Prehistoric Flora & Fauna

Cambrian Period: Facts & Information

Wednesday, December 7, 2016

Cambrian Period

The Cambrian Period is the first geological time period of the Paleozoic Era (the “time of ancient life”). This period lasted about 53 million years and marked a dramatic burst of evolutionary changes in life on Earth, known as the “Cambrian Explosion.” Among the animals that evolved during this period were the chordates — animals with a dorsal nerve cord; hard-bodied brachiopods, which resembled clams; and arthropods — ancestors of spiders, insects and crustaceans.

Though there is some scientific debate about what fossil strata should mark the beginning of the period, the International Geological Congress places the lower boundary of the period at 543 million years ago with the first appearance in the fossil record of worms that made horizontal burrows. The end of the Cambrian Period is marked by evidence in the fossil record of a mass extinction event about 490 million years ago. The Cambrian Period was followed by the Ordovician Period.

The period gets its name from Cambria, the Roman name for Wales, where Adam Sedgwick, one of the pioneers of geology, studied rock strata. Charles Darwin was one of his students. (Sedgwick, however, never accepted Darwin’s theory of evolution and natural selection.)

Trilobites were the dominant species during the Cambrian Period, 540 to 490 million years ago. Credit: Bill Frische | Shutterstock

Climate of the Cambrian Period

In the early Cambrian, Earth was generally cold but was gradually warming as the glaciers of the late Proterozoic Eon receded. Tectonic evidence suggests that the single supercontinent Rodinia broke apart and by the early to mid-Cambrian there were two continents. Gondwana, near the South Pole, was a supercontinent that later formed much of the land area of modern Africa, Australia, South America, Antarctica and parts of Asia. Laurentia, nearer the equator, was composed of landmasses that currently make up much of North America and part of Europe. Increased coastal area and flooding due to glacial retreat created more shallow sea environments.

Cambrian map

At this point, no life yet existed on land; all life was aquatic. Very early in the Cambrian the sea floor was covered by a “mat” of microbial life above a thick layer of oxygen-free mud. The first multicellular life forms had evolved in the late Proterozoic to “graze” on the microbes. These multicellular organisms were the first to show evidence of a bilateral body plan. These near-microscopic “worms” began to burrow, mixing and oxygenating the mud of the ocean floor. During this time, dissolved oxygen was increasing in the water because of the presence of cyanobacteria. The first animals to develop calcium carbonate exoskeletons built coral reefs.

The middle of the Cambrian Period began with an extinction event. Many of the reef-building organisms died out, as well as the most primitive trilobites. One hypothesis suggests that this was due to a temporary depletion of oxygen caused by an upwelling of cooler water from deep ocean areas. This upwelling eventually resulted in a variety of marine environments ranging from the deep ocean to the shallow coastal zones. Scientists hypothesize that this increase in available ecological niches set the stage for the abrupt radiation in life forms commonly called the “Cambrian Explosion.”

Fossils of the Cambrian Period

Scientists find some of the best specimens for the “evolutionary experiments” of the Cambrian Period in the fossil beds of the Sirius Passet formation in Greenland; Chenjiang, China; and the Burgess Shale of British Columbia. These formations are remarkable because the conditions of fossilization led to impressions of both hard and soft body parts and the most complete records of the varieties of organisms alive in the Cambrian Period.

The Sirius Passet formation has fossils estimated to be from the early Cambrian Period. Arthropods are the most abundant, although the groups are not as diverse as those found in the later Burgess Shale formation.

The Sirius Passet has the first fossil indications of complex predator/prey relationships. For example, Halkieria were slug-shaped animals with shell caps at either end. The rest of the body was covered in smaller armor plates over a soft snail-like “foot.” It is unclear whether they are more closely related to the annelids, such as modern-day earthworms and leeches, or are a primitive mollusk. Some specimens have been found in curled up defensive postures like modern pill bugs. Predator/prey relationships provide intensive selection pressures that lead to rapid speciation and evolutionary change.

Evidence in the fossil record shows that all major phylla were established in the transition from Late Precambiran to Early Cambrian time. Author: Mario Barletti

Burgess Shale fossils are from the late Cambrian. Diversity had increased dramatically. There are at least 12 species of trilobite in the Burgess Shale; whereas in the Sirius Passet, there are only two. It is clear that representatives of every animal phylum, excepting only the Bryozoa, existed by this time.

The largest predator was Anomalocaris, a free-swimming animal that undulated through the water by flexing its lobed body. It had true compound eyes and two claw-tipped appendages in front of its mouth. It was the largest most fearsome predator of the Cambrian Period, but did not survive into the Ordovician. The earliest known chordate animal, the Pikaia, was about 1.5 inches (4 centimeters) long. Pikaia had a nerve cord that was visible as a ridge starting behind its head and extending almost to the tip of the body. The fine detail preserved in the Burgess Shale clearly shows that Pikaia had the segmented muscle structure of later chordates and vertebrates. Haikouichythes, thought by some to be the earliest jawless fish, were also found in the Burgess Shale.

A mass extinction event closed the Cambrian Period. Early Ordovician sediments found in South America are of glacial origin. James F. Miller of Southwest Missouri State University suggests that glaciers and a colder climate may have been the cause of the mass extinction of the fauna that evolved in the warm Cambrian oceans. Glacial ice would have also locked up much of the free ocean water, reducing both the oxygen in the water and the area available for shallow water species.

Paleozoic Era

Wednesday, December 7, 2016

Paleozoic underwater

The Paleozoic Era, which ran from about 542 million years ago to 251 million years ago, was a time of great change on Earth. The era began with the breakup of one supercontinent and the formation of another. Plants became widespread. And the first vertebrate animals colonized land.

Life in the Paleozoic

The Paleozoic began with the Cambrian Period, 53 million years best known for ushering in an explosion of life on Earth. This “Cambrian explosion” included the evolution of arthropods (ancestors of today’s insects and crustaceans) and chordates (animals with rudimentary spinal cords).

In the Paleozoic Era, life flourished in the seas. After the Cambrian Period came the 45-million-year Ordovician Period, which is marked in the fossil record by an abundance of marine invertebrates. Perhaps the most famous of these invertebrates was the trilobite, an armored arthropod that scuttled around the seafloor for about 270 million years before going extinct.

After the Ordovician Period came the Silurian Period (443 million years ago to 416 million years ago), which saw the spread of jawless fish throughout the seas. Mollusks and corals also thrived in the oceans, but the big news was what was happening on land: the first undisputed evidence of terrestrial life.

This was the time when plants evolved, though they most likely did not yet have leaves or the vascular tissue that allows modern plants to siphon up water and nutrients. Those developments would appear in the Devonian Period, the next geological period of the Paleozoic. Ferns appeared, as did the first trees. At the same time, the first vertebrates were colonizing the land. These vertebrates were called tetrapods, and they were widely diverse: Their appearance ranged from lizardlike to snakelike, and their size ranged from 4 inches (10 cm) long to 16 feet (5 meters) long, according to a study released in 2009 in the Journal of Anatomy.

As the tetrapods took over, they had company: The Devonian Period saw the rise of the first land-living arthropods, including the earliest ancestors of spiders.

The skeleton of Eryops, one of the earliest land-walking tetrapods. Credit: © Christine M. Janis

Paleozoic evolution

Life continued its march in the late Paleozoic. The Carboniferous Period, which lasted from about 359 million years ago to 299 million years ago, answered the question, “Which came first — the chicken or the egg?” definitively. Long before birds evolved, tetrapods began laying eggs on land for the first time during this period, allowing them to break away from an amphibious lifestyle.

Trilobites were fading as fish became more diverse. The ancestors of conifers appeared, and dragonflies ruled the skies. Tetrapods were becoming more specialized, and two new groups of animals evolved. The first were marine reptiles, including lizards and snakes. The second were the archosaurs, which would give rise to crocodiles, dinosaurs and birds. Most creepily, this era is sometimes referred to as the “Age of the Cockroaches,” because roaches’ ancient ancestor (Archimylacris eggintoni) was found all across the globe during the Carboniferous.

The last period of the Paleozoic was the Permian Period, which began 299 million years ago and wrapped up 251 million years ago. This period would end with the largest mass extinction ever: the Permian extinction.

Before the Permian mass extinction, though, the warm seas teemed with life. Coral reefs flourished, providing shelter for fish and shelled creatures, such as nautiloids and ammonoids. Modern conifers and ginkgo trees evolved on land. Terrestrial vertebrates evolved to become herbivores, taking advantage of the new plant life that had colonized the land.

Paleozoic geology and climate

All this evolution took place against the backdrop of shifting continents and a changing climate. During the Cambrian Period of the Paleozoic, the continents underwent a change. They had been joined as one supercontinent, Rodinia, but during the Cambrian Period, Rodinia fragmented into Gondwana (consisting of what would eventually become the modern continents of the Southern Hemisphere) and smaller continents made up of bits and pieces of the land that would eventually make up today’s northern continents.

The Cambrian was warm worldwide, but would be followed by an ice age in the Ordovician, which caused glaciers to form, sending sea levels downward. Gondwana moved further south during the Ordovician, while the smaller continents started to move closer together. In the Silurian Period, the land masses that would become North America, central and northern Europe, and western Europe moved even closer together. Sea levels rose again, creating shallow inland seas.

In the Devonian, the northern land masses continued merging, and they finally joined together into the supercontinent Euramerica. Gondwana still existed, but the rest of the planet was ocean. By the last period of the Paleozoic, the Permian, Euramerica and Gondwana became one, forming perhaps the most famous supercontinent of them all: Pangaea. The giant ocean surrounding Pangaea was called Panthalassa. Pangaea’s interior was likely very dry, because its massive size prevented water-bearing rain clouds from penetrating far beyond the coasts.



Tuesday, December 6, 2016

Permian landscape

The Permian Period was the final period of the Paleozoic Era. Lasting from 299 million to 251 million years ago, it followed the Carboniferous Period and preceded the Triassic Period. By the early Permian, the two great continents of the PaleozoicGondwana and Euramerica, had collided to form the supercontinent Pangaea. Pangaea was shaped like a thickened letter “C.” The top curve of the “C” consisted of landmasses that would later become modern Europe and Asia. North and South America formed the curved back of the “C” with Africa inside the curve. India, Australia and Antarctica made up the low curve. Inside the “C” was the Tethys Ocean, and most of the rest of Earth was the Panthalassic Ocean. Because Pangaea was so immense, the interior portions of the continent had a much cooler, drier climate than had existed in the Carboniferous.

International Commission on Stratigraphy Subcommission on Permian Stratigraphy

Marine life

Little is known about the huge Panthalassic Ocean, as there is little exposed fossil evidence available. Fossils of the shallower coastal waters around the Pangaea continental shelf indicate that reefs were large and diverse ecosystems with numerous sponge and coral species. Ammonites, similar to the modern nautilus, were common, as were brachiopods. The lobe-finned and spiny fishes that gave rise to the amphibians of the Carboniferous were being replaced by true bony fish. Sharks and rays continued in abundance.


On land, the giant swamp forests of the Carboniferous began to dry out. The mossy plants that depended on spores for reproduction were being replaced by the first seed-bearing plants, the gymnosperms. Gymnosperms are vascular plants, able to transport water internally. Gymnosperms have exposed seeds that develop on the scales of cones and are fertilized when pollen sifts down and lands directly on the seed. Today’s conifers are gymnosperms, as are the short palm like cycads and the gingko.

Permian peat forest


Arthropods continued to diversify during the Permian Period to fill the niches opened up by the more variable climate. True bugs, with mouthparts modified for piercing and sucking plant materials, evolved during the Permian. Other new groups included the cicadas and beetles.

Land animals

Two important groups of animals dominated the Permian landscape: Synapsids and Sauropsids. Synapsids had skulls with a single temporal opening and are thought to be the lineage that eventually led to mammals. Sauropsids had two skull openings and were the ancestors of the reptiles, including dinosaurs and birds.

The earliest known fossil for the synapsid is 312 million years old, while the earliest known fossil for the sauropsid is about 306 million years old. This might indicate that mammal-like traits and reptilian-like traits emerged at around the same time. Therefore one did not necessarily evolve from the other but rather shared common ancestors more similar to the reptile-like amphibians. Very few of the non-mammalian synapsids (mammal-like reptiles) outlasted the Triassic period, although survivors persisted into the Cretaceous and are considered, as a phylogenetic unit, to include mammals as descendants.The Mesozoic era has three major periods: the Triassic, Jurassic, and Cretaceous, and is also known as The Age Of The Reptiles. Author: Miroslav Tuketic

In the early Permian, it appeared that the Synapsids were to be the dominant group of land animals. The group was highly diversified. The earliest, most primitive Synapsids were the Pelycosaurs, which included an apex predator, a genus known as Dimetrodon. This animal had a lizard-like body and a large bony “sail” fin on its back that was probably used for thermoregulation. Despite its lizard-like appearance, recent discoveries have concluded that Dimetrodon skulls, jaws and teeth are closer to mammal skulls than to reptiles. Another genus of Synapsids, Lystrosaurus, was a small herbivore — about 3 feet long (almost 1 meter) — that looked something like a cross between a lizard and a hippopotamus. It had a flat face with two tusks and the typical reptilian stance with legs angled away from the body.

In the late Permian, Pelycosaurs were succeeded by a new lineage known as Therapsids. These animals were much closer to mammals. Their legs were under their bodies, giving them the more upright stance typical of quadruped mammals. They had more powerful jaws and more tooth differentiation. Fossil skulls show evidence of whiskers, which indicates that some species had fur and were endothermic. The Cynodont (“dog-toothed”) group included species that hunted in organized packs. Cynodonts are considered to be the ancestors of all modern mammals.

At the end of the Permian, the largest Synapsids became extinct, leaving many ecological niches open. The second group of land animals, the Sauropsid group, weathered the Permian Extinction more successfully and rapidly diversified to fill them. The Sauropsid lineage gave rise to the dinosaurs that would dominate the Mesozoic Era.

A 1968 stamp from Fujeira featured a Dimetrodon. Credit: Brendan Howard /

The Great Dying

The Permian Period ended with the greatest mass extinction event in Earth’s history. In a blink of Geologic Time — in as little as 100,000 years — the majority of living species on the planet were wiped out of existence.  Scientists estimate that more than 95 percent of marine species became extinct and more than 70 percent of land animals. Fossil beds in the Italian Alps show that plants were hit just as hard as animal species. Fossils from the late Permian show that huge conifer forests blanketed the region. These strata are followed by early Triassic fossils that show few signs of plants being present but instead are filled with fossil remnants of fungi that probably proliferated on a glut of decaying trees.

Scientists are unclear about what caused the mass extinction. Some point to evidence of catastrophic volcanic activity in Siberia and China (areas in the northern part of the “C” shaped Pangaea). This series of massive eruptions would have initially caused a rapid cooling of global temperatures leading to increased glaciations. This “nuclear winter” would have led to the demise of photosynthetic organisms, the basis of most food chains. Lowered sea levels and volcanic fallout would account for the evidence of much higher levels of carbon dioxide in the oceans, which may have led to the collapse of marine ecosystems. Other scientists point to indications of a massive asteroid impacting the southernmost tip of the “C” in what is now Australia. Whatever the cause, the Great Dying closed the Paleozoic Era.

Original source:

10 Prehistoric Creatures We’d Love to Have in a Zoo

Monday, December 5, 2016

10 Dinosaur Species We’d Love to Have in a Zoo

If I’d list down all their species then that would be more than a hundred thousand, so diverse was the kingdom of this terrestrial reptile. Since quite enough we have been conjured up by the aura of that one mosquito bite which could bring that vogue extinct race back to the world’s terrene. So what if it actually happens? would we risk it or not i don’t know so avoiding that dispute  and taking you to those ten esteemed dinosaurs out of way so many that people fancy and would like to have in that kind of park.

10. Sinosauropteryx (The Most Colorful Dinosaur)


There have been a number of dinosaurs with feathers but some were not even recognizable. Sinosauropteryx is the first genus of non-avian dinosaur found with the fossilized impressions of feathers, as well as the first non-avian dinosaur where coloration has been determined. It lived in China during the early Cretaceous period and was a close relative of Compsognathus (the smallest dinosaurs ever). The remarkably well-preserved fossils show that Sinosauropteryx was covered with a furry down of very simple feathers — though some contention arose with an alternative interpretation of the filamentous impression as collagen fiber remains. These filaments consisted of a simple two-branched structure, roughly similar to the secondarily primitive feathers of the modern kiwi. Sinosauropteryx is distinguished from other small dinosaurs by several features, including having a skull longer than its upper leg bone (femur) and very short, stout forelimbs, with the arms being only 30% the length of the legs.

9. Liopleurodon (Marine Dinosaur)


Liopleurodon is only on this list which is not scientifically classified as a dinosaur but in popular culture, it is referred to as so because of their co-existence with dinosaurs in the Jurassic era. Liopleurodon fossils have been found mainly in England and France, with one younger species known from Russia. Four strong paddle-like limbs suggest that Liopleurodon was a powerful swimmer. It provides very good acceleration – a desirable trait in an ambush predator by  scanning the water with its nostrils to ascertain the source of certain smells. It’s size was around  34 ft long. In 1999, Liopleurodon was featured in an episode the BBC television series Walking with Dinosaurs. In the programme, Liopleurodon was depicted attacking and devouring the theropod dinosaur, before becoming beached during a typhoon and suffocating under its own weight. The depiction of Liopleurodon leaping onto the land in order to catch land-based prey is entirely speculative.

8. Ankylosaurus (The Armored Dinosaur)

Dino News

Ankylosaurus is often considered the archetypal armored dinosaur. Its well-known features are – the heavily-armored body and massive bony tail club – but Ankylosaurus was the largest known member of the family. In comparison with modern land animals the adult Ankylosaurus was very large. Some scientists have estimated a length of 30 ft. The body shape was low-slung and quite wide. Ankylosaurus was quadrupedal, with the hind limbs longer than the forelimbs. Ankylosaurus was herbivorous, with small, leaf-shaped teeth suitable for cropping vegetation. These teeth were smaller, relative to the body size. Bones in the skull and other parts of the body were fused to increase their strength. The most obvious feature of Ankylosaurus is its armor, consisting of massive knobs and plates of bone, known as osteoderms or scutes, embedded in the skin. The plates were aligned in regular horizontal rows down the animal’s neck, back, and hips, with the many smaller nodules protecting the areas between the large plates. The famous tail club of Ankylosaurus was also composed of several large osteoderms, which were fused. It allowed great force to be transmitted to the end of the tail when it was swung. It seems to have been an active defensive weapon, capable of producing enough of a devastating impact to break the bones of an assailant.

7. Triceratops (Last Dinosaur before Mass Extinction)

Wiki Media

It was one of the last dinosaur genera to appear before the great extinction. Bearing a large bony frill and three horns on its large four-legged body, and conjuring similarities with the modern rhinoceros, Triceratops is one of the most recognizable of all dinosaurs. Although it shared the landscape with and was preyed upon by the fearsome Tyrannosaurus, it is unclear whether the two did battle in the manner often depicted in museum displays and popular images. The function of their frills and three distinctive facial horns has long inspired debate. Although traditionally viewed as defensive weapons against predators, the latest theories claim that it is more probable that these features were used in courtship and dominance displays, much like the antlers and horns of modern reindeer, mountain goats, or rhinoceros beetles.

6. Stegosaurus (Spiky Dinosaur)

Stegosaur by Sergei Krasovskiy

Due to its distinctive tail spikes and plates, Stegosaurus is one of the most recognizable dinosaurs. They lived some 150 to 145 million years ago, in an environment and time dominated by the giants. A large, heavily built, herbivorous quadruped, Stegosaurus had a distinctive and unusual posture, with a heavily rounded back, short forelimbs, head held low to the ground and a stiffened tail held high in the air. Its array of plates and spikes has been the subject of much speculation. The spikes were most likely used for defense, while the plates have also been proposed as a defensive mechanism, as well as having display and thermoregulatory (heat control) functions. Stegosaurus was the largest of all the stegosaurians but still roughly bus-sized. Averaging around 30 ft long and 14 fttall, the quadrupedal Stegosaurus is one of the most easily identifiable dinosaurs, due to the distinctive double row of kite-shaped plates rising vertically along its rounded back and the two pairs of long spikes extending horizontally near the end of its tail. Although a large animal, it was dwarfed by its contemporaries, the giant sauropods. Some form of armor appears to have been necessary, as it coexisted with large predatory dinosaurs.

5. Archaeopteryx (Only Avian Dinosaur)

Image Source: Unknown

Archaeopteryx, from the late Jurassic Period, may be the earliest known theropod dinosaur which may have had the capability of powered flight. If Archaeopteryx is defined as an avian, then there are few non-avian avialans. Avialae is the only clade of dinosaurs containing their only living representatives, birds, and the most immediate extinct relatives of birds.  Similar in size and shape to a European Magpie, Archaeopteryx could grow to about 1 metre  in length. Despite its small size, broad wings, and inferred ability to fly or glide, Archaeopteryx has more in common with small theropod dinosaurs than it does with modern birds. In particular, it shares the following features with the deinonychosaurs (dromaeosaurs and troodontids): jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes (“killing claw”), feathers (which also suggest homeothermy), and various skeletal features. The features above make Archaeopteryx a clear candidate for a transitional fossil between dinosaurs and birds. Thus, Archaeopteryx also plays an important role not only in the study of the origin of birds but in the study of dinosaurs.

4. Compsognathus (Smallest Known Dinosaur)


The animal was the size of a turkey and could weigh as less as 0.26g and lived around 150 million years ago in what is now Europe. It is the smallest known dinosaur. Compsognathus is one of the few dinosaurs for which the diet is known with certainty: the remains of small, agile lizards were found preserved in the bellies of  specimens. Although not recognized as such at the time of its discovery, Compsognathus is the first dinosaur known from a reasonably complete skeleton and the smallest and the closest supposed relative of the early bird Archaeopteryx. Thus, the genus is one of the few dinosaur genera to be well known outside of paleontological circles.

3. Amphicoelias fragillimus (Largest Known Dinosaur)

Amphicoelias herd by Raul Martin

A. fragillimus is the largest and heaviest dinosaur ever discovered. A. fragillimus may have been the longest known vertebrate at 40–60 meters (131–196 ft) in length, and may have had a mass of up to 122 metric tons. Whatever evolutionary pressure caused large size was present from the early origins of the group. Carpenter cited several studies of giant mammalian herbivores, such as elephants and rhinoceros, which showed that larger size in plant-eating animals leads to greater efficiency in digesting food. Since larger animals have longer digestive systems, food is kept in digestion for significantly longer periods of time, allowing large animals to survive on lower-quality food sources. This is especially true of animals with a large number of ‘fermentation chambers’ along the intestine which allow microbes to accumulate and ferment plant material, aiding digestion.

2. Velociraptor (Raptor)


Velociraptor (commonly shortened to ‘raptor’) is one of the dinosaur genera most familiar to the general public that existed approximately 75 to 71 million years ago. Velociraptor was a mid-sized dromaeosaurid, with adults measuring up to 6.8 ft long, 1.6 ft high at the hip, and weighing up to 15 kg. The skull, which grew up to 9.8 in long, was uniquely up-curved, concave on the upper surface and convex on the lower. The jaws were lined with 26–28 widely spaced teeth on each side, each more strongly serrated on the back edge than the front—possibly an adaptation that improved its ability to catch and hold fast-moving prey. It was a bipedal, feathered carnivore with a long, stiffened tail and an enlarged sickle-shaped claw on each hindfoot, which is thought to have been used to kill its prey. Velociraptor can be distinguished from other dromaeosaurids by its long and low skull, with an upturned snout.

1. Tyrannosaurus rex

Wiki Media

T-Rex, yes we can’t forget the dinosaur king for obvious reasons. It was among the last non-avian dinosaurs to exist. It lived throughout what is now western North America, 7 to 65.5 million years ago. Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods (a dinosaur subclassification) rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators, measuring up to 42 ft in length, up to 13 ft tall at the hips, and up to 6.8 metric tons (7.5 short tons) in weight. By far the largest carnivore in its environment, Tyrannosaurus rex was an apex predator.

Runner Ups:


Brachiosaurus (a well known specie known for it’s largest size but new discoveries negated that claim and we had to chose only 1 for our zoo for the big size)
Parasaurolophus (Duck Billed Dinosaur)
Pentaceratops (Triceratops cousin with 5 horns and largest dino skull)


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.

Miocene Epoch

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


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.


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.

Neogene Period

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.

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.

The Pliocene Epoch (5.3-2.6 Million Years Ago)

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

The Oligocene Epoch (34-23 Million Years ago)

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.

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.

The Cenozoic Era (65 Million Years Ago to the Present)

Saturday, November 19, 2016

The Cenozoic Era (65 Million Years Ago to the Present)

Facts About the Cenozoic Era

The Cenozoic Era is easy to define: it’s the stretch of geologic time that kicked off with the Cretaceous/Tertiary Extinction, 65 million years ago, and continues down to the present day. Informally, the Cenozoic Era is often referred to as the “age of mammals,” since it was only after the dinosaurs went extinct that mammals had the chance to evolve into various open ecological niches and dominate terrestrial life on the planet. This characterization is somewhat unfair, however, since (non-dinosaur) reptiles, birds and fish also thrived during the Cenozoic!

Somewhat confusingly, the Cenozoic Era is divided into various “periods” and “epochs,” and scientists don’t always use the same terminology when describing their discoveries. (This situation stands in stark contrast to the preceding Mesozoic Era, which is neatly divided into the Triassic, Jurassic and Cretaceous periods.) Here’s an overview of the subdivisions of the Cenozoic Era; just click on the appropriate links to see more in-depth articles about the geography, climate and prehistoric life of that period or epoch.

The Periods and Epochs of the Cenozoic Era

The Paleogene period (65-23 million years ago) was the age when the mammals began their rise to dominance. The Paleogene comprises three separate epochs:

* The Paleocene epoch (65-56 million years ago) was fairly quiet in evolutionary terms. This is when the tiny mammals that survived the K/T Extinction first tasted their newfound freedom and began to tentatively explore new ecological niches.

* The Eocene epoch (56-34 million years ago) was the longest epoch of the Cenozoic Era. The Eocene witnessed a vast profusion of mammalian forms; this was when the first even- and odd-toed ungulates appeared on the planet, as well as the first recognizable primates.

* The Oligocene epoch (34-23 million years ago) is notable for its change in climate from the preceding Eocene, which opened up even more ecological niches for mammals. This was the epoch when certain mammals (and even some birds) began to evolve to respectable sizes.

The Neogene period (23-2.6 million years ago) witnessed the continuing evolution of mammals and other forms of life, many of them to enormous sizes. The Neogene comprises two epochs:

* The Miocene epoch (23-5 million years ago) takes up the lion’s share of the Neogene. Most of the mammals, birds and other animals that lived during this time would have been vaguely recognizable to human eyes, though often considerably bigger or stranger.

* The Pliocene epoch (5-2.6 million years ago), often confused with the ensuing Pleistocene, was the time when many mammals migrated into the territories that they continue to inhabit during the present day. Horses, primates, elephants, and other animal types continued to make evolutionary progress.

The Quaternary period (2.6 million years ago to the present) is, so far, the shortest of all the earth’s geologic periods. The Quaternary comprises two even shorter epochs:

* The Pleistocene epoch (2.6 million-12,000 years ago) is famous for its large megafauna mammals, such as the Woolly Mammoth and the Saber-Toothed Tiger, that died off at the end of the last Ice Age (thanks partly to predation by the earliest humans).

* The Holocene epoch (10,000 years ago-present) comprises pretty much all of modern human history. Unfortunately, this is also the epoch when many mammals, and other forms of life, have gone extinct due to the ecological changes wrought by human civilization.

The Eocene Epoch (56-34 Million Years Ago)

Saturday, November 19, 2016

The Eocene Epoch (56-34 Million Years Ago)

Prehistoric Life During the Eocene Epoch

The Eocene epoch began 10 million years after the extinction of the dinosaurs, 65 million years ago, and continued for another 22 million years, up to 34 million years ago. As with the preceding Paleocene epoch, the Eocene was characterized by the continuing adaptation and spread of prehistoric mammals, which filled the ecological niches left open by the dinosaurs’ demise. The Eocene constitutes the middle part of the Paleogene period (65-23 million years ago), preceded by the Paleocene and succeeded by the Oligocene epoch (34-23 million years ago); all of these periods and epochs were part of the Cenozoic Era (65 million years ago to the present).

Climate and geography. The Eocene epoch picked up where the Paleocene left off, with a continuing rise in global temperatures to near-Mesozoic levels. The later part of the Eocene saw a pronounced cooling trend, probably related to decreasing levels of carbon dioxide in the atmosphere, which culminated in the re-formation of ice caps at both the north and south poles.

The earth’s continents continued to drift toward their present positions, having broken apart from the northern supercontinent Laurasia and the southern supercontinent Gondwana, though Australia and Antarctica were still connected. The Eocene epoch also witnessed the rise of North America’s western mountain ranges.

Terrestrial Life During the Eocene Epoch

Mammals. Perissodactyls (odd-toed ungulates, such as horses and tapirs) and artiodactyls (even-toed ungulates, such as deer and pigs) can all trace their ancestry back to the primitive mammalian genera of the Eocene epoch. Phenacodus, a small, generic-looking ancestor of hoofed mammals, lived during the early Eocene, while the late Eocene witnessed much bigger “thunder beasts” like Brontotherium and Embolotherium. Carnivorous predators evolved in synch with these plant-munching mammals: the early Eocene Mesonyx only weighed as much as a large dog, while the late Eocene Andrewsarchus was the largest terrestrial meat-eating mammal that ever lived. The first recognizable bats (such as Palaeochiropteryx), elephants (such as Phiomia), and primates (such as Eosimias) also evolved during the course of the Eocene epoch.

Birds. As is the case with mammals, many modern orders of birds can trace their roots to the Eocene epoch (even though birds as a whole evolved, perhaps more than once, during the Mesozoic Era). The most notable birds of the Eocene were giant penguins, as typified by the 100-pound Inkayacu of South America and the 200-pound Anthropornis of Australia. Another important Eocene bird was Presbyornis, a toddler-sized prehistoric duck.

Reptiles. Crocodiles (such as the weirdly hooved Pristichampsus), turtles (such as the big-eyed Puppigerus) and snakes (such as the 33-foot long Gigantophis) all continued to flourish during the Eocene epoch, many of them attaining substantial sizes as they filled the niches left open by their dinosaur relatives. Much tinier lizards, like the three-inch-long Cryptolacerta, were also a common sight (and food source for larger animals).

Marine Life During the Eocene Epoch

The Eocene epoch was when the first prehistoric whales left dry land and opted for a life in the sea, a trend that culminated in the middle Eocene Basilosaurus, which attained lengths of up to 60 feet and weighed in the neighborhood of 50 to 75 tons. Sharks continued to evolve as well, but few fossils are known from this epoch. In fact, the most common marine fossils of the Eocene epoch are of tiny fish, like Knightia and Enchodus, that plied the lakes and rivers of North America in vast schools.

Plant Life During the Eocene Epoch

The heat and humidity of the early Eocene epoch made it a heavenly time for dense jungles and rainforests, which stretched almost all the way to the North and South Poles (the coast of Antarctica was lined with tropical rainforests about 50 million years ago!) Later in the Eocene, global cooling produced a dramatic change: the jungles of the northern hemisphere gradually disappeared, to be replaced by deciduous forests that could better cope with seasonal temperature swings. One important development had only just begun: the earliest grasses evolved during the late Eocene epoch, but didn’t spread worldwide (providing sustenance for plains-roaming horses and ruminants) until millions of years later.