Vertebrates - Dinosaurs, Mammals, Birds, Ammonites – complex sutures Biologic Highlights: Vertebrates - Dinosaurs, Mammals, Birds, Ammonites – complex sutures Protista: Coccolithophores (chalk) Diatoms (diatomite), Forams (sediment), Radiolarians (chert) Angiosperms = first flowering plants (Jurassic/Cretaceous). Massive Extinction - End of Cretaceous (K/T boundary)  

Invertebrates: Insects abundant (but record sparse), Marine bivalves surpassed the brachiopods in colonization of the sea floor. Scleractinian corals dominate. Echinoids are the abundant echinoderm. Cretaceous Fossil Sea Urchin = Echinoid

Ammonoidea Cephalopods- 2 Mesozoic groups: Ceratites (abundant in Permian/Triassic), Ammonites (abundant in Jurassic/Cretaceous). Ammonites have the most complex sutures, became extinct at end of Mesozoic.

Phylum Mollusca Class Cephalopoda SUBCLASS COLEOIDEA ORDER BELEMNOIDEA (belemnites) The belemnoids have an internal calcareous shell (which resembles a cigar in size, shape, and color) Mississippian to Eocene - all extinct

Single-celled Protozoans: Radiolarians (siliceous), Foraminifers (carbonates) Foraminifera (“forams”)

Jurassic Radiolaria – Found in Chert

Land Vertebrates- Based on skull openings – Anapsids: lack openings (includes turtles), Synapsids: single opening (includes mammals), Diapsids: two openings (includes crocodiles, dinosaurs/birds, pterosaurs).

Diapsids divided into: Lepidosaurs (lizards, snakes, etc) Archosaurs (dinosaurs, pterosaurs, crocodiles ) Dinosaurs (Late Trisassic through Cretaceous) divided into: Saurischia = lizard-hip Ornithischia = bird-hip

Saurischian Dinosaurs (lizard hip) divided into: Theropods- dominant land predators (including T-Rex, Carnosaurs). Modern birds descended from Theropods. The oldest remains of a true bird are Archaeopteryx from the Jurassic Sauropodomorphs - plant eaters (includes large plant eating saurpods, such as Apatosaurus)

Include Tree of Figure 14-17

Ornithischians Dinosaurs (bird hip), All were plant eaters Includes Stegosaurs, Anklyosaurs, Ceratopsians 

Birds=Dinosaurs Scaly skin becomes feathers, early birds had characteristics of theropods (3-toed, fused back-bone, lizard-like hip). Dominated early Tertiary after K/T extinction.

Cycads - seed plants without true flowers – common by Jurassic Time. Angiosperms: flowering plants (enclosed seeds and flowers). Pollen dispersal by insects (more efficient), seed dispersal by animals. Early Cretaceous appearance. By the middle Cretaceous these flowing plants had become widespread.

Mammals Mammal-like reptiles (Synapsids) in the Permian First true mammals in the Triassic – primitive species Mammals divided into Prototherians and Therians – Therians – includes marsupials (present by Jurassic) and placental mammals. Oldest known placental mammals from the early Cretaceous

Cretaceous Extinction Extinction of Dinosaurs, Pterosaurs, Ammonoid cephalopods, many groups of bivalves, and groups of foraminifera Asteroid impact 65.5 million years ago – main cause of the extinction, but secondary influence of volcanic activity and climate changes.

Two possible causes of the Cretaceous Extinction. Volcanic eruptions and the meteor impact need to be considered together when studying and modeling the K-Pg extinction event. Meteor Impact – evidence of Iridium layer, tsunami deposits, tektites. Flood Basalt outpouring causes climate change – Deccan Traps of India. A definitive geological timeline shows that a series of massive volcanic explosions 66 million years ago spewed enormous amounts of climate-altering gases into the atmosphere immediately before and during the extinction [Princeton University (2014)]. 

First report of unusual deposits at the KT (KPg) boundary was made by the father and son scientists Luiz and Walter Alvarez (UC Berkeley), based on studies they made of deposits at Gubbio, Italy and elsewhere:

The main eruption phases began 250,000 years before the extinction The main eruption phases began 250,000 years before the extinction. For the next 750,000 years, the volcanoes unleashed more than 1.1 million cubic kilometers of lava, which comprised about 80-90 percent of the total volume of the Deccan Traps' lava flow.

End of Slide Set

Dinosaurs: leg fits under instead of out. hole in hip, S-shaped neck, fused backbone Saurischians (lizard-hip), plant and meat eaters, includes Sauropods and Carnosaurs (including Theropods).