Propalaeoryx Stromer 1926 (Ruminantia, Pecora, Giraffomorpha) revisited: systematics and phylogeny of an African palaeomerycoid 1Israel M. SÁNCHEZ, 2Jorge MORALES, 3Juan López CANTALAPIEDRA, 4Victoria QUIRALTE & 5Martin PICKFORD 1Institut Català de Paleontologia Miquel Crusafont, Universitat Autònoma de Barcelona, Edifici ICTA- ICP, c/ Columnes s/n, Campus de la UAB, 08193 Cerdanyola del Vallès, Barcelona, Spain, (e-mail : [email protected]). 2Departamento de Paleobiología, Museo Nacional de Ciencias Naturales–CSIC, C/ José Gutiérrez Abascal, 2, 28006 Madrid, Spain, (e-mail : [email protected]). 3Departamento de Ciencias de la Vida, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain, (e-mail:[email protected]). 4Museo Geominero (IGME), C/ Ríos Rosas, 23. 28003, Madrid (España), (e-mail : [email protected]). 5 Sorbonne Universités (CR2P, MNHN, CNRS, UPMC - Paris VI) 8, rue Buffon, 75005, Paris, France, (e-mail : [email protected]). Abstract : We describe new mandibular and dental material of Propalaeoryx stromeri from Langental (early Miocene, Sperrgebiet, Namibia), and re-describe the cranial anatomy of this genus of African giraffomorphs. The occipital and nuchal anatomy of the two Propalaeoryx species are described and emended differential diagnoses are presented. Several cranial and postcranial characters are crucial for understanding the position of Propalaeoryx as a basal member of the Palaeomerycoidea within the Giraffomorpha. We define the clade Palaeomerycoidea as the least inclusive clade of giraffomorphs containing Triceromeryx and Propalaeoryx . Finally, the phylogenetic position of Propalaeoryx unveils a putative early African-Eurasian vicariance event among basal palaeomerycoids that probably took place around the Oligo-Miocene boundary, a time when other ruminant lineages were also splitting. Key Words : Ruminants; Early Miocene; Namibia; Sperrgebiet; Evolution; Phylogeny. To cite this paper : Sánchez, I. Morales, J. Cantalapiedra, J.L. Quiralte, V. & Pickford, M. 2018. Propalaeoryx Stromer 1926 (Ruminantia, Pecora, Giraffomorpha) revisited: systematics and phylogeny of an African palaeomerycoid. Communications of the Geological Survey of Namibia . 19, 123-131. Introduction Propalaeoryx (Fig. 1) is a genus of austroafricanus and to a new species P. African pecorans first described by Stromer stromeri , which differed from the former in (1926) on the basis of dental and being more microdont (smaller teeth and postcranial material from Elisabethfeld larger postcranial skeleton) and with a more (early Miocene, Sperrgebiet). Stromer noted derived lower dentition (flatter cuspids, the morphological differences between higher crowns, less developed stylids) Propalaeoryx and extinct and extant besides another characters (Morales et al . ruminants, but he did not elaborate a clear 2008). The authors also described much of hypothesis of relationship with any of them. the postcranial skeleton of Propalaeoryx He described Propalaeoryx as a ruminant as highlighting several characters in the large as a fallow deer ( Dama dama ) with navicular-cuboid in the tarsus that later premolar series as long as the molar series proved relevant for resolving pecoran and wrinkled enamel in the lower molars phylogeny at a large-clade level (see (Stromer, 1926). On the basis of new Sánchez et al . 2015). Morales et al . (2008) material collected in the Sperrgebiet by the referred to Propalaeoryx as a probably Namibia Palaeontology Expeditions, hornless pecoran (no cranial appendages or Morales et al . (2008) described abundant frontal bone fragments have been found) material attributed to the type species P. with large sabre-like upper canines in the 123 males. These canines are of the moschid- Sánchez et al . (2015) recovered type a very conspicuous morphology Propalaeoryx as the sister-group of the among pecorans (Sánchez et al . 2010a). Palaeomerycidae within the Giraffomorpha Morales et al . (2008) attributed Propalae- as the basal offshoot of the Palaeo- oryx to the Climacoceratidae, a Miocene merycoidea, thus rejecting the climaco- African group of giraffoids also including ceratid hypothesis and offering a new and forms such as Orangemeryx and Climaco- more complex evolutionary scenario for the ceras . However, they did not offer a large clade of pecorans of which giraffes phylogenetic analysis. Recently, the total- (Giraffa and Okapia ) are the only living evidence tip-dating phylogenetic analysis of representatives. Figure 1. Reconstruction of an adult male of Propalaeoryx stromeri . Illustration by Israel M. Sánchez. In this paper we aim a) to describe new cranial and postcranial morphological Propalaeoryx austroafricanus material characters that unite Propalaeoryx with the from Langental, b) to describe new cranial Palaeomerycidae and d) to discuss the characters that differentiate the two species evolutionary hypotheses derived from the of Propalaeoryx , offering emended phylogenetic position of Propalaeoryx as diagnoses in detail, c) to describe both the published by Sánchez et al . (2015). Material and methods Material . In this work we studied (2000) - English version in Sánchez & Propalaeoryx austroafricanus mandibular Morales (2008) - has been followed for and cranial material from Elisabethfeld and nomenclature of the dentition. P. stromeri cranial material from Langental. Abbreviations . EF - Elisabethfeld; LT - These fossils are curated by the Geological Langental; GSN - Geological Survey of Survey of Namibia (Windhoek, Namibia) Namibia; MNCN-CSIC - Museo Nacional and are currently on study loan in the de Ciencias Naturales-CSIC (Madrid, MNCN-CSIC (Madrid, Spain). Spain). Nomenclature . Postcranial anatomical terms are based on Barone (1999). Azanza 124 Systematic Palaeontology Ruminantia Scopoli, 1777 Giraffomorpha Sánchez, Cantalapiedra, Ríos, Quiralte & Morales, 2015 Palaeomerycoidea Ríos, Sánchez & Morales, 2017 Genus Propalaeoryx Stromer, 1926 Emended diagnosis .- Palaeomerycoid metatarsal sulcus; small metatarsal giraffomorph with deep rectilinear groove tuberosity; semicircular P4/ with flat cones; behind the temporal fossa; enlarged upper lower molars with flattened cuspids, canines of moschid-type in males; presence especially the lingual ones. Based on of lateral notch in the facet for the Sánchez et al . (2015). semilunate in the radius; distally closed Type species .- Propalaeoryx austroafricanus Stromer, 1926 Additional species in the genus .- Propalaeoryx stromeri Morales, Soria & Pickford, 2008 Species Propalaeoryx austroafricanus Stromer, 1926 Emended diagnosis .- Propalaeoryx with osities anterior to the occipital condyles; ventrally narrowed foramen magnum that presence of deep lateral fossettes over the displays an almost closed state; slightly occipital condyles in the nuchal plane. developed posterior basioccipital tuber- Description We restudied the cranial (occipital) surface of the condyles. In the outer surface fragment GSN EF 34’01, which shows the fusion is not complete and a relatively some important, and so far undescribed, wide canal appears (see Fig. 2, I). In features. The most conspicuous character is addition to this, the nuchal plane in the presence of a ventrally closed foramen Propalaeoryx austroafricanus is more magnum similar to that observed in the convex than in P. stromeri , and a pair of Prolibytheriidae (see e.g. Danowitz et al . well-developed fossettes is present over 2016). However, in contrast to the each occipital condyle. Finally, the Prolibytherium condition, the fusion in P. posterior basioccipital tubercles are austroafricanus only affects the inner relatively weak (Fig. 2, H-I). Species Propalaeoryx stromeri Morales, Soria & Pickford, 2008 New material .- GSN LT 37’08 + LT 47’06, right hemi-mandible with p/2-m/3 (Fig. 2, A-C). Emended diagnosis .- In Morales et al . osities anterior to the occipital condyles; (2008) plus: loss of p/1; ventrally wide presence of shallow, weakly expressed foramen magnum with open U-shaped lateral fossettes over the occipital condyles morphology; strongly developed and in the nuchal plane. quadrangular posterior basioccipital tuber- Differential diagnosis .- Differs from the ventrally open foramen magnum; stronger type species of the genus in the characters and quadrangular-shaped posterior basi- listed by Morales et al . (2008) plus: more occipital tuberosities; lack of deep fossettes 125 over the occipital condyles in the nuchal plane. Description We here describe a new hemi-mandible describe the occipital fragment GSN LT (GSN LT 37’08 + LT 47’06; Fig. 2, A-C) 194’96a (Fig. 2, D-G). with the complete lower tooth series and re- Figure 2. A, Propalaeoryx stromeri GSN LT 37’08 + LT 47’06, right hemi-mandible with p/2-m/3 in buccal view; B, Propalaeoryx stromeri GSN LT 37’08 + LT 47’06, right hemi-mandible with p/2-m/3 in lingual view; C, Propalaeoryx stromeri GSN LT 37’08 + LT 47’06, right hemi-mandible with p/2-m/3 in occlusal view; D, Propalaeoryx stromeri GSN LT 194’96a, skull fragment, in left lateral view; E, Propalaeoryx stromeri GSN LT 194’96a, skull fragment, in right lateral view; F, Propalaeoryx stromeri LT 194’96a, skull fragment, in caudal view; G, Propalaeoryx stromeri GSN LT 194’96a, skull fragment, in ventral view; H, Propalaeoryx austroafricanus GSN EF 34’01, skull fragment, in caudal view; I, Propalaeoryx austroafricanus GSN EF 34’01, skull fragment, in ventral view. Abbreviation : OGr, Occipital groove. Mandible and adult lower dentition . As is lingual cristid that almost closes the medial