Herpetotherium

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 : 313

† Herpetotherium

SPECIES SCORED: † Herpetotherium fugax (type species), † H. cf. fugax .

GEOLOGICAL PROVENANCE OF SCORED SPECIMENS: White River Formation, Wyoming.

AGE OF SCORED SPECIMENS: All examined specimens come from the Orellan North American Land Mammal Age, which is currently estimated as spanning from 33.9 to 32.0 Mya (Prothero and Emry, 2004; Zanazzi et al., 2009).

ASSIGNED AGE RANGE: 33.900 –32.000 Mya.

REMARKS: † Herpetotherium fugax is known from numerous specimens from the White River Formation, including well-preserved skulls and associated postcranial material (Gabbert, 1998; Sánchez-Villagra et al., 2007; Horovitz et al., 2008). Sánchez-Villagra et al. (2007) included † Herpetotherium in a comprehensive morphological phylogenetic analysis of marsupials and relatives, and found that this taxon fell outside (crown-clade) Marsupialia . Most subsequent morphological and total-evidence analyses have found a similar result, in which † Herpetotherium either falls outside Marsupialia or is not unambiguously a member of this clade (Beck et al., 2008, 2014, 2016; Horovitz et al., 2008, 2009; Beck, 2012, 2017b; Forasiepi et al., 2014a; Suarez et al., 2015; Lorente et al., 2016; Carneiro and Oliveira, 2017a, 2017b; Maga and Beck, 2017; Carneiro, 2018, 2019; Carneiro et al., 2018; Engelman et al., 2020; Muizon et al., 2018; Abello and Candela, 2019; Rangel et al., 2019; Ladevèze et al., 2020; Muizon and Ladevèze, 2020; Zimicz and Goin, 2020). However, a few recent published phylogenetic analyses—namely, the morphological analyses of Forasiepi (2009: fig. 51), Engelman and Croft (2014: fig. 6), and Wilson et al. (2016: fig. 3), and the tip-and-node dated total evidence analysis of Maga and Beck (2017: fig. 39)—have found † Herpetotherium within Marsupialia , so some questions remain regarding its affinities.