Paleontologists in Argentina have identified a new genus and species of unenlagiine dinosaur. Appointed Diuqin lechiguanaefills a substantial gap in the fossil record of these theropod dinosaurs.
Life reconstruction Diuqin lechiguanae. Image credit: Porfiri et al., doi: 10.1186/s12862-024-02247-w.
Diuqin lechiguanae roamed our planet during the Santonian age of the Cretaceous period, between 86 and 84 million years ago.
This species belonged to Unenlagiine, a subfamily of long-snouted paravian theropods in the family Dromaeosauridae.
“Unenlagiines are Gondwanan predatory dinosaurs that are nested within Paraves, a clade that includes birds and their closest non-avian theropod relatives,” said Dr. Juan Porfiri of the Universidad Nacional del Comahue in Buenos Aires and his colleagues.
“The unenlagiine fossil record comes mainly from Argentina, where the largest number of specimens and the most complete skeletons have been found, although additional material, at least tentatively assigned to the Unenlagiinae, has also been recovered from Brazil, Chile, Colombia and Antarctica.”
“The tiny, potentially flying Madagascar theropod.” Rahonavis of the Cape it has also often been considered an unenlagiine, depending on the particular phylogenetic hypothesis used.
“Unenlagiines are most commonly interpreted as early diverging dromaeosaurids, although other authors have instead considered these theropods to be a distinct paravian clade (Unenlagiidae).
“They are an important asset for understanding avian origins because of their close phylogenetic relationship with Avialae.”
“Unfortunately, however, most species are only represented by fragmentary fossils.”
Diuqin lechiguanaea fragmentary but related postcranial skeleton was recovered from the Bajo de la Carpa Formation in Neuquén Province, Patagonia, Argentina.
“The specimen was collected from the isthmus between the southeast shore of Lago Barreales and the northwest shore of Lago Mari Menuco in the province of Neuquén,” the paleontologists said.
According to the authors Diuqin lechiguanae is the first species of unenlagiine dinosaur to be discovered from the Bajo de la Carpa Formation.
“The Bajo de la Carpa Formation has yielded fossils that together represent a diverse and important palaeobiota,” they said.
“Vertebrate remains are abundant and often well preserved and include remains of snakes, lizards, turtles, crocodilians, indeterminate pterosaurs, ornithopods, titanosaurian sauropods, non-avian theropods and birds.”
Diuqin lechiguanae fills a temporal gap of at least 15 million years in the unenlagiines fossil record (conservatively 90-75 million years, possibly more).
“The new species extends the fossil record of South American unenlagiines by filling a significant gap in their temporal distribution,” the researchers said.
“Preserved elements of Diuqin lechiguanae show morphological differences from corresponding bones in other non-enlagine species, such as an accessory lamina on the posterior-most sacral vertebral neural arch, distinct paired foramina on the posterior-most sacral and anterior caudal neural arches, and a humerus with a distally located distolateral deltopectoral ridge and several states that appear midway between the humeri Unenlagia spp. and exceptionally large unenlagiine Austroraptor cabazai.”
“Coupled with the multimillion-year stratigraphic gaps between them Diuqin lechiguanae and geologically older and younger unenlagiines, respectively, these anatomical differences support the validity of the new species.”
“Next, humerus Diuqin lechiguanae the type specimen shows two conical tooth marks, indicating that the carcass was fed by another tetrapod, probably a crocodyliform, mammal, or theropod (perhaps the megaraptorid represented by the tooth found in the same location, or even another non-enlagian individual, potentially a member of the same species).
Discovery Diuqin lechiguanae is featured in a journal article BMC Ecology and Evolution.
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JD Porfiri et al. 2024. Diuqin lechiguanae gene. et sp. nov., a new unenlagiine (Theropoda: Paraves) from the Bajo de la Carpa Formation (Neuquén Group, Upper Cretaceous) of Neuquén Province, Patagonia, Argentina. BMC Ecol Evo 24, 77; doi: 10.1186/s12862-024-02247-w