Apatemyids - large rodent-like incisors but primitive shrew-like cheek teeth
Anagalids - rabbit-like herbivores - broad molars, high jaw joint, retain postorbital process, -most abundant Paleocene mammals in Asia.
Messel Oil Shales
Exquisitely preserved fossils including hair.
Middle Eocene of Germany
Lepitctidium, a small leptictid (or close relative) -bipedal wiht long tail to balance its body weight.
Early Rooters and Browsers
Taeniodonts - pig-sized herbivores - short legs, large forefeet and claws for digging
Tillodonts - up to bear-size - broad teeth (especially incisor 2) for eating tough foods
Pantodonts - tusked herbivores resembling hippos and even ground sloths, possibly related to tillodonts
Arctocyonids - dog-like herbivores - strong teeth and claws for digging and eating plants, some adapted for climbing trees.
Condylarth=early herbivores that gave rise to modern ungulates (horses, cattle, etc.).
Like "thecodont" it is a term hated by cladists because it represents a grade, and a paraphyletic group.
Because relationships among early grazers are poorly known, its useful to refer to a suit of similar hebivores.
Some abundant in Eocene.
(a) Arctocyonid skull
(e) Dinoceratan Uintatherium (=Uintatheres), giants of late Paleocene and early Eocene
largest paleocene carnivores=hoofed Mesonychids (a), formerly thought to be while relative.
Creodonts (b-d) most diverse early Cenozoic carnivores, later replaced by Carnivora. This may be a polyphyletic group. The carnassials the (largest shearing teeth) farther back in the tooth row (M1 or 2, m2 or 3) than in the Carnivora (P4, m1)
Northern Placental Adaptive Radiation
Survivors of early radiation - insectivores, carnivores, dermopterans, bats, primates, perissodactyls and rodents. But many early placentals (especially large) went extinct.
Early Insectivores and Shrews
Mesozoic mammals superficially shrew-like, shrews often considered most primitive living placentals.
Insectivora based on primitive characters.
Tenrecs and golden moles now in Afrotheria.
Shrews (soriconmorphs) arose in Paleocene, relatives moles and hedgehogs arose in Eocen. All insect eaters.
Moles short, flat humerus and large clawed hands for burrowing.
Hedgehogs have evolved spines from modified hairs and look like little porcupines.
Insectivores and Bats
shrews tend to lose jugal and zygomatic arch
giant miocene hedgehog (shown next to living hedgehog)
Eocene bat Icaronycteris
Fragementary remains from Paleocene, well-known and fully-developed in Eocene
(Icaronycteris - Green River Shale, Wyoming)
-Elongated forelimb bones, ulna and radius fused
-Fingers 2-5 greatly elongated to support flight membrane
-Finger 1 short with claw for climbing and hanging
-Feet turned backward for hanging
-Eyes large, ears specialized for ecohlocation
Megachiropterans (large fruit bats) now confirmed by morphology and DNA to form a clade together with Microchiropterans (small insect-eating bats)
Retain all toes and teeth
Digits 2-4 elongated to support wing membrane
Digit 1 remains small, with a claw
Most bats eat insects, some=large fruit eaters
Xenarthra (extra joints)=extra articulations between some trunk and tail vertebrae.
Ischium and ilium fused to come caudal vertebrae, probably to strengthen body for digging.
Edentate (toothless) = frequent loss of teeth.
Mostly South American, invaded North America
Retain primitive features: septomaxillary bone, ossified ribs reaching the sternum, low and variable body temperature, primitive reproductive system.
Armadillos, Glyptodonts, Tree sloths, Ground Sloths, Anteaters.
Oligocene of South America, five species of tree sloths survive today
Ground Sloths originated in the Miocene and became giants.
Megatherium of the Pleistocene reached 6 meters in length.
Several ground sloths ranged into North America during the Ice Age, as far north as Alaska!
Some caves filled with sloth dung, often with no bones.
Glyptodonts armored against phorosrhacids and saber tooth "cats."
Ground sloths herbivores only
Megatherium, size of elephant
Glyptodonts: size of Volkzwagen beetle.
Anteaters of the world
Convergent evolution. Pangolins once considered edentates, but no longer.
Began as small cat-like hunters in Paleocene without ossified auditory bullae.
Feliforms: ectoympanic bone formed bulla
-Cats, civets, mongooses, hyaenas, and extinct nimravids
Caniforms: entotympanic bone formed bulla
-Dogs and Arctoids (bears, racoons, weasels, and seals)
Carnassial teeth P4 and m1-good grinding teeth farther back in tooth row (better than creodonts)
Took over prominence from creodonts in Oligocene, leading to final creodont extinction in Miocene.
Relationship of creodonts and carnivores hotly debated - two groups may have originated independently.
Carnivores - slower start - gradually out competed creodonts, resulting in gradual extinction.
Cats=shortest skulls and lose teeth behind the carnassials for a stronger bite.
Dots retain longest jaw with no tooth loss, retain crushing postcarnassial teeth.
Weasels, bears, adn other carnivores fall between extremes.
Saber canines in several cat lineages. Lower canines generally reduced.
Smilodon: Holocene saber-tooth cat preyed on large herbivores
One subspecies of (Panthera leo) adapted to Ice age cold - lived in caves in Europe, probably hunting deer, cattle, and horses.
Late Oligocene of California (a-c)
Hindfeet rotated backward to work together as a paddle.
Early forms only semi-aquatic and retain carnassial teeth (d).
With time teeth become simplified, turning to simple homodont pegs in sea lions (e).
Seals and sea lions fed on fish.
Walruses crush shellfish with blunt teeth
Modern pangolins (scaly anteaters) live in south Asia and north Africa.
Early fossils are known from Europe and North America.
Toothless with long tongue
DNA evidence suggests a relationship to carnivores!
Major groups appear in early Eocene of North America.
Brontotheres - giants of early Badland faunas.
Perissodactyls decline over time in competition with artiodcatyls.
Axis down the middle of toe 3
Number of toes reduced from 5 to 3 to 1
Brontotheres (a) sister group to horses - late Eocene giants - North America Badlands National Park.
Chalicotheres (b) sister group of tapirs and rhinos, horse-like heads, long hooved forelimbs and short clawed hindlimbs - lived until Pleistocene in North America.