Dinosaur Diversity Changes • During the Mesozoic era, dinosaurs dominated the Top levels of the Food Chain Pyramid • Their ecological territory or “Niche” spread out over many environmental conditions; coastal, fluvial and even desert, almost everywhere on the earth’s surface • Even the sea and air were occupied by closely related reptiles (e.g. Plesiosaurus, Ichthyosaurus, Pteranodon) • Mammals hide from them, so their niches were nocturnal Dinosaur diversity change is important to elucidate future predictions of present-day animal biodiversity. Dinosaur Diversity Changes • During Mesozoic era, dinosaurs dominated the Top levels of the Food Chain Pyramid. • Their ecological territory “Niche” spread out over many environmental conditions; coastal, fluvial and even desert, almost everywhere on the earth’s surface. • Even sea and air occupied by closely related reptiles (e.g. Plesiosaurus, Ichthyosaurus, Pteranodon). • Mammals hide from them, so their niches were nocternal Dinosaur diversity change is important to elucidate future predictions of present-day animal biodiversity. Dinosaur Paleontology Dinosaurs originated in South America • Argentinosaurus is the heaviest dinosaur (length: 30m, weight: 100 tons). • Cretaceous Dinosaur assemblages are different from N. Hemisphere. South America “Sauropoda” North America & Asia “Hadrosaurid” No.1 Dinosaur Kingdom • A large variety of dinosaur fossils • Jurassic dinosaur assemblage is similar to other continents • Diversity of Ceratopsian and Hadrosauridae in late Cretaceous Motherland of Dinosaur Research • Iguanodon is the first Dinosaur specimen and species described . No.2 Dinosaur Kingdom • Recently, Bird-related Dinosaur fossils found. Hatching Oviraptor • Australia was located in polar zone in the early Cretaceous • But there were some dinosaurs (e.g. Muttaburasaurus). New Field of Dinosaur Research • Some dinosaur assemblages are similar to N.&S. America and Europe • It’s good evidence that continents were united (1) Paleogeographic distribution and dinosaur migration • Dinosaur diversity change cannot Late Jurassic really be understood without the influence of Continental drift and dinosaur migration. • Many researchers pointed out the similarity of late Cretaceous dinosaur assemblages between Early Cretaceous the North America and East Asia. • Mongolian dinosaur diversity was affected by migration through the Beringian Isthmus which connected NA and Asia during the Late Cretaceous Late Cretaceous Beringian Isthmus NA Asia NA Asia Europe Europe Early Cretaceous Late Cretaceous Milner et al.(2000) Nemegt Fm. Djadokhta Fm. Bayan Shiree Fm. Upper Cretaceous Lower Cretaceous Location of dinosaur-bearing Cretaceous sections in the Gobi basin Lower Cretaceous General stratigraphic column of the Cretaceous in Mongolia (Jerzykiewicz & Russell, 1991) Early Cretaceous Asiatosaurus mongoliensis Ambiortus dementjevi Harpymimus okladnikovi (sauropoda) Enantiornithes indet. (Ornithomimosauria) Lower (Avialae) Cretaceous Prodeinodon mongoliensis (Theropoda) Shamosaurus scutatus (Ankylosauria) Iguanodon bernissartensis Psittacosaurus Altirhinus kurzanovi mongoliensis Mesozoic stratigraphy mongoliensis (Hadrosauridae) (Neoceratopsia) Baynshirenian “Age” Bayn Shire Fm. Garudimimus brevipes Garudimimus brevipes Achillobator giganticus AlectrosaurusAlectrosaurus olseniolseni (Ornithomimosauria) (Ornithomimosauria) (Dromaeosauridae) (Tyrannosauroidea)(Tyrannosauroidea) Segnosaurus galbiensis Microceratops gobiensis Erlikosaurus andrewsi (Neoceratopsia) Enigmosaurus mongoliensis Sauropoda Gen. Undet. (Therizinosauroidea) Mesozoic stratigraphy Talarurus plicatospineus Bactrosaurus mongoliensis Amtosaurus magnus Arstanosaurus sp. Tsagantegia longicranialis (Hadrosauridae) Maleevus disparoserratus (Ankylosauria) Djadokhta “Age” Djadokhta Fm. Saurornithoides mongoliensis Oviraptor philoceratops Velociraptor mongoliensis Byronosaurus jaffei Citipati osmolskae (Dromaeosauridae) (Troodontidae) Khaan mckennai Ingenia sp. (Oviraptorosauria) ProtoceratopsProtoceratops andrewsiandrewsi UdanoceratopsUdanoceratops tschizhovitschizhovi Sauropoda Gen. Undet. Mononykus olecranus BainoceratopsBainoceratops efremoviefremovi (Avialae) BagaceratopsBagaceratops sp.sp. (Neoceratopsia)(Neoceratopsia) Mesozoic stratigraphy Pinacosaurus grangeri Hadrosauridae Gen. Undet. (Ankylosauria)(Ankylosauria) Barungoyotian “Age” Barun Goyot Fm. Velociraptor sp. Oviraptor philoceratops Tyrannosauroidea indet Hulsanpes perlei Conchoraptor gracilis (Dromaeosauridae) Ingenia yanshini (Oviraptorosauria) Quaesitosaurus orientalis Gobipterix minuta (Diplodocoidea) Parvicursor remotus ProtoceratopsProtoceratops kozlovskiikozlovskii Hesperornithiformes indet. BagaceratopsBagaceratops rozhdestvenskyirozhdestvenskyi (Avialae) LamaceratopsLamaceratops tereschenkoitereschenkoi Mesozoic stratigraphy PlatyceratopsPlatyceratops tatarinovitatarinovi (Neoceratopsia)(Neoceratopsia) Saichania chulsanensis Tarchia gigantea Tylocephale gilmorei (Ankylosauridae) (Pachycephalosauria) Nemegt “Age” Nemegt Fm. Avimimus portentosus Mononykus olecranus Oviraptor mongoliensis Judiornis nogontsavensis Gallimimus bullatus Rinchenia mongoliensis Gurilynia nessovi Tarbosaurus bataar Anserimimus planinychus Nomingia gobiensis Parahesperornis sp. Alioramus remotus Deinocheirus mirificus Elmisaurus rarus Bagaraatan ostromi (Ornithomimosauria) Ingenia yanshini Teviornis gobiensis Gorgosaurus novojilovi (Oviraptorosauria) (Avialae) (Tyrannosauroidea) Adasaurus mongoliensis Therizinosaurus Saurornithoides junior cf.Velociraptor Nemegtosaurus mongoliensis cheloniformis Borogovia gracilicrus (Dromaeosauridae) (Diplodocoidea) (Therizinosauroidea) Tochisaurus nemegtensis Opisthocoelicaudia skarzynskii (Troodontidae) (Sauropoda) Mesozoic stratigraphy Prenocephale prenes Homalocephale calathocercos Saurolophus angustirostris (Pachycephalosauria) Tarchia gigantea Barsboldia sicinskii (Ankylosauria) (Hadrosauridae) Mongolian dinosaur biodiversity change • Ceratopsian Lower Cretaceous: Psittacosaurus appeared & flourished Bayanshiree age: only Microceratops apperared. Djadokhta and Baruungoyot age: Protoceratopsids greatly diversified. • Ankylosauridae Ankylosaurids existed through the Cretaceous, declined at the end • Theropoda Nemegt age: Theropoda flourished. Tarbosaurus (Tyrannosaurid) appeared • Hadrosauridae Nemegt age: Saurolophus (Hadrosaurid) diversified. What makes dinosaur diversity change ?! Comparisons of Late Cretaceous Dinosaurs from Mongolia and North America • Many researchers pointed to the similarity of late Cretaceous dinosaur assemblages in North America and East Asia. Theropoda; Tyrannosauridae Dromaeosauridae Troodontidae Saurornithoidae Oviraptoidae Ornithomimidae Sauropoda; Diplodokcidae Camarasauridae Ornithischia; Neoceratopsidae Ankylosauridae Hadrosauridae Pachycephalosauridae • These dinosaurs’ biodiversity was affected by the migration from Asia to NA. • Differences in dinosaur biodiversity may be affected by environmental differences. NA=coastal, Asia=interior continents Dinosaur assemblage differences in Djadokhta Fm. Ulan Nur Basin • Eolian desert condition (Bayan Zag, Tugrikiin Shiree, Udyn Sayr) … Protoceratops dominated. Dinosaur assemblage differences in Djadokhta Fm. Ulan Nur Basin • Eolian desert condition (Bayan Zag, Tugrikiin Shiree, Udyn Sayr) … Protoceratops dominated. • Fluvial condition (Alag Teeg, Abdrant Nuru, Khongil) … Pinacosaurus dominated. Environmental factor control the dinosaur biodiversity !? Dinosaur assemblage differences in Djadokhta Fm. Ulan Nur Basin • Eolian desert condition (Bayan Zag, Tugrikiin Shiree, Udyn Sayr) … Protoceratops dominated. • Fluvial condition (Alag Teeg, Abdrant Nuru, Khongil) … Pinacosaurus dominated. Environmental factor control the dinosaur biodiversity !? • Stratigraphic correlation of each localities are unclear. • Reconstruction of the paleoenvironment setting at several localities. Paleoenvironmental reconstruction of dinosaur-bearing deposits based on the sedimentological study (2) Environment setting and dinosaur communities • Dinosaur diversity changes cannot really be understood without the influence of the environment setting and dinosaur community • Lehman (1987) identified biogeographic zones in (1) (2) (3) several environments in the latest Cretaceous (1) Leptoceratops: semi-arid region. (2) Triceratops: coastal lowland. (1) Piedmont (semi-arid) (2) Coastal lowland (3) Alamosaurus: alluvial plain • North American dinosaurs (1) have enough rich fauna as (2) supported by sufficient (3) geological studies. (3) Alluvial plain Lehman (1987) .