A New Brontothere (Brontotheriidae, Perissodactyla, Mammalia) from the Eocene of the Ily Basin of Kazakstan and a Phylogeny of Asian “Horned” Brontotheres

Abstract

A new genus and species of ''horned'' brontothere, Aktautitan hippopotamopus, from the Ily Basin of Kazakstan is described from three skulls and nearly complete postcranial material. This material occurs in fluvio-lacustrine red beds of the upper part of the Eocene (Irdinmanhan) Kyzylbulak Formation at Aktau Mountain. Trackways occurring in the overlying layers are also attributed to this new brontothere. Additionally, several misleading problems in the taxonomy of Asian horned brontotheres are addressed. We conclude that Protitan khaitshinus Yanovskaya, 1980 is a junior objective synonym of Metatitan relictus Granger and Gregory, 1943. Protitan reshetovi Yanovskaya, 1980

Towards interactive global paleogeographic maps, new reconstructions at 60, 40 and 20 Ma

“…Although some paleogeographic maps have suggested that the Turgai Strait was closed at 40 Ma (www.deepmaptimes.com;Blakey, 2008), and terrestrial fossils are (mis? )placed in the strait at this time (Mihlbachler et al, 2004;www.paleobiodb.org). Geological data show three major sea transgressions in the proto-Paratethys in the Paleogene (Bosboom et al, 2017(Bosboom et al, , 2014b(Bosboom et al, , 2014aKaya et al, 2019).…”

A small-bodied species of Brontotheriidae from the middle Eocene Nut Beds of the Clarno Formation, John Day Basin, Oregon

“…The following diagnosis, description, and phylogenetic analysis of the Nut Beds brontothere follow methods used for other brontotheriids in Mihlbachler (2007, 2008, 2011), Mihlbachler and Deméré (2009, 2010), and Mihlbachler et al (2004a). To maintain equivalency with the taxonomy in these works, the delimitation of this new species is based on the phylogenetic species concept where species are partitioned into the smallest diagnosable clusters of specimens (Cracraft, 1989; Nixon and Wheeler, 1990; Wheeler and Platnick, 2000) using a form of population aggregation analysis (Davis and Nixon, 1992; Sites and Marshall, 2004), modified for dealing with fossil samples rather than extant populations (Mihlbachler, 2008).…”

“…The present matrix consists of 239 character states distributed among 92 characters, and 57 taxa including two outgroups, “ Hyracotherium” (= Xenocohippus osborni sensu Froehlich, 2002), Pachynolophus livinierensis Savage, Russell, and Louis, 1965. Also included are two early brontotherioids Danjiangia pingi Wang, 1995, and Lambdotherium popoagicum Cope, 1880, and 53 brontotheriids, including every known member of Brontotheriidae that produce non-equivalent combinations of character data (Mihlbachler, 2007, 2008, 2011; Mihlbachler et al, 2004a, b; Mihlbachler and Deméré, 2009, 2010) (Supplementary Data, Table 1S). All brontotheres were included in the analysis at the species level, except Palaeosyops , which was included as a genus due to ambiguities in species-level taxonomy (Gunnell and Yarbrough, 2000; Mihlbachler, 2008; Mader, 2009).…”

Linking Sexual Dimorphism and Sociality in Rhinoceroses: Insights from Teleoceras proterum and Aphelops malachorhinus from the Late Miocene of Florida

“…Previously, the shortened limbs of these taxa were presumed to indicate a semiaquatic lifestyle (e.g., Wall & Heinbaugh 1999). However, Mihlbachler (2001a) and Mihlbachler et al (2004b) argued, from a biomechanical perspective, that the shortened limbs of extinct hippo-like ungulates, including Teleoceras, are not clearly indicative of an aquatic lifestyle. An alternative hypothesis put forth by W. D. Matthew (1932), that the shortened limbs may have had more to do with open terrain and grazing habits, is equally plausible and has not been adequately tested.…”