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PALEONTOLOGY 9: CENOZOIC VOLUME 9, ISSUE 9, SEPTEMBER 2020 AGE OF MAMMALS THIS MONTH This issue on the Cenozoic Era • Cenozoic Dioramas page 2 is the last in the Paleontology series. The Cenozoic Era • Complete Your Timeline! page 9 covers the time from the end of dinosaurs to present day. • DNA Mutations • Build Models page 19 Over the course of this series, • Bit of Wobble page 26 we have included information • Meiosis page 33 and activities on DNA. DNA, the • Lethal Gene page 35 blueprint for all life, is the • Mutations page 43 foundation of biology. A fundamental understanding of Megatherium americanum is the POWER WORDS DNA helps us to understand largest ground sloth. It was 30 feet, • Cenozoic Era: current how species originate, have a and lived from 400,000 to 8,000 years and most recent of the 3 range of existence, and go ago in Argentina, Bolivia, and Uruguay. geological eras of the extinct. This issue will complete Phanerozoic Eon; it the DNA activities with are still here and doing well in follows the Mesozoic explorations of how DNA the tropics of South and Central Era 66 MYA to present mutates, and the consequences America! • Eocene: an Epoch in of mutations. the Cenozoic Era from The Cenozoic Era is the Age of 56 to 34 MYA My scientific research is on the Mammals. North America was • Epoch: geologic time mammal group xenarthrans home to many species of saber- within a Period (ground and tree sloths, toothed cats, dire wolves, short- anteaters, armadillos, faced bears, terror birds, CAREER CONNECTION glyptodonts, and pampatheres). elephants, American cheetahs • See separate issue Ground sloths appear in the (not true cheetahs), and other 62.Careers Special fossil record during the Eocene wonderful megafauna. Issue: https:// Epoch (35 million years ago) in tra.extension.colostate.edu/ Patagonia (Argentina and Chili). PBS Digital’s Eon Series is stem-k12/stem-resources/ All ground sloths are extinct, but phenomenal. Check it out! the tree sloths (no fossil record) https://www.youtube.com/channel/ COLORADO STATE UNIVERSITY EXTENSION 4-H PROGRAMS ARE AVAILABLE TO ALL WITHOUT DISCRIMINATION CENOZOIC LIFE — Dioramas 2 The Cenozoic started at ~66 Paleogene Period POWER WORDS MYA, when the fossil record has This Period demarks the • ~: stands for an abrupt loss of dinosaur extinction of non-avian approximately fossils, and the slow rise of dinosaurs at 65.8 MYA. It ends • browse: feed on mammal fossils. It is called the the transition from warm, tropical leaves, twigs, or other K-Pg boundary, the transition Eocene to the cooler Miocene. high-growing vegetation between the Mesozoic and the The tropical forests retreated to • delineation: the action Cenozoic. K-Pg stands for K = the equator, and grasslands of indicating the exact Kreide, a German word for chalk expanded in the mid-latitudes as position of a border or and Pg = Paleogene. It may the climate cooled around 50 boundary also be called K-T. The T MYA. • demark: set the limits stands for Tertiary, an obsolete of something or to term for the Paleogene and The Cenozoic is called the Age distinguish among Neogene. of Mammals. Once dinosaurs things, to divide them went extinct, mammals began to up speciate, increased in body size • KYA: thousand years starting around 40 MYA, and ago dominated the landscape. They • MYA: million years ago thrived until the Pleistocene and • obsolete: no longer began disappearing from the used Australian Continent ~50 KYA (K = 1,000), North America Continent ~10 KYA, and The finger is pointing to the white chalky layer Madagascar ~2 KYA. All these that divides the Mesozoic from the Cenozoic times were shortly after the The Cenozoic contains three Periods: extinct cousins, ground • Paleogene from ~66 MYA to sloths, glyptodonts, and ~23 MYA pampatheres). It is now • Neogene from ~23 MYA to thought to be in an extinct ~2.6 MYA Order Palaeanodonta. • Quaternary from ~2.6 MYA to today The “dawn horse” fossil, appearance of humans. Hyracotherium angustidens, Epochs are divisions within a Ernanodon antelios (image originated in the early Period. Epochs are very useful above) is a fossil found in China. Eocene. This early horse for scientists studying It lived during the Paleocene. It stood 12” at the shoulders, organisms. You will see the was originally placed with the had three toes, and rooted Cenozoic commonly divided by Superorder Xenarthra (sloths, teeth. This small, forest- Epochs, for example, the anteaters, armadillos, and their Pleistocene Ice Ages. The seven Cenozoic Epochs are: MATERIALS • computer with internet • Paleocene • sturdy shoebox with separate lid • Eocene Paleogene • playdough, plaster of Paris, or papier mâché • Oligocene • art supplies (e.g. tape, scissors, markers, glue, • Miocene poster paint, tissue paper, etc.) • Pliocene Neogene • craft knife or box cutter (& parent supervision) • Pleistocene Quaternary • cellophane wrap (party section of store) • Holocene • lots of creativity and imagination CENOZOIC LIFE — Dioramas 3 dwelling horse browsed on Hyracotherium (up to 18 inches POWER WORDS leaves and twigs. Horse at the shoulder). They had three • abrasive: causing speciation is a truly wonderful toes, but the ankle and wrist damage, wear, or story. You will later explore how bones were beginning to removal of surface horses changed through time change. The muzzle elongated. material by grinding or when you complete your The teeth were better for rubbing timeline in the next activity. chewing tough vegetation (tooth • graze: eat grass in a image shown below). field Neogene Period The Neogene Period ends with This Period starts with the the onset of the first of the continued cooling of the climate. The result of this climate change is our modern ecosystems: • tropics retreat to the equator • most deserts are formed around the 30° latitude • higher latitudes are home to hardwood trees and grasslands between 30° to 50° latitude • In latitudes 50°—70° Cenozoic Ice Age. ecosystems are dominated Many of the species we see by conifer forests today originated in the Neogene. • above the 70° latitude is the We find fossil dogs, pigs and tundra primates as well as many other • both the north and south familiar animals from this time. poles of our planet are ice covered Some, however, are preserved only in their fossils. The rise of grasslands are a The terror birds lived through major cause of horse speciation. most of the Cenozoic. They Grasses contain a mineral called originated in South America. silica. We make glass from With the onset of the first Ice silica. That means, eating grass Age, the oceans around the is like chewing bits of glass. It wears down teeth. Horses are grazing herbivores. Deer and elk are browsing herbivores. With the increase in grasslands, horses that inherited teeth better adapted to eating more abrasive vegetation thrived. Through time, inheriting beneficial genes, horses Top image is a North American Terror speciated into new kinds of Bird from the American Museum of horses that were better able to Natural History in New York City. Image eat grasses. below includes my son standing next to a South American terror bird on display in Miohippus sp. were a genus of Museo de La Plata, Argentina. 13 species of horses larger than CENOZOIC LIFE — Dioramas 4 world lowered as water was American species to South POWER WORDS stored in the growing ice sheets. America vastly changed the • †: called dagger and it fauna. It is still home to felids means extinct There was volcanic activity that (e.g. jaguars and pumas), • cause and effect: began forming the Isthmus of canids (amazingly diverse dogs cause is the why Panama. The lowering oceans like wolves, foxes, and bush something happened exposed the Isthmus. South dogs), raccoons, deer, bear, and effect is the what America was isolated from all rodents, horses, camels (llamas happened the other land masses for about and alpaca are both in the camel • Great American Biotic 95 million years. Wonderful family), and so many more Interchange: animals speciated in “Splendid species. (abbreviated Isolation” (the title of a book by GABI) land and paleontologist George Gaylord Quaternary Period freshwater fauna Simpson about this fascinating The Quaternary Period starts migrated from story). 2.6 MYA with the first of the 5 North America via Ice Sheets expanding then Central America to Panama slowly emerged from retreating from the Arctic to the South America and the ocean and became a land USA. If you are interested in vice versa bridge between North and South learning more about climate America starting about 9 MYA. change, see the ST[EMpower] The Great American Biotic issues found here: https:// Interchange (GABI) refers to tra.extension.colostate.edu/stem South American animals -k12/stem-resources/ disbursing north, and North • 46. Weather Forecasting American mammals disbursing • 47. Here Comes the to South America. The symbol Sun “†” (called dagger) means • 48. Climate extinct. †Ground sloths, • 49. Earth in Space †glyptodonts, armadillos, †terror • 50. Oceans Climate birds, opossums, and • 51. Greenhouse porcupines made their way Gases north. The maximum ice The North American species sheet reach 37° N. were much more successful. Only 5 groups of mammals thrived in South America during its 95 million year isolation: • xenarthrans (sloths, anteaters, and armadillos) • ungulates (like deer and cows), but wonderful different species, now all extinct • marsupials (different than Australia’s) • New World monkeys • Rodents, like the largest rodent, the capybaras The massive migration of North CENOZOIC LIFE — Dioramas 5 The southern border of Colorado jumping from a bat species to POWER WORDS is 37° N (orange line on map). humans. This is such a • Holarctic: There were areas not covered fascinating line of research! The Holarctic is the by ice called refugia. As the North America had wonderful name for the name implies, it was a refuge mammals during the biogeographic realm for some species to survive Pleistocene.
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  • Resolving the Relationships of Paleocene Placental Mammals

    Resolving the Relationships of Paleocene Placental Mammals

    Biol. Rev. (2015), pp. 000–000. 1 doi: 10.1111/brv.12242 Resolving the relationships of Paleocene placental mammals Thomas J. D. Halliday1,2,∗, Paul Upchurch1 and Anjali Goswami1,2 1Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, U.K. 2Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, U.K. ABSTRACT The ‘Age of Mammals’ began in the Paleocene epoch, the 10 million year interval immediately following the Cretaceous–Palaeogene mass extinction. The apparently rapid shift in mammalian ecomorphs from small, largely insectivorous forms to many small-to-large-bodied, diverse taxa has driven a hypothesis that the end-Cretaceous heralded an adaptive radiation in placental mammal evolution. However, the affinities of most Paleocene mammals have remained unresolved, despite significant advances in understanding the relationships of the extant orders, hindering efforts to reconstruct robustly the origin and early evolution of placental mammals. Here we present the largest cladistic analysis of Paleocene placentals to date, from a data matrix including 177 taxa (130 of which are Palaeogene) and 680 morphological characters. We improve the resolution of the relationships of several enigmatic Paleocene clades, including families of ‘condylarths’. Protungulatum is resolved as a stem eutherian, meaning that no crown-placental mammal unambiguously pre-dates the Cretaceous–Palaeogene boundary. Our results support an Atlantogenata–Boreoeutheria split at the root of crown Placentalia, the presence of phenacodontids as closest relatives of Perissodactyla, the validity of Euungulata, and the placement of Arctocyonidae close to Carnivora. Periptychidae and Pantodonta are resolved as sister taxa, Leptictida and Cimolestidae are found to be stem eutherians, and Hyopsodontidae is highly polyphyletic.