Paleontologists in Argentina have identified a new genus and species of unenlagiine dinosaur. Called Diuqin lechiguanaeit fills a significant gap in the fossil record of these theropod dinosaurs.
Life reconstruction of Diuqin lechiguanae. Image credit: Porfiri et al., doi: 10.1186/s12862-024-02247-w.
Diuqin lechiguanae roamed our planet during the Santonian era of the Cretaceous, between 86 and 84 million years ago.
This species belonged to Unenlagiine, a subfamily of long-snouted paravian theropods within the family Dromaeosauridae.
“Unenlagiines are Gondwanan predatory dinosaurs nested in Paraves, the clade that includes birds and their closest non-avian theropod relatives,” said Dr. Juan Porfiri of the Universidad Nacional del Comahue, Buenos Aires, and his colleagues.
“The non-enlagiine fossil record comes mainly from Argentina, where the largest number of specimens and most complete skeletons have been found, although other materials at least tentatively attributed to Unenlagiinae have also been recovered from Brazil, Chile, Colombia and Antarctica.”
‘The small, potentially volant theropod from Madagascar Rahonavis ostromi is also often considered an unenlagiine, depending on the specific phylogenetic hypothesis used.”
“Unenlagiines are usually interpreted as early divergent dromaeosaurids, although other authors have instead considered these theropods as a separate paravian clade (Unenlagiidae).”
“They are an important clade for understanding the origins of birds because of their close phylogenetic relationship with Avialae.”
“Unfortunately, however, most species are only represented by fragmentary fossils.”
Diuqin lechiguanaeThe fragmentary but associated 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 southeastern coast of Lago Barreales and the northwest coast 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 discovered in the Bajo de la Carpa Formation.
“The Bajo de la Carpa Formation has yielded fossils that together represent a diverse and important paleobiota,” they said.
“Vertebrate remains are abundant and often well preserved, and include those of snakes, lizards, turtles, crocodilians, indeterminate pterosaurs, ornithopods, titanosaurian sauropods, non-avian theropods, and birds.”
Diuqin lechiguanae fills a temporary gap of at least 15 million years in the unenlagine fossil record (conservatively 90-75 million years, possibly longer).
“The new species increases the fossil record of South American unenlagines by filling a significant gap in their temporal distribution,” the researchers said.
“Preserved elements of Diuqin lechiguanae show morphological differences from similar bones in other non-enlagic species, such as an accessory lamina on the posterior sacral neural vertebral arch, characteristic paired foramina on the posterior sacral and anterior caudal neural arches, and a humerus with a distally located distolateral deltopectoral ridge and several conditions that appear between the humeri Unenlagia spp. and the exceptionally large unenlagiine Austroraptor cabazai.”
“In combination with the stratigraphic differences of several million years in between Diuqin lechiguanae and geologically older and younger unenlagines, these anatomical differences support the validity of the new species.’
“Furthermore, the humerus of the Diuqin lechiguanae 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 a tooth found at the same site, or even another non-enlagiine individual, possibly a member of the same species).”
The discovery of Diuqin lechiguanae is reported in an article in the journal BMC Ecology and Evolution.
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JD Porfiri et al. 2024. Diuqin lechiguanae gene. and sp. November, 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