QUATERNARY FOSSIL FAUNA

It is made up of the large animals that lived during the Quaternary Period, also known as Mega mammals or Mega fauna, as their weight exceeded, in some cases, a thousand kilograms.

They were mostly herbivores: Megatherium, Stegomastodon, Glyptodon and Macrauchenia.

They became extinct about 8,000 years ago and occupied a large part of South America, when the climate was colder and drier than today. Global climate change is thought to be one of the possible causes of their extinction.

None of these animals have any living representatives today, although some mammals, that survive today, resemble them.

Other large animals, even older, were the dinosaurs – reptiles – that dominated the Earth for millions of years. It is believed that one of the causes of their extinction may have been meteorite impacts.

Stegomastodon: it was a North American immigrant mastodon, whose first records in Argentinean territory correspond to the Lower-Middle Pleistocene. Its general appearance was similar to that of its relatives, the elephants.

As in elephants, the upper incisors or “tusks” are of continuous straight or slightly curved growth, with a band of enamel that disappears in adults.

Glyptodon: this group of herbivorous mammals had a great variety; some of them were 4 metres long and others were less than 2 metres long. They had a large, more or less hemispherical shell with thick, rigid plates, similar to that of a tortoise, but being a mammal, it was far removed from the nature of a reptile.

The body of the animal was enclosed underneath it, on short, massive legs. The head was protected by a kind of bony cap and the very long tail was also enclosed in bony armour.

The primitive glyptodon lived in the early Tertiary period and was not very large; some were similar to today’s armadillos. Later, larger species appeared until the Quaternary, when the megatheres were already in existence, when they were larger and inhabited the Argentinean pampas.

Smilodon: the most outstanding characteristic of this carnivore was its enormous upper tusks, which is why it was called the “sabre-toothed tiger”. It also possessed powerful claws that made it a ferocious hunter. An adult male could have weighed 350 kilograms.

As far as the Argentine province of Santiago del Estero is concerned, at the end of the 19th century, the Wagner brothers recovered numerous vertebrate remains on the banks of the Dulce river, in the departments of Río Hondo, Banda and Capital.

Palaeontological sites in Santiago del Estero

They are divided into six sub-areas

Sub-area 1: margins of the Río Dulce. Dpt: Río Hondo-Banda -Capital

Sub-area 2: Valley of the Río Dulce: Silípica Dept.

Subarea 3: Bajos del Río Dulce: Dpt. Quebracho, Mitre and Rivadavia.

Sub-area 4: Sierras de Guasayán – eastern slopes: Guasayán and Choya dept.

Sub-area 5: Chaco-Santiagueño: Alberdi Dept.

Sub-area 6: Pampa del Este: Belgrano Dept.

Sub-area 1 is the richest in fossils, as it comes from the Salí-Dulce system, which has transported these materials from the Tucumán plains.

An important detail that would allow us to maintain that it is material from dragging and redepositing is undoubtedly due to the fact that a complete skeleton was never found, but only loose pieces; as well as the depth at which the fossils were found, from approximately 6 to 14 metres.