LIFE AFTER JURASSIC PARK: LIFE AFTER JURASSIC PARK: MAMMAL EVOLUTION DURING THE MAMMAL EVOLUTION DURING THE

CENOZOICCENOZOIC

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 inthe 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 1.8 MaPLIOCENE 5.3 MaMIOCENE 23 MaOLIGOCENE 34 MaEOCENE 55.5 Ma PALEOCENE 65.5 Ma

CRETACEOUS

10 Ma

21.5 Ma

11 Ma17.7 Ma3.5 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 worldThe Palaeocene world 65-56 ma65-56 ma Earth was in a ‘greenhouse’ phaseEarth was in a ‘greenhouse’ phase Warm and wetWarm and wet Land covered in rainforestLand covered in rainforest

Early Palaeocene Early Palaeocene MammalsMammals

Small and mostly arborealSmall and mostly arboreal UnspecialisedUnspecialised Few leaf eatersFew leaf eaters Few carnivoresFew carnivores

Late PalaeoceneLate Palaeocene

Stronger seasonalityStronger seasonality Larger Herbivores and CarnivoresLarger Herbivores and Carnivores Usually lumped into trash-can: the Usually lumped into trash-can: the

“Condylarths”“Condylarths” Dominant carnivores were the Dominant carnivores were the

MesonychidsMesonychids

Brachyodont (low crowned) and bunodont (rounded cusps) molars

Hypsodont (high crowned) and lophodont (with crests) molars

Molar changes in herbivores

BROWSER GRAZER

Merychippus

17-11 Mya

Hyracotherium

55-45 Mya

Equus

5 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

Limb changes in Perissodactyla

Calcaneum

Phalanges

Metapodialelement

Mesopodial (tarsal)element

Specializations in limb anatomy in relation to gait

WP

RETURN OF DINOSAURSRETURN OF DINOSAURS

Carnassial teethCarnassial teeth Specialised slicing teeth, where the Specialised slicing teeth, where the

trigonid and talonid are modified trigonid and talonid are modified into bladesinto blades

Present in two orders: Creodonta Present in two orders: Creodonta and Carnivoraand Carnivora

CreodontaCreodonta Carnassial pair towards back of jaws; MCarnassial pair towards back of jaws; M11/M/M22 or M or M22/M/M33

Late Palaeocene to Early Miocene, dominant Late Palaeocene to Early Miocene, dominant carnivores in North America, Asia, Europe and Africa carnivores in North America, Asia, Europe and Africa in the Eocene and Oligocenein the Eocene and Oligocene

Two main Families : Oxaenidae and HyaenodontidaeTwo main Families : Oxaenidae and Hyaenodontidae

OxaenidaeOxaenidae

More cat-like forms, specialised for pure meat dietsand ambush predationAlso some bone-crushing, hyaena-like formsNever made it to Africa

Patriofelis; Palaeocene

HyaenodontidaeHyaenodontidae

More dog-like forms, broader diet and adaptations to runningMade it into Africa and survived there longer than elsewhere in the world

MegistotheriumMegistotherium

A giant hyaenodontid. The largest creodontAlso had the largest skull of any terrestrial carnivore From the Miocene of northern Africa

True Carnivores: True Carnivores: Order CarnivoraOrder Carnivora

First appeared in the Late Palaeocene First appeared in the Late Palaeocene (small)(small)

By the Late Miocene had replaced creodonts By the Late Miocene had replaced creodonts as the dominant terrestrial carnivores in as the dominant terrestrial carnivores in Africa, North America, Europe and AsiaAfrica, North America, Europe and Asia

Carnassial pair are P4/M1Carnassial pair are P4/M1 Have evolved herbivorous and fully aquatic Have evolved herbivorous and fully aquatic

formsforms Two main branches: Feliformia (cat branch) Two main branches: Feliformia (cat branch)

and Caniformia (dog branch)and Caniformia (dog branch)

First Large CarnivoraFirst Large Carnivora

Appeared in the Oligocene, mostly Appeared in the Oligocene, mostly extinct dog-branch families: extinct dog-branch families: amphicyonids, nimravids and amphicyonids, nimravids and hemicyonine bears but the cat-hemicyonine bears but the cat-branch radiation of hyaenids soon branch radiation of hyaenids soon followed in the Early Miocenefollowed in the Early Miocene

Amphicyonidae: Bear-dogsAmphicyonidae: 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 omnivoresSpread throughout northern continents Entered Africa in the Miocene

Nimravidae: False Sabre-Nimravidae: False Sabre-ToothsTooths

Very similar to sabre-toothed felids (including retractable claws)A case of convergenceOligocene-MioceneNorth America, Europe, Asia and probably Africa

Bears - UrsidaeBears - Ursidae Two types: Hemicyoninae and UrsinaeTwo types: Hemicyoninae and Ursinae Early Hemicyoninae (first occurrence in Early Hemicyoninae (first occurrence in

the Late Oligocene) running dog-like the Late Oligocene) running dog-like predators (although broader diet than predators (although broader diet than true dogs)true dogs)

Hemicyoninae were present in Africa in Hemicyoninae were present in Africa in Early MioceneEarly Miocene

Hemicyon

Ursinae - modern bearsUrsinae - modern bears Large, heavily built and omnivorousLarge, heavily built and omnivorous Has produced an herbivorous species Has produced an herbivorous species

(Giant Panda)(Giant Panda) Were present in Africa in the Late Were present in Africa in the Late

MioceneMiocene Agriotherium

Dogs - CanidaeDogs - Canidae Evolved in the Eocene of North Evolved in the Eocene of North

AmericaAmerica Earliest form was Earliest form was HesperocyonHesperocyon

(Late Eocene - Oligocene)(Late Eocene - Oligocene) It was small, fox-like and It was small, fox-like and

omnivorousomnivorous

Dogs 2: The BorophaginaeDogs 2: The Borophaginae

A uniquely North American radiation of large predators including bone-crushing hyaena-like forms (Oligocene-Miocene)

Dogs 3: Caninae -modern Dogs 3: Caninae -modern dogsdogs

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: Marine Carnivores: PinnepediaPinnepedia

Part of the dog branch, related to Part of the dog branch, related to weasels and bearsweasels and bears

Evolved on the Pacific coast of Evolved on the Pacific coast of North America in the Early MioceneNorth America in the Early Miocene

Enaliarctos, earliest seal

The hyaenid radiationThe hyaenid radiation

Started as small, civet-like hunters of small game and Started as small, civet-like hunters of small game and insectsinsects

First found in Europe but quickly moved to Asia and AfricaFirst found in Europe but quickly moved to Asia and Africa The aardwolf is a modern example of such small-game The aardwolf is a modern example of such small-game

specialised hyaenasspecialised hyaenas

Later hyaenasLater hyaenas

Became larger game meat eaters, Became larger game meat eaters, The early large hyaenas were fast The early large hyaenas were fast

runnersrunners

Ictitherium, Miocene, Africa

Bone-cracking hyaenasBone-cracking hyaenas

Evolved in the Late MioceneEvolved in the Late Miocene Spread as far as North America for Spread as far as North America for

a brief time in the Pleistocenea brief time in the Pleistocene

Pachycrocuta50% larger than modern hyaenaLate Pliocene-Early Pleistocene

Cats - FelidaeCats - Felidae

Started as small (caracal-sized) aboreal Started as small (caracal-sized) aboreal ambush predators in the Late Oligocene ambush predators in the Late Oligocene of Europeof Europe

Sabre-Tooths (Machairodontinae) were Sabre-Tooths (Machairodontinae) were the dominant large cats in the Miocene the dominant large cats in the Miocene to the Early Plioceneto the Early Pliocene

Short tooth big cats (Pantherinae) don’t Short tooth big cats (Pantherinae) don’t appear until the latest Plioceneappear until the latest Pliocene

ProailurusProailurus

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

Machairodontinae - Sabre Toothed Machairodontinae - Sabre Toothed CatsCats

Smilodon, Pleistocene, America (North and South)Typical heavy- bodied ambush predator

Homotherium Homotherium a running a running machairodontinemachairodontine

Pliocene, Africa, Europe and North AmericaSloping back, small claws, small sabres

Megaherbivorous Terrestrial Mammals

Mammal groups that include large-sized species are

EXTANT GROUPSArtiodactyla (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

Dinocerata, the largest of all the archaic Paleocene-Eocene herbivores. Laurasia

Pantodonts, the very first of the large, herbivorous placental mammals to evolve after the Cretaceous. 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

MesonychidsMesonychids

Early carnivores, weasel to bear sizedLived in Asia, Europe and North AmericaSharp teeth (but no carnassials), five fingers and toes that were tipped with small hoofsRelated to Artiodactyls (cows, camels, pigs etc.)

Andrewsarchus Andrewsarchus

Giant mesonychid, skull was 83 cm long.The body was probably rhino-sized or largerLargest ever terrestrial carnivorous mammalMay have done a lot of scavenging

Dinocerata includes uintatheres,enormous size, 1450 kilograms

rhino-like, with three pairs of largebony protuberances

without upper incisors and large upper canines

PALEOCENE-EOCENE MEGAHERBIVOROUS MAMMAL

EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS

70 cm

Closely related to elephants but withhippo-like lifestyle

EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS

Mongolia, U.S.

Artiodactyl, related to pigs

2.1 mts

Omnivorous, scavengerLow bunodont molarsSize varying from that of peccary to bisonSkull is half a meter long in Eocene forms and nearly one meter long in Miocene forms

Bony lumps

Mental and mandibular tubercles

Perissodactyl lineage well diversified in the Eocene, restricted to North America and Asia

2.5 mts

Mongolia, U.S.

EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS

EOCENE-OLIGOCENE HERBIVOROUS MEGAMAMMALS

Perissodactyl, closely related to rhinos

Paracetatherium is the largest terrestrial mammal ever4.5 mts

Oligocene Asian group1.3 mts

Browser on leaves well above the reach of any other mammals

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

Late Eocene, Fayum, EgyptSemiaquatic animals

Complete dentition without tusks or enlarged canines, hypsodont molars

Perissodactyl from Europe, Asia and, latter, Africa

Short, strong hind legs. The long front legs had enormously long, curved claws; knuckle-walking

2.6 m

MIOCENE HERBIVOROUS MEGAMAMMALS

Somewhat larger than a horse

MIOCENE HERBIVOROUS MEGAMAMMALS

Perissodactyl, from Asia and Africa, one of the last surviving chalicotheres

Sparse remains of this animal have been found in famous hominid fossil sites in East Africa

But didn’t walk on their knuckles

2 mts

PROBOSCIDEAN DIVERSITY

Miocene of Europe

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

MEGAHERBIVORES FROM SOUTH AMERICA

1.5 mts

Toatherium

MERIDUNGULATA, Litopterna

Miocene, with a equid-like condition of the limbs

One of the last South American survivors. Extinct in the Pleistocene

It is a camel-like mammal with elongated neck and 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

1.5 mts

Edentate glyptodont, with an osseous carapace and tail with ring of bones and spines

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

Megaloceras or giant deer is a cervid artiodactyl from Europe

2.5 mts

Colour patterns known from cave paintings

Mamuthus primigenius or woolly mammut

3 mtsKnown from bones and frozen carcasses from Ireland to North America. The best preserved carcasses are from Siberia.

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 (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.

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.