Wednesday, October 5, 2011

October 2011 Fossil of the Month


Amber is fossilized tree resin (not sap), which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. Because it originates as a soft, sticky tree resin, amber sometimes contains animal and plant material as inclusions. Amber occurring in coal seams is also called resinite, and the term ambrite is applied to that found specifically within New Zealand coal seams. Amber is globally distributed, mainly in rocks of Cretaceous age or younger. Historically, the coast around Konigsberg in Prussia was the world's leading source of amber. About 90% of the world's extractable amber is still located in the Kaliningrad Oblast of Russia on the Baltic Sea. Pieces of amber torn from the seafloor are cast up by the waves, and collected by hand, dredging, or diving. Elsewhere, amber is mined, both in open works and underground galleries. Amber occurs in a range of different colors. As well as the usual yellow-orange-brown, amber itself can range from a whitish color through a pale lemon yellow, to brown and almost black. Other more uncommon colors include red amber, sometimes known as "cherry amber", green amber, and even blue amber, which is rare and highly sought after. Much of the most highly-prized amber is transparent, in contrast to the very common cloudy amber and opaque amber. Opaque amber contains numerous minute bubbles. This kind of amber is known as "bony amber". Although all Dominican amber is fluorescent, the rarest Dominican amber is blue amber. It turns blue in natural sunlight and any other partially or wholly ultraviolet light source. In long-wave UV light it has a very strong reflection, almost white. Only about 100 kg is found per year, which makes it valuable and expensive. Sometimes amber retains the form of drops and stalactites. It is thought that, in addition to exuding onto the surface of the tree, amber resin also originally flowed into hollow cavities or cracks within trees, thereby leading to the development of large lumps of amber of irregular form.

Wednesday, August 31, 2011

September 2011 Mineral of the Month

Petrified Wood

Petrified wood comes from the Greek root petro meaning "rock" or "stone"; literally translating to "wood turned into stone". It is the name given to a special type of fossilized remains of terrestrial vegetation. It is the result of a tree having turned completely into stone by the process of permineralization. All the organic materials have been replaced with minerals, mostly silica such as quartz while retaining the original structure of the wood. Unlike other types of fossils which are typically impressions or compressions, petrified wood is a three dimensional representation of the original organic material. The petrifaction process occurs underground, when wood becomes buried under sediment and is initially preserved due to a lack of oxygen. This inhibits aerobic decomposition. Mineral-laden water flowing through the sediment deposits minerals in the plant's cells and as the plant's lignin and cellulose decay, a stone mold forms in its place. In general, wood takes less than 100 years to petrify. The organic matter needs to become petrified before it decomposes completely. A forest where the wood has petrified becomes known as a Petrified Forest. Elements such as manganese, iron and copper that are present in the water or mud during the petrification process give petrified wood a variety of color ranges. Pure quartz crystals are colorless, but when contaminants are added to the process the crystals can take on a yellow, red, or other tint. Petrified wood can preserve the original structure of the wood in all its detail, down to the microscopic level. Structures such as tree rings and the various tissues are often observed features. Petrified wood has a Mohs hardness of 7, the same as quartz. Petrified wood is the provincial stone of Alberta, Canada and also the state gem of Washington.

Wednesday, July 6, 2011

July 2011 Fossil of the Month


Ammonites or ammonoids (both terms are used interchangeably) are an extinct group of marine invertebrate animals in the subclass Ammonoidea of the class Cephalopoda. These mollusks are more closely related to living coleoids (i.e. octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species. Ammonites are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods. Their fossil shells usually take the form of planispirals, although there were some helically-spiraled and non-spiraled forms as well. The name ammonite, from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder (circa. 79 AD. near Pompeii) called fossils of these animals’ ammonis cornua ("horns of Ammon") because the Egyptian god Ammon was typically depicted wearing ram's horns. Ammonites first appeared in the Devonian Era (circa 400 MYA) and became extinct at the close of the Cretaceous around 65 MYA along with the dinosaurs. Few of the ammonites occurring in the lower and middle part of the Jurassic period reach a size exceeding 9 inches in diameter. Much larger forms are found in the later rocks of the upper part of the Jurassic and the lower part of the Cretaceous, such as Titanites from Jurassic of southern England, which are often 2 feet in diameter and another species of the Cretaceous period of Germany, which is one of the largest known ammonites, have been known to reach 6.5 feet in diameter. The largest documented North American ammonite is Parapuzosia bradyi from the Cretaceous with specimens measuring 4.5 feet in diameter, although a newly discovered 7.5-foot British Columbian specimen, if authentic, would appear to trump even the European champion

Wednesday, June 1, 2011

June 2011 Fossil of the Month


Trilobites, meaning "three lobes”, are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record dates back to the early Cambrian period approximately 526 million years ago. They flourished throughout the lower Paleozoic era before beginning a drawn-out decline to extinction when, during the Devonian, all trilobite orders with the sole exception of Proetida, died out. Trilobites finally disappeared in the mass extinction at the end of the Permian about 250 million years ago. The trilobites were among the most successful of all early animals, roaming the oceans for over 270 million years.

When trilobites first appeared in the fossil record they were already highly diverse and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton an extensive fossil record was left, with some 17,000 known species spanning the Paleozoic era. The study of these fossils has facilitated important contributions to biostratigraphy, paleontology, evolutionary biology and plate tectonics.

Trilobites had many life styles; some moved over the sea-bed as predators, scavengers or filter feeders and some swam, feeding on plankton. Most life styles expected of modern marine arthropods are seen in trilobites, with the possible exception of parasitism where there is still some scientific debate. Some trilobites are even thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived food. Trilobites range in length from .04 inch to 28 inches, with a typical size range of 1-4 inches. The world's largest trilobite, Isotelus rex, was found in 1998 by Canadian scientists in Ordovician rocks on the shores of Hudson Bay. It measured 28 inches long by 16 inches wide by 3 inches high.

Wednesday, May 4, 2011

May 2011 Fossil of the Month

Corals, Crinoids & The Like

Crinoids are unusually beautiful and graceful members of the phylum Echinodermata. This is the phylum that brings you starfish, sea urchins, and sand dollars. The crinoids are a breed apart however, they resemble an underwater flower. Some even have parts that look and act like roots anchoring them to the ocean floor. They are commonly called sea lilies. Their graceful stalks can be meters long. Other varieties have no stalks or root like parts. They are commonly known as feather stars. Unlike the sea lilies the feather stars can move about on tiny hook like structures called cirri. Crinoids are alive and well and living in an ocean near you! They are also some of the oldest fossils on the planet. The earliest come from the Ordovician Period. Most of the Paleozoic forms died out in the great Permian extinctions. The few species surviving into the Mesozoic Era thrived. Many new species evolved during this time including the ancestors of the present day class Articulata. Corals are among the most colorful animals in the sea. Most corals live in warm, shallow, tropical seas and feed on plankton. The oldest fossil corals are from the Ordovican period, over 450 million years ago. Corals are marine animals with a sac-like body, mouth, tentacles and skeleton. It is the skeleton that survives in the fossil record. Of the varieties of fossilized corals found throughout the world exquisitely detailed specimens from the mountains of Indonesia are among the most unique. In Indonesia, entire coral heads are often completely preserved and appear just as they did 20 million years ago, although their density is much changed by replacement with silica, iron, manganese and other minerals. There are fern corals, brain corals, hex corals, honeycomb corals and many more. Florida and Georgia in the USA are also import sources of fossil coral. In fact Florida has declared fossil coral to be the Florida State Rock. Fossil coral pieces are sought after by gemstone and fossil collectors around the world as well as being used in beads and other jewelry.

Wednesday, March 2, 2011

March 2011 Fossil of the Month

Fossil Plants

Paleobotany, from the Greek words “paleon”, meaning old and "botany", meaning the study of plants), is the branch of paleontology or paleobiology dealing with the recovery and identification of plant remains from geological contexts.

A plant fossil is any preserved part of a plant that has long since died. Such fossils may be prehistoric impressions that are many millions of years old, or bits of charcoal that are only a few hundred years old. Prehistoric plants are various groups of plants that lived before recorded history (before about 3500 BC). Plant fossils can be preserved in a variety of ways, each of which can give different types of information about the original parent plant.

1. Adpressions (compressions-impressions). These are the most commonly found type of plant fossil. They provide good morphological detail, especially of dorsiventral (flattened) plant parts such as leaves. If the cuticle is preserved, they can also yield fine anatomical detail of the epidermis. Little other detail of cellular anatomy is normally preserved.

2. Petrifactions (anatomically preserved fossils). These provide fine detail of the cell anatomy of the plant tissue. Morphological detail can also be determined by serial sectioning, but this is both time consuming and difficult.

3. Molds and casts. These only tend to preserve the more robust plant parts such as seeds or woody stems. They can provide information about the three-dimensional form of the plant, and in the case of casts of tree stumps can provide evidence of the density of the original vegetation. However, they rarely preserve any fine morphological detail or cell anatomy. Subsets of such fossils are pith casts, where the center of a stem is either hollow or has delicate pith. After death, sediment enters and forms a cast of the central cavity of the stem.

4. Authigenic mineralization. These can provide very fine, three-dimensional morphological detail, and have proved especially important in the study of reproductive structures that can be severely distorted in adpressions. However, as they are formed in mineral nodules, such fossils can rarely be of large size.

5. Fusains. Fire normally destroys plant tissue but sometimes charcoalified remains can preserve fine morphological detail that is lost in other modes of preservation; some of the best evidence of early flowers has been preserved in fusains. Fusains fossils are delicate and often small, but because of their buoyancy can often drift for long distances and can thus provide evidence of vegetation away from areas of sedimentation.

Wednesday, February 2, 2011

February 2011 Fossil of the Month

Fossil Sea Shells

Imagine that you are hiking in
California’s blazing desert, 100 miles from the Pacific coastline. Imagine the huge mountains and the winding canyons that would surround you. Cacti dot the sandy landscape. What is the last thing you would expect to find? Seashells! Yet find them you will: in dried out washes, on an ancient shell reef, in canyon walls. Located 20 to 25 miles west of today’s El Centro, California, the basin offers a vast shell bed of 6-million-year-old oyster fossils. Erosion has left the dry wash streambeds littered with the shells. Strata in the streambed walls clearly show where oysters once covered the basin floor. California’s Shell Reef, located in the middle of an active off-road vehicle area in Anza Borrego State Park, is another treasure trove of fossils. Although a small fence protects the reef, you can still enter the area and examine the fossilized oyster shells. Shell Reef formed about four million years ago. We could also search America’s Great Plains, more than 1000 miles east of the California Desert. Any chance we might find seashells there, in the middle of the continent? You bet. The shells provide evidence of an ancient sea – the Western Interior Seaway – that existed in what is now America’s Heartland. Over time, the Western Interior Seaway receded, leaving the floor exposed. Vast rock and sediment layers remain along with fossils from creatures that once lived in the sea. The Pierre Shale is a formation deposited by the Western Interior Seaway. Exposures occur in Canada and in many U.S. states, including South Dakota, Colorado, Nebraska, Minnesota, New Mexico and Wyoming. The shale contains many species of fossilized shells, including ammonites, which we will be covering in depth as they are scheduled to be a future fossil of the month.

Wednesday, January 5, 2011

January 2011 Fossil of the Month

Fossil Teeth

Shark------------------ Megalodon----------

Alligator----------- Orca Killer Whale

The most commonly found fossil teeth are shark teeth although mammoth, mastodon, horse, bison, primate, and the teeth of skates, rays, whales and dolphins are also highly sought after. In general, the larger the tooth the more valuable although value is also based on whether the fossil teeth are rare. For example, mastodon teeth are smaller than mammoth teeth but are more valuable due to the rarity of the mastodon teeth. Fossil teeth found take many different forms. Many animals, including mammoths, sharks and reptiles go through quite a few sets of teeth during their lifetime, making it easier to find them.

Mammoth teeth are often found after being tossed around by the ocean for many years, so their appearance may be rounded. Mammoth teeth from the Pleistocene can be found in the North Sea, Alaska and Russia among other places.

Mastodon teeth are most commonly found from the Shovel-Tusker Mastodon, since the teeth from the American Mastodon are much harder to find. Both the Shovel-Tusker Mastodon and the American Mastodon are a part of an extinct group of proboscidians with cusped molar teeth.

The teeth of a shark are the only part of its body that is easy to fossilize because they are made up of bone while the rest of the shark is made up of cartilage. Small shark teeth are extremely common on some East Coast beaches but larger fossilized shark teeth are harder to find. The Megalodon shark was over 40 feet long and is now extinct. Fossil teeth from this shark are extremely valuable and are about 3 times as big as the teeth from a great white shark. Alligator teeth are commonly found in Florida. These fossil teeth are very important to the study of terrestrial vertebrates in North America. Many species of fossil whale teeth can be found in both North & South Carolina as well as several other locations around the world.