Tratayenia

Phylogeny: Dinosauria > Saurischia > Theropoda > Neotheropoda > Tetanurae > Avetheropoda > Coelurosauria > Tyrannosauroidea (?) > Megaraptora > Megaraptoridae

Overview: Tratayenia is known from partial skeletal remains, mainly comprised of vertebrae and some other bones, but enough features are readily observable to determine what kind of dinosaur it was in life. Tratayenia was probably a member of the family Megaraptoridae, which is itself a part of the larger clade Megaraptora. Megaraptorans are a mysterious group of theropods, with many studies over the years placing them in widely different lineages, largely due to them having a mix of derived and basal theropod traits. In years prior, megaraptorans were classified as allosaurs, more derived than Allosaurus itself and closely related to the carcharodontosaur Neovenator. The most recent studies, however, have instead classified megaraptorans within the Coelurosauria, so they were likely closer to birds and possibly related in some way to the tyrannosaurs.

Length estimates for Tratayenia put it at eight or so meters long, which made it one of the larger known megaraptorans and a decently large theropod overall. Notably, megaraptorans were often a lot more lightly built than other theropods of comparable lengths, which was likely the case with Tratayenia itself. This implies they were somewhat more agile. Megaraptorans tended to have long, narrow jaws, but quite enormous arms, often equipped with enlarged, curving claws. Unlike some other theropods, such as Tyrannosaurus, Tratayenia and its kin mainly relied upon their arms to capture their prey. Described in 2018, Tratayenia takes its name from the fossil site of Tratayén, a part of Argentina’s Bajo de la Carpa Formation, where it was originally found. It was probably one of the top predators of its local environment, possibly competing with some abelisaurids.