Cuyi relates to the place the fossil remains were found, El Cuy.
Tralkasaurus would have been dwarfed by its distant cousin Tyrannosaurus rex which could grow to 14 metres in length.
"The size of the Tralkasaurus body is smaller than other carnivores in its group – the abelisaurids," said Dr Federico Agnolin, an investigator from the Argentine Museum of Natural Sciences.
Other abelisaurids usually measured seven to 11 meters.
This "demonstrates that the group of abelisaurid theropods encompassed a much wider ecological niche than we thought," said Mauricio Cerroni, another researcher.
The team found a skull, teeth, ribs and part of the hip and tail.
Just like Tyrannosaurus, it was a short-necked and muscular biped with four claws on each of its hind legs, and arms that were very short in comparison to the rest of its body. The bones of its extremities were light and hollow.
"This new discovery helps us to define the ecological habits of carnivorous dinosaurs as well as herbivores," said Cerroni.
According to the researchers, Tralkasaurus possibly fed on small herbivore dinosaurs called iguanodonts that have been found nearby by the same team of researchers.