Calendar of events


1
Calendar of events

• Lab schedule changes
• Nov. 26 microfossils
• Dec. 3 hominids
• Dec. 10 Lab exam 2

2
Tyrannosaurus rex
3
Cretaceous World
65

• Cretaceous System was named in 1822 for deposits
  that are chalky in many parts of the world
• Duration of Cretaceous time is longer than any
  other system
• Youngest system of Mesozoic Era

Cretaceous System
Mesozoic Era
142
Jurassic System
206
Triassic System
251
4
Todays outline

• Marine life of the Cretaceous
• Pelagic marine life
• Benthic marine life
• Origin of the angiosperms
• Terrestrial vertebrates

5
Marine life of the Cretaceous

• Pelagic organisms
• Expansion of diatoms silica planktonic
  foraminifera calcite and calcareous
  nannoplankton calcite
• Diatoms à deep sea siliceous ooze high
  latitudes
• Planktonic forams calcareous nannos à deep sea
  calcareous ooze mid and low latitudes chalk

6
Calcareous ooze producers
7
Deep sea oozes
8
Marine life of the Cretaceous

• Pelagic organisms
• Teleost fishes originated in Cretaceous time the
  subclass containing todays dominant freshwater
  and marine fish
• Ammonoids and belemnoids continued to flourish

9
Marine life of the Cretaceous

• Pelagic organisms
• Ichthyosaurs and marine crocodiles became rare
  but.
• Plesiosaurs were thriving and even bigger than
  before Up to 35 feet long.
• Marine lizards mosasaurs were bigger still
  Up to 55 feet long

10
Mosasaur
11
Marine life of the Cretaceous

• Benthic marine communities began to resemble
  those of todays oceans
• Benthic forams
• Burrowing bivalves
• Marine snails
• Crabs

12
Benthic forams
13
Marine life of the Cretaceous

• Surfacedwelling bivalves became spectacular
• Coiled oysters reach softball size and larger
• Rudists
• imitated corals in ecology
• formed large tropical reefs

14
Rudist reef
15
Marine life of the Cretaceous

• By end of Mesozoic time few immobile animals
  lived on seafloor in contrast to Paleozoic
  time
• Brachiopods stalked crinoids bryozoans were
  largely replaced by mobile and predatory
  bivalves snails crustaceans
• Teleost fishes were efficient predators too

16
Cretaceous invertebrates
17
Rise of the angiosperms

• Gymnosperms continued to dominate terrestrial
  floras in Cretaceous just as in Triassic and
  Jurassic
• Angiosperms initial appearance was in middle
  Cretaceous time
• Doublefertilization and enclosed seeds
• Flowers for attracting insects
• Faster reproductive cycles

18
Angiosperm diversification
19
Angiosperms and insects

• Coevolution of angiosperms and insects
• Certain species of insects are specialized to
  feed only on certain flowers
• Certain species of angiosperms are specialized to
  attract only certain insects
• Result is an increase in rates of speciation
  taxonomic diversification

20
Cretaceous terrestrial vertebrates

• Late Cretaceous dinosaur communities resembled
  modern mammal communities of Africa

Niche Cretaceous world Modern world Grazing
herds duckbilled dinos wildebeests antelopes
maiasaurs zebras Nasty herbivores horned
dinos rhinoceroses Carnivores T. rex
terrestrial crocs lions Flying
scavengers flying reptiles vultures
21
Maiasaur mom and pups
22
Warmblooded Dinosaurs?

• Evidence in support of endothermy
• Cretaceous dinos lived in high latitudes
• Birds are warmblooded and birds are highly
  specialized dinosaurs
• Dinosaur bone structure resembles that in
  warmblooded mammals
• Haversian canals

23
Dinosaur bone structure
24
Late Cretaceous scene from Alberta
25
Terrestrial crocodile
6 feet
Total length of animal was 50 feet
26
Cretaceous mammals

• Remained small and inconspicuous
• Relatively well developed sense of smell and
  hearing
• Enlarged brain areas associated with those senses
• Adaptation for nocturnal activity?
• By late Cretaceous time placental and marsupial
  groups had differentiated

27
Mammalian evolution
28
Cretaceous mammal