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| Ypupiara lopai Brum, Pêgas, Bandeira, Souza, Campos & Kellner, 2021 DOI: 10.1002/spp2.1375 |
Abstract
The record of unenlagiines in Brazil, except for one dorsal vertebra, is still under debate based on isolated teeth. Here, we describe Ypupiara lopai gen. et sp. nov., the first dromaeosaurid species from Brazil, from the Maastrichtian of the Bauru Group, Paraná Basin. The specimen consists of a partial right maxilla (with three teeth in loci) and a right dentary. Ypupiara is characterized by a restricted number of neurovascular foramina on the lateral surface of the maxilla, a rectangular and anteroposteriorly expanded interdental plate, and a labiolingual compression of the teeth, which have a labiolingual diameter more than 3/5 of the rostrocaudal diameter. Our phylogenetic analysis recovers Ypupiara as an unenlagiine based on the fluted teeth and places it as the sister taxon of Austroraptor due to the ratio of the labiolingual and mesiodistal diameters of the teeth being more than 3/5. We also erect the new group Unenlagiinia, which includes Unenlagiinae and Halszkaraptorinae. Ypupiara nests within Unenlagiinia based on the widely spaced teeth and the lack of mesial and distal carinae in the maxillary teeth. The morphology of the teeth is similar to Buitreraptor, although the proportions are markedly distinct. The teeth and comparisons with other Unenlagiinia also support fish being part of the diet for Ypupiara. We also performed a parsimony analysis of endemicity, which suggested that the presence of unenlagiines in Brazilian Upper Cretaceous outcrops is explained by dispersion or extinction events. The new species provides new information on the evolution of Gondwanan dromaeosaurids, and its preserved teeth provide new data to enable the assignment of isolated dromaeosaurid teeth from the Bauru Group.
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| Ypupiara lopai sp. nov. Right maxilla of DGM 921-R with details of teeth. Details of the maxilla in: A, lateral; B, medial; C, ventral view. Abbreviations: idp, interdental plate; mes, mesial shelf; nug, nutrient groove. Scale bar represents 10 mm. |
DINOSAURIA Owen, 1842
THEROPODA Marsh, 1881
COELUROSAURIA Huene, 1914
MANIRAPTORA Gauthier, 1986
DROMAEOSAURIDAE Matthew & Brown, 1922
UNENLAGIINIA nov.
Included clades: Unenlagiinae (sensu Bonaparte 1999) and
Halszkaraptorinae (sensu Cau et al. 2017).
Branch-based definition:
All taxa closer to Unenlagia comahuensis Novas & Puerta, 1997 and Halszkaraptor escuilliei Cau et al., 2017 than to Microraptor zhaoianus (Sloan, 1999) or Dromaeosaurus albertensis Matthew & Brown, 1922.
UNENLAGIINAE Bonaparte, 1999
Genus YPUPIARA nov.
Type species: Ypupiara lopai sp. nov., type by monotypy.
Derivation of name: ‘Ypupiara’, which means ‘the one who lives in the water’, an allusion to a Tupian myth about an aquatic creature. This also alludes to the inferred fish diet of Ypupiara.
Ypupiara lopai sp. nov.
Derivation of name: The specific epithet ‘lopai’ is in honour of Alberto Lopa (of the former Divisão de Geologia e Mineralogia, Departamento Nacional de Produção Mineral–DNPM of Peirópolis). He is responsible, together with Llewellyn I. Price, for starting the systematic palaeontological exploration of the region of Peirópolis, Minas Gerais state, and for recovering most of the material studied by Price. In addition, Alberto Lopa also recovered the fossil material studied here.
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| Comparison of Unenlagiinae maxillae and anatomical placement of DGM 921-R. A, Austroraptor cabazai; B, DGM 921-R; C, Buitreraptor gonzalezorum. Abbreviations: aofe, antorbital fenestra; aofo, antorbital fossa; aor, antorbital ridge; ifs, interfenestral strut; man, maxillary antrum; mfe, maxillary fenestra; pab, preantorbital body. Scale bars represent 50 mm. |
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| Calibrated consensus phylogenetic tree focusing on Dromaeosauridae and the classification of Ypupiara lopai. |
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| Artist’s reconstruction of two individuals of Ypupiara lopai foraging in an alluvial river, the setting of the Marília Formation during the Maastrichtian. Artist, Guilherme Gehr. |
Conclusion:
Specimen DGM 921-R represents a new species, Ypupiara lopai gen. et sp. nov., that can be recognized as an unenlagiine and which exhibits a combination of features observed in both Buitreraptor gonzalezorum and Austroraptor cabazai. The dental features, however, share more morphological similarities with B. gonzalezorum. The recovery of such cranial material with associated teeth is important to diagnose and trace comparisons with the dromaeosaurid teeth from Bauru Group outcrops, and as an indicator of the diversity of these small theropods. Such an unenlagiine occurrence in the Campanian–Maastrichtian intervals of Brazil indicates that the lineage was present not only in the Neuquén Basin (Argentina), but also in the Upper Cretaceous of the Paraná Basin (Brazil).
Arthur S. Brum, Rodrigo V. Pêgas, Kamila L. N. Bandeira, Lucy G. Souza, Diogenes A. Campos and Alexander W. A. Kellner. 2021. A New Unenlagiine (Theropoda, Dromaeosauridae) from the Upper Cretaceous of Brazil. Papers in Palaeontology. DOI: 10.1002/spp2.1375
