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.