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Cryolophosaurus

Saturday, November 19, 2016

Cryolophosaurus by PaleoGuy on DeviantArt

Cryolophosaurus is a genus of large theropods known from only a single species Cryolophosaurus ellioti, known from the early Jurassic period of Antarctica. It was about 6.5 metres (21.3 ft) long and 465 kilograms (1,025 lb) in weight, making it one of the largest theropods of its time.

Individuals of this species may have grown even larger, because the only known specimen probably represents a sub-adult. Cryolophosaurus is known from a skull, a femur and other material, the skull and femur of which have caused its classification to vary greatly. The femur possesses many primitive characteristics that have classified Cryolophosaurus as a dilophosaurid or a neotheropod outside of Dilophosauridae and Averostra, where as the skull has many advanced features, leading the genus to be considered a tetanuran, an abelisaurid, a ceratosaur and even an allosaurid. Since its original description, the consensus is that Cryolophosaurus is either a primitive member of the Tetanurae or a close relative of that group.

Cryolophosaurus possessed a distinctive crest on its head that spanned the head from side to side, similar to a Spanish comb. Based on evidence from related species and studies of bone texture, it is thought that this bizarre crest was used for intra-species recognition. The brain of Cryolophosaurus was also more primitive than those of other theropods.

Reconstructed holotype skeleton

Cryolophosaurus was first excavated from Antarctica’s Early Jurassic, Sinemurian to Pliensbachian aged Hanson Formation, formerly the upper Falla Formation, by paleontologist Dr. William Hammer in 1991. It was the first carnivorous dinosaur to be discovered in Antarctica and the first non-avian dinosaur from the continent to be officially named. The sediments in which its fossils were found have been dated at ~194 to 188 million years ago, representing the Early Jurassic Period.

All known specimens of Cryolophosaurus have been recovered in the Hanson Formation, which is one of only two major dinosaur-bearing rock formations found on the continent of Antarctica. It was discovered in “tuffaceous” siltstone deposited in the Sinemurian to Pliensbachian stage of the Early Jurassic, approximately 194 to 188 million years ago. This geological formation is part of the Victoria Group of the Transantarctic Mountains, which is approximately 4,000 metres (13,000 ft) above sea level. The high altitude of this site supports the idea that early Jurassic Antarctica had forests populated by a diverse range of species, at least along the coast. The Hanson Formation was deposited in an active volcano−tectonic rift system formed during the breakup of Gondwana.

What is Paleontology?

Saturday, November 19, 2016

Because paleontologists are interested in finding out about all life on earth, they study all kinds of fossils, not just dinosaur bones. There are many different types of paleontologists. Some study fossil plants, some study fossil fish, some study fossil mammals, and some study dinosaurs. Pick a type of fossil and there’s bound to be a paleontologist that studies that type of fossil.

Paleontology is a combination of Geology (study of rocks) and Biology (Study of Life). Paleontologists also use many other types of sciences to help them understand the past. For example, they used engineering to figure out how hard a Tyrannosaurus rex bites.

There are two main types of science: Historical science, and experimental science. In experimental science, scientists come up with a hypothesis (an idea you can test) and conduct experiments to see if they can disprove their idea. If they can’t disprove the hypothesis and other scientists can’t find experiments that disprove the hypothesis, the hypothesis becomes a scientific theory.

In historical science, scientists work a little bit differently. They come up with a hypothesis, but rather than conduct experiments to disprove the hypothesis, they go out and try to find evidence that supports the hypothesis. If enough evidence is found to support the hypothesis, the hypothesis is accepted as a scientific theory. Paleontology is a historical science.

The History Of Paleontology

Saturday, November 19, 2016

The History Of Paleontology

Some of the earliest attempts of using fossils in a scientific way come from China and Ancient Greece. The Chinese naturalist, Shen Kou, used bamboo fossils to show climate changes. He found fossilized bamboo in places that, at his time, were too dry for bamboo to live. An even earlier Greek philosopher, Xenophanes, found fossilized sea shells on dry land, concluding that the dry land must have been covered by water at some time.

In the 1800’s there was a worldwide interest in geology and paleontology. This interest was sparked by two men, Charles Marsh and Edward Cope, who were responsible for discovering 142 species of dinosaurs. Both Marsh and Cope were wealthy, and used their personal wealth and influence to find dinosaur bones. Somehow, the two men got into a personal feud to see who could discover more dinosaurs. They even went as far as stealing the other’s bones, and spying to get ahead. People called Marsh’s and Cope’s feud the Great Bone War. The two men and their assistants would discover enough dinosaur bones to keep paleontologists working for several decades.

They also discovered the Morrison Formation. The Morrison Formation is a layer of rock that holds more Jurassic dinosaur bones than any other formation in North America. Years after the bone wars, people got tired of looking for dinosaurs. It wasn’t until the 1960’s when scientists uncovered new facts about dinosaurs, and people’s interest began to grow again.

What Are Fossils?

Saturday, November 19, 2016

What Are Fossils?

When asked what a fossil is, most people think of petrified bones or petrified wood. Permineralization is a process. For bone to be permineralized, the body must first be quickly buried. Second, ground water fills up all the empty spaces in body, even the cells get filled with water. Third, the water slowly dissolves the organic material and leaves minerals behind. By the time permineralization is done, what was once bone is now a rock in the shape of a bone. Unlike what you see in cartoons, dogs wouldn’t be interested in these bones.

When an animal or plant dies, it may fall into mud or soft sand and make an impression or mark in the dirt. The body is then covered by another layer of mud or sand. Over time, the body falls apart and is dissolved. The mud or sand can harden into rock preserving the impression of the body, leaving an animal or plant shaped hole in the rock. This hole is called a mold fossil. If the mold becomes filled over time with other minerals the rock is called a cast fossil.

Visual representation of the sequence of events leading to the fossilisation of organic material and the subsequent discovery of the fossil. (i) Death of the organism, (ii) decay of soft tissues and burial, (iii) sediment deposition and fossilisation, (iv) uplift, erosion and exposure and (v) discovery and extraction.

A simple experiment can show you how this works. Take some clay and press a seashell or some other object into the clay. Pull the sea shell out of the clay any you will see a detailed impression of your seashell in the clay. If, over time, the clay hardens into rock the result would be a fossil mold. But really, who has millions of years to wait to make their own fossil? Here’s the quick way. Pour plaster of Paris, dental stone, or other plaster into the mold. Wait for it to harden and you have just made your own cast fossil.

Another type of fossil is a resin fossil. Resin is sometimes called amber. Plants, mostly trees, secrete sticky stuff called resin. Sometimes insects, other small animals, or bits of plants get stuck in the sticky resin. The resin hardens overtime and is preserved in rock making a fossil.

How Are Fossils Formed?

Saturday, November 19, 2016

How Are Fossils Formed?

Trace fossils are the remains of trackways, burrows, eggs, nests, and fossil coprolites (poop). Trace fossils can tell us a lot about the animals that left them. For example, from trackways we can tell about how fast an animal was moving when they made the tracks. From coprolites we can tell what kind of things an animal ate. Trace fossils are important because they tell us how an animal lived, and what it was like in their environment.

Anyone can find fossils. I have been finding fossils for nearly as long as I can remember, and finding fossils is still one of my favorite things to do. I found many fossils as a small child near my grandmother’s house in Huntington, Utah. Huntington, Utah, is near the famous Cleveland Lloyd Dinosaur Quarry and is surrounded by the Morrison Rock Formation. The Morrison Rock Formation is famous worldwide for having dinosaur fossils in it. Near the home where I grew up I could find Trilobites and the trace fossils made by ancient worms as they burrowed though soft mud at the bottom of an ancient sea.

Fossils are found in sedimentary rocks. Sedimantary rocks are one of the three main types of rock. The other two are igneous and metamorphic rocks. Sedimentary rocks are formed when other types of rocks are eroded away. Broken down bits of rock, called sediments, pile up in what geologists call beds or layers. Over time sediments get buried by new layers of sediments. Sometimes these sediments harden into rock. These rocks are now sedimentary rocks. Of the three different rock types only sedimentary rocks can hold fossils. Igneous rocks are formed when liquid melted (magma or lava) rock cools and hardens. Metamorphic rocks are formed under intense heat and pressure. Metamorphic rocks can be formed out of either sedimentary or igneous rock; however, the process of forming metamorphic rock would mess up or destroy any fossils that happened to be in the rock.

If you want to find fossils you will need to find the right kind of sedimentary rocks. While digging on the beach in England in 2010, 5-year-old Emily Baldry discovered the fossil of a 160 million year old sea creature. Sedimentary rocks typically do not live in your backyard, so please don’t go digging, unless you have your parents’ permission. When you are outside where the rocks “live,” keep your eyes open, you just might find a fossil. Even if you don’t find a fossil, rocks are just plain cool.

How Old Are Fossils?

Saturday, November 19, 2016

We know how fast radioactive elements fall apart. We know what radioactive elements turn into after they have fallen apart. We can compare the amount of radioactive elements in a rock to the amount of specific non-radioactive elements in a rock, do some math and determine how old the rock is. For example, uranium falls apart into lead. So, if we find a rock that has uranium in it, we can compare it to the amount of lead in the rock to find out how old the rock is. If you have the right kind of rocks, this method is very accurate. The trouble with using this method to date fossils is: Radioactive elements are only found in ingenious rocks, and you can’t find fossils in igneous rocks.

So, if you can’t date the fossil directly with scientific tests, how do you date the fossil? You have to use what scientists call relative dating. The relative dating method most commonly used by paleontologists and geologists is called stratigraphy. Stratigraphic dating works like this. Rocks are formed in horizontal (flat, not up and down) beds or layers. These layers are called strata. The oldest layers are on the bottom and the youngest layers are on the top. So, the oldest fossils are on the bottom layer and the newest fossils are on the top layers. If you find a layer of the right kind of igneous rocks you can use the exact dating method to determine and exact date of that layer.

Paleontologists have found certain fossils that are different from all other fossils. These organisms lived for a relatively short amount of time, and they know when these animals lived. Paleontologists call these fossils index fossils. Index fossils can be used to determine approximately how old an unknown fossil is. For example, if you find an unknown fossil in the same layer of rock as one of the index fossils, you know your fossil is the same age as the index fossil.

Geologists and paleontologists have used a combination of dating techniques, which are radiometric dating, strati graphic dating, and index fossils, to determine the approximate age of rocks all over the world. Once you know the approximate age of rocks, you can determine the approximate age of the fossil.

Miocene Epoch

Saturday, November 19, 2016

Miocene by Mauricio Anton

The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago(Ma). The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words μείων (meiōn, “less”) and καινός(kainos, “new”) and means “less recent” because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene Epoch and is followed by the Pliocene Epoch.

The earth went from the Oligocene through the Miocene and into the Pliocene, with the climate slowly cooling towards a series of ice ages. The Miocene boundaries are not marked by a single distinct global event but consist rather of regional boundaries between the warmer Oligocene and the cooler Pliocene Epoch.

The apes arose and diversified during the Miocene, becoming widespread in the Old World. By the end of this epoch, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path. As in the Oligocene before it, grasslands continued to expand and forests to dwindle in extent. In the Miocene seas, kelp forests made their first appearance and soon became one of Earth’s most productive ecosystems. The plants and animals of the Miocene were fairly modern. Mammals and birds were well-established. Whales, seals, and kelp spread. The Miocene is of particular interest to geologists and palaeoclimatologists as major phases of the Himalayan orogeny had occurred during the Miocene, affecting monsoonal patterns in Asia, which were interlinked with glaciations in the northern hemisphere.

Mollewide [Oval-Globe] Plate Tectonic Map of the Earth from the Miocene

Prehistoric Life During the Miocene Epoch

Life during the Miocene Epoch was mostly supported by the two newly formed biomes, kelp forests and grasslands. This allows for more grazers, such as horses, rhinoceroses, and hippos. Ninety five percent of modern plants existed by the end of this epoch.

The “Middle Miocene disruption” refers to a wave of extinctions of terrestrial and aquatic life forms that occurred following the Miocene Climatic Optimum (18 to 16 Ma), around 14.8 to 14.5 million years ago, during the Langhian stage of the mid-Miocene. A major and permanent cooling step occurred between 14.8 and 14.1 Ma, associated with increased production of cold Antarctic deep waters and a major growth of the East Antarctic ice sheet. A Middle Miocene δ18O increase, that is, a relative increase in the heavier isotope of oxygen, has been noted in the Pacific, the Southern Ocean and the South Atlantic.

Neogene Period

Saturday, November 19, 2016

The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago (Mya) to the beginning of the present Quaternary Period 2.58 Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary.

During this period, mammals and birds continued to evolve into roughly modern forms, while other groups of life remained relatively unchanged. Early hominids, the ancestors of humans, appeared in Africa near the end of the period. Some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to the Atlantic ocean, leaving only the Gulf Stream to transfer heat to the Arctic Ocean. The global climate cooled considerably over the course of the Neogene, culminating in a series of continental glaciations in the Quaternary Period that follows.

The Neogene Period and its subdivisions by Encyclopedia Britannica

Geography

The continents in the Neogene were very close to their current positions. The Isthmus of Panama formed, connecting North and South America. The Indian subcontinent continued to collide with Asia, forming the Himalayas. Sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America.

Climate

The global climate became seasonal and continued an overall drying and cooling trend which began at the start of the Paleogene. The ice caps on both poles began to grow and thicken, and by the end of the period the first of a series of glaciations of the current Ice Age began.

Flora and fauna

Scene featuring Miocene (Early Neogene) fauna

Marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the early part of the period, while the amphibians known as Allocaudata disappeared at the end. Mammals and birds continued to be the dominant terrestrial vertebrates, and took many forms as they adapted to various habitats. The first hominids, the ancestors of humans, appeared in Africa and spread into Eurasia.

The Neogene Period: A map of the world 20 million years ago

In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones and grasslands replaced many forests. Grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison.

The Pliocene Epoch (5.3-2.6 Million Years Ago)

Saturday, November 19, 2016

 High Arctic camels, like those shown in this illustration, lived on Ellesmere Island during the Pliocene warm period about 3.5 million years ago. Julius Csotonyi

Prehistoric Life During the Pliocene Epoch

By the standards of “deep time,” the Pliocene epoch was relatively recent, commencing only five million years or so before the start of the modern historical record. During the Pliocene, prehistoric life around the globe continued to adapt to the prevailing climatic cooling trend, with some notable local extinctions and disappearances. The Pliocene was the second epoch of the Neogene period (23-2.6 million years ago), the first being the Miocene (23-5 million years ago); all of these periods and epochs were themselves part of the Cenozoic Era (65 million years ago to the present).

Climate and geography. During the Pliocene epoch, the earth continued its cooling trend, with tropical conditions holding at the equator (as they do today) and more pronounced seasonal changes at higher and lower latitudes; still, average global temperatures were 7 or 8 degrees (Fahrenheit) higher than they are today. The major geographic developments were the reappearance of the Alaskan land bridge between Eurasia and North America, after millions of years of submersion, and the formation of the Central American Isthmus joining North and South America.

Not only did this latter development allow an interchange of fauna between the two continents, but it had a profound effect on ocean currents, as the relatively cool Atlantic ocean was cut off from the much warmer Pacific.

Terrestrial Life During the Pliocene Epoch

Mammals. During large chunks of the Pliocene epoch, Eurasia, North America and South America were all connected by narrow land bridges–and it wasn’t all that difficult for animals to migrate between Africa and Eurasia, either. This wreaked havoc on mammalian ecosystems, which were invaded by migrating species, resulting in increased competition, displacement and even outright extinction. For example, ancestral camels (like the huge Titanotylopus) migrated from North America to Asia, while the fossils of giant prehistoric bears like Agriotherium have been discovered in Eurasia, North America and Africa. Apes and hominids were mostly restricted to Africa, though there were scattered communities in Eurasia and North America.

Examples of migrant species in the Americas after the formation of the Isthmus of Panama. Olive green silhouettes denote North American species with South American ancestors; blue silhouettes denote South American species of North American origin.

The most dramatic evolutionary event of the Pliocene epoch was the appearance of a land bridge between North and South America. Previously, South America had been much like modern Australia, a giant, isolated continent populated by a variety of strange mammals, including giant marsupials. (Confusingly, some animals had already succeeded in traversing these two continents, before the Pliocene epoch, by the arduously slow process of “island hopping”; that’s how Megalonyx, the Giant Ground Sloth, wound up in North America.) The winners in this “Great American Interchange” were the mammals of North America, which either wiped out or greatly diminished their southern relatives.

The late Pliocene epoch was also when some familiar megafauna mammals appeared on the scene, including the Woolly Mammoth in Eurasia and North America, Smilodon (the Saber-Toothed Tiger) in North and South America, and Megatherium (the Giant Sloth) and Glyptodon (a gigantic, armored armadillo) in South America. These plus-sized beasts persisted into the ensuing Pleistocene epoch, when they went extinct due to climate change and competition with (combined with hunting by) modern humans.

Birds. The Pliocene epoch marked the swan song of the phorusrhacids, or “terror birds,” as well as the other large, flightless, predatory birds of South America, which resembled meat-eating dinosaurs that had gone extinct tens of millions of years earlier. One of the last surviving terror birds, the 300-pound Titanis, actually managed to traverse the Central American isthmus and populate southeastern North America; however, this didn’t save it from going extinct by the start of the Pleistocene epoch.

Reptiles. Crocodiles, snakes, lizards and turtles all occupied an evolutionary backseat during the Pliocene epoch (as they did during much of the Cenozoic Era). The most important developments were the disappearance of alligators and crocodiles from Europe (which had now become much too cool to support their cold-blooded lifestyles), and the appearance of some truly gigantic turtles, such as the aptly named Stupendemys of South America.

Marine Life During the Pliocene Epoch

As during the preceding Miocene, the seas of the Pliocene epoch were dominated by the biggest shark that ever lived, Megalodon. Whales continued with their evolutionary progress, approximating the forms familiar in modern times, and pinnipeds (seals, walruses and sea otters) flourished in various parts of the globe. (An interesting side note: the pliosaurs of the Mesozoic Era were once thought to date from the Pliocene epoch, hence their misleading name, Greek for “Pliocene lizards.”)

Plant Life During the Pliocene Epoch

There weren’t any wild bursts of innovation in Pliocene plant life; rather, this epoch continued the trends seen during the preceding Oligocene and Miocene epochs, the gradual confinement of jungles and rain forests to equatorial regions, while vast deciduous forests and grasslands dominated higher northern latitudes, especially in North America and Eurasia.

The Oligocene Epoch (34-23 Million Years ago)

Saturday, November 19, 2016

Oligocene Wildlife by Jay Matternes

Prehistoric Life During the Oligocene Epoch

The Oligocene epoch wasn’t especially innovative with regard to its prehistoric animals, which continued along the evolutionary paths that had been pretty much locked in during the preceding Eocene (and continued on in turn during the ensuing Miocene). The Oligocene was the last major geologic subdivision of the Paleogene period (65-23 million years ago), following the Paleocene (85-56 million years ago) and Eocene (56-34 million years ago) epochs; all of these periods and epochs were themselves part of the Cenozoic Era (65 million years ago to the present).

Climate and geography. While the Oligocene epoch was still fairly temperate by modern standards, this 10-million-year stretch of geologic time saw a decrease in both average global temperatures and sea levels. All of the world’s continents were well on their way toward moving into their present positions; the most striking change occurred in Antarctica, which drifted slowly south, became more isolated from South America and Australia, and developed a polar ice cap.

Giant mountain ranges continued to form, most prominently in western North America and southern Europe.

Mollewide [Oval-Globe] Plate Tectonic Map of the Earth from the Oligocene [35 Ma]

Terrestrial Life During the Oligocene Epoch

Mammals. There were two major trends in mammalian evolution during the Oligocene epoch. First, the spread of newly evolved grasses across the plains of the northern and southern hemispheres opened a new ecological niche for grazing mammals. Early horses (such as Miohippus), distant rhinoceros ancestors (such as Hyracodon), and proto-camels (such as Poebrotherium) were all common sights on grasslands, often in locations you might not expect (camels, for instance, were especially thick on the ground in Oligocene North America, where they first evolved).

The other trend was mostly confined to South America, which was isolated from North America during the Oligocene epoch (the Central American land bridge would not form for another 20 million years) and hosted a bizarre array of megafauna mammals, including the elephant-like Pyrotherium and the meat-eating marsupial Borhyaena (the marsupials of Oligocene South America were every match for the contemporary Australian variety). Asia, meanwhile, was home to the largest terrestrial mammal that ever lived, the 20-ton Indricotherium, which bore an uncanny resemblance to a sauropod dinosaur!

Birds. As with the preceding Eocene epoch, the most common fossil birds of the Oligocene epoch were predatory South American “terror birds” (such as the unusually pint-sized Psilopterus) and giant penguins that lived in temperate, rather than polar, climates–Kairuku of New Zealand being a good example. Other types of birds also undoubtedly lived during the Oligocene epoch; we just haven’t identified many of their fossils yet!

Reptiles. To judge by the limited fossil remains, the Oligocene epoch wasn’t an especially notable time for lizards, snakes, turtles or crocodiles. However, the plenitude of these reptiles both before and after the Oligocene provides at least circumstantial evidence that they must have prospered during this epoch as well; a lack of fossils doesn’t always correspond to a lack of wildlife.

Marine Life During the Oligocene Epoch

The Oligocene epoch was a golden age for whales, rich in transitional species like Aetiocetus,Janjucetus and Mammalodon (which possessed both teeth and plankton-filtering baleen plates).Prehistoric sharks continued to be the apex predators of the high seas; it was toward the end of the Oligocene, 25 million years ago, that the gigantic Megalodon first appeared on the scene. The latter part of the Oligocene epoch also witnessed the evolution of the first pinnipeds (the family of mammals that includes seals and walruses), the basal Puijila being a good example.

Plant Life During the Oligocene Epoch

As remarked above, the major innovation in plant life during the Oligocene epoch was the worldwide spread of newly evolved grasses, which carpeted the plains of North and South America, Eurasia and Africa–and spurred the evolution of horses, deer, and various ruminants, as well as the meat-eating mammals that preyed on them. The process that had begun during the preceding Eocene epoch, the gradual appearance of deciduous forests in place of jungles over the earth’s spreading non-tropical regions, also continued unabated.

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