The tarsus ofUkhaatherium nessovi(Eutheria, Mammalia) from the Late Cretaceous of Mongolia: an appraisal of the evolution of the ankle in basal therians

The Eutherian Mammal Maelestes gobiensis from the Late Cretaceous of Mongolia and the phylogeny of cretaceous eutheria

“…The element in question is an astragalus, reminiscent of the astragalus of the asioryctithere Ukhaatherium (Horovitz, 2000), which has a dentary and humerus that are comparable in size to those of Maelestes: mandibular length in Ukhaatherium PSS-MAE 102 is 23.3 mm on the left and 23.8 mm on the right, and in Maelestes is 23.9 mm; and humeral length is 15.2 mm in the former (Horovitz, 2003) and 14.9 in the latter. In contrast, the astragalus in Ukhaatherium PSS-MAE 102 is 2.1 mm in length and 1.6 mm in width (Horovitz, 2000), whereas the astragalus that Wible et al (2007) referred to Maelestes is 3.8 mm by 3.65 mm. Despite the apparent close depositional association of the ''isolated'' astragalus and Maelestes, we no longer refer this element as part of the isotype, because of its large size and incongruence with the pedalmandibular proportions in the otherwise closely related Ukhaatherium.…”

“…Additional specimens have been collected by MAE and temporarily are housed at AMNH-VP, six of which have been reported, three from Tugrugeen Shireh, two from Bayn Dzak, and one from Zos Wash near Ukhaa Tolgod . Three specimens are fairly complete skulls and two also have nearly complete skeletons Horovitz et al, 1998;Horovitz, 2000). Nessov (1985b) named a lower jaw fragment with m2 from the Bissekty Formation of Uzbekistan (Turonian; Archibald and Averianov, 2005) as Zalambdalestes mynbulakensis Nessov, 1985b, but later Nessov et al (1994) considered this taxon a junior synonym of the mixotheridian Sorlestes budan Nessov, 1985a, which recently has been included in the zhelestid Zhelestes temirkazyk Nessov, 1985a (Archibald and .…”

“…The single species Ukhaatherium nessovi Novacek et al, 1997, is represented by eight specimens, all with skulls and six with skeletons currently housed at AMNH-VP Horovitz et al, 1998;Horovitz, 2000Horovitz, , 2003. Novacek et al (1997) erected Asioryctitheria to include K. gobiensis and the asioryctids A. nemegtensis and U. nessovi.…”

The Geology of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia)

“…Johnston et al (1996) discussed alleged vertebrate eggs that they identified as fossilized pupal chambers. Recent publications regarding the mammalian fauna include Horovitz (2000); Kielan-Jaworowska (1998); Kielan-Jaworowska et al (2000); Novacek et al (1997); Rougier et al (1996Rougier et al ( , 1997Rougier et al ( , 1998; Wible and Rougier (2000), and Wible et al (2004). In all, over 1,000 skulls, many with associated skeletons, of mammals, lizards, and dinosaurs have been identified.…”

Craniodental anatomy of a new late cretaceous multituberculate mammal from Udan Sayr, Mongolia.

“…The recent American-Mongolian expeditions (1990 to the present) have followed that tradition and results have been plentiful, including the discovery of one of the richest Mesozoic localities in the world, Ukhaa Tolgod (Norell et al, , 2001(Norell et al, , 2006Novacek et al, 1994;Dashzeveg et al, 1995Dashzeveg et al, , 2005Rougier et al, 1996aRougier et al, , 1998Gao and Hou, 1996;Chiappe et al, 1998;Norell, 1998, 2000;Makovicky and Norell, 1998;Horovitz, 2000;Wible and Rougier, 2000;Clarke et al, 2001;Clarke and Norell, 2002;Makovicky et al, 2003;Ksepka and Norell, 2004;Norell and Hwang, 2004;Pol and Norell, 2004;Andres and Norell, 2005;Joyce and Norell, 2005;Dingus et al, 2008;Minjin, 2008). The Cretaceous localities of Mongolia, especially those of the Djadochta and similarly aged Barun Goyot Formations (Shuvalov, 2000;Jerzykiewicz, 2000), are exceptionally rich in well-preserved small vertebrates when compared to those in other parts of the world.…”