Submitted : September 26 th , 2020 – Accepted : June 4th , 202 1 – Posted online : June 16 nd , 202 1 To link and cite this article: doi: 10.5710/AMGH.04.06.2021.3403 1 NEW RECORD OF A PHOCID (MAMMALIA, CARNIVORA, PHOCIDAE) IN 2 THE LATE MIOCENE OF PATAGONIA, ARGENTINA 3 NUEVO REGISTRO DE UN FÓCIDO (MAMMALIA, CARNIVORA, PHOCIDAE) EN 4 EL MIOCENO TARDÍO DE PATAGONIA, ARGENTINA 5 6 SEBASTIÁN ECHARRI,*,1 DAMIÁN E. PEREZ,2 MARCELO MIÑANA,1 AND 7 SERGIO O. LUCERO,1 8 1 Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" – CONICET. 9 Av. Ángel Gallardo 470, C1405DJR, Buenos Aires, Argentina. 10 [email protected]; [email protected]; 11 [email protected] 12 2 Instituto Patagónico de Geología y Paleontología (IPGP CCT CONICET-CENPAT), Bvd. 13 Brown 2915, U9120CD, Puerto Madryn, Chubut, Argentina. [email protected] 14 15 16 págs. (text+references); 2 figs. 16 17 Running header: ECHARRI ET AL.: NEW PHOCID FROM PATAGONIA 18 Short description: New fossil record of a phocid from Puerto Madryn Formation, the first 19 skull remains for the group in Patagonia. 20 21 Corresponding author: Sebastián Echarri, [email protected] 1 22 23 Keywords. Chubut. Kawas. Neogene. Pinnipedia. Properichtychus. Puerto Madryn 24 Formation. South Atlantic. 25 Palabras clave. Chubut. Kawas. Neógeno. Pinnipedia. Properichtychus. Formación Puerto 26 Madryn. Atlántico Sur. 20 27 28 TRUE SEALS (family Phocidae) include 19 living species grouped in two living subfamilies: 29 Monachinae Gray, 1869 and Phocinae Gray, 1821 (e.g., King, 1964; Bastida et al., 2007). 30 Monophyly of the Phocidae is supported by morphological and molecular evidence (Davis 31 et al., 2004; Higdon et al., 2007; Amson & Muizon, 2014; Berta et al., 2018). A third 32 subfamily, the Devinophocinae, includes only one genus with two fossil species: 33 Devinophoca claytoni and D. emryi (Koretsky & Holec, 2002; Koretsky & Rahmat, 2015; 34 Rahmat & Koretsky, 2018). The subfamily Monachinae presents three well-differenced 35 clades: the tribes Monachini (monk seals), Miroungini (elephant seals), and Lobodontini 36 (leopard seals and others); while the subfamily Phocinae includes: the tribes Erignathini 37 (bearded seals), Cystophorini (hooded seals), and Phocini (common seals) (Muizon, 1981; 38 Koretsky, 2001; Davis et al., 2004; Higdon et al., 2007; Fulton & Strobeck, 2010; Scheel et 39 al., 2014; Berta et al., 2018). This classification is primarily based on living taxa, but other 40 authors proposed different arrangements. For example, Koretsky & Rahmat (2013) 41 suggested a fourth subfamily, the Cystophorinae, including some former members of the 42 Monachinae. 43 Based on current distributions, species of Phocinae are commonly considered 44 Boreal seals (King, 1964; Dewaele et al., 2018a,b). However, during the Neogene, the 45 Phocinae has at least one record in the Southern Hemisphere (Cozzuol, 2001), and the 46 species of the Monachinae seals were present in the Northern and Southern Hemispheres 47 (Muizon, 1981; Berta et al., 2015; Govender, 2015; Dewaele et al., 2018b). 48 In the Southern Hemisphere, fossil phocids are restricted to a few scattered 49 localities in Chile, Perú, Argentina, South Africa, Australia, and New Zealand (Hendey & 20 50 Repenning, 1972; Muizon & Hendey, 1980; Muizon, 1981; Cozzuol, 2001; Walsh & Naish, 51 2002; Fitzgerald, 2005; Valenzuela-Toro et al., 2013, 2015; Berta et al., 2018; Rule et al., 52 2019, 2020). On the South Eastern Atlantic coast, fossils of seals are restricted to few 53 localities from the Miocene and Pleistocene of Argentina (Muizon & Bond, 1982; Cozzuol, 54 1996, 2001; Soibelzon & Bond, 2013). 55 Two phocid species are known for the Miocene of Argentina, Properiptychus 56 argentinus (Ameghino, 1893) and Kawas benegasorum Cozzuol, 2001. The holotype of P. 57 argentinus is a right maxilla from the Paraná Formation, Entre Ríos Province, originally 58 described by Ameghino (1893) as a condylarth, but posteriorly assigned to Monachinae 59 (Muizon and Bond,1982; see also Rule et al., 2020a,b). Additional specimens include teeth 60 and isolated postcranial elements (Muizon & Bond, 1982; Soibelzon & Bond, 2013). 61 Kawas benegasorum is only known by the holotype, a partially articulated skeleton from 62 the Puerto Madryn Formation, but no parts of the skull are known for this species, except 63 for three isolated teeth (Cozzuol, 2001). This taxon was described initially as a Phocinae 64 (Cozzuol, 2001) but this phylogenetic interpretation was later discussed (Koretsky and 65 Domning, 2014). Recent phylogenetic analyses placed Kawas as a stem Phocinae (Berta et 66 al., 2018; Dewaele et al., 2018a) or related to Devinophoca Koretsky & Holec, 2002 (Rule 67 et al., 2020b). 68 In this contribution, we describe a dentary fragment attributed to a phocid from the 69 Puerto Madryn Formation, late Miocene of Valdés Peninsula, Chubut, Argentina (Figs. 1– 70 2). Despite its fragmentary nature, the scarce fossil record of Pinnipedia in the South 71 Eastern Atlantic coast makes the present record noteworthy. This dentary is the second 72 report of a phocid in the Miocene of Patagonia. 20 73 Institutional Abbreviations. MACN, Museo Argentino de Ciencias Naturales “Bernardino 74 Rivadavia”, Ciudad Autónoma de Buenos Aires, Argentina (A, Colección Ameghino, Pv, 75 Colección Paleontología de Vertebrados, MA, Colección Mastozoología); MEF, Museo 76 Paleontológico “Egidio Feruglio”, Trelew, Chubut, Argentina; MASP, Museo de Ciencias 77 Naturales y Antropológicas “Prof. Antonio Serrano” (ex Museo de Entre Ríos), Paraná, 78 Entre Ríos, Argentina. 79 Specimens used for comparisons. MACN-A 11593 (holotype of Properiptychus 80 argentinus); MACN-Pv 3538 (Properiptychus argentinus); MASP 685 (Phocidae indet.); 81 MEF-PV 601 (Kawas benegasorum); MACN-Ma 13.26 (Mirounga leonina); MACN-Ma 82 20435 (Hydrurga leptonyx); MACN-Ma 20628 (Leptonychotes weddellii); MACN-Ma 83 19.20 (Lobodon carcinophaga); MACN-Ma 48.259 (Ommatophoca rossii). 84 85 SYSTEMATIC PALEONTOLOGY 86 Order CARNIVORA Bowdich, 1821 87 Suborder PINNIPEDIA Illiger, 1811 88 Superfamily PHOCOIDEA Gray, 1825 89 Family PHOCIDAE Gray, 1821 90 Phocidae gen. et sp. indet. 91 Fig. 2.1–2.3 92 Referred material. MACN-Pv 20064, a fragment of an edentulous right dentary (Fig. 2.1– 2.3). 93 2.3). 94 Geographic occurrence. MACN-Pv 20064 was collected from the cliffs southeast of 95 Puerto Pirámides, Valdés Peninsula, Patagonia, Argentina. 20 96 Stratigraphic occurrence. MACN-Pv 20064 comes from the upper levels of the Puerto 97 Madryn Formation (Fig. 1). This unit is formed by 150 meters of intercalation of coquinas, 98 tuffs, limestones, sandstones, and heterolithic sandstones. A regressive phase is recognized 99 towards the top of the sequence (del Río et al., 2001). A late Miocene age was proposed 100 based on microfossils (Malumián & Masiuk, 1973; Masiuk et al., 1976; Malumián, 1978) 101 and supported by vertebrates (Dozo et al., 2010) and mollusks (del Río, 1990). Also, early 102 late Miocene radiometric ages were determined close to the top (10 ± 0.3 Ma; Scasso et al., 103 2001) or at the top (9.41 Ma; Zinsmeister et al., 1981) of the unit. Sedimentation of the 104 Puerto Madryn Formation corresponds to a marine transgression informally known as the 105 “Entrerriense” Transgression (see Cuitiño et al., 2017 for stratigraphic description and 106 palaeoenvironmental reconstruction). 107 The Puerto Pirámides stratigraphic section of the Puerto Madryn Formation exposes 108 northeast of the Golfo Nuevo and 2 km east from the homonym locality. It is formed by 50 109 meters of sandstones, tuffaceous sandstones, and limestones, with cross-bedded 110 stratification and ondulites. These deposits correspond to a closed marine environment 111 dominated by tidal regimes in normal marine conditions (del Río et al., 2001). Fossil 112 vertebrates remains are well-preserved and usually disarticulated, and they are mainly 113 cetacean fragments, such as balaenids, neobalaenines, balaenopterids, and ziphiids (Cuitiño 114 et al. 2017). Fossil invertebrates include significant accumulations of the echinoid 115 Monophoraster darwini (Desor, 1847), abundant oysters, the pectinid ‘Aequipecten’ 116 paranensis (d’Orbigny, 1842), and the brachiopod Pachymagas piramidesia (Ihering, 117 1903). The horizon where the Patagonian Phocinae K. benegasorum (MEF-Pv 601, Punta 118 San Román, north of the Valdés Peninsula) was collected (Cozzuol, 2001) correlates with 20 119 the level where MACN-Pv 20064 was found. 120 Description. MACN-Pv 20064 is an incomplete right dentary (Fig. 2.1–2.3), preserving the 121 medial portion of the body, with the alveoli for p3, p4, and m1. The body is low and 122 narrow, and it widens anteriorly. The mandibular canal is visible in anterior and posterior 123 views. The lingual and labial surfaces on the dentary are smooth. The symphysis and 124 masseteric fossa are not preserved (Fig. 2.1–2.3). 125 In occlusal view (Fig. 2.1), the margins of the dentary are sub-parallel. MACN-Pv 126 20064 has six well-defined alveoli corresponding to three birradiculated postcanine teeth 127 (p3, p4, and m1), with a rounded outline for alveoli of p3 and p4, and slightly oval for m1, 128 which is longer than wide. Alveoli are placed in a straight line and are nearly similar in 129 size. In labial view (Fig. 2.2), MACN-Pv 20064 presents a smooth surface and a concave 130 area at the level of p4, where the texture of the bone becomes slightly porous. There are 131 two mental foramina, opening in a common depression, located ventral to the position of 132 the interalveolar septum of p3 (Fig. 2.2). This position is almost identical to that of the 133 posteriormost mental foramina of Piscophoca sp. (Walsh & Naish, 2002) and a Phocidae 134 indet. of the Pliocene of Australia (Fitzgerald, 2005). Measurements are provided in Table 1. 135 1. 136 The concavity observed at the level of the p4 in labial and occlusal views could be 137 consistent with a pathology. The alveoli of p4 are damaged, but they remain open.