraphic prov-
enance. MNHN-BOL-V-004152, juvenile right maxilla with
P4-M2.
From Argentina (Corrientes and Entre Ríos provinces): PZ-
Ctes 3755, left dentary fragment with p3-p4; PZ-Ctes 3767, max-
illary fragment with P3, and PZ-Ctes 3766, maxillary fragment
with M1; PZ-Ctes 3744, right dentary fragment with m3; PZ-Ctes
3748/49, right dentary fragment with p2-m1 and m3; MLP 84-
XII-5-1, dentary fragment with p4-m2.
Remarks—Kraglievich (1932) erected the species Propachy-
rucos?schiaffinoi on a maxillary fragment with P2-M2. Based on
Simpson’s (1936) observations, Reguero (1999) determined that
the holotype of Propachyrucos?schiaffinoi (MNHN-DP-186)
does not pertain to Propachyrucos, because it lacks a lingual
groove on the upper molars. He concluded that it should be
assigned to Prohegetotherium, along with the small species from
Salla, although the occlusal outline of the type (Kraglievich,
1932:fig. 3) seems to be more convex lingually. Examination of
photographs of the holotype, recently relocated in the MNHN of
Montevideo, indicates that the general tooth size and morphol-
ogy is closer to the small species of Bolivia than to other hegeto-
theriines, especially in the lack of imbrication of the molars.
Mones (1976) doubtfully assigned to Propachyrucos schiaffinoi a
right dentary fragment with p3-m1 (MNHN-DP 682) collected in
1974 by from Cañada de Las Mulas, Departamento de Monte-
video, Uruguay. He did not give any description and figure on
this specimen. The fossil-bearing bed was considered with doubts
lower Pliocene in age. The specimen has not been reviewed by
us. The assignment of this material to P. schiaffinoi by Mones
seems to be dubious given that the holotype of P.schiaffinoi is
only known from upper teeth and the age of the fossil-bearing
horizon is questionable. It should be compared with Salla mate-
rial assigned to P. schiaffinoi.
The revised diagnosis and the following description of Prohe-
getotherium schiaffinoi are based on the Bolivian material. Ar-
gentinean specimens from Corrientes and Entre Ríos present
dental morphology similar to Prohegetotherium (Bond et al.,
1998), but their size is clearly less than that of Prohegetotherium
sculptum from Patagonia, and more similar to that of the small
hegetotheriine from Salla (Tables 3–4). Even though some diag-
nostic characters cannot be checked on these Argentinean re-
mains, we tentatively include them in P.schiaffinoi.
Ethegotherium carettei (Minoprio, 1947) is a small hegeto-
theriine from the Divisadero Largo Formation (Divisaderan
SALMA, Mendoza, Argentina). Simpson et al. (1962) and López
(2002) regarded it as generically distinct from Prohegetotherium.
Chaffee (1952:524) differentiated E.carettei from P.sculptum
“...inhaving a closed dental series, a deeper symphysis, a nar-
rower i1, a wider i2, and larger i3-p4”. Reguero (1999) consid-
ered E.carettei as a possible junior synonym of P.sculptum.
However, study of the type material (MACN 16609) leads us to
reconsider this assignment; we now note the lack of dental im-
brication; the rounded talonids of p4-m3; the absence of a labial
groove on the talonid of m3; and the m3 slightly longer than m2
(Fig. 4C). AMNH 45913 from the Divisadero Largo Formation,
identified as Ethegotherium carettei, has thin nasals as in the
small hegetothere from Salla. All these characters indicate closer
affinity of these specimens to P.schiaffinoi from Salla than to P.
FIGURE 4. Prohegetotherium schiaffinoi from Uruguay and Argen-
tina. A, occlusal, and B, labial views of MNHN-DP-186, holotype,
Cañada Las Mulas, Departamento de Canelones, Uruguay. C, occlusal
view of right dentary of MACN 16609, holotype of Ethegotherium
carettei (here considered a junior synonym of Prohegetotherium schiaf-
finoi) from Divisadero Largo, Mendoza, Argentina. Scale bars equal 2
cm.
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 25, NO. 3, 2005678
sculptum. Consequently, we now consider E.carettei as a junior
synonym of P.schiaffinoi. This reassignment implies that the
oldest record of this species and the genus Prohegetotherium is
from the Divisaderan beds of Divisadero Largo, in Mendoza,
considered to be early Oligocene (Flynn and Swisher, 1995).
Description and Comparisons
Skull and Mandible—The skull is shorter and lower than that
of Prohegetotherium sculptum, but the rostrum is relatively long
(UF 91661). The nasal is long and narrow, with terminal nares
(UF 172458), and enlarged posteriorly (UF 91661), contrary to
what is observed in S.altiplanense. The nasal is imbricated with
the premaxilla and maxilla on the anterior portion of the rostrum
(UF 172458). Premaxilla and maxilla are somewhat “excavated”,
but without reaching the degree observed in members of the
Pachyrukhinae. UF 91647 preserves part of the left zygomatic
root, showing less development than in Hegetotherium mirabile,
because the anteriormost extent of the arch is restricted to the
level of M3. The sagittal crest is short, low, and acute (UF 91647,
172445), similar to Hegetotherium. The tympanic bulla (UF
91647, 91661, 91662) is more inflated than in Hegetotherium. The
epitympanic sinus is rather well developed, and the well-marked
TABLE 4. Lower tooth dimensions of P. schiaffinoi from Salla (UF) Bolivia, and Corrientes (Pz-Ctes, MLP), Argentina.
i1 i2 i3 c
LWLWLWLW
UF 172447 3.5 2.1 2.2 1.7 2.1 1.8 1.8 1.4
UF 91662 3.3 2.2 2.5 1.8 2.3 1.9 ——
UF 172129 3.4 2.0 2.5 1.7 ————
p1 p2 p3 p4 m1 m2 m3
LWLW L WLWLWLWLW
UF 172447 2.6 1.7 3.0 1.8 3.8 2.3 4.7 2.7 5.3 3.1 5.9 3.1 7.1 2.7
UF 172457 ————— ———5.3 3.0 5.7 3.3 ——
UF 91661 ————— —4.4 2.7 5.3 3.1 5.9 3.5 7.2 3.1
UF 91662 ———— 3.8 2.3 4.3 2.7 5.4 3.1 5.8 3.2 6.9 3.1
UF 91321 ————— ———5.7 3.0 5.5 3.1 6.9 2.6
UF 172129 ——2.9 2.0 3.9 2.5 4.7 2.9 5.6 3.4 6.0 3.4 6.6 2.9
UF 172481 ————— —4.8 2.9 6.4 3.4 5.9 3.3 6.8 3.0
UF 91333 ———— 3.8 2.4 4.6 3.0 6.1 3.3 6.1 3.3 6.8 2.6
UF 26951 ————— —4.6 2.8 6.1 3.2 6.1 3.2 ——
UF 172482 ————— ———6.1 3.0 6.2 3.1 6.4 2.6
UF 26951 ————— —4.5 3.8 6.0 3.1 5.5 3.0 6.1 2.5
UF 26918 ————— —4.8 2.9 6.2 3.4 5.9 3.4 —3.0
PZ-Ctes 3748/49 ————?4.5 2.6 5.3 3.1 6.9 3.1 ——7.5 2.7
PZ-Ctes 3744 ————— ———————5.8 2.5
PZ-Ctes 3755 ———— 4.6 2.8 4.9 3.1 ——————
TABLE 3. Upper tooth dimensions of P. schiaffinoi from Salla (UF), Bolivia, and Corrientes (Pz-Ctes), Argentina.
I1 I2 I3 C
LWLWLWLW
UF 172458 5.7 2.5 2.5 1.8 2.2 1.6 2.4 2.0
UF 91350 ——————2.4 1.9
UF 91311 6.0 2.5 2.8 1.9 2.3 1.7 2.6 2.1
UF 172447 5.4 2.8 2.3 2.0 2.2 1.5 2.7 2.0
UF 91661 6.0 2.8 2.9 2.2 2.2 1.8 2.1 2.1
UF 91662 5.9 2.0 2.9 1.8 2.2 1.4 1.9 2.0
P1 P2 P3 P4 M1 M2 M3
LWLWLWLWLWLWLW
UF 172458 ——5.0 3.1 5.4 3.4 5.6 4.3 5.8 3.5 ————
UF 91350 3.0 2.3 4.5 3.2 4.9 3.5 5.3 3.5 6.1 3.6 5.9 3.7 5.4 3.2
UF 91311 3.2 2.2 3.8 2.6 4.8 3.8 5.2 4.2 6.8 3.7 ————
UF 91602 ——3.1 3.2 4.9 3.9 5.0 3.8 6.9 4.4 6.3 4.1 ——
UF 91647 ——3.8 2.4 4.0 2.8 5.5 3.7 6.5 4.1 6.5 4.0 6.1 3.2
UF 91317 ——4.5 2.6 4.9 2.8 5.3 3.9 6.7 3.9 6.6 4.0 5.4 3.1
UF 26952 ————————6.8 4.2 6.9 4.1 6.0 3.3
UF 91674 ————————6.4 3.5 6.3 3.6 4.8 2.9
UF 172447 3.1 2.0 ————5.4 3.2 6.9 4.2 6.6 3.8 4.8 3.1
UF 172457 ———4.7 3.3 6.6 3.8 7.0 3.9 5.8 3.5
UF 172483 3.4 2.2 3.9 2.8 5.0 3.4 5.7 3.8 7.2 4.0 7.1 4.1 5.8 3.5
UF 91661 3.5 2.3 4.4 3.0 5.0 3.4 5.8 3.3 6.9 4.0 7.5 3.9 5.8 3.5
UF 91662 3.6 2.0 4.4 2.8 4.2 3.0 5.0 3.5 6.7 3.8 6.8 3.8 5.2 3.1
UF 172445 2.7 2.3 4.5 3.3 4.5 3.8 5.6 4.5 7.3 4.8 7.7 4.9 6.8 4.0
UF 91623 ——————5.5 3.8 6.8 3.8 6.8 4.0 6.1 3.4
UF 91624 ——————5.9 3.8 7.4 4.2 7.6 4.2 6.0 3.5
UF 91312 ————————7.2 4.0 7.3 4.1 5.2 3.2
UF 26952 ————4.6 2.8 5.2 3.8 6.2 3.7 6.4 3.7 5.2 3.1
PZ-Ctes 3766 ————————6.2 4.0 ————
PZ-Ctes 3767 ————4.8 3.6 ————————
MLP 84-XII-5-1 ——————5.6 3.3 7.0 3.8 6.8 3.6 ——
REGUERO AND CERDEÑO—NEW HEGETOTHERES FROM BOLIVIA 679
prolongation of the lambdoid crest runs above it. The occipital
face is not very wide.
Total skull length is 92.7 (UF 91661) and 90.2 mm (UF
172445); occipital width, 45.9 mm (UF 172445) and 40.06 mm
(UF 91662); length I1-M3, 47.9 (right) /48.6 (left) mm (UF
91662). Total skull length of E.carettei is 80.8 mm.
The palate is wider than in P.sculptum at the symphysis (at the
level of I3), but not posteriorly (at the level of M2) (Fig. 5A).
Measurements: (A) I3-I3 distance: UF 91661, 14.8; UF 91662,
13.8; UF 91311, 15.1; UF 172447, 12.3; and UF 172458, 14.7. (B)
M2-M2 distance: UF 91661, 25.8; UF 91662, 26.2; UF 91311, 25.8;
UF 91350, 27.0; UF 91647, 26.4; and UF 172445, 31.1
Upper Dentition—The I1 is very procumbent and obliquely
implanted (Fig. 5A) with enamel restricted to the labial side. The
I2 is reduced, less procumbent than I1, and also with labial
enamel only. The I3 is similar in size and shape to the I2, but not
procumbent. Small diastemata are present between the incisors.
The canine is somewhat larger than either I2 or I3, oval in cross-
section, and longer than wide.
There is an abrupt difference in size between premolars and
molars (Fig. 5A). P1 is a simple tooth, whereas P3 and P4 have
deep parastylar grooves and are more triangular in outline, but
not molariform. There is a smooth posterolingual groove on P3-
M3. In the molars, the paracone is slightly more evident than the
metacone. On the ectoloph of M1-M2 there is a smooth groove
between para- and metacone. Premolars and molars are imbri-
cated. M3 is smaller than M1 and M2, but not narrower as in S.
altiplanense. A small metastyle projects posteriorly, and two un-
dulations on the ectoloph correspond to the metacone and para-
cone.
The immature upper dentition of P.schiaffinoi is represented
by several specimens in the MNHN-BOL and UF collections. A
right maxillary fragment with M1 and M2 (MNHN-V-004152,
Fig. 6) is instructive because it is very lightly worn. In occlusal
view, the M2 has the pattern of fossettes that give the tooth the
typical “face”pattern that Simpson (1967) observed in Archaeo-
pithecidae, Archaeohyracidae, and several genera of primitive
Interatheriinae, e.g. Santiagorothia and Proargyrohyrax (Hitz et
al., 2000). The paracone is distinct although cusp relief is not
high. The ectoloph is sinuous and has a shallow paracone/
parastyle groove. In its unworn state, the anterolabial fossette
connects lingually with the central fossette (not yet developed).
A small, rounded extra fossette is between the antero- and pos-
terolabial fossettes, as in the archaeohyracid Pseudhyrax. The
posterolabial fossette is connected with the posterior cingulum
by a low loph.
Lower Dentition—There is no imbrication among the lower
teeth (Fig. 5B–C). The size difference between premolars and
molars is greater in P.schiaffinoi than in P.sculptum and He-
getotherium mirabile. The p2 has the anterior lobe relatively
more elongated than P.altiplanense. The talonid of m3 is long,
wide, and subtriangular in outline.
Postcranial Skeleton—Some postcranial bones have been
found associated with dental remains attributed to P.schiaffinoi.
They suggest a very small animal, with slender metapodials (Fig.
5D). The overall morphology suggests close resemblance to He-
getotherium mirabile. However, it was beyond the scope of this
study to conduct a study of postcranials of all hegetotheriids.
PROHEGETOTHERIUM SCULPTUM Ameghino, 1897
Prohegetotherium sculptum Ameghino, 1897:425–426, fig. 10a,b;
1909:114, fig. 129.
Propachyrucos crassus Ameghino, 1897:427.
Prohegetotherium shumwayi Loomis, 1914:64–65, fig. 29.
Lectotype—MACN A52-443, left maxillary fragment with the
alveolus of the canine and P1-P3. Probably from Cabeza Blanca,
Chubut, Argentina (Patterson, 1952).
FIGURE 5. Prohegetotherium schiaffinoi from Salla, Bolivia. A, occlu-
sal view of UF 91661, skull. B, occlusal, and C, lateral views of UF 91661,
mandible. D, anterior view of UF 172502, articulated right tarsus and
metatarsus. Scale bars equal 2 cm.
FIGURE 6. Immature dentition (right P4-M2) of Prohegetotherium
schiaffinoi (MNHN-Bol-V-4152) from Salla, Bolivia. Abbreviations:
Aef, anterolabial fossette; Cf, central fossette; M, metacone; P, proto-
cones; Pcr, paracone ridge; Pef, posterolabial fossette; Post Cg, posterior
cingulum; and Post f, posterior fossette.
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 25, NO. 3, 2005680
Paralectotype—MACN A52-444, fragment of left maxilla
bearing P3-M2. Probably from Cabeza Blanca (Patterson, 1952).
In the catalogue of the MACN, the syntypes of Prohegetoth-
erium sculptum have the following listed geographic location:
“Mazarredo, Santa Cruz”, handwritten by Miguel F. Soria in the
1970s. Mazarredo or Mazaredo is a small locality to the northeast
of Santa Cruz Province, where Carlos Ameghino collected a few
Deseadan mammals. Patterson (1952), based on the preservation
of those fossils, pointed out that they probably derived from
Cabeza Blanca. The uncertainty about the provenance of the
syntypes is not very important because their stratigraphic loca-
tion is equivalent (Feruglio, 1949; Mazzoni, 1985). Until now, no
hegetotheriid has been recorded from the Deseadan beds of the
Santa Cruz province.
Revised Diagnosis—A species of Prohegetotherium larger
than P.schiaffinoi and similar in size to H.mirabile. Dentition
complete and closed. Lower incisors (i2-i3) and canine not re-
duced. Symphysis more robust than P.schiaffinoi and S.alti-
planense, with posterior end at the level of p3. Talonid of m3
longer than in P.schiaffinoi, but shorter than in S.altiplanense.
Geographic and Chronologic Distribution—Argentina,
Chubut (Cabeza Blanca, Las Cascadas, Laguna Los Machos, and
Rincón del Zampal) and Mendoza Provinces. Late Oligocene,
Deseadan SALMA (see Appendix 1). Stratigraphically, the
Deseadan land mammal-bearing horizon at Chubut and Santa
Cruz seems to be, by correlation, within the Puesto Almendra
Member of the Sarmiento Formation at Gran Barranca in
Chubut (Mazzoni, 1985; Kay et al., 1999). Marshall et al. (1986)
reported a K/Ar date of 28.8 ± 0.9 Ma from basalt near the top
of this member. George G. Simpson collected only a few typical
Deseadan mammals (housed at AMNH) at Gran Barranca, and
he established no direct association between the basalt and these
mammals.
Referred Specimens—The types and the following specimens:
MACN A52-449, left dentary fragment with the alveolus of the
canine, p1-p2 (broken) (paralectotype of Propachyrucos cras-
sus), from Cabeza Blanca,Chubut; MACN A52-450, right den-
tary fragment with p1-p2 (broken) (paralectotype of Propachy-
rucos crassus), from Cabeza Blanca; MACN A52-463, left den-
tary fragment with m1-m3 (paralectotype of Propachyrucos
crassus), from Cabeza Blanca; MACN A52-446, left m2-m3;
MACN A52-447, lot with two right I1, from Cabeza Blanca;
MACN A52-448, right dentary fragment with c, p1-p2 (broken)
(lectotype of Propachyrucos crassus), from Cabeza Blanca.
AMNH 29579 (field number 102), palate with right P3 (broken),
P4-M2, and left P4-M2 from Cañadón Las Víboras, Las Casca-
das, Chubut. AMNH 29605 (Simpson’s field number 178), an
incomplete mandible with right and left i1-i3, c and p1-m3 from
Rinconada de los López, Chubut. ACM, uncatalogued, fragment
of maxilla with right P2-M1 (Loomis, 1914, fig. 29) from Cabeza
Blanca. AMNH 116421 (field number 93), mandibular fragment
with left p3-m3 and right p2-m3, and left maxilla bearing p4 and
m1-m2 (broken) from Las Cascadas. FMNH P13414, fragment of
maxilla with right P2-M3 from Cabeza Blanca. FMNH P14695,
poorly preserved skull and mandible with an associated calca-
neum and other bone fragments, from Cabeza Blanca.
Discussion—Prohegetotherium sculptum was described on
two partial maxillae by Ameghino (1897), probably from Cabeza
Blanca, Chubut, Argentina (see above). In the original descrip-
tion, Ameghino (1897) emphasized the resemblance to Hegeto-
therium of the Santacrucian age, but he differentiated P.sculp-
tum as having a labial groove near the anterior margin of the
cheek teeth and a well-developed canine. Another feature men-
tioned by Ameghino (1897) were grooves and radial channels
around several centers on the external side of several of the skull
bones (frontal, maxilla, etc.), a rare characteristic within mam-
mals. Loomis (1914) doubted this, and suggested it was an arti-
fact caused by weathering.
The specimens used by Ameghino to erect this species are very
fragmentary. Additional specimens housed in the AMNH de-
serve to be mentioned because they are more complete and pro-
vide more diagnostic features. Among them, AMNH 29605, an
incomplete mandible from Rinconada de los López, shows the
rather procumbent symphysis; i1-i3 and canine are also procum-
bent. This specimen was referred to P.sculptum by Chaffee
(1952). FMNH P14695 has unusually imbricated p4-m2, as in the
pachyrukhines. This is attributed to incorrect preparation; ap-
parently the entire labial side of this specimen was broken off
and then inaccurately glued back together.
Patterson (1952) examined the Deseadan hegetotheriids of the
Ameghino Collection and stated that Propachyrucos crassus is
conspecific with P.sculptum. He selected MACN A52-448 as the
lectotype. We agree with this synonymization.
In general, Prohegetotherium is rather similar to Hegetoth-
erium mirabile (Sinclair, 1909), but the former has wider, more
lingually rounded upper cheek teeth; I3-P1 and i3-p1 are not so
reduced; I1 is more ovoid in section, not lingually concave; the
anterior lobe of the lower cheek teeth is relatively greater; and
m3 lacks a clearly developed third lobe.
In addition to Prohegetotherium sculptum, a second species
was described from the Deseadan of Patagonia, Prohegeto-
therium shumwayi Loomis, 1914. It was differentiated by its
smaller size and less developed labial furrow. Reguero (1999)
questioned the validity of this species, because he did not con-
sider these differences sufficient to justify a different species.
Also, there is significant size variation among the referred speci-
mens of P.sculptum. According to the poor figure in Loomis
(1914:64), the teeth (ACM uncatalogued, P2-M1) are relatively
longer and narrower than in P.sculptum, with more acute para-
styles, and with smooth posterolingual grooves. These features
are more similar to the M3 of Hegetotherium mirabile (Sinclair,
1909) or MLP 12-1744 referred to H. mirabile (complete upper
series with left D2-D3 still in place, Santacrucian age, cliffs of the
Santa Cruz River, Santa Cruz Province) than to the cheek teeth
of S.altiplanense from Salla.
Another interesting specimen included in P.sculptum by
Reguero (1999) is the mandibular fragment MLP 77-VI-1-1 from
the Deseadan of Quebrada Fiera, Mendoza. This specimen
presents the peculiarity of having a sinuous lingual wall on the
lower cheek teeth, but this could be due to the aged condition of
the individual. This feature is also observed in old individuals of
Archaeohyracidae.
CONCLUSION
The specimens described here increase the diversity of hegeto-
theriines during the Oligocene. A new genus and species is de-
scribed from the Deseadan of Bolivia, Sallatherium altiplanense,
and a second species from the same region is recognized as Pro-
hegetotherium schiaffinoi, a poorly known species first described
from the Deseadan of Uruguay. This has allowed a much better
characterization of P.schiaffinoi, which is also recognized in the
Argentinean provinces of Corrientes and Entre Ríos. Based on
the present study, the smaller P.schiaffinoi lived in Bolivia,
northeastern Argentina, and Uruguay, while the larger S.alti-
planense and P.sculptum occurred in Bolivia and Patagonia,
respectively. Additionally, the Divisaderan species Ethegoth-
erium carettei is here considered a junior synonym of P.schiaf-
finoi, implying a temporal and geographic extension of the genus
and species into the Divisaderan SALMA (early Oligocene) of
the Argentinean province of Mendoza. The recognition of P.
sculptum in Quebrada Fiera (Mendoza) extends the distribution
of this species into central western Argentina.
The biostratigraphic distribution of Sallatherium altiplanense
at Salla corresponds to Unit 5 (Branisella Level) and Unit 6
(Upper White Level), whereas P.schiaffinoi is recorded in Unit
REGUERO AND CERDEÑO—NEW HEGETOTHERES FROM BOLIVIA 681
4 (Principal Guide Level, 24.9 ± 0.5 Ma, Kay et al., 1995), Unit
5(Branisella Level) and Unit 6 (Upper White Level) (Appendix
1). The Branisella Level lies about 15 m above two K-Ar ages of
25.1 ± 0.7 and 26.4 ± 1.0 Ma (MacFadden, 1990). The smaller
taxon (P.schiaffinoi) is much more abundant than the larger
one. The record of P.sculptum ranges between 27 and 29 Ma,
following the temporal range established by Flynn and Swisher
(1995) for the Deseadan in Patagonia. The only dated Deseadan
fauna that contains P.sculptum is Scarritt Pocket (Marshall et al.,
1986) with dates of 27–29 Ma.
MacFadden et al. (1985) suggested that the observed differ-
ences between Deseadan faunas from Patagonia and Salla may
be due to the age of the deposits, based on associated radiomet-
ric dates. Salla probably represents deposits that are younger
than typical Deseadan localities in Patagonia. Sallatherium alti-
planense supports this view, because it represents an advanced
taxon with respect to the Patagonian P.sculptum in having a
specialized rostrum with long, thin nasals. On the other hand, the
presence of a primitive Prohegetotherium,P.schiaffinoi,
strengthens the pattern of heterochroneity observed for some
primitive ungulate genera that are known from the late Eocene
(Tinguirirican and ‘Astraponotéen plus supérieure’ages) of
Patagonia and from the Deseadan of lower latitudes; this pattern
suggests that the northward dispersal of genera such as the ar-
chaeohyracid Protarchaeohyrax (⳱“Bryanpattersonia”)
(Reguero and Cifelli, 1997; Reguero et al., 2003b) and the inter-
atheriid Eopachyrucos (Reguero et al., 2003a) probably reflects
a migration of taxa resulting from a change in climatic condi-
tions. Both S.altiplanense and P.schiaffinoi are biostratigraphi-
cally important taxa because their first and last occurrences help
to define the “Upper Salla Beds”(Fig. 7).
The degree of hypsodonty and the muzzle morphology of S.
altiplanense are interesting and likely related to diet. In general,
browsing herbivores have narrow muzzles, whereas grazers have
broader muzzles (Owen-Smith, 1985). Based on this pattern in
modern herbivores, it can be inferred that this species would
have more browsing habits than other hegetotheriines. In gen-
eral, the ungulates from the “Upper Salla Beds”(Archaeohyra-
cidae, Interatheriidae, and Hegetotheriidae) are less hypsodont
than those from the Deseadan of Patagonia (Reguero, 1999;
Reguero et al., 2003a). The geochronologic and faunistic evi-
dence suggests that the differences between the Deseadan of
Patagonia and Bolivia seem to be a combination of temporal and
ecological differences.
ACKNOWLEDGMENTS
We sincerely thank Darin Croft, Richard Madden, and Sergio
Roig for their critical reading of the manuscript and valuable
comments. MR acknowledges financial support from the Verte-
brate Paleontology Visitor’s Research Fellowship, Department
of Vertebrate Paleontology, Florida Museum of Natural History,
Gainesville, which allowed the visit to the UF collections. This
author also thanks Bruce J. Shockey and Federico Anaya for
providing an opportunity to visit the Salla locality. The following
museum scientists and staff were generous and helpful regarding
their research collections: JoséBonaparte and Alejandro Kra-
marz, MACN; Federico Anaya, MNHN de La Paz; Bruce J.
MacFadden, Bruce J. Shockey, and Marc Frank, UF; John Flynn,
Darin Croft, Steve McCarroll and William Simpson, FMNH;
Malcolm McKenna, Michael Novacek, and Mark Norell,
AMNH. Dr. Alvaro Mones (MNHN of Montevideo) sent pho-
tographs of the holotype of Propachyrucos schiaffinoi. This re-
search was partially financed by M .O. Woodburne and NSF. We
are also grateful to Erika Simmons (UF) and Florencia Castets
(MLP) who assisted in photography, and AgustínViñas for the
drawings.
LITERATURE CITED
Álvarez, B. B. 1978. Noticias sobre una fauna de la Formación Fray
Bentos (Oligoceno inferior), Provincia de Corrientes, Argentina.
FACENA (Revista de la Facultad de Ciencias Exactas y Naturales,
Universidad del Noreste) 2:253–258.
Ameghino, F. 1894. Enumération synoptique des espèces de mammifères
fossiles des formations éocènes de Patagonie. Boletín de la Aca-
demia Nacional de Ciencias en Córdoba 13:259–452.
Ameghino, F. 1897. Mammifères crétacésdel’Argentine (Deuxième
contribution àla conaissance de la faune mammalogique des couches à
Pyrotherium). Boletín del Instituto Geográfico Argentino 18:406–521.
Bond, M. 1991. Sobre las capas de supuesta edad Divisaderense en los
“Estratos de Salla”, Bolivia; pp. 701–705 in R. Suárez-Soruco (eds.),
Fósiles y facies de Bolivia, I. Revista Técnica de YPFB 12, La Paz.
Bond, M., and G. López. 1997. Los Hegetotheriinae (Notoungulata, He-
getotheriidae) de la Formación Arroyo Chasicó(Mioceno superior),
Provincia de Buenos Aires, Argentina. Ameghiniana 34:533.
Bond, M., G. López, M. A. Reguero, G. J. Scillato-Yané, and M. G.
Vucetich. 1998. Los mamíferos de la Formación Fray Bentos (Edad
Deseadense, Oligoceno superior?) de las provincias de Corrientes y
Entre Ríos, Argentina. Asociación Paleontológica Argentina, Pub-
licación Especial 5:41–50.
Castro, P. V. 2001. Los Hegetotheriidae (Mammalia: †Notoungulata:
Hegetotheria) del Paleógeno de Patagonia, Argentina: sistemática,
FIGURE 7. Chronostratigraphic and biochronologic ranges of Prohegetotherium,Sallatherium, and Hegetotherium from Argentina, Bolivia, and
Uruguay as determined in this study. Abbreviations:Cha, Chasicoan; Co, Colhuehuapian; Col, Colloncuran; Div, Divisaderan; Fr, Friasian; Huay,
Huayquerian; Lav, Laventan, M, Montehermosan; Ma, Mayoan; San, Santacrucian; T, Tinguirirican. SALMA chronology after Flynn and Swisher
(1995).
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 25, NO. 3, 2005682
filogenia y paleoecología. Unpublished Masters thesis, Universidad
Nacional de Patagonia “San Juan Bosco”, Chubut, 140 pp.
Cerdeño, E., and V. H. Contreras. 2000. El esqueleto postcraneal de
Hemihegetotherium (Hegetotheriidae, Notoungulata) del Mioceno
superior de Puchuzum, San Juan, Argentina. Revista Española de
Paleontología 15:171–179.
Chaffee, R. G. 1952. The Deseadan vertebrate fauna of the Scarritt
Pocket, Patagonia. Bulletin of the American Museum of Natural
History 98:503–562.
Feruglio, E. 1949. Descripción Geológica de la Patagonia. Yacimiento
Petrolíferos Fiscales (Y.P.F.) 2, Buenos Aires, 342 pp.
Flynn, J. J., and C. C. Swisher, III. 1995. Cenozoic South American Land
Mammal Ages: correlation to global geochronologies; pp. 317–333
in W. A. Berggren, D. V. Kent, M.-P. Aubry, and J. Hardenbol
(eds.), Geochronology, Time Scales and Global Stratigraphic Cor-
relation. Society of Sedimentary Geology, Special Publication 54.
Francis, J. C. 1965. Los géneros de la subfamilia Mesotheriinae (Typoth-
eria, Notoungulata) de la República Argentina. Boletín del Labo-
ratorio de Paleontología de Vertebrados (Montevideo) 1:1–31.
Hitz, R., M. A. Reguero, A. R. Wyss, and J. J. Flynn. 2000. New inter-
atheriines (Interatheriidae, Notoungulata) from the Paleogene of
Central Chile, and Southern Argentina. Fieldiana (Geology) New
Series 42:1–26.
Hoffstetter, R. 1968. Un gisement de mammifères déséadiens (Oligocène
inférieur) en Bolivie. Comptes Rendus de l´Académie de Sciences
267:1095–1097.
Hoffstetter, R. 1969. Un primate de l’Oligocène inférieur sud-american:
Branisella boliviana gen et sp. nov. Comptes Rendus de l´Académie
de Sciences 269:434–437.
Hoffstetter, R. 1976. Rongeurs caviomorphes de l’Oligocène de Bolivie.
I. Introduction au Déséadien de Bolivie. Palaeovertebrata 7:1–14.
Hoffstetter, R., and R. Lavocat. 1970. Découverte dans le Déséadien de
Bolivie des genres pentalophodontes appuyant les affinités afric-
aines des rongeurs Caviomorphes. Comptes Rendus de l´Académie
de Sciences 271:172–175.
Hoffstetter, R., and G. Petter 1983. Paraborhyaena boliviana et Andino-
gale sallaensis, deux marsupiaux (Borhyaenidae) nouveaux du
Déséadien (Oligocène inférieur) de Salla (Bolivie). Comptes Ren-
dus de l´Académie de Sciences 296:205–208.
Kay, R. F., B. J. MacFadden, R. H. Madden, H. Sandeman, and F.
Anaya. 1998. Revised age of the Salla Beds, Bolivia, and its bearing
on the age of the Deseadan South American Land Mammal “Age”.
Journal of Vertebrate Paleontology 18:189–199.
Kay, R. F., R. H. Madden, M. G. Vucetich, A. A. Carlini, M. M. Mazzoni,
G. H. Re, M. Heizler, and H. Sandeman. 1999. Revised geochronol-
ogy of the Casamayoran South American Land Mammal Age: cli-
matic and biotic implications. Proceedings of the National Academy
of Sciences of the United States of America 96:13235–13240.
Kraglievich, L. 1932. Nuevos apuntes para la geología y paleontología uru-
guayas. Anales del Museo de Historia Natural de Montevideo 3:1–65.
Lavocat, R. 1976. Rongeurs caviomorphes de l’Oligocène de Bolivie. II.
Rongeurs du Bassin Déséadien de Salla-Luribay. Palaeovertebrata
7:15–90.
Loomis, F. B. 1914. The Deseado Formation of Patagonia. Rumford
Press, Concord, New Hampshire, 232 pp.
López, G. M. 2002. RedescripcióndeEthegotherium carettei (Notoungu-
lata, Hegetotheriidae) de la Formación Divisadero Largo de la pro-
vincia de Mendoza. Ameghiniana 39: 295–306.
MacFadden, B. J. 1990. Chronology of Cenozoic primate localities in
South America. Journal of Human Evolution 19:7–22.
MacFadden, B. J., K. E. Campbell, R. L. Cifelli, O. Siles, N. M. Johnson,
C. W. Naeser, and P. K. Zeiter. 1985. Magnetic polarity stratigraphy
and mammalian fauna of the Deseadan (Late Oligocene-Early Mio-
cene) Salla beds of Northern Bolivia. Journal of Geology 93:223–250.
MacFadden, B. J., and C. D. Frailey. 1984. Pyrotherium, a large enig-
matic ungulate (Mammalia, incertae sedis) from the Deseadan (Oli-
gocene) of Salla, Bolivia. Paleontology 27:867–874.
Marshall, L. G., R. L. Cifelli, R. E. Drake, and G. H. Curtis. 1986.
Vertebrate paleontology, geology and geochronology of the Tapera
de López and Scarritt Pocket, Chubut Province, Argentina. Journal
of Paleontology 60:920–951.
Mazzoni, M. M. 1985. La Formación Sarmiento y el vulcanismo
paleógeno. Revista de la Asociación Geológica Argentina 40:60–68.
Minoprio, J. L. 1947. Fósiles de la Formación del Divisadero Largo.
Anales de la Sociedad Científica Argentina 146:365–378.
Mones, A. 1976. Notas paleontológicas uruguayas, III, Vertebrados fó-
siles nuevos o poco conocidos (Chondrichthyes, Amphibia, Mam-
malia). Ameghiniana 12:343–349.
Naeser, C. W., E. H. McKee, N. M. Johnson, and B. J. MacFadden. 1987.
Confirmation of a late Oligocene-early Miocene age of the
Deseadan Salla beds of Bolivia. Journal of Geology 95:825–828.
Owen-Smith, N. 1985. Niche separation among African ungulates; pp.
161–171 in E. S. Vrba (ed.), Species and Speciation. Transvaal Mu-
seum Monograph 4, Pretoria.
Pascual, R., E. Ortiz Jaureguizar, and J. L. Prado. 1996. Land mammals:
paradigm for Cenozoic South American geobiotic evolution.
Münchner Geowissenschaftliche Abhandlungen 30:265–319.
Patterson, B. 1952. Catálogo de los Typotheria del Colhuehuapiano y
Deseadiano. Unpublished manuscript on file, Sección Paleontología
Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino
Rivadavia”, Buenos Aires, pp. 1–4.
Patterson, B., and A. E. Wood. 1982. Rodents from the Deseadan Oli-
gocene of Bolivia and the relationships of the Caviomorpha. Bulle-
tin of the Museum of Comparative Zoology 149:371–543.
Petter, G., and R. Hoffstetter. 1983. Les marsupiaux du Déséadien (Oli-
gocène inférieur) de Salla, Bolivia. Annales de Paléontologie 69:
175–234.
Reguero, M. A. 1999. El problema de las relaciones sistemáticas y filo-
genéticas de los Typotheria y Hegetotheria (Mammalia, Notoungu-
lata): Análisis de los taxones de Patagonia de la edad-mamífero
Deseadense (Oligoceno). Unpublished Ph.D. dissertation, Univer-
sidad Nacional de Buenos Aires, Facultad de Ciencias Exactas y
Naturales, Buenos Aires, 301 p.
Reguero, M. A., and E. Cerdeño. 2001. New Hegetotheriidae (Notoun-
gulata) from the Deseadan (late Oligocene) of Salla (Bolivia).
Ameghiniana, Resúmenes: 17R.
Reguero, M. A., and R. L. Cifelli. 1997. Deseadan Archaeohyracidae
from Salla, Bolivia. Ameghiniana 34:539.
Reguero, M. A., M. Ubilla, and D. Perea. 2003a. New species of Eo-
pachyrucos (Mammalia: Notoungulata: Interatheriidae) from the
Late Oligocene of Uruguay. Journal of Vertebrate Paleontology
23:445–457.
Reguero, M. A., D. Croft, J. J. Flynn, and A. R. Wyss. 2003b. Small
archaeohyracids (Typotheria, Notoungulata) from Chubut Province,
Argentina, and central Chile: implications for trans-Andean tempo-
ral correlation. Fieldiana (Geology) new series 48:1–17.
Roth, S. 1903. Los ungulados sudamericanos. Anales Museo La Plata,
Sección Paleontología 5:1–36.
Shockey, B. J. 1997a. Toxodontia of Salla, Bolivia (late Oligocene): tax-
onomy, systematics, and functional morphology. Unpublished Ph.D.
dissertation, University of Florida, Gainesville, 276 p.
Shockey, B. J. 1997b. Two new notoungulates (family Notohippidae)
from the Salla Beds of Bolivia (Deseadan: Late Oligocene): system-
atics and functional morphology. Journal of Vertebrate Paleontol-
ogy 17:584–599.
Simpson, G. G. 1945. The principles of classification and a classification
of mammals. Bulletin of the American Museum of Natural History
85:1–350.
Simpson, G. G. 1967. The beginning of the age of mammals in South
America, part 2. Bulletin of the American Museum of Natural His-
tory 137:1–259.
Simpson, G. G., and J. L. Minoprio. 1949. A new adianthine litoptern and
associated mammals from a Deseadan faunule in Mendoza, Argen-
tina. American Museum Novitates 1434:1–27.
Simpson, G. G., and J. L. Minoprio. 1950. Fauna del Deseadense en
Mendoza. Anales de la Sociedad Científica Argentina 149: 245–253.
Simpson, G. G., J. L. Minoprio, and B. Patterson. 1962. The mammalian
fauna of the Divisadero Largo Formation, Mendoza, Argentina.
Bulletin of the Museum of Comparative Zoology 127:139–293.
Sinclair, W. J. 1909. Typotheria of the Santa Cruz beds. Reports of the
Princeton University, Expeditions to Patagonia 1896–1899 6 (Pale-
ontology), 110 pp.
Soria, M. F., and R. Hoffstetter 1983. Presence d’un Condylarthre (Sal-
ladolodus deuterotherioides gen et sp. nov.) dans le Déséadien (Oli-
gocène inférieur) de Salla, Bolivia. Comptes Rendus de l´Académie
de Sciences 297:549–552.
Villarroel, C. 1974. Les Mésothérinés (Notoungulata, Mammalia) du
Pliocène de Bolivie. Leurs rapports avec ceux d’Argentine. Annales
de Paléontologie 60:245–281.
Villarroel, C., and L. G. Marshall. 1982. Geology of the Deseadan (early
REGUERO AND CERDEÑO—NEW HEGETOTHERES FROM BOLIVIA 683
Oligocene) age Estratos Salla in the Salla-Luribay basin, Bolivia,
with description of new Marsupialia. Géobios 6 (Mémoire speciale),
201–211.
Vucetich, M. G. 1991. Los roedores de Salla y Lacayani (Bolivia) y su
correlación con las otras faunas de edad Deseadense (Oligoceno);
pp. 625–629 in R. Suárez-Soruco (ed.), Fósiles y Facies de Bolivia, I.
Vertebrados. Revista Técnica de YPFB 12, La Paz.
Wolff, R. G. 1984. New early Oligocene Argyrolagidae (Mammalia, Mar-
supialia) from Salla, Bolivia. Journal of Vertebrate Paleontology
4:108–113.
Wolff, R. G. 1985. New specimens of the primate Branisella boliviana
from the early Oligocene of Salla, Bolivia. Journal of Vertebrate
Paleontology 4:570–574.
Submitted 6 January 2005; accepted 7 February 2005.
APPENDIX I Specimen catalog numbers, localities, general geographic location, stratigraphy, and biochronology of species of Hegetotheriidae
included in this study. * ⳱type specimen; highest strat. level ⳱highest stratigraphic level.
Catalog number Locality name Geographic location Stratigraphy SALMA
Prohegetotherium schiaffinoi
UF 26951 Tapial Pampa Salla, Bolivia Branisella Level Deseadan
UF 26952 Tapial Pampa Salla, Bolivia Branisella Level Deseadan
UF 91312 Tapial Pampa Salla, Bolivia Branisella Level Deseadan
UF 91317 Tapial Pampa Salla, Bolivia Branisella Level Deseadan
UF 91321 Tapial Pampa Salla, Bolivia Branisella Level Deseadan
UF 91333 Tapial Pampa East Salla, Bolivia Upper White Level Deseadan
UF 91350 Tapial Pampa West Salla, Bolivia Branisella Level Deseadan
UF 91623 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 91624 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 91647 Tapial Pampa West Salla, Bolivia Branisella Level Deseadan
UF 91661 Tapial Pampa West Salla, Bolivia Branisella Level Deseadan
UF 91662 Tapial Pampa West Salla, Bolivia Branisella Level Deseadan
UF 91674 Tapial Pampa West Salla, Bolivia Branisella Level Deseadan
UF 172129 Tapial Pampa East Salla, Bolivia Branisella Level Deseadan
UF 172445 Tapial Pampa West Salla, Bolivia Upper White Level Deseadan
UF 172447 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 172457 Tapial Pampa East Salla, Bolivia Branisella Level Deseadan
UF 172482 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 172483 Tapial Pampa East Salla, Bolivia Branisella Level Deseadan
UF 172445 Tapial Pampa East Salla, Bolivia Upper White Level Deseadan
MNHN-BOL-V-004152 Tapial Pampa West Salla, Bolivia Branisella Level Deseadan
* MNHN-DP-186 Can˜ada de Las Mulas Fray Bentos, Uruguay Fray Bentos Fm. Deseadan
* MACN 16609 Divisadero Largo Mendoza, Argentina Divisadero Largo Fm. Divisaderan
AMNH 45913 Divisadero Largo Mendoza, Argentina Divisadero Largo Fm. Divisaderan
PZ-Ctes 3744 Rı´o Corrientes Corrientes, Argentina Fray Bentos Fm. Deseadan
PZ-Ctes 3748/49 La Matilde Entre Rı´os, Argentina Fray Bentos Fm. Deseadan
PZ-Ctes 3755 Arroyo A
´valos Corrientes, Argentina Fray Bentos Fm. Deseadan
PZ-Ctes 3766 Arroyo A
´valos Corrientes, Argentina Fray Bentos Fm. Deseadan
PZ-Ctes 3767 Arroyo A
´valos Corrientes, Argentina Fray Bentos Fm. Deseadan
MLP 84-XII-5-1 Colo´ n Entre Rı´os, Argentina Fray Bentos Fm. Deseadan
Sallatherium altiplanense
* UF 91621 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 91622 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 91836 Alpha Pata North Salla, Bolivia “highest strat. level” Deseadan
UF 172150 Tapial Pampa East Salla, Bolivia Upper White Level Deseadan
UF 172406 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 172429 Jaccha Tapial Chuchu Salla, Bolivia Branisella Level Deseadan
UF 172454 Huichinca Salla, Bolivia Upper White Level Deseadan
Prohegetotherium sculptum
* MACN A52-443 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
* MACN A52-444 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
MACN A52-446 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
MACN A52-447 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
* MACN A52-448 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
* MACN A52-449 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
* MACN A52-450 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
* MACN A52-463 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 29579 Las Cascadas Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 29605 Scarritt Pocket Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 29570 Las Cascadas Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 116421 Las Cascadas Chubut, Argentina Sarmiento Fm. Deseadan
FMNH P13414 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
FMNH P14695 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
MLP 59-II-26-108 Rinco´ n del Zampal Chubut, Argentina Sarmiento Fm. Deseadan
MLP 59-II-26-36 Laguna Los Machos Chubut, Argentina Sarmiento Fm. Deseadan
MLP 77-VI-1-1 Quebrada Fiera Mendoza, Argentina Agua de la Piedra Fm. Deseadan
MLP 77-VI-1-18 Quebrada Fiera Mendoza, Argentina Agua de la Piedra Fm. Deseadan
FMNH P13414 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
FMNH P14695 Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 312 c Cabeza Blanca Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 93 Las Cascadas Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 29570 Las Cascadas Chubut, Argentina Sarmiento Fm. Deseadan
AMNH 116421 Las Cascadas Chubut, Argentina Sarmiento Fm. Deseadan
JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 25, NO. 3, 2005684
