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A Re-Appraisal Ofaralosaurus Tuberiferus (Dinosauria, Hadrosauridae) from the Late Cretaceous of Kazakhstan

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A Re-Appraisal Ofaralosaurus Tuberiferus (Dinosauria, Hadrosauridae) from the Late Cretaceous of Kazakhstan bulletin de l'institut royal des sciences naturelles de belgique sciences de la terre. 74-suppl.: 139-154, 2004 bulletin van het koninklijk belgisch instituut voor natuurwetenschappen aardwetenschappen, 74-suppl.: 139-154, 2004 A re-appraisal ofAralosaurus tuberiferus (Dinosauria, Hadrosauridae) from the Late Cretaceous of Kazakhstan by Pascal GODEFROIT, Vladimir ALIFANOV & Yuri BOLOTSKY Godefroit, P., Alifanov V. & Y. Bolotsky, 2004. - A re-appraisal of sauridae than to Iguanodon (Weishampel & Horner, Aralosaurus tuberiferus (Dinosauria, Hadrosauridae) from the Late Cretaceous of Kazakhstan. Bulletin de l'Institut royal des Sciences 1990; Sereno, 1998). They were the most successful naturelles de Belgique, Sciences de la Terre, 74 supplement: 139- herbivorous dinosaurs in Laurasia during the closing 154, 1 pl., 7 figs, Bruxelles - Brussel, December 15, 2004. - ISSN stages of the Cretaceous. During the Campanian and 0374-6291. Maastrichtian, they were the primary constituents of many terrestrial vertebrate faunas. In western North Abstract America, hundreds of fragmentary to complete hadro¬ saurid specimens have been collected, including remains Aralosaurus tuberiferus Rozhdestvensky, 1968 (Dinosauria: Hadro¬ of eggs, embryos, hatchlings and juvéniles. They were sauridae) is based on a fragmentary skull from the Beleutinskaya Svita apparently spread world-wide: besides North America, (?Turonian, Late Cretaceous) from the Sakh-Sakh locality of central fossils have also been discovered in Central America, Kazakhstan. Redescription of the type material reveals that it is a valid South taxon, characterised by a hollow nasal crest-like structure located far in America, Europe, Asia (Weishampel & Horner, front of the orbits and by a well-developed curved crest on the maxilla 1990) and apparently even in Antarctica (Rich et al., that borders laterally the caudal part of the premaxillary shelf. Phylo- 1999). The main reason for this evolutionary success genetic analysis, based on 36 cranial characters, indicates that A. tube¬ was riferus is the most basai lambeosaurine hadrosaurid known to date; it is probably their very efficient plant-processing masti- therefore not a gryposaur-like hadrosaurine as previously described. catory apparatus, characterised by an improved mobility Lambeosaurines originated from Asia and then migrated to North of the upper jaw and by an elaborated dental battery well America before or at the beginning of the late Campanian. They remained well diversifted in eastern Asia until the late Maastrichtian. adapted for feeding on hard vegetables (Norman, 1984; Weishampel, 1984). Besides typical hadrosaurids, the Key-words: Aralosaurus tuberiferus. Hadrosauridae, Lambeosauri- hadrosauroid clade includes a number of less derived nae. Late Cretaceous, Kazakhstan, phylogeny, palaeobiogeography. forms that evolved in Laurasia from the late Early Cre¬ taceous (You et al., 2003) until the Maastrichtian. Ha¬ drosauridae includes members of Hadrosaurinae and Résumé Lambeosaurinae subfamilies and their most recent com- Aralosaurus tuberiferus Rozhdestvensky, 1968 (Dinosauria: Hadro¬ mon ancestor (Weishampel & Horner, 1990; Weisham¬ sauridae) est décrit sur base d'un crâne fragmentaire découvert dans la pel et al., 1993). With the exception of Horner (1988, Beleutinskaya Svita (?Turonien, Crétacé supérieur) du site de Sakh- 1990, 1992), ail the authors working on hadrosauroid Sakh au Kazakhstan central. La redescription du matériel type indique qu'il s'agit bien d'un taxon valide, caractérisé par la présence d'une phylogeny accept the monophyly of Hadrosauridae and, structure en forme de crête creuse située bien à l'avant des orbites et par within this family, that of the subfamilies Hadrosaurinae une crête courbée très développée sur le maxillaire bordant la portion and Lambeosaurinae. 'Flat-headed' Hadrosaurinae is e.g. caudale du rebord prémaxillaire. L'analyse phylogénétique, basée sur characterised 36 caractères crâniens, indique qu' A. tuberiferus est le lambéosauriné by the development of depressed areas le plus basai connu à ce jour; ce n'est donc pas un hadrosauriné proche around the external nares and by the latéral expansion de Gryposaurus, comme on le pensait avant. Les lambéosaurinés sont of their premaxillary beak. Some hadrosaurines, such as apparus en Asie et ont migré en Amérique du Nord avant ou au début du Campanien supérieur. Ils sont restés bien diversifiés en Asie jus¬ Prosaurolophus, Saurolophus, Brachylophosaurus or qu'au Maastrichtien supérieur. Maiasaura are characterised by the presence of a low, solid cranial crest, whereas others, such as Edmonto- Mots-clefs: Aralosaurus tuberiferus, Hadrosauridae, Lambeosaurinae, saurus, Anatotitan, or Gryposaurus, lack any crest Crétacé supérieur, Kazakhstan, phylogénie, paléobiogéographie. kind of development. Lambeosaurinae is characterised by an im¬ portant diversity of hollow cranial crests. The nasal cavity Introduction is completely modified and extends into this hollow crest, following a very tortuous route. With this hollow crest, it Hadrosauroidea, or "duck-billed" dinosaurs, can be de- is postulated that lambeosaurines could produce different fined as those dinosaurs more closely related to Hadro- kinds of trumpeting noises. As different species are char- 140 Pascal GODEFROIT, Vladimir ALIFANOV & Yuri BOLOTSKY Furmanovo D&iambeyty WF.ST KAZAJ^HSTAI^H KalmykovoV r -* Dzhambul •A \ Saryshagan Beyrieu ,> Osrrora u fj/VanoifKluniya ?„ ^Zhetybay ARAL\g~'" SEA 'JL Kïis.akskiy Zaiiv TURKMENISTAN Samarqam 65° TAJ1KISTAN Fig. 1 — Geographical location of sites from which hadrosauroid dinosaurs have been recovered in Kazakhstan. acterised by different shapes of crests, they produced to juvénile individuals. This taxon is unanimously re- different noises. garded as a nomen dubium (Maryanska & Osmólska Dinosaur discoveries in Central Asia began at the end 1981; Weishampel & Horner 1990). Jaxartosaurus ara- of the 19th century, when the Russian geologist Roma- lensis was described from the caudal part of one skull, novsky (1882) described dinosaur tracks on the right one dentary, one surangular and a few postcranial élé¬ bank of Yaknob River, in Tajikistan. In the second decade ments. This taxon can be regarded as a basai Lambeo- of the 20th century, more intensive and systematic geo- saurinae (Godefroit et al., in press; see also below). logical investigations in Eastern Russia and Central Asia Efremov (1932, 1933, 1944) subsequently investigated lead to the discovery of new dinosaur localities in the Central Asian dinosaur localities, from the Aral Sea (Ka¬ Transbaikal Région, along Amur River, and in Kyzyl zakhstan - Uzbekistan) to Issyk-Kul Lake (Kirgizstan), Kum Desert of Central Asia (Rozhdestvensky, 1977). especially from a taphonomic point of view. He concluded From 1923 to 1926, the Geological Committee of that dinosaur-bearing beds were intensively re-deposited USSR excavated the Kyrk-Kuduk dinosaur locality in during the Paleogene in a vast area north of the Tien-Shan the Chuley région of Shymkent / Tashkent area in eastern Mountains. As a resuit oftheir secondary re-déposition, the Kazakhstan (Fig. 1). Most of the fossils were discovered bones are found separated and rolled in this area. This within a conglomerate, possibly Santonian in âge (Aver- theory led to a decreasing interest to Central Asian dino¬ anov & nessov, 1995). Riabinin (1939) described two saur localities, because the probability to find more or less hadrosaurid taxa from this locality: Jaxartosaurus ara- complete skeletons appeared very low. lensis and Bactrosaurus prynadai. Bactrosaurus pryna- Subséquent discoveries of more complete dinosaur dai is based on two dentaries and one maxilla belonging material in Central Asia partly invalidated Efremov's A re-appraisal of Araiosaurus tuberiferus (Dinosauria, Hadrosauridae) 141 theory, indicating that the reworking of bone-bearing In the present paper, the holotype specimen of Aralo¬ sediments north of the Tien-Shan was more local than saurus tuberiferus will be re-examined, because it ap- previously thought and occurred during the first half of pears to us that its phylogenetic affmities have not yet the Late Cretaceous rather than during the Paleogene been correctly established. (Rozhdestvensky, 1977). In 1957, an expédition of the USSR Academy of Sciences discovered a hadrosaur skull Abbreviations: AEHM: Amur Natural History Museum in situ in the Beleutinskaya Svita of Sakh-Sakh locality in (Blagoveschensk, Russia); PIN: Palaeontological Insti- central Kazakhstan. The age of this formation is not well tute of the Russian Academy of Sciences (Moscow). established: Rozhdestvensky (1974, 1977)advocatedfor a Turonian age, but without any justification. This speci¬ men, regarded as a hadrosaurine, was described under the Systematic palaeontology name Aralosaurus tuberiferus Rozhdestvensky, 1968. In 1961, the nearly complete skeleton of a hadrosaurid Dinosauria Owen, 1842 was discovered at the Syuk-Syuk wells site, in the same Ornithischia Seeley, 1887 area as the type material of Jaxartosaurus, but in a Ornithopoda Marsh, 1881 different formation: the Dabrazinskaya Svita (Santo- Ankylopollexia Sereno, 1986 nian-Campanian: Rozhdestvensky; lower Santonian: Hadrosauriformes Sereno, 1986 Rozhdestvensky, 1977). This specimen, named Proche- Hadrosauroidea Cope, 1869 neosaurus convincens Rozhdestvensky, 1968, may be Hadrosauridae Cope, 1869 attributed to a juvénile lambeosaurine. Lambeosaurinae Parks, 1923 Arstanosaurus akkurganensis Shilin
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