THE FOSSIL MAMMALS COLLECTED BY CHARLES DARWIN IN SOUTH AMERICA DURING HIS TRAVELS ON BOARD THE HMS BEAGLE
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Revista de la Asociación Geológica Argentina 64 (1): 147 - 159 (2009) 147
THE FOSSIL MAMMALS COLLECTED BY CHARLES
DARWIN IN SOUTH AMERICA DURING HIS TRAVELS
ON BOARD THE HMS BEAGLE
Juan Carlos FERNICOLA1, Sergio F. VIZCAÍNO2 and Gerardo DE IULIIS 3
1
Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Buenos Aires, Argentina.
Email: jctano@macn.gov.ar
2
División Paleontología Vertebrados, Museo de La Plata, La Plata, Argentina. CONICET. Email: vizcaino@fcnym.unlp.edu.ar
3
School of Nursing, George Brown College of Applied Arts and Technology, Toronto; and Department of Ecology and Evolutionary
Biology, University of Toronto, Toronto, Canada. Email: gerry.deiuliis@utoronto.ca
ABSTRACT
During the first two years of his voyage aboard HMS Beagle, Charles Darwin collected a considerable number of fossil mam-
mals from various localities in Argentina and Uruguay. Among these remains are those of large mammals that Darwin infor-
mally assigned to Megatherium and Mastodon, the only large taxa then known for South America, and of small and medium-
sized mammals that Darwin recognized as representing at least two rodents and a horse. The study of Darwin's collection was
entrusted to Richard Owen, who described eleven taxa between 1837 and 1845, including the six following ones: Toxodon pla-
tensis, Macrauchenia patachonica, Equus curvidens, Scelidotherium leptocephalum, Mylodon darwini and Glossotherium sp. This contribution
provides a synthesis of Darwin's preliminary assignments and evaluates the reasons that led him to recognize only megathe-
res and mastodonts for the large fossil remains. Also, it discusses the current taxonomic status of the taxa described or erec-
ted by Owen between 1837 and 1845 and the influence that Owen's taxonomic and phylogenetic conclusions had on the deve-
lopment of Darwin's ideas on evolution.
Keywords: Darwin, Taxonomy, South America, Fossil mammals.
RESUMEN: Los mamíferos fósiles colectados por Charles Darwin en América del Sur durante su viaje a bordo del HMS Beagle. Durante los dos
primeros años de su viaje a bordo del HMS Beagle, Charles Darwin colectó en distintas localidades de Argentina y Uruguay
un considerable número de mamíferos fósiles. Entre estos se cuentan los grandes mamíferos que informalmente Darwin asig-
nó a Megatherium y Mastodon, únicos grandes taxones conocidos hasta ese momento para América del sur y entre los pequeños
y medianos mamíferos reconoció la presencia de al menos dos tipos de roedores y un caballo. El estudio posterior de todos
los ejemplares colectados por Darwin fue llevado a cabo Richard Owen, quien entre 1837 y 1845 describió once taxones, entre
los cuales, seis eran nuevos taxones: Toxodon platensis, Macrauchenia patachonica, Equus curvidens, Scelidotherium leptocephalum, Mylodon
darwini y Glossotherium sp. En esta contribución se brinda una síntesis de las asignaciones preliminares efectuadas por Charles
Darwin y se evalúan los motivos que lo habrían llevado a reconocer sólo megaterios y mastodontes entre los grandes mamí-
feros fósiles por él colectados. También tiempo, se discute el estatus taxonómico de los taxones descritos o fundados por
Richard Owen entre 1837 y 1845 y la influencia que habrían tenido las conclusiones taxonómicas y filogenéticas de Owen en
el desarrollo de las ideas evolutivas de Darwin.
Palabras clave: Darwin, taxonomía, América del Sur, mamíferos fósiles.
INTRODUCTION (Buenos Aires Province, Argentina). Dar- from the Arroyo Sarandí near the city of
win returned to Punta Alta between Mercedes (Soriano Department). He re-
Charles Darwin collected fossil mammals August 29 - 31, 1833. Several weeks la- turned to Argentina and collected his last
from various South American localities ter, around September 19, he collected specimens at Puerto San Julián (Santa
during his voyage aboard HMS Beagle. in Guardia del Monte (Buenos Aires Pro- Cruz Province) during the first several
He recovered his first fossil at Punta Alta vince); the Rio Carcarañá or Tercero months of 1834 (see Fig. 1). All the spe-
(Buenos Aires Province, Argentina) on (Santa Fe Province, Argentina) on Octo- cimens, sent to his mentor John Stevens
September 23, 1832, and continued co- ber 1; and the Bajada Santa Fe (Paraná, Henslow and later deposited in the Royal
llecting intermittently at this locality until Entre Ríos Province, Argentina) on Oc- College of Surgeons (London, England),
October 16. Three days later he collected tober 10. Moving to Uruguay, he collec- were studied by Richard Owen beginning
several specimens from Monte Hermoso ted fossils during November 25 - 26 in 1836.148 J. C. F E R N I C O L A , S. F. V I Z C A Í N O A N D G. D E I U L I I S
in the earliest histories of America (e.g.
Cieza de León 1553, Falkner 1774). The-
se objects were interpreted as the re-
mains of an ancient race of giant hu-
mans that inhabited this part of the
world before being smitten by divine
force. Cieza de León (1553, p. 183) pro-
vided the following vivid tale about huge
bones found in Santa Elena, Ecuador: "Y
así, dicen que, estando todos juntos envueltos en
su maldita sodomía, vino fuego del cielo temero-
so y muy espantable, haciendo gran ruido, del
medio del cual salió un ángel resplandeciente, con
una espada tajante y muy refulgente, con la cual
de un solo golpe los mató a todos y el fuego los
consumió, que no quedó sino algunos huesos y
calaveras, que para memoria del castigo quiso
Dios que quedasen sin ser consumidas por el
fuego. Esto dicen de los gigantes; lo cual creemos
que pasó, porque en esta parte que dicen se han
hallado y se hallan huesos grandísimos. Y yo he
oído a españoles que han visto pedazo de muela
que juzgaban que a estar entera pesara más de
media libra carnicera, y también que habían
visto otro pedazo del hueso de una canilla, que es
cosa admirable contar cuán grande era, lo cual
hace testigo haber pasado…".
This sort of general belief persisted, in
South America at least, until the end of
the 18th century, even though some of
Figure 1: Map of the localities the remains were recognized as nonhu-
where Charles Darwin collec- man, as indicated in the following passa-
ted fossil mammals.
ges by the English Jesuit Thomas Falkner
Regrettably, the intense bombardment Surgeons retained only a single specimen, (1774, p. 54-55) "On the banks of the River
suffered by this institution during April the remains of the Megatherium america- Carcarania, or Tercero, about three or four lea-
10 and 11, 1941, destroyed a large part of num specimen that apparently allowed gues before it enters into the Parana, are found
its paleontological treasures. Cave's (1942) Owen (1840) to recognize the presence great numbers of bones, of an extraordinary
catalogue of the surviving specimens of a fifth upper molariform in this taxon bigness, which seem human. There are some gre-
revealed that some 95% of the collection (see appendix 1). ater and some less, as if they were of persons of
had been lost - of 5,000 specimens, only The aim of this contribution is to provi- different ages. I have seen thigh-bones, ribs, bre-
175 remained. Among these, fortunately, de an update on the taxonomic status of ast-bones, and pieces of skulls. I have also seen
are various of the specimens collected by the various taxa recognized or establis- teeth, and particularly some grinders which were
Charles Darwin and described by Ri- hed by Owen (1837-45), and to consider three inches in diameter at the base. These bones
chard Owen (1837-1845) as new taxa, in- the influence the specimens and their (as I have been informed) are likewise found on
cluding Equus curvidens, Glossotherium sp; assignment had on the development of the banks of the Rivers Parana and Paraguay,
Macrauchenia patachonica, Mylodon darwini, Darwin's ideas. as likewise in Peru. The Indian Historian,
Scelidotherium leptocephalum and Toxodon Garcilasso de la Vega Inga, makes mention of
platensis (Cave 1942). Beginning in 1946, HISTORICAL BACKGROUND these bones in Peru, and tells us that the Indians
nearly all of Darwin's collection was have a tradition, that giants formerly inhabited
transferred to the Natural History Mu- The first notices of South American those countries, and were destroyed by God for
seum (London), where it is still housed "fossils" appear in the reports of early the crime of sodomy.
(see appendix 1). The Royal College of Spanish explorers to South America and I myself found the shell of an animal, composedThe fossil mammals collected by Charles Darwin in South America ... 149
of little hexagonal bones, each bone an inch in dillierès" and "mastodonte humboldien". Cu- ments that Owen (1837-1845) later mo-
diameter at least; and the shell was near three vier (1823) later formally named them dified. Several of his assignments were
yards over. It seemed in all respects, except it's Mastodon angustidens, Mastodon andium and considered taxonomic errors or misinter-
[sic] size, to be the upper part of the shell of the Mastodon humboldti, respectively (see Ca- pretations (e.g., Sulloway 1982, Keynes
armadillo; which, in these times, is not above a brera 1929). In this paper, Cuvier (1823, 2001), even though his inferences were in
span in breadth." p. 179) included a handwritten communi- accordance with what was then known.
It was during this period that the illus- cation by "don Dámaso Antonio Larrañaga,
trious French naturalist George Cuvier a priest of Montevideo, to Mr. Augusto de DARWIN'S FOSSIL MAMMALS
(1796) published the first scientific work Saint-Hilaire" that briefly described a
on a South American fossil, which he group of fossil specimens, including a The following presents a synthesis of
described and named Megatherium america- partial exoskeleton (or carapace), under Owen's initial taxonomic assignments
num based on the specimen recovered by the name "Dasypus (Megatherium Cuv)." (1837-45) of the remains collected by
Fray Manuel Torres in 1787 from Luján Cuvier (1823) thus acknowledged that Darwin in South America, including the
in Buenos Aires Province, Argentina and this carapace probably belonged to Mega- preliminary assignments made by Dar-
sent the following year by the Marquis of therium. Whatever the reasons that prom- win. The latter's assignments were glea-
Loreto, Viceroy of Río de la Plata, to the pted Larrañaga's subgeneric assignment ned from field notes (Darwin 2002-
Real Gabinete de Historia Natural in Ma- (that is, in recognizing the existence of 2008), personal correspondence (Darwin
drid, Spain. Mones (1986) considered the armored megatheres), the fact that his 1985) and Charles Darwin's Beagle Diary
erection of this species as the first Lin- opinion appeared in a work by Cuvier en- (in Keynes 2001), all material written by
nean nomenclatorial act for a South sured its credibility, so that several in- Darwin before 1836, the year of his
American fossil species. This specimen complete remains later sent to Europe return to England. The suprageneric
had, however, previously been described were similarly recognized (e.g., as by classification used here follows McKen-
and figured by Juan Bautista Bru de Ra- Weiss 1830, Clift 1835). It was not until na and Bell (1997).
món, an artist and first taxidermist of the later that Owen (1839a) demonstrated
Real Gabinete de Historia Natural. In this that megatheres were not armored and SYSTEMATIC
regard, Garriga (1796, as quoted in Ló- that the remains belonged instead to the PALEONTOLOGY
pez Piñeiro and Glick 1993, p. 126) noted group of mammals he termed glypto-
that "… restaba superar la dificultad de que donts, a group closely related to armadi- Grandorder Ungulata Linnaeus, 1776
permitiese Bru que se diese a luz una obra que llos. Mirorder Meridiungulata McKenna, 1975
él había tenido en otro tiempo intento de publi- Knowledge of South American fossil Order Notoungulata Roth, 1903
car, y por varias circunstancias imprevistas mammals remained at this elementary le- Suborder Toxodontia Owen, 1853
sepultó en el olvido." López Piñeiro and vel for much of the early part of the 19th Family Toxodontidae Owen, 1845
Glick (1993, p. 66) maintained that the century, as is made clear from Owen's Subfamily Toxodontinae Owen, 1845
preparation of the monograph "… no fue (1838, p. 13) opening paragraph on his Genus Toxodon Owen, 1837
entonces editada, pero su preparación debía estar work on the fossil mammals in Darwin's
tan adelantada que un tal Roume, representan- The Zoology of the Voyage of H.M.S. Beagle: Toxodon platensis Owen, 1837
te del gobierno de francés en Santo Domingo, "It may be expected that the description of the Fig. 2
consiguió un juego de pruebas de las planchas a osseous remains of extinct Mammalia, which
su paso por Madrid en 1793. rank amongst the most interesting results of The specimens assigned to this taxon by
Roume envió las pruebas de las planchas al Mr. Darwin's researches in South America, Owen (1837, 1838) were recovered by
Institut de France, del que era miembro corres- should be preceded by some account of the fossil Darwin from various South American
pondiente, acompañadas de una "corta descrip- mammiferous animals which have been pre- localities. On October 1 and 10, 1833, he
ción" del esqueleto. La sección de ciencias del Ins- viously discovered in that Continent. The results collected at Río Carcaraña o Tercero
titut encargó a George Cuvier un informe sobre of such a retrospect are, however, necessarily (Santa Fe Province) and at Bajada Santa
el tema, que apareció publicado en 1796…" comprised in a very brief statement; for the Fe (Paraná, Entre Ríos Province). His
Cuvier (1806) also studied fossil probos- South American relics of extinct Mammalia, field notes (Darwin 2002-2008) describe
cidean remains found by Dombey in Pe- hitherto described, are limited, so far as I know, a fossil specimen as "…a large rotten tooth
ru and by Humboldt in various localities to three species of Mastodon, and the gigantic & in the layer large cutting tooth", a descrip-
in Bolivia, Chile, Colombia, and Ecua- Megatherium." tion that agrees with those included in
dor, among which he recognized three It was against this systematic framework his Beagle Diary ("… a curious & large cut-
morphotypes, designated informally as that Darwin began his efforts in collec- ting tooth"; in Keynes 2001, p. 193) and
"mastodonte a dents étroites", "mastodonte Cor- tion and preliminary taxonomic assign- written to John Stevens Henslow ("In ye150 J. C. F E R N I C O L A , S. F. V I Z C A Í N O A N D G. D E I U L I I S
R. Carcarana I got a tooth, which puzzles even
my conjectures, it looks like an enormous gna-
wing one"; Letter 229 in Darwin 1985).
Darwin's (2002-2008) field notes for No-
vember 26, 1833, state: "Started went round
by a house to see large head & bones, washed
out of Barranca & found after a flood. - pieces
here also of Casca - Barranca" while his Bea-
gle Diary (in Keynes 2001) records: "Be-
gan my return in a direct line to M. Video; went
by an Estancia where there was a part, very per-
fect, of the head of a Megatherium. I purcha-
sed it for a few shillings". An alveolus of this
specimen, recovered from Arroyo Saran-
dí, Departament of Soriano, Uruguay,
easily accommodated a molariform tooth
found by Darwin in Carcaraña (Owen
1838).
Toxodon sp.
The mandible and isolated molariforms
assigned by Owen (1837, 1838) to this
genus were collected between September
23 - October 16, 1832, at Punta Alta
(Buenos Aires Province, Argentina). On
Figure 2: Skull of Toxodon
the molariforms, Darwin (1985, Letter
platensis in ventral view (from
192) noted that "some large molar teeth, Owen 1838). Scale bar = 10
which in some respects would seem to belong to cm.
an enormous Rodentia". Burmeister (1866)
based the species Toxodon darwini on the from the Rodentia, and the existing Pachyder- gulates of South America. The Notoun-
mandible described by Owen (1838) mata, and it manifests an affinity to the Dino- gulata, a clade of the Mirorder Meridiun-
Bond (1999) acknowledged the possible therium and the Cetaceous order. Mr. Owen, gulata, shares an ancestry with North
synonymy of Toxodon darwini with Toxo- however, observed, that the development of the American condylarths (Cifelli 1993) In
don platensis, although he recognized that nasal cavity and the presence of frontal sinuses, other words, Toxodon has no close phylo-
a revision of the genus was required. renders it extremely improbable that the habits genetic relationships with the groups
Owen (1837, 1838, p. 16) recognized To- of he Toxodon were so exclusively aquatic as mentioned by Owen (1838).
xodon as "A gigantic extinct mammiferous ani- would result from the total absence of hinder
mal, referrible to the Order Pachydermata, but extremities; and concludes, therefore, that it was Grandorder Ungulata Linnaeus, 1776
with affinities to the Rodentia, Edentata, and a quadruped, and not a Cetacean; and that it Mirorder Meridiungulata McKenna, 1975
Herbivorous Cetacea". Darwin (1839, p. manifested an additional step in the gradation of Order Liptopterna Ameghino, 1889
180) summarized the morphological ba- mammiferous forms leading from the Rodentia, Superfamily Macrauchenioidea Gervais,
sis leading to this idea of multiple affini- through the Pachydermata to the Cetacea; a gra- 1855
ties: "Mr. Owen says, judging from the portion dation of which the water-hog of South Ame- Family Macraucheniidae Gervais, 1855
of the skeleton preserved, the Toxodon, as far rica (Hydrochærus capybara) already indi- Subfamily Macraucheniinae Gervais, 1855
as dental characters have weight, must be refe- cates the commencement amongst existing Ro- Genus Macrauchenia Owen, 1838
rred to the rodent order. But from that order it dentia, of which order it is interesting to observe
deviates in the relative position of its supernu- this species is the largest, while at the same time Macrauchenia patachonica Owen, 1838
merary incisors, in the number and direction of it is peculiar to the continent in which the re- Fig. 3a
the curvature of its molars, and in some other mains of the gigantic Toxodon were discovered".
respects. It again deviates, in several parts of its The genus Toxodon is now considered In a letter from March, 1834, to John
structure which Mr. Owen enumerated, both among the more derived native notoun- Stevens Henslow, Darwin (1985, LetterThe fossil mammals collected by Charles Darwin in South America ... 151
238) recounted that "At Port St Julian I
found some very perfect bones of some large ani-
mal, I fancy a Mastodon". On this speci-
men, the only one found by Darwin in
Puerto San Julián, Owen (1838, p. 35)
erected Macrauchenia patachonica, which he
considered "A large extinct Mammiferous
Figure 3: a) Cervical vertebra
Animal, referrible to the Order Pachydermata; of Macrauchenia patachonica in
but with affinities to the Ruminantia, and espe- lateral and ventral views (from
cially to the Camelidae". The evolutionary Owen 1838). Scale bar = 5 cm;
b) Tooth of Equus sp. in
significance of this purported kinship occlusal and lateral views
impressed Darwin (1839, p. 210): "The (from Owen 1840). Scale bar
most important result of this discovery, is the = 1 cm.
confirmation of the law that existing animals Diary (in Keynes 2001), or personal co- Currently Stegomastodon platensis is the only
have a close relation in form with extinct species. rrespondence (Darwin 1985). Although proboscidean species recognized from
As the guanaco [Camelidae] is the characteris- Owen (1840) did not attempt specific as- the areas yielding Darwin's specimens
tic quadruped of Patagonia, and the vicuna of signation of these molars, he did note (Alberdi and Prado 1995).
the snow-clad summits of the Cordillera, so in that the only difference between them
bygone days, this gigantic species [Macrauche- and those of Equus caballus was the sma- Magnorder Xenarthra Cope, 1889
nia patachonica] of the same family must ller size of the former. Owen (1845) Order Pilosa Flower, 1883
have been conspicuous on the southern plains". erected Equus curvidens based on Darwin's Suborder Phyllophaga Owen, 1842
The genus Macrauchenia is now conside- specimens, a species which is considered Infraorder Mylodonta McKenna and
red as among the more derived native synonymous with Equus (Amerhippus) neo- Bell, 1987
South American litopterns. As with the geus Lund by Prado and Alberdi (1994). Superfamily Mylodontoidea Gill, 1872
Notoungulata, the Litopterna comprises Family Scelidotheriidae Ameghino, 1889
a clade of the Mirorder Meridiungulata Grandorder Ungulata Linnaeus, 1776 Subfamily Scelidotheriinae Ameghino,
and is closely related to North American Order Uranotheria McKenna and Bell, 1889
condylarthrans, rather than camelids, as 1987 Genus Scelidotherium Owen, 1839b
erroneously proposed by Owen (1838). Suborder Tethytheria McKenna, 1975
Infraorder Behemota McKenna and Bell, Scelidotherium leptocephalum Owen, 1839b
Grandorder Ungulata Linnaeus, 1776 1987 Fig. 4
Mirorder Altungulata Protero and Schoch, Parvorder Proboscidea Illiger, 1811
1989 Superfamily Elaphantoidea Gray, 1821 This taxon was based by Owen (1839b)
Order Perissodactyla Owen, 1848 Family Gomphotheriidae Hay, 1922 on the only nearly complete skeleton
Suborder Hippomorpha Word, 1937 Subfamily Rhynchoteriinae Hay, 1922 found by Darwin at Punta Alta (Buenos
Family Equidae Gray, 1821 Tribe Cuvieroniini Cabrera, 1929 Aires Province). We are unable to find
Genus Equus Linnaeus, 1758 Genus Mastodon Rafinesque, 1814 any preliminary assignment of this speci-
men by Darwin, although Sulloway
Equus sp. Mastodon sp. (1982, p. 353) noted that Darwin consi-
Fig. 3b dered the specimen as "allied to the Rhi-
The specimens assigned to this taxon, noceros". Darwin made this conjecture on
The remains assigned to this genus re- collected by Darwin at Bajada Santa Fe September 23, 1832 (in Keynes 2001) in
present the first fossil horses found in (Entre Ríos Province) and Río Carcarañá the following Beagle Diary entry: "… I
South America. The two molars from or Tercero (Santa Fe Province), were walked on to Punta Alta to look after fossils; &
Argentina were recovered from Punta noted by Owen (1840, p. 180) as "…the to my great joy I found the head of some large
Alta (Buenos Aires Province) and Bajada fragments of the teeth and portions of the skele- animal, imbedded in a soft rock. … It took me
Santa Fe (Entre Rios Province). The spe- ton which reached England, are not sufficient to nearly 3 hours to get it out: As far as I am able
cimen from Bajada Santa Fe was referred lead to a determination of the species; but suffi- to judge, it is allied to the Rhinoceros. … I
to by Darwin as a horse (in Keynes ciently prove it to have been nearly allied, if not did not get it on board till some hours after it was
2001). We have not been able to find any identical, with the Mastodon angustidens of dark". However, the specimen assigned
mention of the other specimen in his Cuvier, and unquestionably distinct from the by Owen (1839b) to Scelidotherium was co-
field notes (Darwin 2002-2008), Beagle Mastodon giganteum of the United States". llected by Darwin in Punta Alta in Au-152 J. C. F E R N I C O L A , S. F. V I Z C A Í N O A N D G. D E I U L I I S
ther it was collected during his first or
second sojourn to this area. In a letter
sent to John Stevens Henslow in No-
vember, 1832, Darwin (1985, Letter 192)
noted a completed list of fossils collected
in Bahia Blanca, among which he empha-
sized "… the upper jaw & head of some very
large animal, with 4 square hollow mo-
lars….& the head greatly produced in front….
I at first thought it belonged either to the Me-
galonyx or Megatherium…. In confirma-
tion, of this, in the same formation I found a
large surface of the osseous polygonal plates,
which ``late observations'' (what are they?) show
belong to the Megatherium". A footnote on
this page, presumably inserted by the edi-
tors, indicates that this specimen was
"Described in Fossil Mammalia, p. 63-73, by
Richard Owen, who identified it as belonging to
a distinct subgenus of Megatheroid Edentata, to
which he gave the name Mylodon darwinii".
However, we believe this to be incorrect
- the specimen is not the one that Owen
(1839b) later assigned to Mylodon darwini,
as Dar-win indicated that the specimen
was an upper jaw and skull, rather than
the mandible on which Mylodon darwini is
based. Darwin's indication of the presen-
ce of four molariforms possibly led to
Figure 4: Partial skeleton of
Scelidotherium leptocephalum in the assumption (i.e., in the footnote) that
ventral view (from Owen, the specimen belonged to Mylodon darwi-
1838b). Scale bar = 10 cm. ni, given that five upper molariforms are
gust, 1833, the time during which Darwin Suborder Phyllophaga Owen, 1842 present in Megatherium. However, the
had returned to this locality (Keynes Infraorder Mylodonta McKenna and earliest descriptions of Megatherium indi-
2001, p. 178). Further confirmation of Bell, 1987 cate four upper molariforms. As noted
this date appears in a letter from Darwin Superfamily Mylodontoidea Gill, 1872 above, it was Owen (1840, p. 102) who
(1985, Letter 188), dated September 20, Family Mylodontidae Gill, 1872 recognized the presence of a fifth upper
1833, to Caroline S. Darwin, in which he Subfamily Mylodontinae Gill, 1872 molariform: "Upon clearing away the matrix
recounts that "I likewise at Bahia Blanca Genus Mylodon Owen, 1839b from the palatal and alveolar surface of one of
found some more bones more perfect than those I the cranial fragments of the Megatherium in
formerly found, indeed one is nearly an entire Mylodon darwini Owen, 1839b Mr. Darwin's collection, I was gratified by the
skeleton". As indicated below, Darwin's Fig. 5a detection of the crown of a fifth molar".
"allied to the Rhinoceros" comment may The taxonomic history of Mylodon is
more likely have been a reference to one The specimen assigned to this genus by among the more complex for the taxa
of the cranial remains that Owen (1840) Owen (1839b, p. 69) consists of "…the erected by Owen (1838-1840), due main-
later assigned to the genus Megatherium, lower jaw with the series of teeth entire on both ly to the ambiguity in the type species.
particularly as Owen's generic assigna- sides: but the extremity of the symphysis, the Owen (1839b) erected Mylodon for two
tions of the sloths are for the most part coronoid and condyloid processes, and the angu- species, Mylodon darwini and Mylodon harla-
still considered correct. lar process of the left ramus, are wanting". ni. The former species was based on a
This specimen was recovered by Darwin left dentary from Punta Alta (Buenos Ai-
Magnorder Xenarthra Cope, 1889 at Punta Alta (Buenos Aires Province), res Province), whereas the second was
Order Pilosa Flower, 1883 but we were unable to determine whe- based on a cast of a mandible fromThe fossil mammals collected by Charles Darwin in South America ... 153
North America that Harlan (1835) had
assigned to Megalonyx laqueatus. Owen
(1839b) was unclear about his choice of
type species, given that in the title of his
description of his new genus he referred
to the fossil collected by Darwin, but in
the text Owen noted that Mylodon darwini
was the second species of the genus.
This ambiguity would be trivial if the two
species were congeneric, but they have
been subsequently considered as belon-
ging to different genera. Consequently,
some later researchers, such as Reinhardt
(1879), Lydekker (1887) and Brown
(1903), considered Mylodon harlani as the Figure 5: a) Mandible of
type of the genus, whereas other, such as Mylodon darwini in occlusal
Leidy (1855), bestowed this status on view (from Owen, 1839b).
Scale bar = 10 cm; b)
Mylodon darwini. The issue was resolved Cranial fragment of the skull
by Kraglievich (1928) in favor of Mylodon of Glossotherium in lateral
darwini based on the following reasons: view (from Owen 1839b)
Scale bar = 10 cm.
1) the title of the generic description re-
fers to the mandible collected by Dar- Tribe Glossotheriini McKenna, 1987 Mylodon robustus, and 3) that the cranial
win; Genus Glossotherium Owen, 1839b fragment originally assigned by Owen
2) the original material available to Owen (1839b) to Glossotherium was closely allied
was the dentary from Punta Alta; Glossotherium sp. generically to Mylodon robustus. Not recog-
3) Owen (1842) recognized Mylodon harla- Fig. 5b nizing Mylodon darwini as type of the
ni as the second species of the genus; genus, Reinhardt (1879) proposed the
4) in his "Conspectus familiarum, generum et This genus was erected by Owen (1839b) new genus Grypotherium, in which he pla-
specierum", Owen (1842, p. 169) listed My- based on the posterior half of a skull ced the dentary assigned by Owen
lodon darwini as the first species of the recovered from Arroyo Sarandí (Soriano (1839b) to Mylodon darwini and the speci-
genus. Departament, Uruguay). In his Beagle men from Pergamino as the species
Kraglievich's (1928) logic has been ac- Diary, Darwin (in Keynes 2001) noted Grypotherium darwini; and recognized My-
cepted by the scientific community, so that "We heard of some giants bones, which as lodon robustus as the type species of My-
that Mylodon darwini is currently conside- usual turned out to be those of the Megatherium lodon. Ameghino (1889) accepted the ge-
red the type species of Mylodon, whereas - With much trouble extracted a few broken neric differences noted by Reinhardt
Mylodon harlani is placed in the genus fragments". As with Mylodon darwini, the (1879), but considered, as Owen (1842)
Paramylodon. The taxonomic solution pro- taxonomic history of Glossot-herium is had before, that the cranial fragment of
vided by Kraglievich (1928) not only re- complex. Owen (1842) erected the new Glossotherium and the dentary of Mylodon
solved the taxonomic problem with My- species Mylodon robustus on remains darwini belonged to the same species, and
lodon, but also helped clarify the proble- incluiding a nearly complete skull; and so included these specimens - as well as
matic nomenclature of the genus Glosso- assigned to Mylodon darwini (based on a the skull and mandible from Pergamino -
therium (see below). dentary) the cranial fragment previously in Glossotherium darwini, given that in this
described by Owen (1839b) as Glossothe- scenario Glossotherium has priority over
Magnorder Xenarthra Cope, 1889 rium. Reinhardt's (1879) detailed descrip- Grypotherium. Smith-Woodward's (1900)
Order Pilosa Flower, 1883 tion of a fossil sloth skull and mandible revision of Darwin's South American
Suborder Phyllophaga Owen, 1842 from Pergamino (Buenos Aires Pro- fossil sloth collection concluded that the
Infraorder Mylodonta McKenna and vince) recognized, 1) that the mandible cranial fragment originally assigned to
Bell, 1987 was very similar to that described as Glossotherium was congeneric with the
Superfamily Mylodontoidea Gill, 1872 Mylodon darwini by Owen (1839b), 2) that specimen assigned to Mylodon robustus by
Family Mylodontidae Gill, 1872 its skull features were sufficiently distinct Owen (1842) and that the dentary of
Subfamily Lestodontinae Ameghino, 1889 as to suggest generic separation from Mylodon darwini and the specimen from154 J. C. F E R N I C O L A , S. F. V I Z C A Í N O A N D G. D E I U L I I S
Pergamino, described by Reinhardt
(1879), were conspecific. However, as
Smith-Woodward did not recognize
Mylodon darwini as type species of Mylo-
don, he resurrected Reinhardt's (1879)
Grypotherium.
Kraglievich (1928) modified the taxo-
nomy of these taxa based on a detailed
revision of the group. This author held
that the root of the problem was the
rejection of Mylodon darwini as type spe-
cies of Mylodon and the lack of agree-
ment on the assignment of the cranial
fragment assigned to Glossotherium by Figure 6: a) Parasagittal sec-
Owen (1839b). Once Kraglievich (1928) tion through the maxilla of
had established Mylodon darwini as type Megatherium cuvieri (=
Megatherium americanum, see
species of Mylodon, Grypotherium fell as a text) showing the five mola-
synonym of Mylodon. Kraglievich (1928) riforms (from Owen 1840).
agreed with Reinhardt (1879) and Smith- Scale bar = 10 cm; b)
Mandible of Megalonyx jeffer-
Woodward (1900) that the cranial frag- soni (= Mylodon darwini, see
ment of Glossotherium was congeneric text) in occlusal view (from
with Mylodon robustus but not conspecific Owen 1840). Scale bar = 10
with it. Consequently, and with the gene- cm.
ral understanding that Mylodon robustus Suborder Phyllophaga Owen, 1842 above) from consideration, and leaving
was generically distinct form Mylodon dar- Infraorder Megatheria McKenna and Megatherium as the only taxon to which he
wini, Kraglievich (1928) revalidated Glos- Bell, 1987 assigned skull material from Punta Alta.
sotherium, but with two species, i.e., Glos- Superfamily Megatheroidea Gray, 1821 Owen's (1840) assignment to the species
sotherium robustus and Glossotherium urugua- Family Megatheriidae Gray, 1821 Megatherium cuvieri was based on acceptan-
yense, the latter including Owen's (1839b) Subfamily Megatheriinae Gray, 1821 ce of the specific name change proposed
cranial fragment. These nomenclatural Genus Megatherium Cuvier, 1796 by Desmarest (1822) for Megatherium ame-
conclusions were accepted by Cabrera ricanum. However, this proposed nomen-
(1936), although in this author's revision Megatherium cuvieri Desmarest, 1822 clatural alteration is unsupported and the
of the species of Glossotherium, he recog- Fig. 6a name was considered a nomen illegiti-
nized its two valid species as Glossotherium mum by Mones (1986). In this context,
robustum and Glossotherium lettsomi (Owen), Owen (1840) assigned to this species va- the specimens assigned to Megatherium cu-
with Glossotherium uruguayense a synonym rious cranial fragments collected by Dar- vieri by Owen (1840) correspond to Mega-
of the latter (Glossotherium lettsomi was ori- win in Punta Alta (Buenos Aires Pro- therium americanum.
ginally assigned to Pleurolestodon lettsomi by vince). Although Darwin referred most
Gervais and Ameghino (1880), based on of the large remains he recovered to Magnorder Xenarthra Cope, 1889
observation of a skull exhibited in the Megatherium, as shown by his field notes, Order Pilosa Flower, 1883
Natural History Museum, London, that Beagle Diary, and personal correspon- Suborder Phyllophaga Owen, 1842
had been labeled by Owen as Mylodon lett- dence, Owen (1840) did likewise only for Infraorder Megatheria McKenna and
somi (see Ameghino 1889). the specimens collected from Punta Alta. Bell, 1987
Esteban's (1996) review of Mylodonti- In discussing Darwin's (in Keynes 2001, Superfamily Megatheroidea Gray, 1821
nae considered Glossotherium lettsomi (sen- p. 107) "allied to the Rhinoceros" com- Family Megalonychidae Gervais, 1855
su Cabrera 1936) a synonym of Glossothe- ment, we noted that it did not pertain to Subfamily Megalonychinae Gervais, 1855
rium robustum, so that the cranial fragment the Scelidotherium skeleton but to various Tribe Megalonychini Gervais, 1855
collected by Darwin in Uruguay is skulls assigned by Owen (1840) to Mega- Subtribe Megalonychina Gervais, 1855
currently assigned to the latter species. therium. Indeed, Darwin's comment, da- Infratribe Megalonychi Gervais, 1855
ted September 23, 1832, could only refer Genus Megalonyx Harlan, 1825
Magnorder Xenarthra Cope, 1889 to those skulls collected up to this time,
Order Pilosa Flower, 1883 effectively excluding Scelidotherium (see Megalonyx jeffersonii (Desmarest, 1822)The fossil mammals collected by Charles Darwin in South America ... 155
Fig. 6b rosettes, and so closely correspond in size and tober 19, 1832. Owen (1840, p. 10) com-
pattern with the bony armour described by M. mented that "Mr. Darwin discovered the
Owen (1840) assigned a mandible collec- Lund [1839], as characterizing his species, decomposed molar of a Rodent, equalling in
ted by Darwin at Punta Alta (Buenos Hoplophorus euphractus, that I feel no size, and closely resembling in the disposition of
Aires Province) to this species. A particu- hesitation in referring them to that animal". its oblique component laminae, the hinder molar
lar feature of this specimen, figured by Burmeister (1870-1874) assigned the os- of the Capybara (Hydrochoerus.) The fossil
Owen (1840, pl. 29), is that it preserves teoderms figured by Owen (1840, pl. 32, differs, however, in the greater relative breadth of
only one of the molariforms of the right figs 4 and 5) to Hoplophorus ornatus (= the component laminae.
dentary. This agrees with the description Neosclerocalyptus ornatus) and Hoplophorus ele- I have, lastly, to notice the head of a femur, and
given by Darwin (in Keynes 2001, p. 109) gans, respectively. Ameghino (1889) syno- some fragments of pelvic bones from the same
for a mandible collected October 8, nymized the latter with Lomaphorus elegans. formation which bear the same proportion to the
1832: "After breakfast I walked to Punta tooth above alluded to, as subsists between the
Alta, the same place where I have before found Magnorder Xenarthra Cope, 1889 teeth and bones of the Capybara, and which are
fossils… I obtained a jaw bone which contained Order Cingulata Illiger, 1811 sufficient to prove that there once has existed in
a tooth: by this I found out that it belongs to the Superfamily Glyptodontoidea Gray, 1869 South America a species of the family Caviidæ,
great ante-diluvial animal the Megatherium". Family Glyptodontidae Gray, 1869 as large as the present Capybara, but now appa-
Leidy (1852) erected a new taxon, Gna- Subfamily Glyptodontinae Gray, 1869 rently extinct".
thopsis oweni on this specimen, which Kra- Tribe Glyptodontini Gray, 1869 These elements were among those that
glievich (1928) assigned to Mylodon darwini. Genus Glyptodon Owen, 1839c Darwin (in Keynes 2001, p. 110-111) en-
countered as follows: "The Captain landed
Magnorder Xenarthra Cope, 1889 Glyptodon clavipes Owen, 1839c for half an hour at Monte Hermoso, (or Star-
Order Cingulata Illiger, 1811 vation point as we call it) to take observations. -
Superfamily Glyptodontoidea Gray, 1869 Owen (1840) tentatively assigned to this I went with him & had the good luck to obtain
Family Glyptodontidae Gray, 1869 species distinct osteoderms collected by some well preserved fossil bones of two or three
Subfamily Hoplophorinae Huxley, 1864 Darwin from the Uruguayan locality of sorts of Gnawing animals. - One of them must
Tribe Hoplophorini Huxley, 1864 Arroyo Sarandí (Mercedes, of Soriano have much resembled the Agouti but it is sma-
Genus Hoplophorus Lund, 1938 Departament, Uruguay); and the Argen- ller". Even so, it is not possible to deter-
tinean localities of Bajada Santa Fe (Pa- mine which of the remains Darwin
Hoplophorus euphractus Lund, 1938 raná, Entre Ríos Province) and Guardia thought similar to an agouti, though it is
Fig. 7a del Monte (Buenos Aires Province). worth noting that what Darwin conside-
red an agouti was a Patagonian hare
In general, the carapace fragments and Magnorder Epitheria McKenna, 1975 (Darwin, in Keynes 2001, p. 103).
osteoderms collected by Darwin in South Superorder Preptotheria McKenna, 1975 The following Hydrochoeridae are cu-
America were assigned preliminarily to Grandorder Anagalida Slazay and Mc rrently recognized from the fossiliferous
Megatherium. Certainly such assignments Kenna, 1971 horizons of Monte Hermoso: Phugathe-
were due to Cuvier's (1823) tacit approval Mirorder Simplicidentata Weber, 1904 rium cataclisticum, Anchimysops villalobosi
of Larrañaga's (in Cuvier 1823) sugges- Order Rodentia Bowdish, 1821 and Chapalmatherium perturbidum. Vucetich
tion that megatheres were armored. Suborder Hystricognatha Woods, 1976 et al. (2005) considered the type speci-
Owen (1840, p. 107) recognized the close Infraorder Hystricognathi Tullberg, 1899 mens of the first two species to represent
relationship, still considered correct, bet- Parvorder Caviida Bryant and McKenna, juvenile individuals and that they might
ween glyptodonts and living armadillos 1995 be conspecific with Chapalmatherium per-
and remarked the following about Superfamily Cavioidea Fisher de Wald- turbidum. If this is correct, then the valid
Hoplophorus euphractus: "The portions of the heim, 1817 name, as determined by Vucetich et al.
tesselated bony dermal covering of a Dasypodoid Family Hydrochoeridae Gray, 1825 (2005), for the species would be Phu-
quadruped, figured in Pl. XXXII. figs. 5 and Subfamily Hydrochoerinae Gray, 1825 gatherium cataclisticum. In this respect, the
4, of the natural size, were discovered folded Genus Hydrochoerus Brisson, 1762 specimen collected by Darwin might
round the middle and ungueal phalanges, figs. 2 represent this latter species.
and 3, at Punta Alta, in Bahia Blanca, in an Hydrochoerus sp.
earthy bed interstratified with the conglomerate Magnorder Epitheria McKenna, 1975
containing the remains of the fossil Edentals. The fossils that Owen (1940) assigned to Superorder Preptotheria McKenna, 1975
In one of these fragments, measuring six inches this genus were collected by Darwin (in Grandorder Anagalida Slazay and Mc
long by five broad, the tesserae are arranged in Keynes 2001) in Monte Hermoso on Oc- Kenna, 1971156 J. C. F E R N I C O L A , S. F. V I Z C A Í N O A N D G. D E I U L I I S
Mirorder Simplicidentata Weber, 1904
Order Rodentia Bowdish, 1821
Suborder Hystricognatha Woods, 1976 Figure 7: a) Osteoderms
Infraorder Hystricognathi Tullberg, 1899 assigned by Owen (1840) to
Parvorder Caviida Bryant and McKenna, Hoplophorus euphractus (=
Neosclerocalyptus ornatus, see
1995 text) in dorsal and lateral
Superfamily Octodontoidea Waterhouse, views (from Owen 1840).
1839 Scale bar = 1 cm; b) Maxilla
and mandible assigned by
Family Octodontidae Waterhouse, 1839 Owen (1840) to Ctenomys
Subfamily Octodontinae Waterhouse, priscus (= Actenomys priscus,
1839 see text) (from Owen 1840).
Scale bar = 5 mm.
Genus Ctenomys Blainville, 1826
Owen (1840) but not assigned to a genus. representing the genus Hydrochoerus.
Ctenomys priscus Owen, 1840 Owen (1840, p. 110) described "The por- Among the large mammals, Darwin re-
Fig. 7b tion of the right hind-foot of the Rodent figured cognized an enormous rodent and four
at fig. 12, includes the calcaneum, astragalus, genera: Rhinoceros, Megalonyx, Megatherium
This species was erected by Owen (1840) cuboides, external and middle cuneiform bones, and Mastodon. The first two listed do not
based on remains collected by Darwin (in and the metatarsals and proximal phalanges of appear in Cuvier's (1823) taxonomic list
Keynes 2001) on October 11, 1832. the toes corresponding with the three middle toes of fossil South American mammals. The
Owen (1840, p. 109) allocated to this spe- of five-toed quadrupeds. The metatarsals are assignment to Rhinoceros was the first
cies a "…fragment of the upper jaw, figured in chiefly remarkable for the well-developed double- such attempt by Darwin (in Keynes 2001,
Pl. XXXII. fig. 6" and a "...fragment of the trochlear articular surface, and intermediate rid- p. 107) for a South American fossil skull,
lower jaw of the same fossil Rodent . figured at ge. These remains, as well as the jaws and teeth collected during his first visit to Punta
fig. 10 and 11". It should be noted that of the Ctenomys, were discovered at Monte Alta (September, 1832). However, this
Owen's (1840) figure 6 possibly does not Hermoso in Bahia Blanca". These pedal re- assignment does not appear in the taxo-
represent an upper jaw, but a posterior mains are possibly those that Darwin nomic list of specimens collected from
fragment of a mandible that may corres- (1985, Letter 192) described in a letter, Punta Alta and Monte Hermoso sent to
pond to the posterior part of the mandi- dated November 12, 1832, to John Ste- John Stevens Henslow (Darwin 1985,
ble figured by Owen (1840, figs. 10, 11) vens Henslow as "the Tarsi & Metatarsi Letter 192). Darwin may possibly have
(D. Verzi, pers. comm.). very perfect of a Cavia" although it is not changed his first impression, but it is not
Mones (1994) provided a detailed discus- possible to determine this with certainty. easily ascertainable with the available
sion of the taxonomy of Ctenomys priscus, evidence.
concluding that it might belong to the Mastodonts and armored megatheres The only mention of Megalonyx appears
genus Dicoelophorus, erected by Ameghino in the previously noted list as "2nd the upper
(1888). However, the generic name As noted in the preceding historical sum- jaw & head of some very large animal, with 4
currently in use for this species is Ac- maries, the large South American fossil square hollow molars.-& the head greatly pro-
tenomys, erected by Burmeister (1888). mammals recognized by Cuvier (1823) duced in front.- I at first thought it belonged
The reasons for maintaining Actenomys amounted to an armored megathere and either to the Megalonyx or Megatherium.- In
were clearly set forth by Verzi (1994, p. three mastodonts. A detailed considera- confirmation, of this, in the same formation I
183), as follows "Dicoelophorus Ame- tion of Darwin's preliminary assign- found a large surface of the osseous polygonal
ghino, 1888 es, por prioridad, un sinónimo "se- ments demonstrates that he was strongly plates, which “ate observations” (what are they?)
nior" de Actenomys Burmeister… . Sin em- influenced by Cuvier's taxonomic sche- show belong to the Megatherium.- Immediately I
bargo, luego de que Reig (1958) adoptara el me. In essence, the fossil specimens re- saw them I thought they must belong to an enor-
nombre genérico Actenomys para todos los cognized by Darwin may be grouped as mous Armadillo, living species of which genus
materiales referibles a las formaciones Monte large vs. medium and small mammals. are so abundant here…". In this as in many
Hermoso y Chapadmalal, este nombre ha sido Among the latter is the first fossil of a other cases (see below) Darwin decided
ampliamente usado hasta el presente por lo cual South American horse, obviously identi- in favor of Megatherium based on the pre-
nosotros nos inclinamos a mantenerlo". fied as such by Darwin, and three ro- sence of osteoderms collected in the
dents, two of which were assigned by same formation.
Rodentia Darwin to Cavia and the Patagonian hare Owen (1838-1840) recognized the speci-
(Dolichotis patachonica), whereas the third mens assigned by Darwin to Megatherium
A third rodent was briefly described by was later considered by Owen (1840) as as glyptodonts, toxodonts, and largeThe fossil mammals collected by Charles Darwin in South America ... 157
ground sloths. In our estimation, the on- the Origin of Species and only two years af- erroneous taxonomic assignments, Sullo-
ly factor that led Darwin to assign re- ter he had begun recording his thoughts way (1982, p. 353) recognized that "The
mains of such a heterogeneous group of on transmutation, Darwin (1839, p. 209- general effect of these confusions during the Bea-
forms to Megatherium was the presence of 210) had this to say about the South gle voyage was to minimize the evolutionary
osteoderms or carapace fragments in the American paleofauna: "The most important implications of the diverse fossil forms".
same horizon. In effect, all the specimens result of this discovery, is the confirmation of Paradoxically, many of Owen's (1838-
that Darwin assigned to Megatherium were the law that existing animals have a close rela- 1840) proposed relationships that so
recovered from the Arroyo Sarandí (Uru- tion in form with extinct species. As the guana- influenced Darwin (1839, 1845, 1859) in
guay) and Punta Alta (Argentina), and co is the characteristic quadruped of Patagonia, the development of his transformatio-
Darwin also reported carapace elements. and the vicuna of the snow-clad summits of the nist theory were later rejected. Indeed,
Further evidence supporting our conten- Cordillera, so in bygone days, this gigantic species toxodonts and macrauchenids are highly
tion appears in Darwin's (1985, Letter of the same family must have been conspicuous derived native South American ungulates
215) letter of September 20, 1833 sent to on the southern plains. We see this same relation distantly related phylogenetically to
Caroline S. Darwin, in which he wrote of type between the existing and fossil Cte- rodents and guanacos, whereas the large
"At the Guardia del Monte, I found some more nomys, between the Capybara (but less plain- glyptodonts are not the ancestors of
of the armour of the giant Megatherium, ly, as shown by Mr. Owen) and the gigantic armadillos, but to the contrary, the latter
which was to me very interesting, as connecting Toxodon; and lastly, between the living and are antecedent to the former. In this res-
the Geology of the different parts of the Pam- extinct Edentata. At the present day, in South pect, we may suppose that the affinities
pas". Indeed, Darwin used the presence America, there exist probably nineteen species of proposed by Owen (1838-1840) maximi-
of osteoderms as a diagnostic feature of this order, distributed into several genera; while zed the evolutionary implications of the
Megatherium. throughout the rest of the world there are but South American paleofauna.
In this context, one might hypothesize five. If, then, there is a relation between the living
that it was the absence of osteoderms in and the dead, we should expect that the ACKNOWLEDGMENTS
the layers yielding the only Santa Cruz Edentata would be numerous in the fossil state.
specimen, which led Darwin to regard I need only reply by enumerating the Megathe- We are grateful to the editors for the invi-
this specimen as follows: "At Port St Ju- rium, and the three or four other great species, tation to participate in this special issue
lian I found some very perfect bones of some discovered at Bahia Blanca; the remains of some of Revista de la Asociación Geológica Argen-
large animal, I fancy a Mastodon" (Darwin of which are also abundant over the whole im- tina, and to Greg McDonald and Mariano
1985, Letter 238) and Darwin (1839) later mense territory of La Plata. I have already Bond for their thoughtful comments and
admitted that "I had no idea at the time, to pointed out the singular relation between the suggestions that improved the manus-
what kind of animal these remains belonged". armadilloes and their great prototypes, even in a cript. Andrew Currant, Curator of Fossil
Certainly, this is the only mention of point apparently of so little importance as their Mammals Palaeontology, Natural Histo-
Mastodon that was not later corroborated external covering". Similarly, Darwin (1845, ry Museum London, Simon Chaplin, Di-
by Owen (1838-1840). 1859, p. 339) noted that "In South Ame- rector of Museums and Special Collec-
Lastly, Toxodon was the only species the rica, a similar relationship is manifest, even to tions and Sarah Pearson, Assistant Cu-
remains of which Darwin (1985, Letter an uneducated eye, in the gigantic pieces of ar- rator, The Royal College of Surgeons of
192, 2002-2008) assigned to different mour like those of the armadillo, found in seve- England, for information on Darwin's
species. Darwin assigned a molar collec- ral parts of La Plata; and Professor Owen has fossil mammal collections, and Louise
ted in Punta Alta to an enormous rodent shown in the most striking manner that most of King, Assistant Archivist of The Royal
and a skull from Arroyo Sarandí to Megat- the fossil mammals, buried there in such num- College of Surgeons of England, for
herium. The latter assignment makes bers, are related to South American types… … invaluable help on the bibliography.
sense in that the horizon yielding the I was so much impressed with these facts that I
skull also preserved osteoderms, whereas strongly insisted, in 1839 and 1845, on this WORKS CITED IN THE TEXT
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