FIGURE 1. Maps of Kyrgyzstan showing the location of Ortok and important topographical structures. A, Google Earth imagery (accessed May 2018) of the Kochkor and Issyk Kul Basins showing major basins, main bodies of water, Tien Shan mountains, and major fault lines for Kyrgyzstan. The Tien Shan mountains run roughly east to west, leaving high altitude basins infilled with Cenozoic sediments between each sub range. The Kochkor Basin is roughly 80 km long and 24 km wide. Map data: Google, Mapabc.com. Scale equals 96 km; B, additional zoomed in map of Kochkor Basin with fossil localities. Furthest left star is the Ortok site, other fossil collections are from both Tarasov (1970) and McLaughlin (2018). Map data: Google, Digital Globe. Scale equals 16.2 km; C, zoomed in Google Earth map of Kochkor Basin showing main body of water and topographic features. Likely, the Kochkor Basin was connected to the Issyk Kul Basin (the large lake in the figure) until geologically very recently, as shown by the low hills dividing the two basins. Map data: Google, Landsat Copernicus. Scale equals 65 km; D, Google Earth imagery of the Ortok. Base of measured stratigraphic and paleomagnetostratigraphic section (see McLaughlin, 2018) marked with a blue star. Fossiliferous outcrop extends to east and north of the star in the pale tan exposure. To the east, a gorge cut into reddish Paleozoic granite with the thin layer of Chu unconformably resting on it. Strata at Ortok are dipping very gently to the north and are the least deformed structurally of any site included in this study. Additionally, the fossils are the least diagenically altered, indicating little to no diagenic alteration to the site as well. Map data: Google, Digital Globe. Map Scale equals 300 m.
FIGURE 2. Stratigraphy, sediment and partially reconstructed fossil from Ortok site. A, Schematic and generalized stratigraphic column for the Cenozoic formations outcropping in the Kochkor Basin. Relative average grainsize is indicated by the X axis, while stratigraphic position is related on the Y axis; B, specimen UOMNH F-70508 in situ prior to removal by W.N.F. McLaughlin to demonstrate fossil completeness and surrounding matrix. Scale bar equals 10 cm; C, cleaned and reconstructed UOMNH F-70508. Note: some diagnostic features were damaged and lost during preparation; see Figure 3 for complete specimen. Scale bar equals 5 cm.
FIGURE 3. Specimen UOMNH F-70508, Adcrocuta eximia, right partial mandible, pre-breakage and reconstruction. A, annotated line drawing of buccal view, demonstrating two mental foramina and partial preservation of masseteric fossa (light grey). Note alveolus of p1 anterior to p2; B, UOMNH F-70508 after excavation and preliminary reconstruction demonstrating diagnostic features. Abbreviations: aac, anterior accessory cusp; ap, angular process; cp, coronoid process; mc, mandibular condyle; mf, masseteric fossa; mnf, mental foramina; pac, posterior accessory cusp; pad, paraconid; ptd, protoconid; tld, talonid. Scale bar equals 5 cm.
FIGURE 4. Isolated left P4 of UOMNH F-70508, Adcrocuta eximia. A, schematic of preserved features in occlusal view; B, occlusal view of specimen displaying minimal wear on metastylar blade; C, lingual view of specimen. Note reduced protocone that does not extend anterior to the anterior face of the parastyle. Scale bar equals 10 mm.
FIGURE 5. Specimen UOMNH F-70508, Adcrocuta eximia, in occlusal view with insets of morphological features discussed in text. A, occlusal schematic diagram of preserved dentition and p1 alveolus (arrow); B, occlusal view of m1 (anterior to the left) illustrating early stage wear on paraconid and protoconid, respectively; C, occlusal of preserved specimen; D, buccal view of p3 showing examples of transitional acute-angle Hunter-Schreger Bands. These are associated with robust hyaenines (Tseng, 2011); E, detail oblique lingual view of talonid of carnassial (m1) with reduced hypoconid and entoconid. Abbreviations: Encd, entoconid; Hypcd, hypoconid; Ptd, protoconid. Scale bar A and C, equals 5 cm, B, equals 5 mm, D, equals 20 mm, and E, equals 10 mm.
FIGURE 6. Annotated views of UOMNH F-70509, cf. Paramachaerodus . A, distal tip of canine, labial view; B, distal tip of canine, posterior view, note incipient crenulations on posterior edge (arrows); C, distal tip of canine, lingual view; D, schematic representation of preserved post-canine elements, not to common scale, inferred missing anatomy modified from Li and Spassov (2017); E, occlusal view of preserved left M1; F, anterior view of preserved left M1; G, occlusal view of preserved P4 paracone; H, lingual view of preserved P4 paracone; I, labial view of preserved P4 paracone; Abbreviations: cc, centrocrista; cn, carnassial notch; mt, metacone; pc, paracrista; *prt, flared portion of paracone cusp leading to protocone; ps, parastyle. Scale bar A-C, and G-I, equals 15 mm, E-F, equals 6 mm.
FIGURE 7. Time-scaled phylogeny of the Paramachaerodus genus and UOMNH F-70509’s placement within it. The depicted tree is a strict consensus of two most-parsimonious trees of score 32. Note the location of UOMNH F-70509 as unresolved relative to “Promegantereon” ogygia at the base of the genus even though it occurs much later in the rock record. Time-scaling was performed in R, version 3.6.1 (R Core Team, 2019) with the Strap package (Bell and Lloyd, 2014) using the “basic” method. Taxa ages derive from Li and Spassov (2017). The outgroup taxon Proailurus lemanensis has an Oligocene occurrence, not shown for clarity, but its basal position in our analysed taxa is depicted with dotted lines.