Harenadraco prima is the first species of troodontid dinosaur ever found in the Late Cretaceous Baruungoyot Formation of Mongolia.
Life reconstruction of Harenadraco prima. Image credit: Yusik Choi.
Harenadraco prima lived in what is now Mongolia during the Late Cretaceous epoch, between 72 and 71 million years ago.
The new species belongs to Troodontidae, a group of bird-like theropod dinosaurs known from the Late Jurassic to Late Cretaceous epoch.
“Troodontids are a diverse group of theropod dinosaurs, generally characterized by large orbits, long hind limbs with asymmetrical metatarsi, and an enlarged ungual on the second pedal digit as well as many bird-like features,” said Seoul National University paleontologist Sungjin Lee and colleagues.
“They have been found in the sedimentary deposits that range from the Late Jurassic to the latest Cretaceous of Asia and North America.”
Harenadraco prima was a small-sized troodontid approximately 1 m (3.3 feet) in length.
“Harenadraco prima was small and lightly built like other species of troodontid dinosaurs, but its tarsometatarsus exhibits extreme slenderness comparable only to Philovenator among cursorial non-avian maniraptorans,” the paleontologists said.
“It also implies high cursoriality that could be an adaptation of Harenadraco prima to its environment where potential prey animals like mammals and predators such as eudromaeosaurs were likely to be agile.”
Harenadraco prima’s incomplete skeleton that mainly consisted of left hindlimb elements was unearthed in the Baruungoyot Formation at Hermiin Tsav in the Mongolian province of Ömnögovi.
“The Upper Cretaceous beds in the Gobi Desert have been a rich source of many troodontid species, especially the Nemegt and Djadochta formations in the Nemegt Basin, Mongolia as well as the Wulansuhai Formation in Bayan Mandahu, China,” the researchers said.
“From the former, eight troodontid species are currently known.”
“The Baruungoyot Formation, however, has been a puzzling exception because no troodontids have been found even though it is one of the major sedimentary formations in the Nemegt Basin and interpreted to be intermediate to the Djadochta and Nemegt formations in terms of age and/or environment.”
“As the faunal compositions of the Djadochta and Baruungoyot formations are very similar, the absence of troodontids in the latter is even more puzzling.”
The discovery of Harenadraco prima confirms the presence of troodontids in all three formations in the Nemegt Basin.
“With the discovery of Harenadraco prima, it is now apparent that the ‘gap’ in the troodontid record was a sampling artifact,” the scientists concluded.
“The fragile nature of the holotype of Harenadraco prima further supports this.”
“The presence of Harenadraco prima in the Baruungoyot Formation also demonstrates that troodontids of the Nemegt Basin were diverse enough to adapt to various environments.”
The team’s work was published in the Journal of Vertebrate Paleontology.
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Sungjin Lee et al. The first troodontid (Dinosauria: Theropoda) from the Upper Cretaceous Baruungoyot Formation of Mongolia. Journal of Vertebrate Paleontology, published online July 15, 2024; doi: 10.1080/02724634.2024.2364746
Source : Breaking Science News