Submitted : May 2 0th , 2020 – Accepted : July 30 th , 2020 – Posted online : August 3 rd , 2020 To link and cite this article: doi: 10.5710/AMGH.30.07.2020.3368 1 Paleontological Notes 2 ‘A VERY LAZY DEER’: REVISION OF THE COTYPE OF NOTHROPUS 3 CARCARANENSIS (MAMMALIA, XENARTHRA) 4 RAÚL IGNACIO VEZZOSI 1,2,3, ALLINE ROTTI4,5 and LEONARDO DOS SANTOS 5 AVILLA4,5 6 7 1Laboratorio de Paleontología de Vertebrados, Centro de Investigación Científica y de 8 Transferencia Tecnológica a la Producción (CONICET, Gob. E.R., UADER), España 9 149, Diamante E3105BWA, Argentina. E-mail: [email protected] 10 2 Facultad de Ciencia y Tecnología, Universidad Autónoma de Entre Ríos, Ruta 11 Provincial 11 km 10,5, Oro Verde E3100XAD, Entre Ríos, Argentina. 12 3Programa de Desarrollo de las Ciencias Básicas (PEDECIBA – UDELAR) and Museo 13 Nacional de Historia Natural de Montevideo, Uruguay. 14 4Laboratório de Mastozoologia, Instituto de Biociências, Universidade Federal do 15 Estado do Rio de Janeiro. Avenida Pasteur, 458, sala 501, Urca. 22290-240, Rio de 16 Janeiro, RJ, Brasil. E-mails: [email protected], [email protected] 17 5Programa de Pós-graduação em Biodiversidade e Biologia Evolutiva (PPGBBE), 18 Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Prédio das Pós- 19 graduações do Instituto de Biologia, Interbloco B/C, Cidade Universitária. 21941-902, 20 Rio de Janeiro, RJ, Brasil. 21 22 23 Total number of pages (14), figures (3) 24 Proposed header. VEZZOSI ET AL.: REVISION OF NOTHROPUS CARCARANENSIS 25 BORDAS, 1942. 1 26 Corresponding author: [email protected] 27 Short Description. The cotype of the sloth Nothropus carcaranensis is reviewed and 28 systematically assigned to the extinct Cervidae Morenelaphus. 29 30 Key words. Anatomy. Systematic. Cervidae. Morenelaphus. Braincase 31 Palabras clave. Anatomía. Sistemática. Cervidae. Morenelaphus. Caja craneana. 2 32 THE HOLOTYPE of the nothrotheriid Nothropus carcaranensis Bordas, 1942 is a partial 33 dentary from the Pleistocene of Santa Fe Province (Argentina) associated to other 34 isolated bones (see Bordas, 1942; Brandoni & McDonald, 2015). Among these remains, 35 an isolated braincase had been considered the cotype of N. carcaranensis in the original 36 publication of Bordas (1942:174–175). 37 This contribution provide for the first time detailed anatomical description and 38 analysis of this braincase assigned to N. carcaranensis, and to discuss its original 39 assignment. 40 Anatomical abbreviations. Acr, articular crest; af, articular fossa; ali, 41 alisphenoid; atu, articular tuberosity; bs, basisphenoid; bo, basioccipital; bu, bumps; 42 eam, external acoustic meatus; eop, external occipital process; fm, foramen magnum; 43 fo, foramen ovale; for, foramen orbitorotundum; fr, frontal; hf, hypoglossal foramen; 44 jf, jugular foramen; lf, lacerum foramen; mp, mastoid process; ms, mesiodistal sulcus; 45 mt, meatus temporalis; oc, occipital condyle; orb, orbital; p, pedicle; pal, palatine; pm, 46 procesus muscularis; par, parietal; ppa, paroccipital process; pop, postglenoid process; 47 pos, parieto-occipital suture; ptub, posterior tuberosity; pte, pterygoid; sc, sagittal 48 crest; sf, stylohyoid fossa; so, supraoccipital; sq, squamosal; tc, temporal crest; th, 49 tympanohyal recess; tm, tuberculum musculare; tyb, tympanic bulla; zp, zygomatic 50 process of squamosal. 51 MATERIALS AND METHODS 52 A direct comparison of the cotype of Nothropus carcaranensis with the skulls of 53 nothrotheres (e.g., Mionothorpus cartellei De Iuliis, Gaudin, Vicars [2011], 54 Nothrotherium maquinense [Lund, 1839], Pronothrotherium mirabilis [Kraglievich, 55 1925], Thalassocnus spp. McDonald & Muizon, 2012) and extant and extinct deer (see 56 Appendix 1) was made. The cranial nomenclatural of mammals and deer follows 3 57 Cabrera (1941), NAV (2005), and Heckeberg (2020). Comparisons to some taxa, such 58 as Megaloceros giganteus Blumenbach, 1799, Navahocerus fricki (Schultz & Howard, 59 1935) were based on Webb (1992) and Vislobokoba (2013). A list of the analyzed 60 specimens and their institutional collections are present in Appendix 1 (Supplementary 61 Online Information). 62 GEOGRAPHIC AND STRATIGRAPHIC PROVENANCE OF THE FOSSIL 63 DEER 64 The cotype of Nothropus carcaranensis (MACN-Pv 12630, Fig. 1) was 65 recovered by Osvaldo Coronel between 1930 to 1940 from the Carcarañá beds at the 66 National Road number 11, near Villa La Rivera, Santa Fe Province, Argentina 67 (32°38'23.03''S; 60°48'54.16''W). The fossiliferous strata can be correlated to the Upper 68 Pleistocene sequence (Cohen et al., 2013; ICC, 2018), which is part of the Timbúes 69 Formation (Iriondo & Kröhling, 2009; Vezzosi et al., 2019a, 2019b). 70 [Figure 1 insert here] 71 72 SYSTEMATIC PALEONTOLOGY 73 74 Order CETARTIODACTYLA Montgelard, Catzeflis & Douzery, 1997 75 Suborder RUMINANTIA Scopoli, 1777 76 Infraorder PECORA Linnaeus, 1758 77 Family CERVIDAE Goldfuss, 1820:374 78 Genus Morenelaphus Carette, 1922 79 Type species. Morenelaphus brachyceros (Gervais & Ameghino, 1880) 80 Morenelaphus sp. 81 Figures 1–3 4 82 83 Referred material. MACN-Pv 12630 posterior portion of the braincase of a young-adult 84 deer (Fig. 1), originally considered as cotype of Nothropus carcaranensis by Bordas 85 (1942:174–175). 86 Locality and age. Late Pleistocene levels of La Rivera town (Carcarañá River between 87 Timbúes and Oliveros, 32°38'23.03"S – 60°48'54.16"W), Santa Fe Province, Argentina. 88 89 Description and comparisons. MACN-Pv 12630 does not resemble another species of 90 Nothrotheriidae, and its general morphology is clearly different of any sloth braincases 91 (Fig. 1–3). In fact, it lacks features clearly recognized in best-known nothrotheriid 92 species like Mionothorpus cartellei, Nothrotherium maquinense, Pronothrotherium 93 mirabilis, even in Thalassocnus spp., including: circular and flat ectotympanic bone 94 (Fig. 2.3–2.4); flat basioccipital-basiesphenoid bones without posterior tuberosities (Fig. 95 2.5–2.6); absence of tympanic bullae and deep tympanohyal recess (Fig. 2.3–2.6); large 96 sagittal crest (Fig. 2.8); and large occipital condyles, very conspicuous and with oval 97 section; (Fig. 2.9); amongst others (Fig. 2). Moreover, the braincase of MACN-Pv 98 12630 is very similar to a young-adult deer in several aspects (Fig. 1), which include a 99 weak sagittal crest and basioccipital-basisphenoid bones fused (Fig. 3.3). The nuchal 100 plane of the occipital is composed by fully fused bones, but keeping a parieto-occipital 101 suture (Fig. 3.4). This suture is positioned dorsally near the parietal bone and disto- 102 laterally from the dorso-posterior area of squamosal. The mastoid process extends 103 ventro-laterally to the posterior edge of squamosal. Posteriorly, some specimens of 104 Morenelaphus (e.g., MFA-G-Pv 1311) lack a lateral constriction near the mastoid 105 process and the nuchal area of the occipital has a subcircular shape (Fig. 3.5). The 106 mastoid in Morenelaphus is a vertical and wide plate, which is compressed between the 5 107 posterior surface of the squamosal and the anterolateral edge of the infraoccipital; the 108 entire occipital area is subcircular in a posterior view (Fig. 3.6). Such as in Blastocerus 109 dichotomus males (Fig. 3.1), the posterior edge of the braincase, in lateral view, is 110 extremely concave and both the supraoccipital region and the occipital condyles are 111 projected much more posteriorly than other extant Cervidae (Fig. 3.3–3.4). 112 Nevertheless, senile individuals of Odocoileus virginianus have a very prominent edge 113 along the lambdoid suture (Cabrera, 1941), but never at the level recognized for B. 114 dichotomus and MACN-Pv 12630 (Fig. 3). Although both paroccipital processes are 115 slightly fragmented, they are ventrally evident such as in Hippocamelus spp. Leuckart, 116 1816; B. dichotomus; Ozotocerus bezoarticus (Linnaeus, 1758); Mazama spp. 117 Rafinesque, 1817; Cervus elaphus Linnaeus, 1758 and Rangifer tarandus Linnaeus, 118 1758 (Fig. 3). The occipital condyles are comparatively large and well-developed as in 119 Navahocerus fricki (Webb, 1992), much more than in all extant South American 120 Cervidae (SAC). MACN–Pv 12630 and Morenelaphus have similar large size and 121 reniform occipital condyles (Fig. 2.10–3). Adult individuals of Morenelaphus that bear 122 large antlers (MFA-G-Pv 1312, MFA-G-Pv 1722; Fig. 3.5) have one or two 123 conspicuous bumps dorsally to the foramen magnum. MACN–Pv 12630 lacks this 124 feature (Fig. 3.6), probably because it is a young-adult. Both petrosals in MACN–Pv 125 12630 bear a similar morphology to Morenelaphus (see Orcesi et al., 2019), in which 126 the promontorium is short and ovoid, the epitympanic wings are short and have a flat 127 surface and the tegmen tympani is concave, with an oval transverse section and with less 128 conspicuous anterior process (see Vezzosi, 2015, fig. II.102). In contrast with the 129 Nothrotheriidae, the basioccipital-basisphenoid have a triangular section in ventral 130 view, with two posterior tuberosities, which are distally project to both sides of 131 paroccipital processes (Fig. 3.8). These tuberosities exhibit a similar development in B. 6 132 dichotomus (MACN-Ma 13-1), O. bezoarticus (MACN-Ma 49183), and O. virginianus 133 (AMNH 100289); while in Hippocamelus spp., Mazama spp., and Pudu puda Molina, 134 1782, these are proportionally less developed. As in Morenelaphus, the mesiodistal 135 sulcus continues in a convex crest, limited by two conspicuous tuberculum musculare 136 with variable size (Fig. 3.7–3.8). Although MACN–Pv 12630 has the basisphenoid 137 preserved only until the level of its convex crest, it stills very similar to the one in 138 Morenelaphus (Fig. 3.7); showing a basicranium with small jugular foramen and 139 associated to the lacerum foramen, circular foramen orbitorotundum and similar in size 140 to the foramen ovale (Fig. 3.8). The concave articular fossa and the postglenoid process 141 are transversely positioned, but this latter is crosswise to foramen ovale. Behind this 142 foramen, the tympanic bulla is less inflated compared to Mazama spp., O.