Zeusdelphys complicatus Marshall, 1987

Carneiro, Leonardo M. & Oliveira, Édison Vicente, 2017, The Eocene South American metatherian Zeusdelphys complicatus is not a protodidelphid but a hatcheriform: Paleobiogeographic implications, Acta Palaeontologica Polonica 62 (3), pp. 497-507 : 499-500

Zeusdelphys complicatus Marshall, 1987

Fig. 1.

1987 Zeusdelphys complicatus sp. nov.; Marshall 1987: 124, fig. 45.

2011 Zeusdelphys complicatus Marshall, 1987 ; Oliveira and Goin 2011: 121, fig. 14.

Holotype: MCT 2830-M, M1 tooth.

Type locality: Municipality of São José de Itaboraí , Rio de Janeiro ,

Brazil ( Bergqvist et al. 2009).

Type horizon: Fresh water travertine deposits of Itaboraí Formation,

early Eocene, Itaboraian SALMA (ca. 53–50 Ma; Woodburne et al.

2014).

Material.— Holotype is the only known specimen.

Diagnosis.—Differs from other Metatheria in the following combination of characters: large, lingually shifted and centrally placed StC; pyramidal shape of StB and StD; presence of labial and lingual accessory crests of StB and StD; developed labial cingulum, oblique crest that separates the parastyle from the anterobasal cingulum; broad and well developed anterobasal cingulum; lingual border of the metacone markedly more lingual in position than the lingual edge of the paracone; presence of three large supernumerary cusps on the postmetacrista; reduced stylar shelf and postmetacrista; very compressed talon, and protocone not eccentric. Differs from Protodidelphidae and Glasbiidae in the absence of eccentric protocone, basal expansions of upper molars, the presence of pyramidal StB and StD, lingually shifted StC, and larger size of StC (Fig. 1).

Description. —The molar is 8.30 mm in length and 8.47 mm in width; it presents relatively low cusps, wrinkled enamel, pyramidal shape of StB and StD; concave mesial borders of StB and StD; StB and StD with labial and lingual accessory crests; bifurcated medium crest of StD; large and lingually shifted StC; developed StE; three well-developed accessory cusps on the postmetacrista; reduced postmetacrista; developed labial expansion; discontinuous centrocrista (premetacrista oblique oriented and postparacrista straight); pyramidal para- and metacone; paracone much smaller than the metacone; broad and mesially expanded anterobasal cingulum; compressed and relatively broad talon; reduced conules; not eccentric and mesiodistally expanded protocone.

Remarks.—When compared to most of Late Cretaceous and Paleogene metatherians, Zeusdelphys complicatus is more similar to Hatcheritherium alpha from the Late Cretaceous of USA than to any other metatherian, as both share the presence of three developed cusps on the postmetacrista, discontinuous centrocrista (i.e., the premetacrista is oblique oriented, while the postparacrista is straight), wide and mesially expanded anterobasal cingulum, compressed talon, large StC, and pyramidal shape of StB and StD.

Stratigraphic and geographic range. — Type locality and horizon only.

Fig. 2. Single most parsimonious tree found in the phylogenetic analysis. The metatherian lineages are identified by vertical bars. Numbers below the ramus indicate the Bremer Support.