1. LIFE AFTER JURASSIC PARK: MAMMAL EVOLUTION DURING THE CENOZOIC

5. 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.

6. EPOCHS OF THE CENOZOIC ERA
CENOZOIC ERA BEGINS
65.5 MILLIONS YEARS AGO
AND CONTINUES UNTIL TODAY
EPOCHS OF THE CENOZOIC ERA
PLEISTOCENE Ma
PLIOCENE Ma
3.5 Ma
MIOCENE Ma
17.7 Ma
OLIGOCENE Ma
11 Ma
EOCENE Ma
21.5 Ma
PALEOCENE Ma
10 Ma
CRETACEOUS

8. 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

10. The Palaeocene world 65-56 ma Earth was in a ‘greenhouse’ phase
Warm and wet
Land covered in rainforest

11. Early Palaeocene Mammals
Small and mostly arboreal
Unspecialised
Few leaf eaters
Few carnivores

12. Late Palaeocene Stronger seasonality Larger Herbivores and Carnivores
Usually lumped into trash-can: the “Condylarths”
Dominant carnivores were the Mesonychids

13. Molar changes in herbivores
Brachyodont (low crowned) and bunodont (rounded cusps) molars
Hypsodont (high crowned) and lophodont (with crests) molars
GRAZER
BROWSER

14. Two ways to deal with the new kind of aliments the grass is to increase fermentation area: in some cases having a hindgut fermenter portion like the colon which is much more developed that what we can see here and then the fetrmentation anteriorly in the rumen of ruminants that allow a double traetment of the food.

15. Limb changes in Perissodactyla
Miohippus
33-29 Mya
Merychippus
17-11 Mya
Equus
5 Mya
Hyracotherium
55-45 Mya
The central digit became increasingly stronger while the lateral ones became less important, and are virtually lost in the modern horse

16. Specializations in limb anatomy in relation to gait
Calcaneum
Mesopodial (tarsal)
element
Metapodial
element
Phalanges WP

20. RETURN OF DINOSAURS

23. Carnassial teeth
Specialised slicing teeth, where the trigonid and talonid are modified into blades
Present in two orders: Creodonta and Carnivora

24. Creodonta 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

25. 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

26. Hyaenodontidae
More dog-like forms, broader diet and adaptations to running
Made it into Africa and survived there longer than elsewhere
in the world

27. Megistotherium A giant hyaenodontid. The largest creodont
Also had the largest skull of any terrestrial carnivore
From the Miocene of northern Africa

28. True Carnivores: Order Carnivora
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)

30. First Large Carnivora
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

31. 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

32. 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

33. Bears - Ursidae 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

34. Ursinae - modern bears Large, heavily built and omnivorous
Has produced an herbivorous species (Giant Panda)
Were present in Africa in the Late Miocene
Agriotherium

35. Dogs - Canidae Evolved in the Eocene of North America
Earliest form was Hesperocyon (Late Eocene - Oligocene)
It was small, fox-like and omnivorous

36. Dogs 2: The Borophaginae
A uniquely North American radiation of large predators including
bone-crushing hyaena-like forms (Oligocene-Miocene)

37. 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

38. Marine Carnivores: Pinnepedia
Enaliarctos, earliest seal
Part of the dog branch, related to weasels and bears
Evolved on the Pacific coast of North America in the Early Miocene

39. The hyaenid radiation
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

40. Later hyaenas Became larger game meat eaters,
Ictitherium, Miocene, Africa
Became larger game meat eaters,
The early large hyaenas were fast runners

41. Bone-cracking hyaenas
Pachycrocuta
50% larger than modern hyaena
Late Pliocene-Early Pleistocene
Evolved in the Late Miocene
Spread as far as North America for a brief time in the Pleistocene

42. Cats - Felidae
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

43. Proailurus Earliest cat. More teeth than modern cats.
Also flat footed (plantigrade).

44. Machairodontinae - Sabre Toothed Cats
Smilodon, Pleistocene, America (North and South)
Typical heavy- bodied ambush predator

45. Homotherium a running machairodontine
Pliocene, Africa, Europe and North America
Sloping back, small claws, small sabres

46. 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.

47. 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

48. 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

49. 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.)

50. 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

51. 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

52. EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
Closely related to elephants but with
hippo-like lifestyle
70 cm

53. EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
2.1 mts
Artiodactyl, related to pigs
Mongolia, U.S.
Bony
lumps
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
Mental and mandibular tubercles

54. EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS
2.5 mts
Mongolia, U.S.
Perissodactyl lineage well diversified in the Eocene, restricted to North America and Asia

55. 4.5 mts EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS Oligocene Asian group
Paracetatherium is the largest terrestrial mammal ever
4.5 mts
Browser on leaves well above the reach of any other mammals
Perissodactyl, closely related to rhinos

56. EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS

57. 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
Late Eocene, Fayum, Egypt
Semiaquatic animals

59. MIOCENE HERBIVOROUS MEGAMAMMALS
Perissodactyl from Europe, Asia
and, latter, Africa
Somewhat larger than a horse
2.6 m
Short, strong hind legs. The long front legs had enormously long, curved claws; knuckle-walking

60. 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

61. PROBOSCIDEAN DIVERSITY
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
4 mts
Miocene of Europe

62. MEGAHERBIVORES FROM SOUTH AMERICA
MERIDUNGULATA, Litopterna
One of the last South American survivors. Extinct in the Pleistocene
It is a camel-like mammal with elongated neck and limbs
1.5 mts
Toatherium
Miocene, with a equid-like condition of the limbs

63. MEGAHERBIVORES FROM SOUTH AMERICA
MERIDUNGULATA, Notoungulata
Most diverse meridiungulates
Extremely variable in size
Toxodonts size of a rhino, from Miocene to Pleistocene

64. 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
With huge claws on its feet. Like a modern anteater, it had to walk on the sides of its feet
6 mts

65. MEGAHERBIVORES FROM AUSTRALIA
Giant marsupial Diprotodon
2.5 m at the shoulder
Browsing on soft vegetation

66. PLEISTOCENE HERBIVOROUS MEGAMAMMALS
Mamuthus primigenius or woolly mammut
Known from bones and frozen carcasses from Ireland to North America. The best preserved carcasses are from Siberia.
3 mts
Colour patterns known from cave paintings
2.5 mts
Megaloceras or giant deer is a cervid artiodactyl from Europe

67. AMERICAN BIOTIC INTERCHANGE

69. 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 (5-40 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.

70. 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 hypsodont-toothed 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.