Mesozoic birds of Mongolia and the former USSR EVGENII N. KUROCHKIN Introduction Institutional abbreviations The first Mesozoic avian skeletal remains from Asia IVPP, Institute of Vertebrate Palaeontology and were found in Mongolia by the Polish-Mongolian Palaeoanthropology, Beijing, China; IZASK, Institute Palaeontological Expedition (Elzanowski, 1974, 1976, of Zoology of the Kazakh Academy of Sciences, 1981). Feathers from the Late Cretaceous of Alma-Aty, Kazakhstan; JRMPE, Joint Russian- Kazakhstan were described by Bazhanov (1969) and Mongolian Palaeontological Expedition; MGI, Shilin (1977) and numerous fossil feathers from the Geological Institute of the Mongolian Academy of Lower Cretaceous of Mongolia and East Siberia were Sciences, Ulaanbaatar; PIN, Palaeontological Institute collected by palaeoentomologists from PIN at the of the Russian Academy of Sciences, Moscow, Russia; beginning of the 1970s. From the 1970s to the 1990s PO, Collection of the Zoological Institute of the skeletal remains of various avian fossils were recov- Russian Academy of Sciences, St. Petersburg, Russia; ered from the Cretaceous of Mongolia by the Joint TsNIGRI, F.N. Chernyshev Central Museum for Russian-Mongolian Palaeontological Expedition and Geological Exploration, St. Petersburg, Russia; VPM, in the Cretaceous of Middle Asia by the late Lev Volgograd Provincial Museum, Volgograd, Russia; Nesov as a result of his persistent exploration. ZPAL, Institute of Palaeobiology of the Polish Further remains of birds were found in recent years Academy of Sciences, Warsaw, Poland. in Central Asia by the American-Mongolian expedi- tions (see Chapter 12) and it now appears that earlier Systematic description American expeditions in the 1920s also recovered fossil birds, though they were not recognized as such Class Aves Linnaeus, 1758 until the 1990s (see Chiappe et al., 1996, and refs Subclass Sauriurae Haeckel, 1866 therein). Infraclass Enantiornithes Walker, 1981 Mesozoic birds from Mongolia and the former Order Alexornithiformes Brodkorb, 1976 Soviet Union (FSU) are rare and usually fragmentary, Family Alexornithidae Brodkorb, 1976 but they provide some data regarding the early history Contents. Gobipteryx Elzanowski, 1974; Alexornis of the group in this territory. In addition, many Brodkorb, 1976; Kizylkumavir Nesov, 1984; Zbyraornis Mesozoic birds have recently been found in China Nesov, 1984 (2 spp.); Nunantius Molnar, 1986 (2 spp.); (Chiappe, 1995). Together, these records provide the Sazavis Nesov and Yarkov, 1989; Neuquenornis Chiappe basis for analyses of Mesozoic avian assemblages in and Calvo, 1994; Lenesornir Kurochkin, 1996. Asia (Kurochkin, 199Sa). This chapter presents a Diagnosis. Cranial half of the synsacrum low and summary of Mesozoic birds from the FSU and broad; synsacrum convex dorsally; ischium narrow; Mongolia, primarily discovered by Russian palaeon- acrocoracoid and coracoidal process narrow and tologists. Avian macro-taxonomy follows Kurochkin tapered; shaft of the coracoid strut-like and narrow; (1995~). shaft of the coracoid with a deep and short depression on the dorsal side; scapular facet and scapular glenoid Kizylkumavis cretacea Nesov, 1984 fused; ventral epicondyle of the humerus protrudes Holotypr. TsNIGRI 5111 1915, distal fragment of a distad to a striking degree; wing digits clawless; shaft right humerus. Dzharakhuduk locality, Navoi District, of the tihiotarsus thin; metatarsal 111 straight; metatar- Rukhara Province, Uzbekistan. Outcrop CBI-Sa, sals 11-1V short and gracile. Rissekty Svita (Coniacian). Diagno.ri.r. Same as for genus. Kizylkumavis Nesov, 1 984 Comments. K cretacea is a very small enantiornithine; Type .rpecie.r. Kky1kumavi.r cretacea Nesov, 1984. the maximum width of the distal end of humerus is Diagnosis. Original diagnosis of Nesov (1984): olecra- 5.1 mm. K. creracea was the first member of the non fossa is narrow and displaced in the direction of Enantiornithes to be described from the Old World the flexor process; flexor process is strongly projected (Nesov, 1984), although in the original description it distally; dorsal condyle very narrow and aligned at an was assigned to Aves inccrrae sedis. In spite of its frag- angle of 65" to the longitudinal axis of the humeral mentary condition, there are no doubts as to the enan- shaft; ventral condyle is short, aligned almost trans- tiornithine relationships of K crctacea since it has no versely to the longitudinal axis of the humeral shaft, fossa for the .&I. brachiali.~,a transverse position of the and only slightly projected in cranial aspect; intercon- dorsal condyle of the humerus, and an inclined posi- dylar furrow runs slightly on the cranial side; brachial tion of the ventral condyle. depression is not developed; a small groove is devel- oped distal to a small ventral supracondylar tubercle Z~yraor?zisNesov, 1984 on the cranial surface of the distal end, and aligned at Type specie.^. Z&yraorni.r kashkarovi Nesov, 1084. an angle of 70" to the longitudinal axis of the shaft. content^: Z. kashkarovi Nesov, 1984; Z. logu?zovi Nesov, Commenr~:As I have not seen the specimen recently, 1002. the original diagnosis, which includes the generic Diag?zosi~:Cranial portion of the synsacrum notice- characters of Kizylkumavis, as well as characters of the ably convex dorsally; cranial end of the synsacrum Enantiornithes and Alexornithiformes is presented remarkahly broad; synsacrum only slightly broadened here. The following characters form an emended diag- across both sacral vertebrae; onty one thoracic verte- nosis for this genus: distal end of the humerus is very bra precedes two sacral vertebrae; caudal half of the wide in the dorsoventral direction; the ventral portion synsacrum long and narrow; the two largest costal of the distal end of the humerus is remarkably processes are inclined caudally; no longitudinal enlarged; the dorsal condyle is broad; the intercondy- groove on the ventral side of the synsacrum. lar furrow is narrow; and the flexor process is strongly Commenr.~.There are four species of bird from projected distally. Dzharakhuduk that are based on synsacra and The humeri of Kizylkumavis and Alexornir of Mexico assigned to the Ichthyornithiformes (Nesov, 1984, (Brodkorb, 1976) are similar in some respects. For 1986, 1990, 1992b, d; Nesov and Yarkov, 1989; example, they share: a remarkable distal projection of Nesov and Psnteleev, 1993). Comparison of these the ventral epicondyle, distal displacement of a remains with the synsacrum of ,lia?zantius valifanovi shallow olecranal fossa, and an abrupt transition from Kurochkin, 1996 showed that they should be the distal end to the shaft. However, they also exhibit assigned to the Enantiornirhes (Kurochkin, 1995c, some differences: the shape of the dorsal condyle 1996). (which is broad in Kizylkumavis and narrow and olive- shaped in Alexornis); a more spacious intercondylar Zhyraornis kashkarovi Nesov, 1984 furrow in Alexornis, and more distal projection of the Holotypc TsNIGRl42/11915, incomplete synsacrum, flexor process in Kizylkumavis. having at least seven coossified vertebrae and lacking the most caudal portion. Dzharakhuduk locality, Mesozoic birds of Mongolia and the former USSK Navoi District, Bukhara Province, Uzbekistan. 1.ene.ronzi.r Kurochkin, 1906 Outcrop CRI-4, Rissekty Svita (Coniacian). rypespecies. Lene.t.omi.r mcz/t.lhr-~~.kyi(Nesov, 1986). Diagnosis. First vertebra on synsacrum expands grad- Diagnn.ri.~: The cranial portion of the synsacrum is ually in the cranial direction; transverse processes on only slightly con\,es dorsally, the cranial articular the second sacral vertebra are slightly marked on the surfice of the synsjcrurn is transversely elongated; the dorsal surface; two pairs of the largest costal processes third and fourth vertehrae of the synsacrurn possess are slender and distinctly inclined length\vise; the the largest costal processes; the costal processes are at synsacrum is generally extended and narrow. a right angle to the sagittal plane; and the ventral comment.^. A thoracic vertebra (TsNIGRI 43/1191.i) groove is uide and shallow. from the Khodzhakulsai locality (lihodzhakul settle- Comments. This skmsacrum was described as ment, Karakalpakia, Uzbekistan; lihodzhakul Svita, Ichtbyov~~ismaltsh~z~skyi I)!. Nesov ( 1 98 6) in the lirnily Cenomanian) (Nesov, 1984, 1992b; Nesov and Borkin, lchthyornithidae (see also Nesov, 1992b, d). However, 1983), regarded as an indeterminate hlesozoic bird by the similarity ol' this hssil to .'n?za?ztius z~al~/2rnnvi Nesov (I 992d), a left scapula ('TsNIGRI 4411 1915) Kurochkin, 1006, and the at~undanceof postcranial and the shaft of a left humerus (TsNIGRI 45/11915) remains of Enantiornithes at the Dzharakhuduk from Dzharakhuduk (Nesor, 1984), were also assigned locality enabled it to be reidentihed as an enantiorni- to Z. kashkarovi. The vertebra has a wide neural canal, thine (Kurochkin, 1996). Because of a noticeable deep lateral excavations on the centrum, and nearly diff'erence from Zbyvanvflis, it was assigned to a separ- flat cranial and ca11da1 articular surfaces. It is compar- ate gent~s. able in size to the vertehrae of the synsacrum of Z. kashkaroz~j.The structure of the glenoid facet on the I,ene.rovui.r nzalt.sbev.rkyi (Nesov, 1 980) scapula and its acrornion show a certain similarity to Holo~ypc. PO 3434, cranial half of the s\ nsacrum. that of the enantiornithines, but this is not sufficient Dzharakhuduk locality, Navoi District. Bukhara evidence for its assignment to Z. kashkavovi 'She Province,