LIFE AFTER JURASSIC PARK:
MAMMAL EVOLUTION DURING THE
CENOZOIC
PALEOGEOGRAPHY AND CLIMATIC CHANGES IN THE CENOZOIC
There were a series of climatic changes during the Cenozoic that
were the product of changes in the continental masses.
This has a direct relationship with changes in the vegetation and in
the animals represented in the different continents and latitudinal
regions of the world.
We will see first the changes in the geography in the past, and then
how that produced change in landscapes (principally vegetation)
and influenced the evolution of certain traits in herbivorous
mammals.
CENOZOIC ERA BEGINS
65.5 MILLIONS YEARS AGO AND CONTINUES UNTIL TODAY
EPOCHS OF THE CENOZOIC ERA
PLEISTOCENE
PLIOCENE
MIOCENE
OLIGOCENE
EOCENE
PALEOCENE
CRETACEOUS
1.8 Ma
5.3 Ma 3.5 Ma
17.7 Ma
23 Ma
11 Ma
34 Ma
55.5 Ma 21.5 Ma
65.5 Ma 10 Ma
Landscape changes
In the early Cenozoic the global
temperatures remains high and
there are tropical-like forests in
high latitudes (750 North)
The Miocene was hot and dry
and produced a reduction in
forest and an increase in
savanna environments with
grassland
The Palaeocene world
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65-56 ma
Earth was in a ‘greenhouse’ phase
Warm and wet
Land covered in rainforest
Early Palaeocene Mammals
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Small and mostly arboreal
Unspecialised
Few leaf eaters
Few carnivores
Late Palaeocene
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Stronger seasonality
Larger Herbivores and Carnivores
Usually lumped into trash-can: the
“Condylarths”
Dominant carnivores were the
Mesonychids
Molar changes in herbivores
Brachyodont (low crowned)
and bunodont (rounded
cusps) molars
Hypsodont (high crowned)
and lophodont (with
crests) molars
BROWSER
GRAZER
Limb changes in Perissodactyla
Hyracotherium
55-45 Mya
Miohippus
33-29 Mya
The central digit became increasingly
stronger while the lateral ones
became less important, and are
virtually lost in the modern horse
Merychippus
Equus
17-11 Mya
5 Mya
Specializations in limb
anatomy in relation to gait
Calcaneum
Mesopodial (tarsal)
element
Metapodial
element
Phalanges
WP
RETURN OF DINOSAURS
Carnassial teeth
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Specialised slicing teeth, where the
trigonid and talonid are modified into
blades
Present in two orders: Creodonta and
Carnivora
Creodonta
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Carnassial pair towards back of jaws; M1/M2 or M2/M3
Late Palaeocene to Early Miocene, dominant
carnivores in North America, Asia, Europe and Africa
in the Eocene and Oligocene
Two main Families : Oxaenidae and Hyaenodontidae
Oxaenidae
Patriofelis; Palaeocene
More cat-like forms, specialised for pure meat diets
and ambush predation
Also some bone-crushing, hyaena-like forms
Never made it to Africa
Hyaenodontidae
More dog-like forms, broader diet and adaptations to running
Made it into Africa and survived there longer than elsewhere
in the world
Megistotherium
A giant hyaenodontid. The largest creodont
Also had the largest skull of any terrestrial carnivor
From the Miocene of northern Africa
True Carnivores:
Order Carnivora
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First appeared in the Late Palaeocene (small)
By the Late Miocene had replaced creodonts
as the dominant terrestrial carnivores in
Africa, North America, Europe and Asia
Carnassial pair are P4/M1
Have evolved herbivorous and fully aquatic
forms
Two main branches: Feliformia (cat branch)
and Caniformia (dog branch)
First Large Carnivora
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Appeared in the Oligocene, mostly extinct
dog-branch families: amphicyonids,
nimravids and hemicyonine bears but the
cat-branch radiation of hyaenids soon
followed in the Early Miocene
Amphicyonidae: Bear-dogs
Pouncing predators of samll to middle size game, probably able to
climb to some degree.
Some later members became heavy-built bear-like omnivores
Spread throughout northern continents
Entered Africa in the Miocene
Nimravidae: False Sabre-Tooths
Very similar to sabre-toothed felids (including retractable claws)
A case of convergence
Oligocene-Miocene
North America, Europe, Asia and probably Africa
Bears - Ursidae
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Two types: Hemicyoninae and Ursinae
Early Hemicyoninae (first occurrence in the
Late Oligocene) running dog-like predators
(although broader diet than true dogs)
Hemicyoninae were present in Africa in Early
Miocene
Hemicyon
Ursinae - modern bears
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Large, heavily built and omnivorous
Has produced an herbivorous species (Giant
Panda)
Were present in Africa in the Late Miocene
Agriotherium
Dogs - Canidae
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Evolved in the Eocene of North America
Earliest form was Hesperocyon (Late
Eocene - Oligocene)
It was small, fox-like and omnivorous
Dogs 2: The Borophaginae
A uniquely North American radiation of large predators including
bone-crushing hyaena-like forms (Oligocene-Miocene)
Dogs 3: Caninae -modern dogs
Evolved the fast pack-hunting wolf-like forms that radiated out of
North America in the Late Miocene.
Did not reach Africa until the Pliocene
Marine Carnivores: Pinnepedia
Enaliarctos, earliest seal
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Part of the dog branch, related to
weasels and bears
Evolved on the Pacific coast of North
America in the Early Miocene
The hyaenid radiation
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Started as small, civet-like hunters of small
game and insects
First found in Europe but quickly moved to
Asia and Africa
The aardwolf is a modern example of such
small-game specialised hyaenas
Later hyaenas
Ictitherium, Miocene, Africa
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Became larger game meat eaters,
The early large hyaenas were fast runners
Bone-cracking hyaenas
Pachycrocuta
50% larger than modern hyaena
Late Pliocene-Early Pleistocene
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Evolved in the Late Miocene
Spread as far as North America for a
brief time in the Pleistocene
Cats - Felidae
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Started as small (caracal-sized) aboreal
ambush predators in the Late Oligocene of
Europe
Sabre-Tooths (Machairodontinae) were the
dominant large cats in the Miocene to the
Early Pliocene
Short tooth big cats (Pantherinae) don’t
appear until the latest Pliocene
Proailurus
Earliest cat. More teeth than modern cats.
Also flat footed (plantigrade).
Machairodontinae - Sabre Toothed Cats
Smilodon, Pleistocene, America (North and South)
Typical heavy- bodied ambush predator
Homotherium a running
machairodontine
Pliocene, Africa, Europe and North America
Sloping back, small claws, small sabres
Megaherbivorous Terrestrial Mammals
Mammal groups that include large-sized species are
EXTANT GROUPS
Artiodactyla (even-toed ungulates); the most diverse group of
living ungulates includes pigs, hippos, camels, giraffes, deer,
and bovids (cattle and antelope). Laurasia
Perissodactyla (odd-toed ungulates) represented by horses,
rhinos and tapir. Laurasia
Proboscideans are elephants and relatives. African
Edentata which are represented by sloths, anteaters and
armadillos are from America. Fossils of this group (e.g.
gliptodonts and ground-sloths) were part of the American
Megafauna.
Marsupials which are known only in Australia and America.
Fossils of this group (e.g. Diprotodon) were part of the
Australian Megafauna.
Megaherbivorous Terrestrial Mammals
EXTINCT GROUPS
Meridiungulata, an extremely diverse group of South American ungulates.
This include at least four orders
Pantodonts, the very first of the large, herbivorous placental mammals
to evolve after the Cretaceous. Laurasia
Dinocerata, the largest of all the archaic Paleocene-Eocene herbivores.
Laurasia
Embrithopoda, huge rhinoceros-sized showing skull with massive horns
known from the Eocene. Africa
PALEOCENE-EOCENE
Pantodonta 5 toed plantigrade,
2.5 metres length; 650 kg (weight of
an eland)
Coryphodon, with large canines; a
semiaquatic life is suggested for this
animal
Mesonychids
Early carnivores, weasel to bear sized
Lived in Asia, Europe and North America
Sharp teeth (but no carnassials), five fingers and toes that were
tipped with small hoofs
Related to Artiodactyls (cows, camels, pigs etc.)
Andrewsarchus
Giant mesonychid, skull was 83 cm long.
The body was probably rhino-sized or larger
Largest ever terrestrial carnivorous mammal
May have done a lot of scavenging
PALEOCENE-EOCENE MEGAHERBIVOROUS MAMMAL
Dinocerata includes uintatheres,
enormous size, 1450 kilograms
rhino-like, with three pairs of large
bony protuberances
without upper incisors and large
upper canines
EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
Closely related to elephants but with
hippo-like lifestyle
70 cm
EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
2.1 mts
Artiodactyl, related to pigs
Mongolia,
U.S.
Omnivorous, scavenger
Low bunodont molars
Size varying from that of peccary to bison
Skull is half a meter long in Eocene forms
and nearly one meter long in Miocene
forms
Bony
lumps
Mental and mandibular tubercles
EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
2.5 mts
Mongolia,
U.S.
Perissodactyl lineage well diversified in the Eocene, restricted to
North America and Asia
EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
Oligocene Asian
group
1.3 mts
4.5 mts
Paracetatherium
is the largest
terrestrial
mammal ever
Browser on leaves
well above the
reach of any other
mammals
Perissodactyl, closely related to rhinos
EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
Embrithopoda (Arsinoitherium) rhino-sized, massive and hollow horns
almost of the same size of the skull and second small horns above the
orbit
Complete dentition
without tusks or
enlarged canines,
hypsodont molars
Semiaquatic animals
Late Eocene, Fayum, Egypt
MIOCENE HERBIVOROUS MEGAMAMMALS
Perissodactyl from Europe, Asia
and, latter, Africa
Somewhat larger than a horse
Short, strong hind legs. The long front
legs had enormously long, curved
claws; knuckle-walking
2.6 m
MIOCENE HERBIVOROUS MEGAMAMMALS
Perissodactyl, from Asia and Africa,
one of the last surviving chalicotheres
But didn’t walk on their knuckles
2 mts
Sparse remains of this animal have
been found in famous hominid fossil
sites in East Africa
PROBOSCIDEAN DIVERSITY
4 mts
The deinotheres were the gigantic
cousins of the elephants and flourished
at the time of Australopithecus
Tusks of Deinotherium are a pair of
lower incisors extending ventrally
due to a downward reflection of the
symphysis of the lower jaw
Miocene of Europe
MEGAHERBIVORES FROM SOUTH AMERICA
MERIDUNGULATA, Litopterna
One of the last
South American
survivors. Extinct
in the Pleistocene
1.5 mts
It is a camel-like
mammal with
elongated neck
and limbs
Toatherium
Miocene, with a
equid-like condition
of the limbs
MEGAHERBIVORES FROM SOUTH AMERICA
MERIDUNGULATA, Notoungulata
Most diverse meridiungulates
Extremely variable in size
Toxodonts size of a rhino, from
Miocene to Pleistocene
MEGAHERBIVORES FROM SOUTH AMERICA
Edentate glyptodont, with an
osseous carapace and tail
with ring of bones and
spines
1.5 mts
Edentate pilosa known from many
skeletons, fossilised footprints
and mummified hair
6 mts
With huge claws on its
feet. Like a modern
anteater, it had to walk
on the sides of its feet
MEGAHERBIVORES FROM AUSTRALIA
Giant marsupial Diprotodon
2.5 m at the shoulder
Browsing on soft vegetation
PLEISTOCENE HERBIVOROUS MEGAMAMMALS
Mamuthus primigenius or woolly mammut
3 mts
Known from bones and frozen carcasses
from Ireland to North America. The best
preserved carcasses are from Siberia.
Colour patterns
known from
cave paintings
2.5 mts
Megaloceras or
giant deer is a
cervid artiodactyl
from Europe
AMERICAN BIOTIC INTERCHANGE
Megaherbivorous mammals from the Cenozoic. Summary
1. The majority of Paleocene mammals were still small-bodied insectivores
and omnivores, but there were several new groups that were medium-sized (540 kg) and large (>40 kg).
2. Some specialized herbivores existed in the northern faunas such as
Pantodonta and Dinocerata that includes the first large, herbivorous placental
mammals to evolve after the Cretaceous.
3. In South America edentates and the first Meridiungulata (or South American
ungulates) are known from the Late Paleocene.
4. In the Eocene, Perissodactyls soon become an important group of medium
to large-sized herbivores. There are already early representatives of the
families of horses, rhino, and tapirs, and also include bizarre, large-bodied
browsing groups, the chalicotheres and the brontotheres. Artiodactyls
remained relatively modest during the Eocene and Proboscidea are also first
known from the Eocene.
5. In the Late Eocene of Fayum, Egypt, the herbivores were dominated by
proboscideans, hyracoidean, and Arsinoitherium. In South America, the
meridiungulates radiated throughout the Eocene.
6. In the Miocene, there is an immigration into Africa (that was previously an
isolated continent) of many Eurasian groups, basics for the development of
the modern African fauna: rhinocerotid and chalicothere, and giraffid, bovid,
suid and tragulid families of artiodactyls. Proboscideans migrate from Africa
northward, at about 20 Ma.
7. Towards the end of the Miocene (about 7 Ma) there was a spread of
grasslands, coincidental with a worldwide faunal change in which hypsodonttoothed mammals, especially artiodactyls, became the dominant ungulates.
8. In the Plio-Pleistocene, the most remarkable episode is the great American
Biotic Interchange, which concerns the exchange of faunas, including
megaherbivores, following the connection of South America and North
America by the Isthmus of Panama.
9. The end of the Pleistocene (~ 10,000 years ago) was marked by the abrupt
extinction of many mammals but especially species of the megafauna.