Hyaenodontidae, Leidy, 1869

Peigné, Stéphane, Morlo, Michael, Chaimanee, Yaowalak, Ducrocq, Stéphane, Tun, Soe Thura & Jaeger, Jean-Jacques, 2007, New discoveries of hyaenodontids (Creodonta, Mammalia) from the Pondaung Formation, middle Eocene, Myanmar - paleobiogeographic implications, Geodiversitas 29 (3), pp. 441-458 : 452-454

Hyaenodontidae sp. indet.

REFERRED MATERIAL. — From Thamingyauk:NMM Tmk- 500 (isolated subcomplete right M3, Fig. 2L, M ).

DISTRIBUTION AND AGE.  Pondaung Formation, Myanmar (see Fig. 1 ); late middle Eocene.

DESCRIPTION

The tooth is complete except for the mesiolabial corner. It is large and transversely elongated. The parastylar wing, which develops transversely, is broken, but it is likely to be short. The paracone is slightly larger than the metacone, which is located roughly distally to it. Both cusps are separated by an

open V-shaped valley continuing by a small notch,

Creodonts from the Pondaung Formation, Myanmar

tor. See text for explanation.

Peigné S. et al.

and they are lingually flanked by a small conule. The metaconule is transversely more elongated than the paraconule, and it is located on the distal rim of the tooth, just lingual to the metacone from which it is separated by a small notch. The paraconule is located on the mesial rim of the preprotocrista. The trigon basin is wide and deep, especially distally. The protocone is a large, triangular transverselydeveloped cusp. The cingulum is poorly developed mesially to the paracone-paraconule and around the protocone; it is slightly more developed labially and on the parastylar shelf; it is completely absent at the level of the metacone-metaconule.

Measurements: M3 L = 9.5; W = 18.7.

COMPARISONS AND DISCUSSION

Although there is a great size difference between NMMTmk-500 and NMMTdg-801 (assigned here to K. lupina , see above) it is less than to the holotype of K. lupina . The great size of NMM Tmk-500 may therefore be insignificant. In addition to the size, however, proportional and morphological differences indicate that this specimen probably represents a different species. Compared to K. lupina, NMM Tmk-500 has a less reduced metacone compared to the paracone and, more or less correlatively, a lesser fusion between the bases of these cusps. It also possesses a shorter parastyle, and a greater length, resulting in part from a less reduced and more distally prominent metacone and from a more open angle (at the parastylar extremity) between the transverse mesial and the distolabial faces. Only the size is a significant difference of NMM Tmk-500 to Yarshea cruenta and Proviverrinae indet. from Pondaung. The distinction is even greater with Paratritemnodon . Besides a much larger size, NMM Tmk-500 differs in lacking a distal cingulum and in the retention of a metaconule, well developed metacone and protocone, and a postmetacrista.

Because we would need more material and a better knowledge of the morphological variations in these Asian creodonts, we refrain from naming this isolated tooth though it possibly represents a new species.If so, it would reveal an even richer creodont fauna from Pondaung than previously thought and would further support the significance of Pondaung

in the evolution of the Creodonta in Asia.

Figures

FIG. 2. — A-K, Kyawdawia lupina Egi et al., 2005 from Pondaung Formation,Myanmar.From Bahin:NMM Bhn-1040,right M1 in occlusal (A) and labial (B) views; from Thandaung: NMM Tdg-801, fragment of left M3 in distal (C) and occlusal (D) views; left M2 in occlusal (E), lingual (F) and labial (G) views; NMM Tdg-802, fragment of right P4 in labial (H) and occlusal (I) views; from Kyaukmagyi: NMM Kmi-500, fragment of right M2 in occlusal (J) and lingual (K) views; L, M, Hyaenodontidae indet. from Pondaung Formation, Myanmar.

FIG. 1. — Geographical map of the Pondaung area (Myanmar) showing the vertebrate fossil localities in the Pondaung Formation that have yielded creodont material; in these names, “Kyitchaung” means “locality” in Myanmar language: 1, Kyawdaw Kyitchaung (Kdw); 2, Thandaung Kyitchaung (Tdg); 3, Kyaukmagyi Kyitchaung (Kmi); 4, Lema Kyitchaung (Lma); 5, UCMP V83106; 6, fossiliferous site 2 km N of Thadut (Orienspterodon); 7, Paukkaung Kyitchaung (Pk 2); 8, Yarshe Kyitchaung (Yse); 9, Thamingyauk Kyitchaung (Tmk); 10, Pangan Kyitchaung (Pgn); 11, Taungnigyin Kyitchaung (= Pangan 2; Pgn 2); 12, Myinthagya Kyitchaung (Mta). Modified after Aung Naing Soe (2004).