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A new Unenlagiinae (Theropoda: Dromaeosauridae) from the Late Cretaceous of Brazil

Citation

Brum, Arthur Souza et al. (2021), A new Unenlagiinae (Theropoda: Dromaeosauridae) from the Late Cretaceous of Brazil, Dryad, Dataset, https://doi.org/10.5061/dryad.crjdfn32j

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 undoubtful nominal unenlagiine dromaeosaurid species from Brazil, from the Marília Formation (Maastrichtian), Bauru Group, Paraná Basin. The specimen comprises a partial right maxilla (with three teeth in loci) and a right dentary. Ypupiara is characterized by the morphology of the maxilla, presenting restrict number of neurovascular foramina on lateral surface, rectangular and anteroposteriorly expanded interdental plate, teeth with labiolingual diameter more than 3/5 of the rostrocaudal diameter, teeth widely spaced and labiolingually compressed. Our phylogenetic analysis recovers Ypupiara as an unenlagiine based on fluted teeth, and places it as the sister taxon of Austroraptor cabazai due to the ratio between the labiolingual and mediodistal diameters of the teeth more than 3/5. We also erect the new group Unenlagiinia, which includes Unenlagiinae and Halszkaraptorinae clades. Ypupiara nests within this new group based on widely spaced teeth and the lack of mesial/distal carinae in maxillary teeth. The morphology of the teeth is similar to Buitreraptor gonzalezorum, although the proportions are markedly distinct. The teeth and comparisons with other Unenlagiinia also support that fish was part of the diet for Ypupiara. We also performed a Parsimony Analisys of Endemicity, which suggests that the presence of unenlagiines in Brazilian Upper Cretaceous outcrops is explained by dispersion or extinct events. The new species provides new information on the evolution of Gondwanan dromaeosaurids, and its preserved teeth provides new data to assign isolated dromaeosaurid teeth from Bauru Group.

Methods

Measurements

The teeth linear morphometric analysis of DGM 921-R was performed after the loss of the specimen. However, the teeth could be measured in ImageJ, via photographs, available herein. To measures of these photos, we also employed the ImageJ.

Linear morphometric abbreviations

AL, apical length; CA, crown angle; CBL, crown base; CBR, crown base ratio; CBW, crown base width; CH, crown height; CHR, crown height ratio; DDL, distal denticles length; MCL, midcrown length; MCW, mid-crown width; MCR, mid-crown ratio; MDL, mesial denticles length; MSL, mesial serrated carina length; LAF, number of flutes on the labial surface of a crown; LIF, number of flutes on the lingual surface of a crown.

Heuristic tree search

The phylogenetic analysis was performed based on the data matrix from Cau et al. (2017), with the inclusion of the specimen DGM 921-R, a new character and a few codification changes.

The modifications in the scoring for some characters in the dataset by Cau et al. (2017) are as follow.

  • Character 198: axis, neural spine in lateral view: low and anteroposteriorly expanded (0); mediolaterally compressed and dorsoventrally elongate (1). We have changed the coding for this character in taxon Buitreraptor from state 1 to state 0. As described by Gianechini et al. (2018), the neural spine of the axis in Buitreraptor is elongate, extending towards the posterior region of the vertebra.
  • Character 401: Ilium, postacetabular process, ventral margin, orientation in lateral view: posterodorsally to subhorizontally (0); posteroventrally (1) directed. We have changed the coding for this character from state 0 to state 1 in taxa Mahakala and Unenlagia paynemili. As can be seen in the works by Turner et al. (2011) and Calvo et al. (2004), the postacebular process of the illium in these taxa is oriented ventrally, similarly to Unenlagia comahuensis.
  • Character 625: pedal ungual II, shape in lateral view: straight or moderately curved (0); strongly curved (1). We have modified the coding for Halszkaraptor and Mahakala. In Halszkaraptor the second pedal ungual is strongly recurved (state 1) as can be seen from the figures and from the description Cau et al. (2017). The same is true for Mahakala, as shown by Turner et al. (2011). We have thus changed their coding into 1.
  • Character 808: ischium, longitudinal ridge dividing lateral surface into anterior and posterior parts: absent (0); present (1). As can be seen in the work of (Gianechini & Apesteguía 2011), there are no signs of a lateral ridge on the ischium of Unenlagia comahuensis. We have therefore changed its coding from 1 to 0.

Furthermore, we have excluded from the analysis the following 50 taxa for which less 10% of the characters could be coded: Alnastheria, Alxasaurus, Ambiorlus, Anchiornis, Apsaravis, Banji, Bohaiornis, Boluochia, Caegnathasia, Chirostenotes, Concornis, Cruralispenna, Eliansaurus, Enigmosaurus, Eocatheyornis, Eopengornis, Feitianus, Hebeiornis, Hexing, Houornis, Iaceornis, Iteravis, Jianchangornis, Longirostravis, Longusungus, Machaiaysaurus, MPC D 100 140, Nankangia, Neimongosaurus, Nomingia, Nothonychus mckinlei, Perigornis, Piscivoravis, Pterygornis, Qiliana, Quipalong, Rapaxavis, Shengyingornis, Shenqiornis, Shinkingia, Sinornis, Sulcavis, Teviornis, Tugriken, Xixianykus, Xollanda, Yanornis, Yxianornis and Zhouornis.

The complete data matrix can be found as an additional TNT file: “Ypupiara_codification.tnt”.

Heuristic search to teeth assignment 

The specimen DGM 921-R was codded and included on the tooth-based matrix provided by Hendrickx et al. (2020), with 148 characters and 108 taxa, including DGM 921-R. The codification of Buitreraptor gonzalezorum was modified from the absence of flutes on lateral surface to flutes on the lateral teeth present on labial or both labial and lingual surfaces (Character 111:2) and the average number of flutes on the crown from inapplicable to varying from one to 7 (Character 112:0). This modification was based on the descriptions provided by (Gianechini pers. comm. 2020; Gianechini et al. 2011). The heuristic search was performed using the TNT 1.5 (Goloboff & Catalano 2016). The memory available for the analysis was 1,000 MBytes, which enabled to the program hold 800,000 trees. We performed two heuristic searches altering some parameters from the described by Hendrickx et al. (2020).

The file of the TBR + New Tech analysis is available as  “Ypupiara Hendrickx et al(2020)_original.tnt”. The file of TBR analysis is avaiabla as “Ypupiara Hendrickx et al(2020)_no force.tnt”.

Linear morphometric analyses to teeth assignment  

We performed the multivariate analysis with the dataset of {Formatting Citation} and we added data of avian-toothed taxa provided by (Dumont et al. 2016). The analyses were performed by the software PAST V.4.02 (Hammer 2016). As the morphometrics protocols (Young et al. 2019; Hendrickx et al. 2020), we regarded 12 morphometric measurements, which comprised the CBL, CBW, CH, AL, CBR, CHR, MCL, MCW, MCR, MSL, LAF+1and LIF+1, and performed a log transformation of them. Although we considered that Buitreraptor gonzalezorum exhibits flutes, we could not include it in morphometrics due to the lack of precision in number and tooth crown surface in which they occur.

The dataset comprising all theropods teeth measurements is available at “Data with Ypupiara (Young et al-2019).dat”. The dataset to the theropods with CH < 20 mm is available at “Data with Ypupiara (Young et al-2019)_CH 20.dat”, which is also  the dataset to perform the Cluster Analyses. All the measurements are Log transformed. The references cited in the datasets are available further in reference list herein.

Parsimony Analysis of Endemicity (PAE)

The matrix to the PAE analysis is available at “PAE.tnt.

Usage Notes

To access the description of the data available here and access supporting data of the results, read the file "READ ME.docx."

Funding

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Award: CAPES-PROANTAR #88887.336584/2019-00

Fundação de Amparo à Pesquisa do Estado de São Paulo, Award: FAPESP #2019/10231-6

Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Award: FAPERJ # E-26/202.905/2018

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Award: CAPES #88882.183263/2018-01

Fundação de Amparo à Pesquisa do Estado do Amazonas, Award: FAPEAM # 062.00166/2020

Paleo and Geohistory Exhibition at Museu da Amazônia, Award: PRONAC 183808

Conselho Nacional de Desenvolvimento Científico e Tecnológico, Award: CNPq #420687/2016-5

Conselho Nacional de Desenvolvimento Científico e Tecnológico, Award: CNPq #313461/2018-0

Paleo and Geohistory Exhibition at Museu da Amazônia, Award: PRONAC 183808