The Miocene Epoch

General Information ~ million years ago Continents similar to modern positions No major extinctions, but some small extinctions of woodland herbivores and oceanic animals Climate: Early on there was much global warming. Some tropical forests began to expand. Mountain formations caused many changes in weather patterns and increases in aridity. Antarctica became further separated from other continents leading to the formation of polar ice caps and changing ocean circulations. By the end of the Miocene epoch, global cooling was a trend. This helped lead to later glaciations. The Miocene epoch is characterized by the emergence of grasslands and the reduction in forests, kelp forest ecosystems and rapid mammal evolution and diversity

Plant Evolution 95% of seed plant families existed by the end of Miocene epoch. Tropical Rainforests and conifer forests dwindled Drove many woodland herbivores to adapt to a grassland environment or go extinct Grasslands expanded Diversification of grasses Supported new grazing species of mammals Kelp forests first appeared in the oceans Supported new species such as otters, fish, and invertebrates such as crab

Kelp forests were a major ecosystem that developed during the Miocene epoch. This is the first time they can been proven to have appeared. Scientists can only date kelp forests by the fossils of animals common to the areas because marine plants do not preserve well. This ecosystem hosted many new animals that prospered in the kelp forests such as sea otters, many fish, prehistoric seahorses, and a variety of invertebrates including crabs and other crustaceans all still common to kelp forests. Kelp Forests

Ocean Animals Many other marine animals were present and evolving in oceans due to changing circulation patterns, temperatures, and nutrient levels. Marine crocodiles were common Families of marine mammals we know today arose such as whales, seals, walruses, and many more. The Megalodon shark and other giant sharks existed during the Miocene and preyed on early whales.

Invertebrates Half of the marine invertebrates that were present during the Miocene epoch are still present today including: Echinoderms Snails Bivalves Crustaceans Cephalopods: In particular squid and nautilus Other invertebrates noted during this time included: Insects: Ants, Bees, Ladybirds, Cockroaches, Dragonflies, Mosquitoes, Aphids Arachnids: Scorpions, Jumping spiders, Orb Weavers, Tarantulas Crabs: Hermit crabs, Spider crabs Millipedes, Goose Barnacules, Slugs, Jellyfish

Grassland Ecosystems Grasslands were the primary new ecosystem to emerge during the Miocene epoch, they were created from a combination of global cooling and the drying of many continental interiors. This emergence of grassland ecosystems forced changes in many species Many woodland herbivores went extinct in regions of Europe and North America and were replaced by prairie grazers as climate cooling reduced forests. This era saw many rapid changes in the cloven hooved mammals. The majority of the precursors to modern hoofed mammals and grazers appeared in this time period, including giraffes, elephants, deer, camels, horses, and many more. Most insects, arthropods, and other invertebrates present resemble those of today. Carnivorous species were also affected Early Feline and Canine species arose as some of the dominant predators, examples would be early hyenas and the ancestors of the sabre-tooth tiger

Horses and Other Grazers Many important changes to the horse and it’s relatives occurred in the Miocene primarily in North America Horses went from small cat-sized herbivores to the large animals we recognize today. The grassland grazers made rapid changes to their tooth structure by having a much deeper crown and more enamel in order to accommodate for the constant wear to their teeth by grass, which is much coarser and wears teeth down faster than leaves. Changes to the digestive tract of these animals is thought to have occurred as well Horses quickly spread around the world as they were very adapted to the rising grassland environments and split off into zebras in Africa.

Mammals There are extensive records of terrestrial mammals as mammals reached their most diverse point. At least half of mammalian families today were present and forming. Primitive: dogs, bears, hyenas, saber-toothed cats, horses, camels, deer, antelope, giraffes, marsupials, sloths whales, seals, walruses, sea otters Larger carnivores and fast running herbivores became popular as well as small, quick rodents most of which possesed more intelligence than previous iterations.

Primates Many of the higher apes and other higher primates underwent extensive evolutions emerging from monkeys. Primates were present across the globe, but apes dominated the ecosystems. Last primate to show in the North American fossil record was a tarsier like animal Early gibbons In South America, many monkey groups were forming. Human like apes found throughout Africa, Asia, and Europe Hominids began to diverge from other primate groups by the late Miocene. Originally Great Ape fossils found primarily through Europe and Asia, but they were later thought to have originated from Africa. These apes resembled modern apes, such as chimpanzees and gorillas, and over time differences have been primarily morphological characteristics, such as jaw shape, skull morphology, size, and teeth. The modern hominid clade also began to develop and split off, including more direct human ancestors.

Birds Similar to mammals, birds that dominated were larger predatory birds and smaller birds. All of the modern day bird groups were present by the end of the Miocene Birds such as ducks, crows, owls, and more representing modern day families appear during this time. Marine birds especially diversified and became more common

References BBC, 2016, Miocene Epoch, Nature Prehistoric Life, 1/31/ Information on Invertebrates present and plant evolution obtained here. Also a picture of Miocene apes was obtained from here. Begun, DR, 2010, Miocene Hominids and the Origins of the African Ape and Humans, 1/31/ Most of our information about primate evolution and apes came from this source. Coppens, Teresa, 2014, Life on Earth During the Miocene Epoch, HubPages, Earth-During-the-Miocene-Epoch#, 1/31/2016http://hubpages.com/education/Life-on- Earth-During-the-Miocene-Epoch# The pictures on the mammal slide, the pictures representing a horse skeleton and common grassland animals, and the pictures on the kelp forests slide were obtained here. Encyclopædia Britannica, 2016, Miocene Epoch, Britannica, 1/31/ Information about mammal diversity was from here, as well as some primate information and general information about the Miocene. Fossil Treasures of Florida, 2016, American Crocodile, 1/31/2016http:// Picture of marine crocodile was obtained here.

References O’Neil, Dennis, 2012, The First Primates, palomar.edu, 1/31/2016http://anthro.palomar.edu/earlyprimates/early_2.htm Information covering primates and primate evolution was obtained here as well as the pictures of a primate skull and primate timeline. Smithsonian National Museum of Natural History, date not listed, The Miocene, Department of Paleobiology, 1/31/ Information on invertebrates obtained here. Smithsonian National Museum of Natural History, date not listed, Miocene Marine life, Department of paleobiology, 1/31/ Information about typical marine animals during the Miocene epoch obtained here University of California Museum of Paleontology, 2011, The Miocene Epoch, 1/31/ Climate information and some information used for new ecosystems was found here. University of California Museum of Paleontology, date not listed, Monterey Formation: Invertebrates, 1/31/ The picture of the crab fossil and the mollusk on the Invertebrates slide was obtained here University of California Museum of Paleontology, date not listed, Miocene Epoch: Life, University of California Museum of Paleontology 1/31/2016http:// Information on plant evolution was obtained here.

References University of Waikato, date not listed, The evolution of life, Earth's History & Evolution, 1/31/ Information about plants and kelp, and horses was obtained here. Wikipedia, January 2016, Miocene, Wikipedia, 1/31/ Various information about Miocene fauna Wikipedia, January 2016, Megalodon, Wikipedia, 1/31/ Obtained pictures of Megalodon’s tooth and size comparison picture