Fossils discovered at a secluded ranch in Argentina reveal a new genus and species of large sauropod dinosaur, identified by an international team of paleontologists from Ludwig-Maximilians-University Munich.
Reconstruction of Vicaracosaurus dionydei. Image credit: Felipe Cutro-Lev.
The newly identified sauropod species roamed the southern region of the Gondwana supercontinent during the Late Jurassic period, approximately 157 million years ago.
Named Vicaracosaurus dionydei, this dinosaur measured around 20 meters (65 feet) in length.
“Sauropods are a key lineage of dinosaurs, representing one of the most significant groups of herbivorous vertebrates from the Mesozoic era,” said lead author Alexandra Reuter, a doctoral student at Ludwig-Maximilians-University Munich, alongside her research team.
“These giant herbivores first emerged in the late Triassic period and thrived until the end of the Cretaceous period.”
“Sauropods displayed considerable taxonomic diversity and included the largest terrestrial animals in history.”
“Neosauropoda eventually branched into two primary clades, Diplodocoideae and Macronariidae, early in their evolutionary journey. This major classification has been widely accepted since the 1990s, though there is ongoing debate regarding the classification of many Jurassic taxa into these subclades or Neosauropoda as a whole.”
Fossil remains identified as Vicaracosaurus dionydei, including vertebrae, ribs, and parts of a hip joint, were first reported to paleontologists in March 2001 by local farmer Dionid Mesa.
This fossil site belongs to the Canadon Carcareo Formation, located in central to northern Chubut province, Argentina.
Historically, researchers have relied heavily on fossils from North America, Europe, and other Northern Hemisphere regions to piece together the evolution of neosauropods.
Both the Canadon Carcareo Formation and the Tendaguru Formation in Tanzania stand out as rare Gondwanan deposits preserving skeletons of multiple sauropods.
“For years, the only significant archaeological site in the southern continent was in Tanzania,” stated lead author Professor Oliver Rauchat, a paleontologist at the Bavarian Institute of Paleontology and Geology, as well as Ludwig-Maximilians-University of Munich.
“The fossils from the Chubut province, including Vicaracosaurus dionydei, provide critical comparative material that enhances our understanding of these creatures’ evolutionary history, particularly in the Southern Hemisphere.”
Fossil evidence indicates that Vicaracosaurus dionydei is part of a giant herbivore group known as Macronaria, which later gave rise to iconic giants like Brachiosaurus.
Yet, this new dinosaur’s anatomy also shows remarkable similarities to diplodocids, another sauropod lineage that includes famous species like Diplodocus.
To ascertain its position within the dinosaur family tree, researchers employed two distinct phylogenetic datasets for analysis.
Most analyses positioned Vicaracosaurus dionydei as sharing traits with Macronaria and Brachiosauridae, including Brachiosaurus and the African giant Giraffatitan.
“Our phylogenetic analysis indicates that Vicaracosaurus dionydei is closely related to brachiosaurids, making it the earliest known brachiosaur to inhabit South America during the Jurassic period,” Reuter concluded.
The research team’s paper was published in the online journal Peer J.
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A. Reuter et al. 2026. Vicaracosaurus dionydei, a new giant herbivorous dinosaur (sauropod) from the Late Jurassic Canadon-Carcareo Formation in Argentina and insights into the early evolution of giant sauropods. Peer J 14: e20945; doi: 10.7717/peerj.20945
Source: www.sci.news
