Sungulusimias unayae Métais, Coster, Licht, Ocakoğlu & Beard, 2023, n. gen., n. sp.
Creators: name: Métais, Grégoire
name: Coster, Pauline
name: Licht, Alexis
name: Ocakoğlu, Faruk
name: Beard, K. Christopher
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Primates
Eosimiidae
Sungulusimias
Sungulusimias unayae

description: Sungulusimias unayae n. gen., n. sp.
(Fig. 3 A-C)
urn:lsid:zoobank.org:act: F21B9D32-30F3-4A64-B0C7-F89DDB9ED92C
TYPE MATERIAL. — Holotype. Sü-2021, isolated right m2, only known specimen.
DIAGNOSIS. — Differs from Eosimias Beard, Qi, Dawson, Wang & Li, 1994, Phenacopithecus Beard & Wang, 2004 and Bahinia Jaeger, Thein, Benammi, Chaimanee, Soe, Lwin, Tun, Wai & Ducrocq, 1999 in having m2 with protoconid and metaconid more closely spaced and of similar height and volume, paraconid more cuspidate and more nearly connate with metaconid, stronger mesiobuccal cingulid, and entoconid without strong connection to hypoconulid via the postcristid. Differs from Phileosimias Marivaux, Antoine, Hassan Baqri, Benammi, Chaimanee, Crochet, de Franceschi, Iqbal, Jaeger, Metais, Roohi & Welcomme, 2005 in having M 2 with paraconid fully lingual in position and hypoconulid distobuccal in position, being located closer to the hypoconid than the entoconid.
ETYMOLOGY. — Generic name from the village of Süngülü and the Latin simias (ape). Specific name in recognition of Prof. Engin Ünay, who discovered the type locality and helped collect the holotype and associated fauna from Süngülü.
TYPE LOCALITY. — Outcrop of unnamed rock unit consisting of c. 40 cm thick tuffite bed containing gastropod operculae superposed by c. 30 cm thick white silty limestone with silicified nodules exposed in a streambed roughly two km northwest of Süngülü, Ardahan Province, Turkey (de Bruijn et al. 2003: fig. 1). Latest Eocene according to de Bruijn et al. (2018, 2019).
DESCRIPTION
The holotype is an isolated right m2 (L = 3.0 mm; W = 2.4 mm). The crown is subrectangular in occlusal outline, although the trigonid is slightly narrower than the talonid. A relatively well-developed mesiobuccal cingulid extends from the base of the paraconid to the level of the hypoflexid. All three trigonid cusps are present, roughly similar in size, and distinctly cuspidate. The protoconid is situated internally rather than peripherally on the trigonid. As a result, the protoconid and metaconid are closely approximated. The metaconid is located slightly posterior to the level of the protoconid, and these two cusps are connected by a protocristid that runs somewhat obliquely with respect to the long axis of the tooth. A short but relatively trenchant paracristid arcs mesiolingually to connect the protoconid with the paraconid. The paraconid is fully lingual in position and almost connate with the metaconid. A short premetacristid fills the gap between the paraconid and metaconid. The postvallid is essentially vertical, separating the trigonid from the broader talonid. The hypoconid is the dominant talonid cusp, being situated near the distobuccal corner of the tooth. It gives rise to a straight, moderately trenchant cristid obliqua, which joins the postvallid near the lingual base of the protoconid. The hypoflexid is moderately deep but partly filled by the mesiobuccal cingulid. The lingual side of the talonid is marked by a relatively tall, isolated entoconid. A notch separates the lingual base of the postvallid from the entoconid, although a weak preentocristid is present. Distobuccally, the entoconid is not strongly connected to the hypoconulid by the postcristid. Instead, the hypoconulid projects slightly distally beyond the rest of the talonid and is more closely associated with the hypoconid than the entoconid.
COMPARISONS
Sü-2021 differs from primitive adapiform (e.g. Donrussellia Szalay, 1976)and omomyid primates (e.g. Teilhardina Simpson, 1940, Steinius Bown & Rose, 1984) in having the paraconid and metaconid of m2 closely approximated but not fully connate and in having an enlarged, distally expansive hypoconulid (Rose & Bown 1991). Most late early Eocene and younger adapiforms (adapids, notharctids, and sivaladapids) and stem lemuriforms (e.g. Djebelemur Hartenberger & Marandat, 1992) have reduced or completely lost the paraconid on m2 (Godinot 2014). Sivaladapid adapiforms (e.g. Yunnanadapis Ni, Li, Li & Beard, 2016, Laomaki Ni, Li, Li & Beard, 2016) retain a large hypoconulid on their lower molars, but this structure is invariably closely approximated with the entoconid in this clade, and it does not project distally beyond the rest of the talonid as it does in Sungulusimias (Ni et al. 2016). Anaptomorphine omomyids, best documented from the early and middle Eocene of North America, are much more bunodont than Sungulusimias and they never possess the enlarged, distally expansive molar hypoconulid found in the latter taxon (Godinot 2014). North American and Asian omomyines, including the middle Eocene Nesomomys Beard, Métais, Ocakoglu & Licht, 2020 from Balkanatolia (Beard et al. 2021), are typically less bunodont than their anaptomorphine relatives, but they differ from Sungulusimias in having lower molars with trigonids much narrower than talonids (e.g. Nesomomys, Hemiacodon Marsh, 1872) and much smaller, less bulbous hypoconulids (e.g. Shoshonius Granger, 1910, Mytonius Robinson, 1968). The European microchoerid radiation, which persisted on the Iberian Peninsula as recently as the early Oligocene (Köhler & Moyà-Solà 1999), differs from Sungulusimias in having reduced both paraconid and hypoconulid on m2, with certain taxa (e.g. Pseudoloris Stehlin, 1916) showing enhanced molar shearing related to insectivory and others (e.g. Microchoerus Wood, 1846) developing heavily crenulated enamel in relation to frugivorous adaptations (Godinot 2014).
The distinctive trigonid and hypoconulid morphology of Sü-2021 allows it to be identified as an eosimiid rather than any other anthropoid clade. Like eosimiids, and in contrast to other stem anthropoids, Sü-2021 retains a lingual, distinctly cuspidate paraconid on m2. Certain stem anthropoids from Africa (e.g. Biretia de Bonis, Jaeger, Coiffait & Coiffait, 1988, Proteopithecus Simons, 1989) sometimes retain small paraconids on m1, but these taxa rarely retain even vestigial paraconids on m2 and their overall molar morphology is more bunodont than that of Sungulusimias (Seiffert 2012). Among stem anthropoid taxa that are generally recognized as eosimiids, the trigonid morphology of Sü-2021 most closely resembles that of Phileosimias from the Oligocene of Pakistan (Marivaux et al. 2005), from which it differs in having a fully lingual paraconid.In other eosimiids (Eosimias, Phenacopithecus and Bahinia), the paraconid of m2 is typically less cuspidate and farther removed from the metaconid. The hypoconulid of Sü-2021 flares distobuccally, as it does in Eosimias and Phenacopithecus. In Bahinia, the talonids of m1-2 lack distinct hypoconulids. In Phileosimias and most early African anthropoids, the lower molar hypoconulids can be substantial and cuspidate, but they are located closer to the entoconid than the hypoconid, in contrast to the more central placement of the hypoconulid in Sungulusimias.
REMARKS
Sungulusimias is the first record of stem anthropoids in Anatolia and only the second example of Paleogene primates from there (Beard et al. 2021). Other eosimiids are known from China (Beard et al. 1994, 1996; Beard & Wang 2004; Ni et al. 2016), Myanmar (Jaeger et al. 1999) and Pakistan (Marivaux et al. 2005), so Sungulusimias is also the westernmost record of this group. Discovery of Anatolian eosimiids is not unexpected, given that eosimiids are well-documented from farther east along the Eurasian Neotethyan margin and that eosimiiforms colonized the African/Arabian Plate prior to its tectonic collision with Eurasia near the Oligocene-Miocene boundary (Chaimanee et al. 2012). However, Sungulusimias is apparently younger than the oldest known African anthropoids, which date to the late middle or early late Eocene (Seiffert et al. 2005; Jaeger et al. 2010; Marivaux et al. 2014). What role, if any, Sungulusimias and its collateral relatives may have played in the colonization of Africa by early anthropoids must await better understanding of its anatomy and phylogenetic relationships.
description: Published as part of Métais, Grégoire, Coster, Pauline, Licht, Alexis, Ocakoğlu, Faruk & Beard, K. Christopher, 2023, Additions to the late Eocene Süngülü mammal fauna in Easternmost Anatolia and the Eocene-Oligocene transition at the periphery of Balkanatolia, pp. 711-727 in Comptes Rendus Palevol 22 (35) on pages 718-719, DOI: 10.5852/cr-palevol2023v22a35, http://zenodo.org/record/10352022