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II.—Notes on the Geology and Palæontology of Argentina

Published online by Cambridge University Press:  01 May 2009

Florentino Ameghino
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Extract

Until a few years ago it was believed that the Territory of Patagonia was of an extremely simple and uniform geological structure; it was supposed that from the Colorado to the Straits of Magellan, and from the Atlantic to the base of the foot-hills of the Andes, it was constituted exclusively by the marine Patagonian Formation, on the age of which the most varied opinions were expressed, although all agreed in referring it to the Tertiary series. This uniformity was interrupted only at intervals by great sheets of basalt which appeared sometimes at the surface, sometimes below the boulder-deposit.

Type
Original Articles
Information
Geological Magazine , Volume 4 , Issue 1 , January 1897 , pp. 4 - 20
Copyright
Copyright © Cambridge University Press 1897

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References

page 5 note 1 Ameghino, C., “Exploracioues geologicas en la Patagonia”: Bol. Inst. Geograf. Argent., vol. xi, 1890, pp. 1–46.Google Scholar

page 6 note 1 Lydekker, R., “The Dinosaurs of Patagonia”: Anal. Mus. La Plata-Pal. Argent., vol. ii, 1894, pt. 1.Google Scholar

page 6 note 2 The gigantic fore-limb of this animal, which serves as the type of the genus and species, was discovered by Carlos Ameghino, together with the almost complete skeleton in position, at the angle which the River Chico makes with Lake Musters (see Ameghino, F., “Contrib. conoc. mamif. fos. Repub. Argentina, ” 1889, p. 879;Google Scholar and Ameghino, C., Bol. Inst. Geogr. Argent., vol. xi, 1890, p. 42). Unfortunately, the incompetent persons employed by the Director of the Museum of La Plata for the exhumation of this skeleton only succeeded in extricating one of the limbs, destroying the remainder. The traveller who has occasion to cross this district still descries from a great distance the accumulation of bones destroyed by their vandal expedition.Google Scholar

page 6 note 3 Revista del Museo de La Plata, vol. iv, 1893, pp. 245–6.Google Scholar

page 6 note 4 Ameghino, Carlos, Bol. Inst. Geogr. Argent., vol. xi, 1890, pp. 42, 44.Google Scholar

page 7 note 1 Ameghino, F., Bol. Acad. Nac. de Cienc., vol. viii, 1885, p. 150;Google Scholar and “Contrib. conoc. mamif. fos. Repub. Argent., ” 1889, pp. 16, 899, 959. The first remains of Dinosaurs met with in Patagonia, consisting of a complete caudal vertebra and a large rib with the articular head complete, were found in the Neuquen in the year 1882 by Captain Buratowich, and presented by him to the then President of the Republic (General Julio A. Eoca), who in his turn presented them to me, and I immediately determined them as belonging to a gigantic Dinosaurian (see La Nacion, March 23, 1883). This was the first notice of the former existence of these singular extinct reptiles on the soil of the Argentine Eepublic.Google Scholar

page 7 note 2 These remains, from Fort Roca, were presented to me by their discoverer, Señor Don Jorge Rohde, then Captain (now Colonel) of the Military Engineers.

page 7 note 3 Ameghino, F., “Première Contribution à la Connaissance de la Faune Mammalogique des Couches à Pyrotherium”: Bol. Inst. Geogr. Argent., vol. xv, 1895, pp. 603Google Scholar 61. In reference to this work, Mr. S. P. Palmer, of the II. S. Department of Agriculture, who is editing a “Nomenclator” of the known genera of mammaiia, writes to me that the names Clorinda and Eurygenium, with which I have designated two extinct mammals from this formation, have been previously employed for other animals. The observation is correct, and it is all the more strange since I had not noticed that the two generic names are recorded in Scudder's “Nomenclator Zoologicus, ” which I always have at hand. I am thus compelled to change those names, replacing that of Clorinda by Plagiarthrus, and that of Eurygenium by Eurygeniops.

page 8 note 1 Lydekker, R., “Extinct Edentates of Argentina“: Anal. Mus. La Plata — Pal. Argent., vol. iii, 1895, pt. 2.Google Scholar

page 10 note 1 Ameghino, F., “Los Monos fosiles de la Republica Argentina”: Eevista Argent. Hist. Nat., vol. i, 1891, pp. 383–97, figs. 85–97.Google Scholar

page 10 note 2 So much interest has been aroused in the fossils of the Patagoniau region that the North American Government has despatched an expedition with the object of collecting fossils for the museums of the United States. This expedition is in charge of Messrs. J. B. Hatcher and O. A. Peterson, who are already in Patagonia.

page 10 note 3 [See supplementary note by the translator, p. 21.]

page 11 note 1 [See supplementary note by the translator, p. 22.]

page 11 note 2 Ameghino, F., “Première Contrib. Connais. Faune Mammal. Couches à Pyrotlierium“: Bol. Inst. Geogr. Argent., vol. xv, p. 605.Google Scholar

page 11 note 3 Ameghino, F., “Enumération Synoptique des Espèces de Mammifères Fossiles des Formations Eocènes de Patagonie, ” p. 5 (Buenos Aires, 1894).Google Scholar

page 12 note 1 Ameghino, F., “Sobre la Presencia de Yertebrados de Aspecto Mesozoico, etc.“: Eevista Jardin Zool. Buenos Aires, vol. i, 1893, p. 85.Google Scholar

page 12 note 2 F. Ameghino, ibid., pp. 79–83.

page 13 note 1 Lydekker, R., “Cetacean Skulls from Patagonia“: Anal. Mus. La Plata—Pal. Argent., vol. ii, 1894, pt. 2. As I have observed on another occasion, this volume, although it bears the date 1893, appeared more recently, in the month of April, 1894.Google Scholar

page 13 note 2 In his work Lydekker designates this Cetacean with two distinct generic names; in the heading of the description he employs the name of Hypocetus, which is also met with below the figure on the corresponding plate, while at the end of the description he uses the name of Paraeetus in substitution for that of Mesocetus, which Moreno had given to replace this latter, preoccupied for another genus of the same group. For my part, I had already replaced the name of Mesoeetus by that of Diaphorocetus (Ameghino, F., Bol. Acad. Nac. Cienc., vol. xiii, p. 437),Google Scholar placing the genus, though only in a provisional way, among the Pontoplanodidæ, since my principal object was to give a complete list of all the Tertiary mammals of Patagonia. I ought to observe that in reality the genus in question exhibits no relationship with the latter group, but with that of the Physeteridæ, as observed by Lydekker, who, notwithstanding this, places it with Physodon in a new family, which he terms Physodontidso. In accordance with the opinions expressed by Cope, it does not appear to me that the presence of teeth in the upper jaw is a character sufficient to justify the creation of a new family, since they are also found, though in less number, in representatives of some species of the allied existing genera (Cope, E. D., “Fourth Contribution to the Marine Fauna of the Miocene Period of the United States”: Proc. Amer. Phil. Soc., vol. xxxiv, 1895, p. 135).Google Scholar

page 13 note 3 Lydekker proposes for this genus the name of Argyrodelphis to replace that of Notoeetus, under which Moreno had described it, because this latter was already employed by me for another Cetacean. For the same reason I had proposed that of Diochoticus, placing the genus among the Platanistidas, the same arrangement as given by Lydekker (Ameghino, F., Bol. Acad. Nac. Cienc., vol. xiii, p. 438).Google Scholar

page 13 note 4 It appears that neither the exact locality nor the precise geological horizon is known whence was obtained the skull described by Lydekker in the same work under the name of CetotheriuM Moreni.

page 14 note 1 Ameghino, F., “Contrib. Conoc. Mamif. Fos. Repub. Argent., “ pp. 16, 17 (Buenos Aires, 1889).Google Scholar

page 14 note 2 Ameghino, F., “Enum. Synopt. Mamm. Foss. Eoc. Patagonie, “ pp. 4, 5 (Buenos Aires, 1894).Google Scholar

page 14 note 3 I cannot, however, omit to mention here a recent discovery which has not yet been published, and which is doubtless destined to rouse great interest in the zoological world. One of the most singular groups of mammals of the Santa Cruz Formation comprises a series of small animals with the dentition somewhat similar to that of the kangaroos of Australia, but still more so to that of the fossil Plagiaulacoidea of the Mesozoic formations of Europe and North America. Those animals, marsupial though not syndactylous like the kangaroos, which I have distributed into the four families of Abderitidæ, Deeastidæ, Epauorthidsæ, and Garzonidæ, were at this period extremely numerous in genera and species, and in respect to individuals they must have been more numerous than all the rodents of our pampa taken together. These animals have hitherto appeared to constitute an entirely extinct group without any direct affinities to any of the existing ones. Great, then, was my surprise when I received a letter from the distinguished zoologist of the British Museum, Mr. Oldfield Thomas, in which he informed me he had just received from Colombia (New Granada) an example of a still existing genus of the group of the EoSene Epanorthidte of Patagonia, a genus which the gentleman in question will shortly describe… Mr. J. B. Hatcher has lately informed me that the National Museum of Washington has just received an example of this same animal [ = Cæenolestes obscttrus, Thomas, O., Proc. Zool. Soc. 1895, p. 870, pl. LGoogle Scholar

page 15 note 1 Ameghino, F., “Enum. Synopt., ” etc., 1894, p. 7.Google Scholar

page 15 note 2 Mr. J. B. Hatcher, who collected all the Cretaceous mammals described by Marsh, recently examined in my house the remains of Plagiaulacoidea from Patagonia, and told me that in his opinion they exhibit the greatest resemblance to those of the Upper Cretaceous (Laramis Formation) of the United States, described by Marsh.

page 16 note 1 Ameghino, F., “Contrib. Conoc. Mamif. Fos. Repub. Argent., ” p. 36.Google Scholar

page 19 note 1 Steinmann, G., “A Sketch of the Geology of South America“: Amer. Nat. 1891, pp 855–60.CrossRefGoogle Scholar

page 19 note 2 von Jhering, H., “Conchas marinas da formaçao pampeana de La Plata”: Eevista do Museo Paulista, vol. i, 1895, pp. 223–31. This collection consists of nineteen species, all still existing on the Argentine coast except three, viz., Purpura hæmastoma, Littorina flava, and Nassa polygona: the first does not survive to the south of the Rio Grande del Sud, and the two last live in Santa Catalina, San Pablo, and more to the north This indicates that the oceanic waters of that period had here a somewhat higher temperature than at present, which is in complete contradiction to the supposed glacial origin which some would attribute to the Pampeau Formation.Google Scholar