Dinosaurs of Argentina

Tuesday, April 25, 2017

Dinosaurs of Argentina

The richness of paleontological sites in Neuquén province turns it into “the center of paleontology”.


Saltasaurus, from which Argentinosaurus was reconstructed (Alain Beneteau).

“Salta’s Lizard” was discovered in 1980. This small titanosaurus sauropod from the Late Cretaciaous made a revolution in the field of Paleontology as its back was covered by hard bone plates. This led the scientists to consider the possibility that other sauropods would also have this kind of armour.
It was approximately 12 meters long and would weigh about 8 tons. As all sauropods, it was purely a plant-eater and could stand on its hind legs to reach the higher branches.

This small South American carnivore dwelled the soils of Northwestern Argentina about 73 million years ago. It was discovered in the Lecho Formation, at estancia El Brete, in the South of Salta. It was between 1 and 3 meters long and would weigh approximately 15 kilos. It was slender and light but its fearful curve claws would move fast. Even if it had certain features in common with the Velociraptors dwelling North America and Asia, it was a totally different species. In fact, it was an Abelisaurus, a relative of the Carnotaurus.
This voracious creature proved that dinosaurs did not have to be large to be the most fearful hunters on the planet. It is believed that it fed on young sauropods.


Herrerasaurus ischigualastensis by Sergey Krasovskiy

It is one of the most ancient dinosaurs with very primitive features. It dates from approximately 228 million years ago. It became extinct at the end of the Triassic. It was a medium-sized carnivore of about 3.5 meters of length. It was similar to the theropods. It would walk on two legs and had sharp teeth and claws. Its arms were short. It was discovered in the Ischigualasto Formation, in San Juan, in 1958 by Don Victorino Herrera, a local rancher.


Riojasaurus, shown in comparison with humans. Debivort. Author: Debivort

A representative of the primitive family of the prosauropods, the Melanosauridae, this is the most common genre registered in the upper sections of the Los Colorados layers, in the Province of La Rioja. It dwelled this area during the Late Triassic, about 220 million years ago. “La Rioja’s lizard” was one of the first large herbivorous dinosaurs. This heavily-built quadruped was about 10 meters long. It had a long neck, a long tail, a small head, a long, bulky body, and thick, elephant-like legs with claws. The back legs were only slightly larger than the front legs. Its limb bones were solid and thick, but its backbone was hollow. It had spoon-shaped, serrated teeth.

This archosaur reptile was found in the Talampaya Canyon, in the Province of La Rioja, by an expedition organized by the paleontologist Alfred Romer, from the University of Harvard in 1964. This creature lived 225 million years ago. It shared certain features with the dinosaurs. After two decades, it was considered a new genre and species which was named Marasuchus lilloensis. From the point of view of evolution, only a step separated this animal from the dinosaurs.
It had a pointed long head and a long thin tail. Among its most outstanding features, the skull had two openings behind each eye, one on top of the other, which would allow for the muscles of the jaw to be enlarged while they chewed. It also had an opening in front of each eye, which might have contained a gland. It is precisely due to these characteristics that it has been classified as an archosaurus, from the Greek: “ruling reptile”.

This herbivore of the order of the ornithischia lived in Las Lajas, in the Province of La Rioja, around 200 million years ago, when the area was humid and tropical, with lakes, rivers and conifers. It would be 90 centimeters long and would weigh from 7 to 10 kilograms. Its compact teeth allowed it to chew the hard plants typical from semi-arid areas. Its hind limbs were thin and they could reach high speed.

Found in the Valley of the Moon, in San Juan, it has been considered the ancestor of the present crocodile. It had a graceful and light skeleton. According to the proportions of the bones found, this animal would stand on two legs. It was a carnivore. It lived 220 million years ago and it belongs to the group of the poposaurus.

It is considered the most primitive and complete dinosaur from the inferior section of the Late Triassic 215 millon years ago and it has very valuable anatomical information to understand the first dinosaur evolution stages. This small carnivore was found in the Ischigualasto Formation, in the Valley of the Moon, in San Juan.

It was an amphibious carnivore that lived during the Late Triassic, around 215 million years ago in the area of the Ischigualasto Formation, in the Valley of the Moon, in the Province of San Juan. It may be compared to the present crocodiles, but its anatomical structure was much more primitive.
It would hunt small dinosaurs that approached the rivers. It was discovered by Professor Osvaldo A. Reig in 1959.

This pterosaurus, whose name means “South Wing”, was found at Lagarcito, in the Province of San Luis. Due to the characteristics of the area where it was found, it is estimated that it would dwell the lagoons of the arid zones and not the sea coast, like most members of this group. It lived 125 million years ago during the Cretaceous. As every pterosaurus, it is not classified as a dinosaur. It could fly long distances using its large light wings.
It was a carnivore: it would eat fish, mollusk and insects. It had 500 bristle-like teeth on either side of is lower jaw to sieve small organisms out of the water. Its upper jaw contained a series of short blunt teeth, enabling the pterosaur to chop its catch into smaller pieces.

The “Silver Lizard” was a herbivorous sauropod that lived 70 million years ago during the Late Cretaceous. Being 8 meters high and 30 meters long, it was one of the largest dinosaurs. It was found in the area of Colón, Province of Entre Ríos.


Abelisaurus size by Nobu Tamura

“Abel’s Lizard”, named after its discoverer, Roberto Abel, former director of the Argentinian Museum of Natural Science, dwelled the area of Río Negro during the Late Cretaceous, approximately 75 million years ago. This bipedal carnivore had a single skull which measured 85 centimeters long.
Discovered in 1985 in the surroundings of Lake Pellegrini, in the Province of Río Negro, its heavy teeth indicate that it was possibly in part a scavenger. It was approximately 7 meters long and 2 meters high and it would weigh 1.5 tons. It is believed to have been related to the Carnotaurus.

It has been found recently in the district of Cinco Saltos, in the Province of Río Negro. This herbivore would be very small (1.50 meters), graceful and very fast. According to scientists speculations, it would live in herds, as several adult, young and offspring specimens have been found within an area of 100 m2. It had a tight row of teeth to grind resistant vegetables. The hind legs indicate that it could run quite fast.
It dates back from the Late Cretaceous, about 90 million years ago, when South America was still joined to Antarctica in the South and this to Australia. The fact that fossils of this dinosaur were found in Africa, Australia and Antarctica indicates that they were distributed all through the world before Pangea was fragmented.

With a small head and a short flat skull, the “Southern Lizard” may have been one of the largest sauropods, according to the fossils found in the Río Colorado Formation sediments, in the Province of Río Negro in the early XX, which include a 2.20-meter-long femur. It is believed that this reptile was approximately 18 meters long and 6 meters high, which turned it into the largest sauropod in South America. It is related to the similarly gigantic Argentinosaurus and it belongs to the group of the titanosaurs.
It dwelled the southernmost tip of the present American continent during the Cretaceous about 75 million years ago. Its teeth were located at the front of its jaw, which indicates that it would rip the food without chewing.


Giganotosaurus carolinii by durbed

The “Carolinii”, considered the largest carnivorous dinosaur in the world, surpasses the famous Tyranosaurus rex in size. It was discovered in July, 1993, by Rubén Darío Carolini, present Director of the Villa El Chocón Municipal Museum, in a former lagoon located 18 kilometers to the South of Villa El Chocón.
80% of the fossil material of this specimen has been rescued and preserved in optimum condition. This carnivore, with reduced fore limbs, biped gait and with three toes in each leg, would measure 13.5 meters of length and its hip could reach 4.6 meters. It is estimated that it would weigh 9.5 tons when it was alive. Its head would measure 2 meters and its longest tooth, 21 centimeters. This specimen belongs to the Mid Cretaceous from the Mesozoic Era and it dwelled the Plaza Huincul area 90 million years ago.


Amargasaurus by Raul Lunia

“Amarga’s Lizard” was a sauropod from the Early Cretaceous. Its fossils were discovered by paleontologist José Bonaparte in 1991 in a canyon in La Amarga, a town in the Province of Neuquén, located approximately 70 kilometers from Zapala. The species name cazaui is due to Dr. Luis Cazau, a geologist who worked for the state oil company YPF and with Bonaparte’s team in 1983 at La Amarga.
This herbivore dwelled the area approximately 120 million years ago. It was 10 meters long and would weigh about five tons. It was differenciated from other sauropods by two parallel rows of large “spikes” that ran along its neck up to the tail. They may have been connected by a skin membrane, forming a double “sail” that might have worked as a thermoregulatory structure, used to absorb and release heat, for mating and dominance rituals, and for making this creature look much larger than it was to predators. Otherwise, the spines were probably used for protection. Amargasaurus was a quadruped, had a small head, a long neck and a very long whip-like tail.
Its front legs were shorter than its back legs, and all the legs had five-toed feet and a thumb claw, probably used for protection.
According to Bonaparte’s investigations, the Amargasaurus is closely related to two species from the Jurassic found in Tanzania.
It is believed that it ate large amounts of plant material a day to sustain itself and that it would swallow leaves without chewing. It had blunt teeth to rip the foliage easily.
It moved in herds and it may have migrated when food supply became scarce.


Argentinosaurus chased by Giganotosaurus by WillDynamo55

Named Huinculensis after the district of Plaza Huincul where its fossil remains were found, in the Province of Neuquén. This is the largest herbivorous dinosaur found so far. Its size is even larger than the “Carolinii”, which was a carnivore.
It belongs to the Mid Cretaceous period. It is estimated that it is 98 million years old. It was rescued by the staff of the Carmen Funes Museum in Plaza Huincul, where original pieces of the find are exhibited.
This is a great sauropod, some of its dorsal vertebras are the largest ever recorded. They are 1.70 meters high.

In 1987, a campaign organized by the Comahue National University extracted some vertebras and part of the hip of a dinosaur that was later called Andesaurus delgadoi after its discoverer Alejandro Delgado.
It was found several meters under the waters of Lake Exequiel Ramos Mejía, formed by the El Chocón Dam. The rescue took place when the level of the lake went lower than its historical records. It is estimated that the creature was 15 meters long.
At present, it is exhibited at the Comahue National University Geology and Paleontology Museum.

In 1988, the most complete specimen in South America was found in Villa El Chocón. It was called Rebbachisaurus Tessonei. This is a sauropod, herbivorous middle-sized dinosaur, which would weight about 10 tons and measure 17 meters of length. Nowadays, it is exhibited at the Geology and Paleontology Museum. In turn, the Rebbachisaurus tessonei was one of the favourite dishes of the largest carnivore of all times -the Giganotosaurus carolinii.
According to experts Jorge Calvo and Leonardo Salgado, these huge animals with very long tails and necks would wander about the area on their four legs over one hundred million years ago, devouring the exuberant vegetation that would cover the marshlands.


This large predator, similar to the Tiranosaurus rex lived in the Argentinian Patagonia around 90 million years ago and was discovered in Chubut by José F. Bonaparte, discoverer of many other South American dinosaurs.
Its most outstanding features include two thick bull-like horns above the eyes that are the reason for its name, and the extremely reduced forelimbs with four fingers. It had a small skull, a thick chest, and a thin tail. The eyes of the Carnotaurus faced forward, which is unusual in a dinosaur, and may indicate binocular vision and depth perception. It was 10 meters long and 4 meters high, and it belonged to the group of the most spectacular South American dinosaurs: the Abelisauridae.

This is one of the sauropod dinosaurs that has been most thouroughly studied. It did not surpass the 8 meters of length, although other representatives of its family (also exhibited in the museum) would loosely surpass this measure. Almost spherical fossil eggs of these animals have been found. One of these eggs belongs to the collection of the museum and may be observed by visitors. This dinosaur stepped on Patagonia approximately 85 million years ago, during the Upper Cretaceous.

Found in the Cañadón Asfalto Formation in the Province of Chubut, this carnivorous dinosaur would belong to the group of the theropods. It dwelled the area during the Mid Jurassic, 165 million years ago. This 5-meter-long creature was an active hunter that may have attacked in groups. It would feed on young sauropods. Its large curve claws were used while hunting as a complement to its formidable conical very compressed long teeth, which were bent backwards and quite sharp. This suggested that the animal was not a fierce predator of large prey but of small vertebrates. It walked on two legs for its hind limbs were long and strong in comparison with its reduced fore limbs. Its strong head would measure approximately 50 centimeters.

The “Giant Robber”, a large predator from the Late Cretaceous, had fearful sickle-shaped claws. It walked on two slender, bird-like legs. It had a curve flexible neck, a huge head and serrated teeth in its powerful jaw. It used its tail to manage perfect balance and turn fast. This 7-meter- long carnivore dwelled the Northwestern area of the Argentinian Patagonia and was discovered by paleontologist Fernando E. Novas.

This quadruped dinosaur was herbivorous and had horns and a beak similar to that of a parrot. It had a large head, a bulky body, a parrot-like beak, cheek teeth, and a small frill on its head. It was quite slow.
It lived in the Late Cretaceous, approximately 80 million years ago, towards the end of the Mesozoic, the Age of Reptiles.
In 1918, Augusto Tapia found part of a lower jaw that would belong to this specimen in Chubut.

Named after the Quilmes Indians, this medium-sized carnivore lived during the Late Cretaceous. It is estimated that it was 5-6 long. Fossil remains of this theropod were found in the Allen Formation, Salitral Ojo de Agua, in the Province of Río Negro.


Skeletal reconstruction of Unenlagia comahuensis. Jaime A. Headden

This is the most bird-like dinosaur ever discovered. This theropod from the Mid-Cretaceous is 90 million years ago. The first birds appeared 150 million years ago, evolving from dinosaurs long before Unenlagia lived. This proves that it is not an ancestor of modern-day birds.
With the size of an ostrich, but shaped like a Velociraptor, this fightless carnivore was 1.20 meters tall and 2 meters long. Its fossil remains have provided evidence to prove how dinosaur forearms evolved into the wings of modern-day birds.
The Unenlagia had a special shoulder structure that allowed it to move its short arms forwards, backwards and inwards to catch their prey, and upwards and downwards in a flapping motion which, even if not used for flying, because its wing-like arms were too short to support the heavy dinosaur, were used for balancing and turning. Although there is no fossil evidence of feathers from its fossils, it may well have had them.
Fernando Novas, from the Museum of Natural History of Buenos Aires gave this dinosaur the name of Unenlagia comahuensis, which means “half-bird from Northwestern Patagonia”.

Source: www.welcomeargentina.com