Acdestis

Beck, Robin M. D., Voss, Robert S. & Jansa, Sharon A., 2022, Craniodental Morphology And Phylogeny Of Marsupials, Bulletin of the American Museum of Natural History 2022 (457), pp. 1-353 : 321-322

† Acdestis

SPECIES SCORED: † Acdestis maddeni , † A. owenii (type species), † A. spegazzinii.

GEOLOGICAL PROVENANCE OF SCORED SPECIMENS: “Nivel I–II” of the Río Rosario Local Fauna and Willajara locality, and “Nivel I” of the Quebrada Honda Local Fauna, both part of the Honda Group, Tarija Department, Bolivia († A. maddeni ); Santa Cruz Formation, Santa Cruz Province, Argentina († A. owenii and † A. spegazzinii).

AGE OF SCORED SPECIMENS: The Río Rosario and Quebrada Honda Local Faunas both belong to the Honda Group and are collectively estimated to span 12.5–13.0 Mya (late middle Miocene) based on radiometric and magnetostratigraphic data (MacFadden et al., 1990). The Santa Cruz Formation spans a maximum of 14–19 Mya (see † Stilotherium above).

ASSIGNED AGE RANGE: 19.000 –12.500 Mya.

REMARKS: Goin et al. (2003) described the fossil paucituberculatan † Acdestis maddeni based on a partial cranium (MNHN-Pal-Bol-V-004000) that includes a well-preserved basicranium, and an additional partial maxilla (MNHN-Pal-Bol- V-003689), both from middle Miocene (11.9– 15.4 Mya) deposits in southernmost Bolivia. We used this material to obtain most of the character scores for our † Acdestis terminal, but a number of dental characters (particularly those of the lower dentition, which is not preserved in known remains of † A. maddeni ) were scored from specimens of † A. owenii (the type species) and † A. spegazzinii, both of which are known from abundant albeit fragmentary dental material from the Santa Cruz Formation (Marshall, 1980; Bown and Fleagle, 1993; Rae et al., 1996; Abello, 2007; Engelman and Croft, 2016). Engelman and Croft (2016) concluded that † Acdestis owenii probably represents males, and the somewhat smaller and more gracile † A. spegazzinii represents females, of a single taxon (for which the name † A. owenii would have priority), but this inference was disputed by Abello et al. (2020: supplemental material).

† Acdestis is currently classified as a member of the family † Palaeothentidae , within the superfamily †Palaeothentoidea (Abello, 2007, 2013; Goin et al., 2009a; Rincón et al., 2015; Engelman et al., 2016; Abello et al., 2020).