1	Mesozoic 248 to 65 Ma Triassic, Jurassic, Cretaceous
2	Earth in the Triassic ~ 245-208 ma Geography & Climate Pangaea assembled until Mid-Triassic when rifting ensues Break-up affects climate and evolution Subduction-related mountain-building in w. NA Sea levels constant, continents relatively high elevation Climate- globally arid & dry; moist river & lake habitats, coastal areas had seasonal monsoons, northern forests No polar ice caps
3	The Setting: Rifting Tethy’s Sea developed an MOR Extension accompanied by faulting & volcanism Rift basins accumulated non-marine red-colored sediments Began break-up of Pangaea, mid-Triassic Gondwana- South America, Africa, India, Antarctica, Australia Laurasia- NA, Eurasia
4	The Setting: Cordilleran Mountain Building Mid-to-Late Triassic Shifts in plate motions adds new stress to NA’s western margin Mountain building shifts from e. NA to w. NA Axis of belts shifts to a nw-se trend Transform movement followed by subduction of ocean plates form mtn ranges in w. NA Trend from Alaska to Chile: “Cordillera” Western US--collage of microcontinents ‘suspect’ & ‘exotic’ terranes Sonomia- largest of the exotic terraness In present day Nevada by Mid-Triassic Seen today in Northern Sierra Mtns
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6	Triassic Rocks Non-marine sediments “Triassic Red Beds” Oxidized clastic sediments eroded from uplifted areas Accumulated on westward on alluvial plains Have yield important animal fossils Some redbeds represent lagoon, tidal flat deposits Marine shales & limestones along Triassic continental margin Famous Redbed locales Newark Supergroup, MA to NC. (NJ) Moenkopi Fm, AZ. Early-mid Triassic Chinle Fm, AZ/UT (Painted Desert/Petrified Natl Forest in AZ). Upper Triassic
7	Life of the Triassic Triassic organisms belong to 1 of 3 groups: Survivors of the Permo-Triassic extinction New groups which flourished briefly New groups which went on to dominate the Mesozoic
8	Life of the Early Triassic Was still recovering from Permian Mass Extinction Oceans resembled Precambrian-like ecology Limited diversity for both land & sea fauna/flora Microbial reefs proliferate Stromatolites were widespread, 1st time in 400 million years Ammonites- took ~ 4 million years for ocean biotic diversity to recover Land diversity did not recover until the middle Triassic Lycopsids dominated forests until Middle Triassic Dinosaurs- do not dominate until end of the Triassic
9	Triassic Oceans Complex reefs composed of scleractinian (modern) corals by late Triassic Molluscs- One of 1st groups to recover Ammonites- dramatic radiation in Early Triassic 150 new species within 5 million years of Permian extinction Best index fossil for Mesozoic. Triassic varieties had ‘U’ shaped sutures Primitive bony fish Marine reptiles- nothosaurs, placodonts
10	Triassic Oceans
11	Triassic Forests Permian land plants continued into Triassic Seed ferns, gymnosperms, gingkoes, cycads Most familiar conifer- Araucaria, or Norfolk Island pine Ferns- most likely food source for herbivorous animals
12	Age of Reptiles -Early Triassic 1st archosauromorphs appear in Early Triassic rhynchosaurs, prolacertiforms, erythrosuchians and proterosuchians Euparkeria, may have been 1st archosaur rather than archosauromorph
13	Age of Reptiles- Late Triassic Reptiles replace synapsid amphibians as dominant vertebrates Modern lizards & snakes Archosaurs (formerly thecodonts) Ichthyosauria Archosaurs Incl. dinosaurs, crocodiles, pterosaurs, birds, & crocodile-like forms such as aetosaurs, phytosaurs, rauisuchians, and crocodylomorphs. modern birds & crocodiles only surviving groups Most Archosaurs of the time belonged to crocodilian branch Archosaurs to appear in late Triassic include pterosaurs and primitive Saurischians & Ornithischians Eoraptor, Herrerasaurus
14	Ichthyosauria “fish lizard” Gave live birth Breathed air & lacked gills like modern whales Appear in Triassic, reach greatest diversity in Jurassic, disappear in Cretaceous well before K-T
15	Archosaurs of Late Triassic
16	2 Major Groups of Dinosaurs Evolve Saurischians (“lizard hipped”) Pelvis--3 bones around hip socket Pubic bone pointed forward from hip Includes all sauropod & theropods (bird-like) Earliest theropods were Ceratosaurs Ornithischians (“bird hipped”) Pubic bone rotated backward along base of ischium
17	True Saurischian Dinosaurs of Late Triassic Plateosaurus
18	True Saurischian Dinosaurs of Late Triassic Tanystropheus
19	True Saurischian Dinosaurs of Late Triassic Coelophysis Ceratasaurian Theropod
20	True Ornithischians Dinosaurs of Late Triassic Heterodontosaurus
21	Dinosaur Physiology Dinosaurs likely had unique physiology: not reptilian or mammalian, or even had a variety of physiologies They display both reptilian & mammalian characteristics Reptilian- temperature in a large body is most easily regulated by ectothermy- environment regulates body heat E.g. Sauropods & Ornithischians with their giant size Mammalian- Fossils found in areas with cool climates more suited to endothermy, presence of Haversian canals in dinosaur bone and flying habits Pterosaurs- active flying requires endothermy. Some had hair-like insulation Small theropods were likely endothermic
22	End of the Triassic Extinction event - 25% of all animal families disappear Ammonites reduced to 1 genus Nearly all land reptile & amphibian families were lost All but last of large synapsids & amphibians extinct Primitive archosaurs replaced by true dinosaurs
23	Earth in the Jurassic ~ 206 to 144 ma Geography & Climate Named for the Jura Mountains on the border between France and Switzerland Pangaea still breaking up; rifting Warm, tropical climate Dinosaurs roamed the Earth Marine reptiles dominated seas Flying reptiles dominated the skies
24	Setting: Rifting & Further Pangaea Break-up Middle Jurassic: Gulf of Mexico created as rifting separates N & S America Aulacogen forms- Mississippi Embayment beneath present lower river valley Indian Ocean forms between e. Africa & Madagascar Late Jurassic: India separates from Africa & Australia
25	The Setting: Cordilleran Mountain Building The Cordilleran margin had become a subduction zone Oceanic Kula & Farallon plates subducting under NA “Nevadan Orogeny” By Late Jurassic, it produced a volcanic arc like the Cascades, but greater size (e.g. modern Andes, South America) Evidence of continuous eruption, throughout Jurassic and Cretaceous. Large granite batholiths & metavolcanics/volcaniclastics all that remains of this volcanism
26	The Setting: Foreland Basins East of the Volcanic Arc a clastic wedge formed in the foreland basin Modern day Rocky Mountain Region Created the famous Morrison Formation- abundant dinosaur fossils Composed of pastel-colored shales, sandstone and conglomerate River & swamps deposits Evidence of semi-aridity indicates it may have been a relatively harsh environment (savannah-like climate, w/out the grass!) Dinosaurs were likely became mired at watering places, & were later carried downriver and buried by floods
27	More Jurassic Rocks Early Jurassic Widespread deposition of sand, heavily cross-bedded, and in places contain dinosaur tracks Navajo Sandstone Water bodies are restricted in rifting areas, creating evaporites Middle Jurassic- Transgression Sundance Sea advanced from west Carbonate/SS interstratified, overlain by limestone, shale & evaporites Sundance Fm. Late Jurassic: Normal marine conditions returned Appalachians had eroded and seas flooded sw end of belt
28	Plant Life of Terrestrial Jurassic Land plants dominated by ferns, ginkgoes, cycadeoids and true cycads, conifers & close relatives of living redwoods, cypresses, pines, and yews
29	Dinosaurs Ruled the Land Sauropods- largest land animals of all time Diplodocus, Brachiosaurus, Apatosaurus, Theropods- Tetanuran Carnosauria- “meat-eating reptiles” Allosaurs (Saurophaganax maximus –NA’s largest allosaur) Coelurosauria- “hollow-tailed reptiles”; extremely bird-like Compsognathus Theropods- Ceratosauria Dilophosaurus Ornithischians Stegosaurus First Bird emerges- Archaeopteryx
30	Jurassic Sauropods: Diplodocus
31	Jurassic Sauropods: Brachiosaurus Length: ~ 85-100 feet Weight: 50-80 tons
32	Jurassic Sauropods: Apatosaurus Length: ~ 70-95 feet Height: ~ 15 feet at hips Weight: 33-38 tons
33	Ceratosaur Theropods: Dilophosaurus “Double-Crested Lizard” Length: ~22 feet Weight: ½ ton
34	Carnosaur Theropods: Allosaurs Largest Jurassic carnivore in North America Length: ~38 ft Height: ~16.5 ft Weight: ~1.5 tons Claw Length: up to 6”
35	Coelurosaur Theropods- Compsognathus Probable ancestor of modern birds; were extremely bird-like More closely related to birds than carnosaurs Major Coelurosaurian groups: Maniraptora: Velociraptor, birds, and other coelurosaurs Ornithomimidae: The bird-mimic coelurosaurs Tyrannosauridae: The giant coelurosaurs
36	Ornithischians: Stegosaurus "plated lizard“ Length: 26-30 feet Weight: >3 tons Time: Late Jurassic
37	First Bird: Archaeopteryx 1^st found in 1860 Total of 10 body fossil & 1 isolated feather All from German Solnhofen Limestone May have evolved from Maniraptora group of the coelurasaur therapods
38	Life of the Jurassic Seas Giant marine reptiles were dominant predators Ichthyosaurs, plesiosaurs, giant crocodiles Modern-looking sharks and rays Cephalopods ammonites, belemnites
39	Life of the Jurassic Seas
40	Jurassic Skies: Pterosaurs
41	The First Mammals Multituberculates – now extinct group Mouse to rat-sized, rodent appearance Over 200 known species are known Layed eggs Evidence shows they burrowed & lived in trees Earliest mammals: Megazostrodon, Eozostrodon, & Morganucodon