LIFE AFTER JURASSIC PARK: MAMMAL EVOLUTION DURING THE CENOZOIC

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. CENOZOIC ERA BEGINS 65.5 MILLIONS YEARS AGO AND CONTINUES UNTIL TODAY EPOCHS OF THE CENOZOIC ERA PLEISTOCENE 1.8 Ma PLIOCENE 5.3 Ma 3.5 Ma 17.7 Ma MIOCENE 23 Ma OLIGOCENE 34 Ma 11 Ma EOCENE 55.5 Ma 21.5 Ma PALEOCENE 65.5 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

15. Hyracotherium 55-45 Mya Miohippus 33-29 Mya Merychippus 17-11 Mya Equus 5 Mya Limb changes in Perissodactyla 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 • Part of the dog branch, related to weasels and bears • Evolved on the Pacific coast of North America in the Early Miocene Enaliarctos, earliest seal

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, • The early large hyaenas were fast runners Ictitherium, Miocene, Africa

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