The Paleogene World
Pleistocene
Cenozoic
• Two-fold subdivision of
Cenozoic: Paleogene,
Neogene
• Previously, Cenozoic was
divided into Tertiary
(Paleocene-Pliocene) and
Quaternary (PleistoceneHolocene)
Holocene
Neogene
Pliocene
24
Miocene
Oligocene
Paleogene
65
Earth History, Ch. 18
Eocene
Paleocene
1
Paleogene life
• In marine realm, most groups that survived
end-Cretaceous mass extinction recovered
and diversified during Paleogene
– Planktonic forams, calcareous nannos,
mollusks, arthropods
• Demise of giant marine reptiles opened the
door to whales (Eocene) and giant sharks!
Earth History, Ch. 18
2
Whale evolution (Eocene-Holocene)
Large, marine
forms
Terrestrial ancestor
Earth History, Ch. 18
3
Giant Eocene shark
Modern shark jaws
Earth History, Ch. 18
4
Paleogene life
• Other interesting newcomers to marine or
marginal marine habitats:
– Penguins (Eocene)
– Pinnipeds (seals, sea lions, walruses)
• Thought to have evolved from terrestrial ancestors
in Paleogene time, but oldest fossils are Neogene
Earth History, Ch. 18
5
Paleogene life
• On land…………..
– Diversification and “modernization” of angiosperms
– By early Oligocene time, half of all angiosperm
genera were ones that still exist today
• Origin of grasses
– Earliest forms were sedge-like (discontinuous growth)
– Late Oligocene-Neogene forms capable of continuous
growth (able to withstand grazing pressure)
Earth History, Ch. 18
6
Paleogene life
• Explosive adaptive
radiation of
mammals!
– By Eocene time, most
modern orders of
mammals had
appeared, including
primates, carnivores
and horses
Earth History, Ch. 18
Cantius, climbing around in
our family tree!
7
Eocene
fossil bat
Earth History, Ch. 18
8
Earth History, Ch. 18
9
Paleogene life
• Other Eocene oddities…………..
– Differentiation of ungulates (hoofed
herbivores)
• Even-toed (cattle, sheep, antelope, bison, pigs,
camels, etc.)
• Odd-toed (horses, tapirs, rhinos)
– Appearance of elephants
– Appearance of Diatryma (giant, flightless
birds)
Earth History, Ch. 18
10
Hyracotherium (“Eohippus”)
earliest horse (odd-toed)
Dog-sized
4 toes
3 toes
Earth History, Ch. 18
11
Diacodexis
(early even-toed ungulate)
Earth History, Ch. 18
12
Eocene elephants
Earth History, Ch. 18
13
Diatryma
(stay away from this turkey!)
8 ft
Earth History, Ch. 18
14
Paleogene life
• Many groups of mammals became extinct
during Eocene time
• Oligocene was noteworthy for:
– Paraceratherium, largest land mammal ever
(member of rhino family)
– Origin of true monkeys
– “Extinction” of horses throughout Eurasia
– Expansion of big cats
Earth History, Ch. 18
15
Earth History, Ch. 18
16
Paraceratherium
18 ft at shoulder
Earth History, Ch. 18
17
Aegyptopithecus
(Oligocene monkey)
Earth History, Ch. 18
18
horses mostly
absent in Old World
Earth History, Ch. 18
19
Dinictis
(Oligocene saber-tooth cat)
Earth History, Ch. 18
20
Oligocene mammalian fauna of
Nebraska & South Dakota
Earth History, Ch. 18
21