Transcriber’s Notes:
Underscores “_” before and after a word or phrase indicate _italics_
in the original text.
Equal signs “=” before and after a word or phrase indicate =bold= in
the original text.
Small capitals have been converted to SOLID capitals.
Illustrations have been moved so they do not break up paragraphs.
Old or antiquated spellings have been preserved.
Typographical and punctuation errors have been silently corrected.
[Illustration: The skull of Pyrotherium sorondoi Ameghino. ⅛ natural
size. See page 175.]
The Deseado Formation
of Patagonia
Frederic Brewster Loomis, Ph.D.
_Professor of Comparative Anatomy
Amherst College_
[Illustration]
EIGHTH AMHERST EXPEDITION
1911
PUBLISHED UNDER THE AUSPICES OF
THE TRUSTEES OF AMHERST COLLEGE
1914
_Copyright, 1914_
BY FREDERIC B. LOOMIS
THE RUMFORD PRESS
CONCORD · N · H ·
CONTENTS
CHAPTER PAGE
I. Organization of the expedition—history of the work done
in the Deseado formation 1
II. Description of the Amherst locality—age of the overlying
beds—age of underlying beds—age of Deseado 6
III. Table of the animals—study of the feeding habits—
character of the habitat—the origin of the elements
of the Deseado fauna 19
IV. Systematic arrangement—the Litopterna, Eoproterotherium,
Notodiaphorus, Deuterotherium, Protheosodon,
Coniopterotherium, Tricoelodus, Proadianthus 28
V. Typotheria, Archaeohyrax, Plagiarthrus, Prohegetotherium,
Prosotherium, Propachyrucos, Phanophilus, Archaeophylus,
Eutrachytherus, Argyrohyrax, Isoproedrium 53
VI. Rhynchippidae, Toxodontia, Rhynchippus, Morphippus,
Eugeniops 86
VII. Leontinirdae, Leontinia, Ancylocoelus 108
VIII. Nesodontidae, Proadinotherium, Pronesodon, Coresodon,
Interhippus, Nesohippus 122
IX. Isotemnidae, Trimerostephanus, Pleurocoelodon,
Lophocoelus, Henricofilholia 129
X. Homalodontotheria, Asmodeus 134
XI. Astrapotheria, Parastrapotherium 142
XII. Pyrotheria, Pyrotherium 156
XIII. Rodents, Cephalomys, Scotamys, Litodontomys, Asteromys,
Eosteiromys 185
XIV. Edentata, Proeutatus, Prozaedius, Stenotatus,
Proeuphractus, Peltephilus, Palaeopeltis, Glyptatelus,
Hapalops, Octodontotherium, Orphodon 197
XV. Marsupialia, Pharsophorus, Notogale, Proborhyaena,
Palaeothentes, Pilchenia, Callomenus, Pseuhalmarhippus,
Parabderites 210
XVI. Birds, Physornis, Loxornis 225
PREFACE
The results of the Amherst Patagonian Expedition were divided into
two parts, the general features, together with the narrative, were
reported in a separate volume entitled, “Hunting Extinct Animals in
the Patagonian Pampas,” published in 1913. For this volume has been
reserved the description of the material found and such conclusions as
are directly derived from that material. The material on which this
work is based has been prepared out and placed on exhibition at Amherst
College.
The material here described forms a unified body of data, which adds
materially to our knowledge of the complete animals of the Tertiary
period in Patagonia. There are beside this some small collections which
offer some isolated new facts, but the working up of these has been
reserved for the future for small articles, as the work may come to
maturity.
The field has only been touched and a vast amount of further work can
be profitably done on the horizons immediately preceding and following
the one described in this volume, after which an interesting study can
be made on the evolution of a fauna which developed in a considerable
degree of isolation.
F. B. LOOMIS.
March 18, 1914.
THE DESEADO FORMATION OF PATAGONIA
CHAPTER I
INTRODUCTION
The material described and the conclusions drawn in the following
pages are the results of the Amherst Expedition to Patagonia in 1911;
an expedition organized and sent out by the Class of ’96 as a part of
their fifteenth reunion. The party consisted of Frederic B. Loomis
’96, Phillip L. Turner ’11, Waldo Shumway ’12, and William Stein of
St. Joe, Wyoming, and left Amherst July 1, 1911, returning the first
of February the ensuing year, having spent its time collecting in the
early Tertiary beds of Patagonia, as exposed in the Territories of
Chubut and Santa Cruz, the aim being to secure from the earlier periods
a fuller knowledge of the vertebrate animals, such as the Princeton
Expeditions obtained for the Patagonian and Santa Cruz formations. The
narrative of the expedition has been told in “Hunting Extinct Animals
in the Patagonian Pampas.”
Material was found in various beds, from the Cretaceous up to the Lower
Miocene; but the major part of the fossils, and most of the facts new
to science came from the work in the Deseado Formation. The collections
from the horizon were so complete and interesting that this report
of the expedition has assumed the form of a monograph of the Deseado
Formation, otherwise known as the Pyrotherium beds.
The first work in this formation was done by Carlos Ameghino who
at various times between 1889 and 1894 collected for his brother,
Florentino Ameghino, the latter studying and describing the
collections of Carlos, whose trips covered the country from Chubut
down to the Straits of Magellan, and the various formations from the
Lower Cretaceous to the Pampean or Pleistocene. Carlos Ameghino and
his brother, Florentino, for years explored in Patagonia, going summer
after summer at their own expense, and in the meantime maintaining a
small book and stationery store in La Plata, the profits of which gave
the two brothers a living and furnished the funds for the continual
expeditions. In the back of the store was the workshop from which
came the continuous stream of knowledge in regard to these strange
faunas. One of the best pieces of work done by the brothers was the
collecting and describing of the fauna of the Pyrotherium beds the bulk
of which is contained in two papers entitled, Première Contribution à
la Connaissance de la Fauna mammalogique des Couches à Pyrotherium,
and Mammifères Crétacés de L’Argentine, Deuxième Contribution, etc.,
both published in the Boletin del Instituto Geográfico Argentino,
tomes 15 and 18 respectively. These two papers give names to most of
the forms which we found, but the genera and species are based on very
fragmentary and incomplete material. It has been a pleasure to find the
accuracy with which these descriptions were made; and our part has been
chiefly to supplement and increase the knowledge of the various forms,
and to determine from the more complete material the relationships of
these strange forms. In some cases we have been able to assemble all
the parts of the animals, and in the others to add more or less to the
completion of the knowledge of the forms. There is one peculiarity
of Ameghino’s descriptions, namely the absence of data as to the
localities where the forms were found.
About 1900 Tournier, in the interests of the Paris Museum, made a
series of expeditions (5) to Patagonia, on some of which he found a
Pyrotherium, or as he has termed it Deseado, locality just south of
the Deseado River, from which he gathered a considerable collection
which has been described by Albert Gaudry in various papers mostly in
the Annales de Paléontologie.
These two collections and their collaborations represent all the work
thus far done on the Deseado beds and fauna. Our collection is the
first one of any considerable size to be brought to North America, and
it seems to be by far the most complete, the various animals being
represented by more complete skeletons than in any of the previous
collections.
The beds were first designated as the Pyrotherium beds, and are
always so referred to by F. Ameghino. Tournier and Gaudry, feeling
the prejudice which is fairly general among Palaeontologists against
names based on any contained animal (which may or may not be present at
other localities, which may extend through more than one period, and
whose name may be changed as a result of further knowledge) used the
term Deseado formation, as his collections came from the neighborhood
of this river. This is a geographical name and avoids the chance
for confusion; so I have adopted it throughout this paper, it being
understood as an equivalent of the term Pyrotherium beds.
Ameghino never gave the exact, or anywhere near the exact, localities
from which his Deseado specimens came. It was not until 1906, when
his Formations Sedimentaires[1] appeared, that any localities were
designated, and there on a sketch map he indicates as Deseado
exposures, about a dozen points, scattered between the upper part of
the Chubut River to some 25 miles south of the Deseado River. These
are included in an oval area some 500 miles long by 150 miles wide.
Ameghino also suggests on this occasion that the Deseado formation
originally extended over at least the whole of this area. As will be
seen in the next chapter, I believe that the deposits of this age
and character have always been local and isolated. We sought for
several of these localities and failed to locate them, especially
those near Mazaredo, and the northern one on the Gulf of St. George.
The point where we did find our material I believe was one of
Ameghino’s localities, though the settlers of that region had never
heard of anyone hunting for fossils there; but the settlement had been
practically all within the previous six years, which was much later
than the time when Carlos Ameghino worked in the region.
[Footnote 1: Anal. Mus. Nac. Buenos Aires, ser. 3, t. 8, p. 99.]
Beside the foregoing, an exposure of this age is reported by A. A.
Romero, just above the fork of the two branches of the Rio Negro, which
is some 500 miles north of the first group of localities mentioned.
Ameghino also refers to another locality in the Province of Misiones
which would be 1,500 miles north of the typical localities.
The collections made by Tournier for Gaudry came chiefly from an
exposure south of the Deseado River, some 15 miles above the mouth of
the river.[2]
[Footnote 2: Bul. Soc. Geol. France, ser. 4, t. 3, 1903, p. 468.]
Our collection came from the Chico Branch of the Chubut River, about
three miles east of the river, and almost due west of Puerto Visser.
As mentioned above on account of the close coincidence of the various
species and because Ameghino indicates a locality in the neighborhood,
I think that our locality is the same as one of his, I should judge
it the one from which he obtained a considerable part of his types.
This is of importance; for, if in Ameghino’s type locality, the
determination of the species, as the same as those of Ameghino’s, is
much more certain.
In the accompanying map I have indicated the localities given by
Ameghino, those of Tournier, and our own.
[Illustration: Fig. 1. Map of Patagonia showing localities of Deseado
beds.]