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Home , Adasaurus, Alectrosaurus, Alioramus, Ambiortus, Anserimimus, Avimimus

Dinosaur Diversity Changes

• During the , dominated the Top levels of the Food Chain Pyramid • Their ecological or “Niche” spread out over many environmental conditions; coastal, fluvial and even desert, almost everywhere on the ’s surface • Even the sea and air were occupied by closely related (e.g. Plesiosaurus, , ) • hide from them, so their niches were nocturnal diversity change is important to elucidate future predictions of present-day . 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 Dinosaurs originated in

• is the heaviest dinosaur (length: 30m, weight: 100 tons). • Dinosaur assemblages are different from N. Hemisphere. South America “” & “Hadrosaurid” No.1 Dinosaur Kingdom

• A large variety of dinosaur • dinosaur assemblage is similar to other • Diversity of Ceratopsian and Hadrosauridae in Motherland of Dinosaur Research

• is the first Dinosaur specimen and described . No.2 Dinosaur Kingdom

• Recently, -related Dinosaur fossils found. Hatching • was located in polar zone in the • But there were some dinosaurs (e.g. Muttaburasaurus). New Field of Dinosaur Research

• Some dinosaur assemblages are similar to N.&S. America and • It’s good evidence that continents were united

(1) Paleogeographic distribution and dinosaur migration • Dinosaur diversity change cannot 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 (Jerzykiewicz & Russell, 1991) Early Cretaceous

Asiatosaurus mongoliensis dementjevi okladnikovi (sauropoda) indet. () Lower () Cretaceous mongoliensis ()

Shamosaurus scutatus () Iguanodon bernissartensis Altirhinus kurzanovi mongoliensis Mesozoic stratigraphy mongoliensis (Hadrosauridae) (Neoceratopsia) Baynshirenian “Age”

Bayn Shire Fm. brevipes Garudimimus brevipes Achillobator giganticus AlectrosaurusAlectrosaurus olseniolseni (Ornithomimosauria) (Ornithomimosauria) () ()(Tyrannosauroidea)

Segnosaurus galbiensis Microceratops gobiensis andrewsi (Neoceratopsia) Enigmosaurus mongoliensis Sauropoda Gen. Undet. (Therizinosauroidea)

Mesozoic stratigraphy

Talarurus plicatospineus mongoliensis Amtosaurus magnus Arstanosaurus sp. Tsagantegia longicranialis (Hadrosauridae) Maleevus disparoserratus (Ankylosauria) Djadokhta “Age”

Djadokhta Fm. mongoliensis Oviraptor philoceratops mongoliensis jaffei osmolskae (Dromaeosauridae) () mckennai sp. ()

ProtoceratopsProtoceratops andrewsiandrewsi UdanoceratopsUdanoceratops tschizhovitschizhovi Sauropoda Gen. Undet. 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 gracilis (Dromaeosauridae) Ingenia yanshini (Oviraptorosauria)

Quaesitosaurus orientalis Gobipterix minuta () Parvicursor remotus ProtoceratopsProtoceratops kozlovskiikozlovskii Hesperornithiformes indet. BagaceratopsBagaceratops rozhdestvenskyirozhdestvenskyi (Avialae) LamaceratopsLamaceratops tereschenkoitereschenkoi Mesozoic stratigraphy PlatyceratopsPlatyceratops tatarinovitatarinovi (Neoceratopsia)(Neoceratopsia)

Saichania chulsanensis Tarchia gigantea gilmorei (Ankylosauridae) () Nemegt “Age” Nemegt Fm.

Avimimus portentosus Mononykus olecranus Oviraptor mongoliensis Judiornis nogontsavensis bullatus mongoliensis Gurilynia nessovi bataar planinychus gobiensis sp. remotus mirificus rarus Bagaraatan ostromi (Ornithomimosauria) Ingenia yanshini Teviornis gobiensis novojilovi (Oviraptorosauria) (Avialae) (Tyrannosauroidea)

Adasaurus mongoliensis Saurornithoides junior cf.Velociraptor mongoliensis cheloniformis gracilicrus (Dromaeosauridae) (Diplodocoidea) (Therizinosauroidea) nemegtensis skarzynskii (Troodontidae) (Sauropoda) Mesozoic stratigraphy

Prenocephale prenes calathocercos 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; Dromaeosauridae Troodontidae Saurornithoidae Oviraptoidae Sauropoda; Diplodokcidae

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) … 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) : coastal lowland. (1) Piedmont (semi-arid) (2) Coastal lowland (3) : alluvial plain

• North American dinosaurs (1) have enough rich as (2) supported by sufficient (3) geological studies. (3) Alluvial plain Lehman (1987)