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Proceedings of the 10th Conference on Fossil Resources
Rapid City, SD May 2014 Dakoterra Vol. 6:191–198
ARTICLE
ARROYO DEL VIZCAÍNO SITE, SAUCE, URUGUAY: FIELDWORK, RESEARCH,
CONSERVATION, EXHIBITION, EDUCATION
RICHARD A. FARIÑA AND MARIANA DI GIACOMO
Sección Paleontología, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay,
faria@fcien.edu.uy, maru.digi@gmail.com
ABSTRAT—Discovered in 1997 during a severe drought, the Arroyo del Vizcaíno site is a richly fossiliferous
Pleistocene locality usually covered by waters in a stream near the town of Sauce, Uruguay. Some of the bones
show marks with features consistent with those made by human tools. Radiocarbon dates yielded an unexpect-
edly old age, ca. 30,000 years before present, which makes it the oldest date for a site with human evidence
in the Americas. Apart from its scientic importance, several activities are in progress or planned to share this
knowledge of the site with the general public. These plans include the creation of a museum where the recovered
material will be kept and exhibited, which will also serve as a place for research and cultural events. Additionally,
a project is being developed to involve the local high school students (and, through them, also their families)
to expand community awareness of the value of the discovery, both in terms of its contribution to scientic
knowledge, and as an important part of their cultural heritage.
INTRODUCTION
The Arroyo del Vizcaíno site (Fariña et al., 2014; www.
arroyodelvizcaino.org) is located near the town of Sauce,
Canelones, Uruguay (Fig. 1). In 1997, the Vizcaíno stream,
used by the local farmers to irrigate their crops, dried up
due to a severe drought. As a result, numerous remains of
the Pleistocene South American megafauna (Fariña et al.,
2013) were exposed in its bed. Most of the bones belong to
the gigantic sloth Lestodon, but a few remains of the South
American ungulate Toxodon and scutes of three genera
of glyptodonts (Glyptodon, Doedicurus, and Panochthus)
were also found (Fig. 2). Many of these remains were
gathered by students of the local high school (then Liceo
de Sauce, now Liceo Nº 1 de Sauce) under the guidance
of some of their teachers.
Fourteen years passed before formal excavations were
initiated. In 2011 and 2012 professional excavations were
undertaken by our team, composed of palaeontologists,
geologists, and archaeologists. Our work conrmed that
this is a most important paleontological site, in which fos-
sil bones are counted by the thousands. Additionally, some
of the bones show marks with interesting features suggest-
ing human tool use while the age is unexpectedly old (see
below). Several projects, including research, exhibition
plans, and outreach were developed.
FIELDWORK
In June 2009, the Intendencia de Canelones (i.e., the
regional authority, equivalent to that of a province or a
state in federal countries) provided the machinery to build
a bypass and divert the course of the stream (Fig. 3). In
March 2011 weather conditions were nally suitable for
excavations to start at the site. With the help of members
of the 14th Battalion of the Uruguayan Army, the stream
was dammed with bags of soil and the water was pumped
out (Fig. 4).
A 30 m2 (320 ft2) area containing fossils was exposed
and this area was divided with rope grid into areas of 1
m2 (11 ft2) (Fig. 5). Collections, restricted only to those
remains that looked more vulnerable, were then mapped
for each square.
In the campsite, the material that was removed was
provisionally classied and catalogued. The elements were
saved with tags in plastic bags (Fig. 6). Over 200 remains
were then cleaned along with other lab treatments. When
the excavation nished, the outcrop, with its thousands of
remains still in place, was carefully covered with geocloth
(Fig. 7), to protect the bones from natural damage as well
as possible (although unlikely) pillage.
In January 2012, a second more systematic excavation
was carried out by the team. Given the great number of
fossils on site, an area of only 12 m2 (130 ft2) was opened.
A rope grid was built again and collecting started. This
area of the site had a great density of bones (Fig. 8), ren-
dering their excavation and extraction very difcult. After
12 days in the eld, due to weather conditions the avail-
able time ran short, and again many bones could not be
removed from that area. However, over 500 fossils were
extracted in 2012, and again they were primarily cata-
logued in the eld. As in 2011, after the excavation, the
site was covered in geocloth and the water was let in again
to cover the site.
RESEARCH
Arribas et al. (2001) rst published a description of a
marked clavicle. A surprisingly old age of about 30,000
years was found for that clavicle and an associated rib
(Fariña and Castilla, 2007). A general account on the South
American megafauna (Fariña et al., 2013) devotes several
pages to the site, while the biogeochemistry of some of
the bones shed light on the fauna’s ecological preferences
(Czerwonogora et al., 2011).
Fariña et al. (2014) fully described the site and its ex-
ceptional character was stressed. More than a thousand
bones have been documented, belonging to 27 individu-
als. The fauna includes three species of ground sloths
192 Dakoterra Vol. 6, 2014
FIGURE 1. Map of Uruguay with the location of the town
of Sauce indicated by the square marker. Source Google
Earth.
FIGURE 2. Reconstruction of animals belonging to the
Pleistocene South American megafauna found in the site
of Arroyo del Vizcaíno. Based on 3D reconstructions by
Mauro Muyano.
(the vast majority of the remains belong to Lestodon, but
there are some elements of Glossotherium and Mylodon),
three species of glyptodonts (Glyptodon, Doedicurus and
Panochthus), the South American ungulate Toxodon, a
horse, a deer, a proboscidean, and a sabertoothed felid. The
taphonomy of the site and its possible geological origin
were also described by Fariña et al. (2014), and many new
radiocarbon dates were reported that corroborate the previ-
ous age ndings. Several aspects of the bone distribution,
of the anatomical regions represented, and the mortality
prole of the individuals found suggest potential human
activity—a surprising possibility most strongly supported
by the marks studied on 15 of the bones.
CONSERVATION
The authorities of the town of Sauce allowed the team
to use a small room in one of the facilities, the local Casa
de la Cultura (Fig. 9), to serve as a fossil repository for the
bones collected in 1997 that had been previously housed
in the local high school. After the excavation of 2011, the
bones were moved to a larger room within the building
(Fig. 10). The current lab/collection is only a temporary
storage solution, because the 20 m2 (220 ft2) room is rather
small for our current needs for housing the collection (let
alone those that will derive from further collections) and
the lack of controlled environmental conditions include
severe humidity and structural issues in the storage room.
Despite those substandard conditions, systematic efforts
have been made in order to guarantee the conservation of
the fossils (Shelton, 1994).
Originally, the remains were kept in and on the avail-
able furniture in plastic crates, using polyfoam beneath
them and plastic to isolate them from the polyfoam (Fig.
11). After the 2012 excavation, the number of bones had
grown so dramatically that the original furniture was re-
placed by more appropriate metal shelves and cupboards
donated by the Facultad de Ciencias of the Universidad
de la República as part of an agreement between that in-
stitution and the local government. Bones were placed in
the shelves and cupboards with no specic order until the
cataloguing of the whole collection was nished (Fig. 12).
In July 2012, a research and exhibition activity was
held in a local venue, called Escaparate (see Exhibition
and Figure 13). This event provided an opportunity to
address the conservation issues of the collection and to
help develop new strategies to improve the state of the
specimens. The bones were classied in color categories
according to their conservation urgency: black (destroyed
specimen, in more than 4–5 pieces, difcult to restore),
red (broken specimen, 1 to 4–5 pieces, xable), yellow
(cracked specimen, consolidation needed) and green (no
supercial damage). This activity also allowed for more
efcient use of the shelves and crates, leaving smaller,
more resistant pieces in the crates and larger, unique, rare
and fragile pieces on the shelves. Moreover, a specic
shelf was used to store a composite complete skeleton
of Lestodon armatus (as said, by far the most abundant
species in the site represented by over 90% of the total
remains), to be used for comparison to aid in the identi-
cation of broken pieces and research in general. A closed
metal cupboard was chosen for cranial and mandible re-
mains (including teeth and ear ossicles). The remaining
cupboard was used for storage of laboratory supplies such
as chemicals, glassware and books. When the fossils went
back to the collection/lab, the space was better distributed
and a dehumidier was bought in order to address some
of the relative humidity issues of the room.
All the specimens from the collection were properly
catalogued and photographed. The digital catalogue in-
cludes taxonomic and anatomical information, location on
193FARIÑA AND DI GIACOMO—ARROYO DEL VIZCAÍNO, URUGUAY
FIGURE 3. Heavy machinery opens a secondary course
of the Vizcaíno stream to divert water away from the bone
bed for the 2011 excavation. Photograph by Jean Philippe
Gibert.
FIGURE 4. Members of the 14th Battalion of the
Uruguayan Army pose on top of the dam they built for
the 2011 excavation. Photograph by Richard A. Fariña.
the eld, the date and time it was extracted, the number of
photographs of each specimen, and other relevant informa-
tion such as its integrity, presence of marks (see Research)
and whether it was glued to another piece or was found
next to an adjacent bone.
Consolidant Paraloid B-72 was imported and differ-
ent concentrations were prepared in order to address the
conservation needs identied in Escaparate (following
Shelton and Chaney, 1994). Currently, the preparators are
working on the new catalogue numbers to be painted in
the bones, using both Paraloid and India ink. In addition,
several of the specimens marked ‘black’ in Escaparate are
being restored.
EXHIBITION
In Sauce, the fossils were exhibited in a local venue
called Escaparate for one week in July 2012. There, a skel-
eton of Lestodon was mounted on the oor so the visitors
could appreciate its size (Fig. 14). In addition, every De-
cember, the fossils are exhibited in the annual’s Casa de
la Cultura showcase. Currently, some of the specimens are
exhibited at a museum in Montevideo, the MAPI (Museo
de Arte Precolombino e Indígena).
Plans for a future Paleontological Museum in Sauce
are currently being developed. This institution will house
these valuable remains, and we hope will develop into a
center for research and cultural inuence that will contrib-
ute to the spread of scientic knowledge. Some plans have
been made to utilize a building near the old train station
(Fig. 15). The Victorian-style building is a 20-m (66-ft)
long, 7-m (23-ft) wide storage facility belonging to the
train station. This structure, which is available to repur-
pose, now belongs to AFE (the Uruguayan state railway
company), which has given its preliminary agreement,
although the ofcial resolution is still pending. Addition-
ally, authorities have expressed their intention to develop
an on-site museum at the Arroyo del Vizcaíno itself. We
are presently looking for funding with which to undertake
the work necessary to exhibit this material in the most
professional way.
EDUCATION
Since the early excavations took place, the team has
been concerned with the exhibition of the fossils from the
site and the development of educational activities related
to them. Initially, the bones were exhibited at the local
high school and were used in several projects generated
by the teachers, and in many talks given to the students
by the team. After the lab/collection was installed in the
Casa de la Cultura, many groups of students from local and
surrounding elementary and high schools have visited it
and received a short presentation about the ndings. This
has made the site and its fossils better known to the local
population.
In 2012 the team created an organized activity to in-
volve local high school students in science and research.
Funded by ProCiencia (a state-driven educational program
in charge of engaging high school students in science), it
involved the teaching of paleontology, palynology, and
the increased awareness of the important heritage found
at the locality.
194 Dakoterra Vol. 6, 2014
FIGURE 5. Grid of 1 m2 (11 ft2) laid over the site to map
the excavated fossils. Photograph by Martin Batallés.
FIGURE 6. Specimens from the 2011 excavation stored in
tagged plastic bags. Photograph by Martin Batallés.
FIGURE 7. Covering the fossils left in the site with
geocloth after the 2011 excavation. Photograph by Martin
Batallés.
FIGURE 8. Detail of the site showing how the bones were
intermingled. Photograph by Ada Czerwonogora.
FIGURE 9. View into the rst room assigned to house the
material in the Casa de la Cultura de Sauce prior to 2011.
Photograph by Martin Batallés.
195FARIÑA AND DI GIACOMO—ARROYO DEL VIZCAÍNO, URUGUAY
During 2013, eight groups of 15–25 students became
‘paleontologists’ for a few days through several activities:
digging out fossils, specimen identication, interpretation
of the fossils, a visit to the lab/collection, and the presen-
tation of a nal student-made project. The students exca-
vated replicas of the bones found at Arroyo del Vizcaíno
and also from living animals. Each larger group of students
was subdivided in 6 groups and each had to extract the
material with the techniques used by paleontologists in
the eld (Fig. 16). The replicas were placed within two
wooden boxes lled with sand and a rope grid was cre-
ated using the sides of the boxes. Each box represented
a different fossil locality. One box contained only fossil
material, and the other box contained remains of extinct
and extant taxa.
In order for the students to identify the bones they
collected, the team created large sheets with information
about the animals, pictures of their bones, life reconstruc-
tions, and a size comparison with humans. The team
helped the students with the identication but made sure
they came to their own conclusions with logic (Fig. 17).
Two different pollen samples were also analysed by the
students, each belonging to one of the wooden boxes in
order to make comparisons about the vegetation present in
each ‘site’. The samples were created using autochthonous
FIGURE 10. Second slightly larger room assigned in 2011
to store the fossils in the Casa de la Cultura de Sauce.
Photograph by Mariana Di Giacomo.
trees, bushes, and grasses, keeping in mind the possible
environments that could have dominated the area in the
past 30,000 years. Informative sheets were also created to
aid the identication of the pollen grains.
The students that worked in the ‘oldest’ box had only
replicas of the bones from Arroyo del Vizcaíno and pollen
indicative of an open environment, whereas the others had
a ‘younger site’ with several smaller taxa and pollen evi-
dence of a forest-like environment. They discussed their
ndings and came to these conclusions by themselves.
They also created hypothesis explaining what could have
happened between those times for the vegetation and ani-
mals to have changed so drastically.
The trip to the lab/collection was a good way to teach
the students how we work in the eld and how we store the
fossils recovered. After watching a video of the excava-
tions, they were shown the collection and all the improve-
ments made in the last few months (Fig. 18). The goals
of showing the fossils to the students were to make them
realize how important the site is for science, and also to
help foster pride in their community.
The students, working in groups, then elaborated proj-
ects of their choice that conveyed what they had learned.
Projects included two theatrical plays, scale models, dif-
ferent types of souvenirs to give to the visitors, informa-
tion sheets and two actual-scale silhouettes of a glyptodont
and a giant sloth for people to compare themselves with
and take photographs (Fig. 19). The projects created by
the students were presented to the local community in an
event attended by over 100 people in a local club (Sauce
Basketball Club), and the students were given certicates
of ‘amateur palaeontologists’.
The response from the teachers and the students was
very positive. Both groups expressed their interest in ac-
tivities like these and wanted to do more. Another interest-
ing outcome was the positive reaction from the parents and
other relatives after seeing their children’s projects – they
showed gratitude towards the team and were excited about
their children’s enthusiasm. The team plans to continue
developing other educational activities with local students
as well as with students from other cities and towns of
the country.
FINAL REMARKS
Even though the great quantity of fossils already ex-
tracted—and those still lying in the depths of the Vizcaíno
stream—ensure there will be work for many years ahead
(thus the enormous importance of the site), there are also
signs that lead us to propose humans left their imprint
on some of them—such as human-made marks found on
a collarbone, a rib and other bones. As if this were not
enough, radiocarbon dating in several labs, with diverse
procedures and on varied remains (bone as well as wood)
shows the fossils to be surprisingly old for human-modi-
ed bone, going back nearly 30,000 years. These results
would double the accepted time of peopling of the Ameri-
cas, excluding Alaska.
196 Dakoterra Vol. 6, 2014
FIGURE 11. Fossils being identied. They were set
on polyfoam with its tag and plastic bag in between.
Photograph by Martín Batallés.
FIGURE 12. One of us (MDG) reconstructs a broken
femur of the giant sloth Lestodon. Shelves with fossils in
the background. Photograph by Martín Batallés.
FIGURE 13. Escaparate, a venue in Sauce where musical
and theatre shows take place. During a week in July 2012,
all the fossils collected in the Arroyo del Vizcaíno site
were displayed there. Photograph by Martín Batallés.
FIGURE 14. Team member Sebastián Tambusso lies
besides a reconstructed composite skeleton of the giant
sloth Lestodon. Photograph by Luciano Varela.
197FARIÑA AND DI GIACOMO—ARROYO DEL VIZCAÍNO, URUGUAY
FIGURE 15. Building associated with the train station
in Sauce, planned to be used for the future museum.
Photography by Sebastián Tambusso.
FIGURE 16. Students of the Sauce high school digging
for fossils in a sand box. Photograph by Martín Batallés.
FIGURE 17. Team member Sebastián Tambusso helping
the students with the identication of the fossil replicas
they collected from the sand boxes. Photograph by Leticia
Tejera.
FIGURE 18. Team member Luciano Varela showing the
fossils in the current lab/collection. Photograph by Martín
Batallés.
FIGURE 19. A group of proud Sauce high school students
show their project, a diorama of the Arroyo del Vizcaíno
site as they conceived it. Photograph by Martín Batallés.
198 Dakoterra Vol. 6, 2014
ACKNOWLEDGMENTS
We thank Á. Beri, X. Martínez, P. Sebastián Tambusso,
L. Tejera, and L. Varela for allowing us to use their mate-
rial of the ProCiencia project. M. Batallés and G. Costoya
took most of the photographs used in the gures. M. Muy-
ano made the 3D reconstruction on which Fig. 2 is based.
LITERATURE CITED
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Arribas, A., P. Palmqvist, J. A. Pérez-Claros, R. Castilla,
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on the interaction between humans and megafauna
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Czerwonogora, A., R. A. Fariña, and E. P. Tonni.
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