Laquintasaura and Tachiraptor, what the Venezuelan dinosaurs were like

In the Jurassic period of the Mesozoic, approximately 201 million years ago, two small dinosaurs lived in our Venezuelan Andean area: Laquintasaura venezuelae and Tachiraptor admirabilis.

These prehistoric "gochos" specimens, whose presence we did not know until the end of 2014, were not like those huge and super fearsome dinosaurs from the movies.

They were no more than a meter and a half tall and fed in different ways.

While Laquintasauria ate plants and possibly insects, from the shape of his teeth; the Tachiraptor made it of animals; maybe turtles, crocodiles, lizards or even dinosaurs if they were smaller than them.

Laquintasauria and Tachiraptor

Laquintasaura, which was barely one meter tall, belonged to the group of ornithischian dinosaurs, which were characterized by their bird hips and their eating preferences: plants.

Their legs, just below the hips, allowed them to outrun any other animal.

The Tachiraptor, measuring one and a half meters, it belonged to the group of carnivorous theropod dinosaurs, which occupied the top of the food pyramid in the world of these prehistoric animals.

These kinds of dinosaurs were killer machines.

Their bodies were made to capture, kill, and dismember their prey. They ran on their two strong hind legs and some helped each other with their hands to finish off their victims.

Like most dinosaurs, they laid eggs and walked on two legs under the body, and not on the sides like reptiles.

On its skin, it is possible that the Tachiraptor's was scaly like that of lizards and crocodiles, while that of Laquintasauria may have had feathers.

La Quinta Formation

Until 2014, many investigations assumed that dinosaurs did not live in the equatorial paleo zone, in which our territory is located.

However, in the eighties, the discovery of fossils in the La Quinta Formation, located in the Venezuelan Andes, by French paleontologists, generated the curiosity of at least two Venezuelan researchers.

But it was not until the XNUMXs that Venezuelan scientists decided to enter this fossil site from the Jurassic period to confirm their doubts about the existence or not of a dinosaur in Venezuela.

Dinosaur fossils

The fossils of the first Venezuelan dinosaur were found at the height of the road cut between the towns of La Grita and Seboruco, in the state of Táchira.

This happened about 20 years before the conclusions of the study of these bones were published.

While the fossils of the second Venezuelan prehistoric specimen were found about 4 km northwest of the town of La Grita, Jáuregui municipality, Táchira state.

This happened one year and eight months before their analysis and publication of the research results.

Both specimens seem to have lived in our territory about 200 million years ago, in the oldest Jurassic.

And it is even possible that the Tachiraptor admirabilises, which was theropod, a carnivorous beast, would have been the predator of Laquintasaura venezuelae, a herbivorous ornithischian.

Laquintasaura venezuelae is an ornithischian dinosaur.

Laquintasaura, the first Venezuelan dinosaur

Laquintasaura venezuelae It is the first dinosaur of Venezuela and the north of South America.

Their find dismantles the hypothesis that this region of the continent was inhospitable to the first dinosaurs.

An ornithischian dinosaur

Laquintasaura es an ornithischian dinosaur "bird hip" equatorial paleo. However, it can be differentiated from other early ornithischians by dental characteristics.

Most of the cranial elements found in the La Quinta Formation, such as the jugal, postorbital, square, and elements of the cranial box, are similar to those of other primitive ornithischians.

The teeth found are unique among ornithischians (and dinosaurs in general), with exceptionally elongated, apically tapered crowns that are sometimes slightly recurved.

Likewise, Laquintasaura exhibits a growth pattern similar to geologically younger small-bodied ornithischians such as the Scutellosaurus "small shield lizard" ylos Fruitadens "Fruit tooth".

Ornithischians were the dominant large herbivores of many late Mesozoic terrestrial ecosystems.

Laquintasaura Characteristics

At a single meter high and 25 meters at the hip, this is the first basal ornithischian recovered from terrestrial deposits directly associated with a precise radioisotopic date.

The largest femur is 90mm long, which corresponds to a total body length of approximately 1m based on comparisons with other bipedal ornithischians.

It walked on its two hind legs and fed on ferns and possibly insects because of the long curves in some of its teeth.

Laquintasaura is represented by abundant teeth, ribs and girdles, and scarcer cranial, limb and vertebral remains

Its generic name is the union of "Laquinta", which is the rocky formation of the Jáuregui municipality where its fossil remains were discovered, and from the Latin 'saurus', which translates lizard; while his species, venezuelae, was named after the country and people of Venezuela.

Tachiraptor admirabilises was a theropod dinosaur.

Tachiraptor, the second Venezuelan prehistoric species

Tachiraptor admirabilis It is the second dinosaur in Venezuela and northern South America.

Their find dismantles the hypothesis that this region of the continent was inhospitable to the first dinosaurs.

A theropod dinosaur

Tachiraptor it was a small theropod, "" Beast, with an estimated body length slightly greater than 1,5 m.

The tibia, found in the La Quinta Formation, approximately 25 cm long, averages 20 mm wide along the mid-diaphysis.

These skeletal proportions are shared by other basal theropods of corresponding size such as the Syntarsus and kayentakatae.

However, the isolated bones (ischium and tibia) of the Tachiraptor differ from all previously known members of the group by a unique set of characteristics of their tibial joints.

His tibia and referred ischium were found in the same location.

They have concordant phylogenetic signals, equivalent relative sizes, and are the only unequivocal theropod remains recovered from the La Quinta Formation, after more than 20 years of research.

Characteristics of the Tachiraptor

Tachiraptor, like theropods, it was carnivorous.

Its generic name derives from Táchira, the Venezuelan state where the fossil was found, and from the Latin 'raptor', which translates to thief, in reference to the likely predatory habits of the animal.

Its species honors the Admirable Campaign of Simón Bolívar, in which La Grita, located about 4 km from the site where the Tachiraptor fossils were found, in the Jáuregui municipality, Táchira State, played a strategic role.

Tachiraptor fossils found in the La Quinta Formation, in the state of Táchira.

The investigations: Laquintasaura and the Tachiraptor

Although the fossils of Laquintasaura and Tachiraptor were discovered in different periods, the conclusions of the two studies were not known until 2014, with just a month of difference in the British scientific journal The Royal Society.

On September 22, 2014 it became known through the scientific article "A paleoequatorial ornithischian and new limitations for the early diversification of dinosaurs" that a unique species of dinosaur that they called Laquintasaura had been found in Venezuela.

The research team consisted of Paul M. Barrett, from the UK Museum of Natural History, Richard J. Butler, from the University of Birmingham; Roland Mundil, from the Berkeley Center, in the United States;

Torsten M. Scheyer, from the University of Zurich; Randall B. Irmis, from the Utah Museum of Natural History, in the United States, and Marcelo R. Sánchez-Villagra, Venezuelan from the University of Zurich.

On October 1, 2014, a second scientific article titled "New dinosaur (Theropoda, stem-Averostra) from the oldest Jurassic of the La Quinta formation, Venezuelan Andes" revealed the discovery of another unique dinosaur in the world, the Tachiraptor.

The research team was made up of Max C. Langer, from the University of Sao Paulo, Brazil; Ascanio D. Rincón, from the Venezuelan Institute for Scientific Research (IVIC);

Jahandar Ramezani, from the Massachusetts Institute of Technology, United States; Andrés Solórzano, from the Venezuelan Institute for Scientific Research (IVIC); and Oliver WM Rauhut, from the University of Munich, in Germany.

Until both finds, paleontologists had only recorded dinosaur fossils only in low-lying areas of South America and North America.

Where do the fossils of these dinosaurs rest?

Although the fossils of Laquintasaura y Tachiraptor, these are not displayed anywhere.

Fossils of Tachiraptor, his right tibia and the proximal left ischium are in the IVIC scientific collection in Caracas.

As for the Laquintasaura, some of its fossil remains are in the Museum of Biology of the University of Zulia, in Maracaibo.

An isolated maxillary or dental tooth, the distal part of a left femur, the proximal part of a left ischium, and a left talocalcaneal rest in that Venezuelan state.

Map indicating the location of the fossil remains of Tachiraptor.

The La Quinta Formation

The La Quinta Formation is located in the Mérida Mountains area, the northernmost extension of the Andes, on the western border of Venezuela.

This reservoir consists mainly of continental red beds and volcanic rocks deposited in an extensional tectonic environment associated with the Mesozoic Pangea break and the opening of the Atlantic Ocean.

In its type locality, near the town of La Grita, the La Quinta Formation is more than 1600 m thick and is exceptionally tuff.

It is found dissatisfied on the low-grade metamorphic rocks of the Mucuchachi Formation of the middle Carboniferous to Permian age, and is covered, through a nonconformity or transition interval, by the Río Negro Formation of the Lower Cretaceous.

The typographic section can be divided into three distinct intervals, half of which comprise 840 m of tuff, interspersed with siltstones, sandstones and local layers of limestone.

Its depositional environment has been interpreted as an alluvial plain, under a seasonally arid and humid tropical climate.

Sedimentation was predominantly fluvial, locally lacustrine, interrupted by generalized pyroclastic entry.

Mafic lavas and surface intrusions that characterize the La Quinta Formation in other areas (eg, Sierra de Perijá) are absent from the type locality.

Formation Age

The age of the La Quinta Formation has been debated in the literature.

In the type area (Mérida Andes), siltstones, shales and limestones of the middle range contain plant remains, ostracods, concostracans, palynomorphs and fish teeth, most of which are poorly preserved.

The fossil plants suggest an age ranging from the Early Jurassic to the Early Cretaceous; while the palynomomorphs indicate an older age from the Late Triassic to the Middle-Late Jurassic.

Furthermore, the record of a dinosaur ilium with a not fully perforated acetabulum suggests an age from the Late Triassic to the Early Jurassic.

In the Perijá Andes, the paleobotanical association of the La Quinta Formation suggests a Middle Jurassic age, and abundant estherid conchostracans range in age from the Late Triassic / Early Jurassic, in the lower part of the unit, to the Late Jurassic / Early Cretaceous. , in its upper part.

During the last few years, several field investigations have been conducted around the type section of the La Quinta Formation, which allowed the collection of new dinosaur material.



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