Division of Paleontology, American Museum of Natural History, New York, NY 10024, USADepartment of Pathology and Anatomical Sciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14214, USA
Cladistic positions of ‘Miacis’ australis and ‘Miacis’ cognitus. Strict consensus of 27 most-parsimonious trees. Branches are labelled with Bremer support values followed by bootstrap support values (‘<’ for less than 50% support). See text and appendix C for apomorphies associated with labelled nodes.
Craniodental morphology of Gustafsonia cognita, gen. et comb. nov. (a) left P3-M2 of cast of holotype TMM 40209-200 in occlusal view; (b) same in oblique lingual view; (c) digital three-dimensional reconstruction (see text) of holotype cranium in ventral view, showing locations of basicranial embayment (blue) for inferior petrosal sinuses; (d) left basicranial morphology, magnified from boxed area in (c) and indicating position of coronal section no. 832 figured in (f); (e) external ventral view of left basicranial region (cast of holotype; basioccipital embayment is invisible, and its approximate medial extent is marked by dashed line); (f) coronal section no. 832 from Digital Morphology Library (see text) showing cross-section through the left auditory region of holotype (ventral to top; lateral to right). Panels (c,d,f) produced with permission from the University of Texas HRXCT Facility. Abbreviations: as, alisphenoid; be, basioccipital embayment for inferior petrosal sinus; bs, basisphenoid; cf, condyloid foramen; cica, canal (dotted line) for anterior loop of internal carotid artery; dbo, dorsal lip of basioccipital; er, epitympanic recess; fc, fenestra cochlea; fs, fossa for stapedius muscle; Gf, Glaserian fissure; mlf, middle lacerate foramen; mp, mastoid process; mt, mastoid tubercle; oc, occipital condyle; pgf, postglenoid fossa; plf, posterior lacerate foramen; pr, petrosal promontorium; vbo, ventral floor of basioccipital.
Upper dentition of Angelarctocyon australis, gen. et comb. nov. (holotype FMNH PM 423). (a) Block of matrix containing right and left maxillae (stereo pair in occlusal view; note anteroposteriorly rotated right maxilla); (b) left facial region in lateral view (anterior to top); (c) left P4–M2 in occlusal view (shaded areas of line drawing indicating damaged surfaces; black lines represent original borders); (d) same in oblique posterior view; (e) right P4–M2 (inverted; white triangle points to minimum posterior extent of maxilla). Same scale bar applies to a and b, and c–e. Abbreviations: apa, apex of paracone; iof, infraorbital foramen; lc, lingual portion of lingual cingulum; mcl, metaconule; pcl, paraconule; psr, parastylar ridge; rlw, broken piece of rotated labial wall.
Lower dentition of Angelarctocyon australis, gen. et comb. nov. (holotype FMNH PM 423). (a) Right dentary in lateral view; (b) left m1 and alveoli for m2–3 in occlusal view (inverted); (c) right p3–m2 in occlusal view; (d) same (inverted) in labial view; (e) same in lingual view. Abbreviations: ecld, vestigial entoconulid; end, entoconid; mf, mental foramina; pac, posterior accessory cuspulid; pmc, broken piece of main cuspid originally described as ‘metaconid’ (, p. 45). Same scale bar applies to (b–e).
Illustration of character AC1. Form of lingual cingulum (extent demarcated by black lines) was assessed immediately lingual to protocone apex along a labiolingual line (vertical white dashed line) perpendicular to the anteroposterior line running across paracone and metacone (horizontal white dashed line). (a) ‘Miacis’ cf. ‘M.’ sylvestris (inverted RM1 of FMNH PM 55953, cast of AMNH FM 129284) showing State 0 (band-like cingulum); (b) Lycophocyon hutchisoni (inverted RM1 of UCMP 170713) showing State 0 (cingulum nearly confluent with lingual base of protocone and poorly defined, even though it is posterolingually expansive); (c) Daphoenus sp. (FMNH PM 8694) showing State 1 (inflated and lingually elongate lingual cingulum); (d) Angelarctocyon australis gen. et comb. nov. (FMNH PM 423) showing State 1 (border between protocone and lingual cingulum is poorly defined, but the latter is clearly elongate in lingual direction); (e) Zodiolestes daimonelixensis (FMNH P 12032) showing State 2 (moderately inflated cingulum lacking sharp lingual edge unlike in amphicyonids).
Illustration of Character AC7. (a) Tapocyon robustus (SDSNH 36000), showing State 0 (trenchant posterior basal cuspulid (pbc) is well developed, but posterior accessory cuspulid (as a structure on the posterior slope of main cuspid) is deemed absent); (b) Hesperocyon gregarius (FMNH PM 1476), showing State 1 (posterior accessory cuspulid (pac) blade-like with parabolic outline in profile; arrow points to prominent notch); (c) Angelarctocyon australis gen. et comb. nov. (FMNH PM 423) showing State 2 (small posterior accessory cuspulid with very small notch and steeply descending posterior slope, giving it a step-like appearance in profile); (d) Daphoenus hartshornianus (FMNH UM 743, inverted) showing State 2 (posterior accessory cuspulid more bulbous than blade-like, with a small notch and monotonically descending, step-like (though somewhat rounded) outline in profile). All in labial view.
Illustration of Character AC10. Width (x) of basicranium lateral to lateral edge of basioccipital ventral floor compared with width (y) of basioccipital ventral floor at the level of external auditory meatus. (a) State 0 (y = 0.71x < x) in ‘Miacis’ cf. ‘M.’ sylvestris (FMNH PM 55953, cast of AMNH FM 129284); (b) State 1 (y = 1.29x > x) in Daphoenus vetus (FMNH PM 8388).
aTaxonomic composition of the amphicyonid clade (as recovered in the consensus tree from the unconstrained search; figure 1)—but not its internal topology—was held constant across all constrained searches.
AMNH FM 105003 (cast of holotype YPM 11861), AMNH FM 11499
AMNH FM 12626 (holotype)
AMNH FM 11500, USNM 214706
AMNH FM 143785 (cast of holotype CM 11900), AMNH FM 104960 (cast of CM 12063)
FMNH PM 538 (T. cf. T. robustus), FMNH PM 22735
UCMP 63172, UCMP 79947 (cast of MNHN F.QU8755)
FMNH P 12004
 (nimravid general)
FMNH UM 420, FMNH UM 474
 (nimravid general)
UCMP 118323, AMNH FM 101931 (cast of holotype MNHN SG3509)
FMNH PM 423 (holotype)
TMM 40209-200 (cast of holotype)
C. sp.a: AMNH FM 10060, UCMP 63170, UCMP 63171, UCMP 63173, UCMP 63175
[3,116] (NMB QV 412)
C. lacustris: AMNH FM 10056, UCMP 62709, UCMP 63054, YPM PU 10614
AMNH FM 39099 (holotype), F:AM 72513, AMNH FM 80223