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Two isolated metatarsals (III and IV) of theropod dinosaurs from the Bostobe Formation (Upper Cretaceous, Santonian–Campanian) of the Shakh-Shakh locality in Kazakhstan are assigned to the representatives of the families Caenagnathidae and Dromaeosauridae, respectively. The metatarsal III of Caena-gnathidae indet. confirms the presence of oviraptorosaurs in the dinosaur assemblage from the Bostobe Formation. This bone is very similar morphologically with the metatarsal III of Elmisaurus rarus Osmólska, 1981 from the Maastrichtian of Mongolia. The metatarsal IV of Dromaeosauridae indet. is characterized by a lateral crest, which among dromaeosaurids is known only for Velociraptor mongoliensis Osborn, 1924 from the Campanian of Mongolia. [ABSTRACT FROM AUTHOR]

Bayshinoryctes shuvalovi gen. et sp. nov. is based on a fragmentary skull including right maxilla associated with right and left dentaries with partially preserved dentition from the Upper Cretaceous (Turonian–Santonian) Bayinshire Formation at Bayshin Tsav locality in Gobi Desert, Mongolia. Undated Bayesian analyses of two different data matrices recover the new taxon as a stem placental mammal within the clade containing also Maelestes from the Upper Cretaceous (Campanian) of Mongolia and Batodon from the Upper Cretaceous (Maastrichtian) of North America. Bayshinoryctes gen. nov. differs from Maelestes by a few dental characters, including three-rooted P4, double-rooted p3, and p5 with metaconid swelling. [ABSTRACT FROM AUTHOR]

Khulsanurus magnificus gen. et sp. nov., is described based on a partial skeleton, including cervical and caudal vertebrae, scapulocoracoids, humerus, and pubis from the Late Cretaceous (Campanian) Barungoyot Formation at Khulsan locality in Gobi Desert, Mongolia. The new taxon differs from other alvarezsaurids by a combination of characters that include cervicals lacking pleurocoels, carotid processes, and epipophyses, dorsoventrally thick and subtriangular in cross-section transverse process of the anterior caudals, prominent infrapostzygapophyseal fossa on the transverse process of anterior caudals, short and mostly anteriorly directed prezygapophyses of anterior caudals, neural arch of anterior caudal lacking the interzygapophyseal ridges and having a prominent dorsal depression around the anterior end of the neural spine. The new taxon retains a number of plesiomorphic traits: slightly convex posterior centrum condyle of anterior caudals, prominent anterior, and posterior bumps at the neurocentral junction in anterior caudals, neural arch of anterior caudals extending for the entire length of the centrum, and pubic foot and apron. Khulsanurus shares with Shuvuuia the deltopectoral crest of humerus that is continuous with the humeral head. The phylogenetic analysis placed Khulsanurus in the Parvicursorinae in a polytomy with Mononykus, Shuvuuia, Albinykus, and Xixianykus. [ABSTRACT FROM AUTHOR]

Asiapator onchin gen. et sp. nov. is based on a dentary fragment from the middle Eocene (Irdinmanhan) Khaychin Formation at Khaychin Ula 3 locality, Mongolia. The preserved dentition includes di1 being replaced by i1, dp2 or p2, roots of dp4, and erupting p4. This is the first record of the Apatemyidae in Central Asia. The holotype of A. onchin provides the first direct evidence for dental replacement in the Apatemyidae, showing diphyodont first lower incisor and fourth lower premolar. Asiapator has only one lower incisor as in all apatemyids except Unuchinia from the Paleocene of North America. Asiapator is similar to Unuchinia and differs from more derived apatemyids in having a simple unmodified anterior premolar (dp2 or p2). Asiapator likely evolved from a North American immigrant. [ABSTRACT FROM AUTHOR]

A distal fragment of tibiotarsus from the Late Cretaceous Kansai locality (Yalovach Formation, Santonian) in Tajikistan was assigned to oviraptorosaurian theropods of the family Avimimidae by the fusion of the tibia and proximal tarsal bones into tibiotarsus, reduction of the fibula and fusion of its distal end with the lateral condyle of the tibiotarsus, and the presence of developed postfibular flange. The described specimen is almost identical to the tibiotarsus of Avimimus portentosus Kurzanov, 1981 from the Late Cretaceous of Mongolia and can be identified as Avimimus sp. It is one of the oldest finds of the family Avimimidae in the fossil record, approximately of the same age as an avimimid from the Iren Dabasu Formation in North China. [ABSTRACT FROM AUTHOR]

Tooth marks preserved on a dentary fragment of eutriconodontan Gobiconodon borissiaki Trofimov, 1978 from the Early Cretaceous Zuun-Höövör locality in northern Gobi Desert (Övörkhangai aimag, Mongolia) are described. It is most probably that these traces were left by incisors of the small gnawing mammals, namely multituberculates. This is the first finding of Cretaceous mammalian tooth marks in Asia and the earliest evidence of scavenging of multituberculates. [ABSTRACT FROM AUTHOR]

Parvicursor remotus Karhu & Rautian, 1996, based on a fragmentary skeleton from the Campanian Barungoyot Formation at Khulsan, in the Gobi Desert of Mongolia, is re-described in detail. Contrary to the original description, we find no evidence that the last dorsal vertebra is opisthocoelous. A biconvex last dorsal vertebra could be present in Parvicursor as in other parvicursorines. The transversely compressed sacral centrum with a sharp ventral keel is the last sacral, not the first sacral as originally alleged. The pelvic bones are not fused at the acetabulum. The holotype of P. remotus, the smallest known alvarezsaurid specimen, is a juvenile individual far from skeletal maturity. New morphological details of Parvicursor that are revealed include a ventral ridge on the posterior dorsal vertebrae; a horizontal supraacetabular crest of the ilium whose anterior end is placed anterior to the most ventrally projecting part of the pubic peduncle; the possible presence of a pubic obturator foramen; an entocondylar tuber on the femur; internal flexor flanges on metatarsals II and IV; a lateral flexor ridge on metatarsal IV; and a proximoventral notch on pedal phalanx IV-1. The Tugriken Shireh alvarezsaurid is not referable to Parvicursor because of its much larger ungual phalanx on the second pedal digit. Kol ghuva is excluded from Alzarezsauridae. The two successive sister taxa for Parvicursor are Ceratonykus and Linhenykus. Ceratonykus differs little from Parvicursor and might be a synonym of the latter. Linhenykus is very similar to Parvicursor in all overlapping skeletal elements. The Parvicursorinae includes all Asian Late Cretaceous alvarezsaurids except Qiupanykus and Nemegtonykus. [ABSTRACT FROM AUTHOR]

Arnebolagus leporinus Lopatin and Averianov, 2008, known previously from a single tooth (P3) from the early Eocene Bumban Member of Naran Bulak Formation at Tsagan-Khushu locality in Mongolia, is redescribed based on additional specimens from the type locality. Phylogenetic relationships of Eocene stem lagomorphs from Asia and North America are reconstructed for the first time based on a parsimony analysis of 54 morphological characters and 32 taxa. Two new node-based clades are proposed, stemming from the most-recent common ancestor of Lepus Linnaeus, 1758 and Dawsonolagus Li, Meng, and Wang, 2007 (Eulagomorpha new clade, 'lagomorphs of the modern aspect') and from the most-recent common ancestor of Lepus and Gobiolagus Burke, 1941 (Epilagomorpha new clade). Arnebolagus Lopatin and Averianov, 2008 is geologically oldest and the most plesiomorphic eulagomorph, similar to Dawsonolagus from the early Eocene Arshanto Formation of China in its weakly pronounced, unilateral hypsodonty of the upper cheek teeth and its brachyodont lower cheek teeth with separate roots. Arnebolagus is more plesiomorphic than Dawsonolagus in having two roots of P4. Arnebolagus is the oldest known eulagomorph, the only taxon known from the earliest Eocene Bumbanian Asiatic Land Mammal Age (ALMA). The other Asiatic early Eocene eulagomorphs (Dawsonolagus, Aktashmys Averianov, 1994, and Romanolagus Shevyreva, 1995) come from the Arshantan ALMA. [ABSTRACT FROM AUTHOR]

A new sauropod, Abdarainurus barsboldi gen. et sp. nov., is described based on several anterior and one middle caudal vertebrae and chevrons from the Late Cretaceous Alagteeg Formation at Abdrant Nuru, northern Gobi Desert, Mongolia. The new taxon is characterized by 16 unique or rare characters of the caudal skeleton, including opisthocoelous centra, longitudinal ridges on the neural canal walls, postprezygapophyseal processes, a hypertrophied postspinal fossa, mediolaterally constricted neural spines, and a deep pocket-like spinodiapophyseal fossa covered laterally by high postzygodiapophyseal lamina. Our preferred phylogenetic analysis places Abdarainurus as a basal titanosaurian sauropod, but this result could be affected by inadequate knowledge of basal titanosaurs. The new taxon likely represents a highly specialized lineage of Asian macronarian sauropods that was unknown previously. [ABSTRACT FROM AUTHOR]

Currently, there are two sauropod taxa known from the Upper Cretaceous (Maastrichtian) Nemegt Formation of Gobi Desert, Mongolia: Nemegtosaurus from the Nemegt locality and Opisthocoelicaudia from the Altan Uul IV locality. Both taxa are represented by not overlapping elements (skull and partial postcranial skeleton respectively), which arises question on their possible synonymy. Five articulated sauropod dorsal vertebrae (PIN 3837/P821, dorsals 6-10) were found in 1949 by the Mongolian Expedition of the Academy of Sciences of the USSR at the Nemegt locality. This specimen is similar to Opisthocoelicaudia in having a strong ventral ridge on dorsal centra, a low neural arch which is anteroposteriorly narrowest at the junction with the centrum and widens dorsally, and lack of hyposphene-hypantrum articulations. PIN 3837/P821 differs from Opisthocoelicaudia by having the less dorsoventrally flattened dorsal centra, a shallow ventral concavity of dorsal centra in lateral view, a vertical posterior centrodiapophyseal lamina (pcdl) in dorsals 8 and 9, a postzygodiapophyseal lamina (podl) that roofs the centrodiapophyseal fossa (pocdf), and strongly developed accessory laminae within the parapophyseal centrodiapophyseal fossa (pacdf). The sauropod femora from Nemegt Formation differ from the femur of Opisthocoelicaudia by the medial condyle extending more distally compared with the lateral condyle. Most likely these femora and PIN 3837/P821 belong to Nemegtosaurus, which would make this taxon distinct from Opisthocoelicaudia by discussed characters of dorsal vertebrae and femur. [ABSTRACT FROM AUTHOR]

There are two species of Gobiconodon in the Early Cretaceous Khoboor locality of Mongolia: G. borissiaki Trofimov, , and G. hoburensis (Trofimov, ). The smaller G. hoburensis has i2 half the size of i1, double-rooted dp2, and two generations of molariforms (m1-5 and m1r-4r). In the larger G. borissiaki, i2 is about ¾ size of i1, dp2 is single-rooted, and there are three generations of molariforms (m1-5, m1r-5r, m1rr-2rr). In larger G. ostromi Jenkins and Schaff, , there are three molariforms of the third generation (m1rr-3rr). The anterior lower dentition of Gobiconodon is interpreted as i1-3, c, and dp1-2. The replacement of dp1 by p1 is known only in G. hoburensis. The dp2 is not replaced and may be lost in some specimens ( G. hoburensis, G. ostromi) with its alveolus plugged by bone. Gobiconodon includes five valid species: G. borissiaki, G. hoburensis, G. ostromi, G. hopsoni Rougier et al., , and G. zofiae Li et al., (= G. luoianus Yuan et al., , syn. nov.). The holotype upper maxilla of G. hopsoni is not diagnostic and a new diagnosis for this species is provided based on lower dentitions from the type locality. Repenomamus Li et al., , and Meemannodon Meng et al., , are the only other members of the Gobiconodontidae. The dental formula of Repenomamus is reinterpreted as I1-3, C, P1, M1-5/i1-2, c, p1-2, m1-5 and thus it differs from Gobiconodon by lack of i3 and P2. Meemannodon is different from Gobiconodon by lack of i3 (the upper dentition is unknown). The Early Cretaceous Jeholodens, Yanoconodon, and Liaoconodon are closer to the Gobiconodontidae than to the Amphilestidae by having only two premolars. Liaoconodon with modified anterior dentition is likely the closest relative to the Gobiconodontidae. The Gobiconodontidae is likely the sister taxon for the clade Amphilestidae + Trechnotheria. [ABSTRACT FROM AUTHOR]

Hapalodectes paradux sp. nov. (Hapalodectidae, Mesonychia) is described on the base of the dentary fragment with M 2 -M 3 from the Tsagan-Khushu locality in Mongolia (Upper Paleocene, Naran Bulak Formation, Zhigden Member). The M 2 and M 3 are approximately the same size, with a high protoconid, anteriorly displaced reduced metaconid, anterolingually directed protocristid, very deep posterior notch, narrow talonid, and distinct hypoconid, entoconid and hypoconulid. Based on dental characters, the new species is presumably related to the base of the lineage of Hapalodectes that dispersed to North America at the beginning of the Eocene. Tsagan-Khushu is the only known locality where two species of Hapalodectes co-occur (larger H. dux Lopatin, 2001 and smaller H. paradux sp. nov.)., (© 2023. The Author(s).)

The holotype of Hapalodectes dux Lopatin, 2001 from the Upper Paleocene of Mongolia (Tsagan-Khushu locality, Naran Bulak Formation, Zhigden Member) is a lower jaw with complete dentition, showing healed alveoli in place of the right P 3 . Examination of the holotype using X-ray microtomography revealed a rare dental anomaly previously unknown in fossil mammals, namely the presence of the inverted (positioned upside down and rotated lingual side labially) impacted premolar inside the dentary. The cause of this anomaly may be an aberration of a tooth bud location or an injury., (© 2023. Pleiades Publishing, Ltd.)

The maxillary fragment of eutriconodontan Gobiconodon borissiaki Trofimov, 1978 (Gobiconodontidae) is described from the Early Cretaceous Zuun-Höövör locality in Mongolia (Övörkhangai aimag, Guchin-Us sum). It demonstrates erupting М 2 RR (second molariform tooth of the third generation) along with the presence of the almost unworn M 4 R and alveoli of M 3 R and M 5 . This is the first direct evidence of the molariform tooth replacement in Gobiconodon from the Early Cretaceous of Mongolia. The CT study of the specimen revealed the absence of mineralized germs of other teeth., (© 2022. Pleiades Publishing, Ltd.)

Ereberix erebericulus gen. et sp. nov., the smallest representative of the Asian Brachyericinae (Erinaceidae, Erinaceomorpha), a peculiar extinct group of short-faced hedgehogs with predatory adaptations, is described from the Lower Miocene Loo Formation of the Taatsiin Gol locality (Valley of Lakes, Mongolia). The description of the new form expands the knowledge on the taxonomic and morphological diversity of the Asian Brachyericinae.