Snapshots from the Tucson 2002 Gem and Mineral Show
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Ammonoidea 2002 III
Arizona Mineral and Fossil Show at the Ramada Inn - Feb 3 to Feb 16 - 1601 North Oracle - 520.623.6666

While making rounds at the Ramada Inn I stopped by Room 120 to visit and chat with David and Roxanne Anderson of Earth's Past, which has become a regular stop at the Fossil Show for me. The Andersons "snowbird" in Rapid City, South Dakota from October-April and spend the remainder of the year in Skagway, Alaska. They regularly source ammonite specimens from the Pierre Shale of South Dakota but also show and resell ammonites from other localities which vary from one year to the next.

Depicted above left an eye catching Cleoniceras sp. that is about 5.5 inches across, with a quarter helping to provide some scale. This ammonite is from the Albian Stage of the Lower Cretaceous, which puts it at a little over 100 million years old. It was recovered in Madagascar Province, Madagascar. This was a very pretty specimen and it is uncommon to see an ammonite this large displaying as much iridescence as this one offered for only $135.

Shown above right is a Discoscaphites conradi, from the Maastrichtien, which is the last stage of the Cretaceous Period. The Maastrichtien borders the Mesozoic/Cenozoic extinction that marks the end of the line for the ammonites. This Discoscaphites was about 3 inches across and was recovered from the Fox Hills Formation, north central South Dakota. It was wanted $75.

Shown at right is another Fox Hills Discoscaphites conradi, this one on country rock with a bonus gastropod fossil. This piece was about 5 inches overall. The Discoscaphites was about 2.75 inches across and the gastropod, which was unidentified, was about 2 inches long. This specimen was priced at $55.

Earth's Past Ramada Inn Room 120 - [May-Sept Tel: 907.983.2880 PO Box 863, Skagway, AK 99840] [October-April Tel: 605.393.2878 3703 Dawn Street, Rapid City, SD 57703]


In Room 104 at the Ramada Inn, Extinction Fossil Company owner Steve Hess was showing a case of fantastically ornamented trilobites from the AM Limestone in Morocco, dating them from the Devonian Period of the Paleozoic Era.

Trilobites are fascinating arthropods that populated the oceans of the world throughout the Paleozoic Era, a time span of 290 million years. The early Cambrian fossil record reveals that trilobites probably ascended and developed during the Late Precambrian, more than 540 million years ago. Trilobites peaked as dominant life forms in Earth's oceans during the Cambrian and Ordovician Periods and went extinct at the end of the Permian during the mother of all mass extinctions which wiped out approximately ninety percent of all living species on Earth, marking the end of the Paleozoic Era. The ammonites survived the Permian/Triassic extinction approximately 250 million years ago that was the end of the line for the trilobites, but just barely.

In comparison, the ammonites arose approximately 409 million years ago at during the Early Silurian and flourished in ancient seas along with the trilobites throughout the remainder of the Paleozoic. The ammonites were greatly reduced by the Permian/Triassic extinction and subsequently re-radiated during the Triassic. At the end of the Triassic the ammonites underwent another and even more devastating extinction which left just one superfamily of Ammonoidea surviving into the Jurassic. The ammonites re-radiated and flourished once again during the Jurassic and Cretaceous Periods, but were in general decline at the end of the Mesozoic Era when that extinction took out approximately sixty percent of all species of life on earth, including all the ammonites along with the dinosaurs.

In hand above left is a Drotops megalomanicus. This enrolled specimen was about 2 inches overall and was priced at $600. Most trilobites were able to enroll themselves as a defensive posture so that only their hard exoskeletons were exposed, providing some degree of protection from predators. When enrolled, the spines on the exoskeletons of some trilobite species protruded, providing an additional degree of defense. The enrollment of this trilobite involved the ends of the thoracic pleurae on the pygidium matching and closing tight with the lateral borders of the cheeks on the cephalon.

This almost completely enrolled Drotops illustrates how well these structures would have fit together when it was completely closed. Enrollment structures can be important to trilobite classification and there are several known enrollment "systems". Above right is shown another Drotops megalomanicus of comparable size which was preserved in the outstretched position it would have assumed when crawling around. This Drotops also wanted $600.

Shown above left is a Ceratarges sp. Type A trilobite. This approximately 1.5" specimen was priced at $1000. Above right is a Ceratarges sp. Type C. This trilo even has spines on its spines! This approximately 3 inch Ceratarges wanted $3500.

The elegant Saganopeltis sp. trilobite at right was about 2" overall and wanted $3500. The spines on this trilo were incredible and I cannot begin to imagine what preparing this specimen must have entailed.

Depicted above left is a Comura sp. trilobite specimen. Check out those spines and peepers! This Comura was about 2.5 inches in length and wanted $2500. Shown above right is a Crotalocephalus gibbus. This specimen was about 3.25 inches long and was priced at $800. While perhaps not quite as flamboyant and ornamental as the some of the spiny specimens, I thought this trilo was none the less interesting and heavy on the cool factor.

Extinctions, Ramada Inn Room 104 - Web: Extinctions Fossils Company Tel: 719.738.1870 PO Box 1040 Walsenburg, Colorado 81809


Dakota Fossils in Room 118 at the Ramada Inn showed this awesome 15 inch Sphenodiscus lenticularis, which is another Late Cretaceous, Maastrichtien Stage, ammonite from the Fox Hills Formation, north central South Dakota. You had to look at this one for a while just to believe the iridescent rainbow of color presented to your eyes.

Sphenodiscus was among the last of the ammonites that lived and is found throughout the world but is very scarce except in North America. While everyone could appreciate visiting with this Sphenodiscus, it was not a specimen for silverpicking by a less than well heeled collector, wanting $9,500 to take home...

Dakota Fossils, Ramada Inn Room 118 - 3716 Dawn Street, Rapid City, South Dakota 57703- Phone: 605.393.1963


I visited again this year with Trevor George and Ken Manion, two English ammonite dealers sharing Room 152 at the Ramada Inn. These dealers always have some great ammonites to show, and a nice pyritized Dactylioceras on country rock I purchased from Trevor several years ago was one of the first pieces I acquired for my fledgling ammonite collection. That great Dactylioceras commune ornamented with the snake's head featured on the first page of this year's show report and depicted again here at left was shown to me by Ken.

Its pedigree was somewhat hazy but Ken related this "snakestone" had come from an old English mineral collection and there was a good possibility it was somewhat of an antique with the snake's head embellishment dating back at least as far as the 19th century. This snakestone was about 3 inches in diameter and I thought it high on cool factor. Ken was asking $200 for this piece.

Shown above left is an Asteroceras sp. ammonite fossil from the Lower Lias Formation, Frodingham Ironstone, Scunthorpe, North Lincolnshire, United Kingdom. This aesthetic Asteroceras specimen is about 8 inches across and was nicely prepared with a country rock base that was about 12 inches overall. Asteroceras is a Lower Jurassic ammonite. This one wanted $1900.

Depicted above right is another Asteroceras sp. ammonite, also from the Lower Lias Formation, Frodingham Ironstone, Scunthorpe, North Lincolnshire, United Kingdom. When I inquired why was this one green, Ken related that a very thin layer of an iron silicate, chamosite, was responsible for the color. Ken explained the chamosite is a bright blue when it first comes out of the ground, but it rapidly turns green when exposed to air. Of course this chamosite layer, which is just a few microns thick, is lost when the specimen is polished such as has been done with the Asteroceras shown above left. This green Asteroceras was about 7 inches across and prepared on a base of country rock that was about 12 inches overall. It was pleasing to my eye and wanted $600.

Shown at right is a nice cluster of Lower Jurassic Arnioceras semicostatum ammonites from the Lower Lias Formation, Zone of Arnioceras, Yorkshire, United Kingdom. This was a handsome display piece which had been prepared in high relief. It was about 6 inches overall and priced at $300.

British Jurassic Fossils, Ramada Inn Room 152 - WWW: www.fossils.demon.co.uk Trevor C. George, 118 North Street, Winterton, Scunthorpe, England DN15 9QN - Phone: (0) 1724-732274 Mobile: +44 0589 181406

Ken Mannion Fossils, Ramada Inn Room 152 - WWW: www.kenmannion.btinternet.co.uk Ken Manion, 59, Barrow Road, Barton upon Humber. North Linconshire, DN18 6AE, UK - Phone: 01652 634827 Fax: 01652 660700


Depicted above left was the top dollar ammonite shown by Canada Fossils in the Colony Room at the Ramada Inn this year. A floppy disk helps scale this specimen, which was about 20 inches in diameter and wanted $20,000. Checking out these mind blowing, ammolite encrusted Placenticeras meeki and Placenticeras intercalare from Southern Alberta at Canada Fossils at the Ramada is a regular stop for me during the Show, and over the years I have made some fair progress with my drooling problem while visiting there. Depicted above right is a very fine 10" specimen which wanted $14,000. Somewhere around $1000 to $1500 per inch seems to be about the going rate for the highest quality if you are a well healed ammonite appreciator in the market for one of these beauties for your coffee table...

Placenticeras is a genus of Late Cretaceous ammonites which were widespread throughout the Earth's oceans. These Southern Alberta, Canada specimens are known and coveted throughout the gem and mineral world for their spectacular iridescent shells, which is known as ammolite, and are recognized as the official gemstone of Canada. Some Placenticeras grew shells exceeding a meter in diameter and their relatively narrow shells tended to be tightly coiled with flattened walls.

Ammolite is of course a popular material with jewelry makers. Only a few percent of the ammonites recovered by Canada Fossils are intact and specimen grade, but there are also eager markets ready to snap up high quality pieces of ammolite for lapidary work. Shown at right is a chunk of ammolite in hand I thought pretty fine. This piece was about 4.5 inches overall and it carried a $460 price tag.

Canada Fossils is also known for and shows a good deal of mammoth ivory in the Colony Room at the Ramada Inn each year. This material ranges from about 30,000-50,000 years old and I was informed it is recovered from the Pamir Peninsula in northern Siberia. The offerings ranged from small blocks for carving to entire specimen tusks. I noted smaller blocks of mammoth ivory priced from about $12 to $112 on the table depicted above. The smallest tusk tip was about 10 inches long and it wanted $900. A 17 inch tusk tip was priced at $1800. An approximately 36 inch long tusk carried a $7,500 price tag. The largest tusk on this table weighed about 140 pounds and it was commanding $35,000.

Canada Fossils also offered pieces of mammoth ivory rough in several boxes, one of which is shown at right. This material was priced at $65 per kilo and I noted pieces in this box ranging from about 1.7 to 6.7 kilograms in weight.

Canada Fossils, Ramada Inn Colony Room - WWW: www.canadafossils.com 536-38A Avenue, SE, Calgary, Alberta, Canada TG2 1X4 Phone: 877.242-6637 Fax: 403.243.3959


Fossil Lake Fish Company showed some attractive "stone aquariums" in Room 151 at the Ramada Inn. These are fossil fish plates quarried from the Green River Formation in southwestern Wyoming, which is considered one of the richest deposits of fossils in the world. The Green River Formation was deposited during the Late Paleocene through Late Eocene Epochs of the Cenozoic Era as sediments accumulating in three great lakes that filled extensive basins created when the Rocky Mountains first formed. These were Lake Gosiute, Lake Unita and Fossil Lake. Conditions in Fossil Lake near present day Kemmerer Wyoming, the smallest but deepest of the three, were particularly facilitating to the fossil preservation of fish and other aquatic life as well as washed in terrestrial plants and animals when they sank in deep, oxygen poor water. Calcium carbonate also precipitated in these lakes when calcium rich water carried in by tributaries mixed with the alkaline lake water.

The table top shown above left was covered with single fossils of Knightia, a small schooling fish that ranged from about 4 to 10 inches long. Knightia are by far the most common of the Fossil Lake fish and individual specimens can be purchased relatively inexpensively. Behind the individual Knightia specimens is a "stone aquarium" on a plate about 5 feet long. In this aquarium are about a dozen Knightia and a 10 inch Heliobatis radians, a freshwater ray. In the lower right hand portion of this one is a Phareodus, a larger Fossil Lake predator fish which reached up to about 30 inches in length. The modern genus Arawana, popular with topical fish hobbyists, is related to Phareodus. This piece wanted $5000.

Above right is another stone aquarium featuring eight Knightia, a 17 inch Heliobatis ray and the larger fish in this one is a Priscaria, which was an intermediate size fish that reached a maximum length of about 16 inches. Priscaria was probably a school fish that fed on gastropods and crustaceans, and which was prey to Phareodus. This stone aquarium is about 3 feet across and also wanted $5000.


Depicted at left is a 5 foot high stone aquarium containing about 10 Knightia, 3 Priscaria and a 13 inch Heliobatis ray. This one wanted $6500. Above is a stone aquarium that is about 44 inches across featuring about 20 Knightia, a 14 inch Heliobatis ray and a Diplomystus, which is another Fossil Lake predator fish that reached a maximum length of about 25 inches. Diplomystus are the second most common Fossil Lake fish and it is not uncommon to find Diplomystus fossils with Knightia in their stomachs or mouths. This one also wanted $6500.

Dense fossil assemblages such as on these plates are due to mass mortalities which were frequent in Fossil Lake and may have been linked to periodic algae blooms/crashes that so depleted the lake water of oxygen the fish suffocated and were killed off in countless numbers.

Of course, just as with keeping live fish, you can start out collecting Fossil Lake fish more modestly if you haven't got the budget for a four figure stone aquarium yet. The fossil specimen shown above left featured a nice Knightia about 4.5 inches in length, with what appeared to be a Diplomystus minnow providing eternal company. The slab was about 8 inches overall and this one was priced at $30. This specimen went home with a buyer who picked it and a good deal of other specimens off the wall at Fossil Lake Fish Company very shortly after I photographed it.

I was curious about what finer, single specimens of these Fossil Lake species command and was informed that a really top, single Knightia specimen typically fetches about $25, putting these within the budget of just about any silverpicking fossil collector and wannabe stone aquarium keeper. The going rate for a fine Diplomystus, the second most common Fossil Lake fish, is about $7 per inch. A fine Phareodus goes for about $30 per inch and a fine Priscaria will set you back about $50 per inch for up to a 4-5 incher and $100 per inch for a larger specimen. If you pine after a fine Heliobatis ray, be prepared to part with about $200-$250 per inch, measured across the disk.

Above right is a fossil bat from Fossil Lake found in August of 2000 by Fossil Lake Fish Company proprietors Bob and Bonnie Finney. Bats are reported to be the rarest mammals found in the Green River Formation. This one was about 4" in length on a 6 x 8 inch slab and it was commanding $12,500. Other vertebrae fossils found in these lake sediments include crocodiles and alligators, frogs, lizards, turtles, and more rarely, birds.

After observing them for a while I noticed the fish in the stone aquariums weren't moving around very quickly, but the upside of these is of course you never have to feed them and cleaning stone aquariums is not as distasteful and time consuming a task or required as frequently as with live fish to keep them looking good... I have a Fossil Lake Diplomystus in my own rock collection, which is one of the first rocks I silverpicked and acquired when I began attending and exploring the Tucson Show some years ago. I have an invite and am planning on traveling to Wyoming in the not too distant future to visit with Bob and Bonnie Finney and do a little rock fishing in their Fossil Lake quarry. Needless to say I am looking forward to that adventure for myself as well as the opportunity it will provide to do a little show and tell about what goes on where these Green River Formation fossils are quarried and recovered.

Fossil Lake Fish Company, Ramada Inn Room 151 - WWW: www.stoneaquarium.com PO Box 92, Frontier, Wyoming 83121 Phone: (307) 877-9636


My last stop at the fossil show at the Ramada Inn this year was to visit and ponder some of the displays in Dinosaur Hall. There is also a very nice topical bookstore set up in Dinosaur Hall that is a must visit for me at the Show each year. This year I purchased a wonderful poster there titled "A Correlated History of the Earth" which illustrates and correlates the development of life on Earth against geological time as well as major meteorite impacts and configuration of the protocontinents. I found this poster quite interesting from the point of view of presenting the "big picture" as well as detailing the stages used by geologists and paleontologists to divide deep time. I like this poster so much I am going to frame it to display on the wall near my desk to use as a handy reference.

Above left is Archelon ischyros, the world's largest known turtle. The original fossil skeleton was collected from the Pierre Shale about 45 miles south of Rapid City, South Dakota in the 1970's and is on display at the National Natural History Museum in Vienna, Austria. It is about 15 feet long from its beak to the end of its tail and about 16.5 feet wide across the carapace from the end of one front flipper to the other. Archelon has a hooked beak and mouth which appears adapted to eating large mollusks such as squid that inhabited Late Cretaceous seas. The live weight of an Archelon is estimated to have been more than 4,500 pounds.

The theropod dinosaur egg clutch shown above right is patterned after two large nests discovered in Upper Cretaceous age sediments in China. It was constructed from casts of original, fossil eggs and clusters of eggs. Theropod embryos have been discovered in similar eggs. Note that the eggs were laid in two circular tiers. This arrangement suggests that the female dinosaur laid her eggs all at one time while standing in the middle of a circle, rotating a few degrees before laying each pair of eggs. The arrangement of the eggs allowed the female to provide contact incubation. The pairing of the eggs indicates that female theropods, unlike the dinosaur's bird descendants, had two sets of ovaries and oviducts.

Displayed wrapped around the egg clutch was this unrelated Plioplatecarpus sp. mosasaur, a close evolutionary relative of the modern monitor lizard. Plioplatecarpus was a marine reptile that lived in the Late Cretaceous seas of North America and a contemporary of Archelon. A powerful swimmer, it propelled itself with its tail rather than flippers. Skeletons of Plioplatecarpus have been found hundreds of miles from any known Cretaceous shoreline. The original fossil skeleton was collected from the Pierre Shale, Pennington County, South Dakota.

Shown above left is the skull of Thescelosaurus neglectus, or "Neglected Wonderful Lizard". Its name refers to the fact that it was not studied and named until 22 years after it was first collected in the late 19th century. Thescelosaurus attained a length of approximately 12 feet and was a little over 3 feet tall at the hips. The original skeleton of this specimen was discovered in the Hell Creek formation, Harding County, South Dakota by Walter Stein in the summer of 2000. One of the rarer vertebrates of the Hell Creek Formation, Thescelosaurs are one of several smaller dinosaur genera that were thriving at the end of the Cretaceous period. A probable omnivore, Thescelosaurus neglectus had a rather plump body, a long tall, and 5 fingered hands with hoof-like claws.

Pictured above right is a quarter scale model of the Tyrannosaurus Rex "Sue", which is the largest, most complete, and best preserved Tyrannosaurus rex ever discovered. Sue was discovered by fossil hunter Sue Hendrickson in the badlands of South Dakota during 1990. Sue is probably also the world's most litigated over fossil... Shortly after Sue was discovered, the ownership of her bones became the center of a dispute between the rancher on whose land Sue was discovered, the Sioux Indian Tribe, and the United States Government. In the end Sue was awarded to the rancher and finally sold at public auction and purchased by The Field Museum for 8.4 million dollars the most money ever paid for a fossil. The full scale Sue is 42 feet long and had an estimated live weight of seven tons. The weight of Sue's skull alone is 600 pounds and its teeth range from about 7.5 to 12 inches in length. Life was harder back in the good old days, eh?

Depicted above left is the skull of a new genus and species of dinosaur. This North American oviraptor is related to the Mongolian oviraptor but is giant by comparison. It is an undescribed genus and species, closely related to Chirostenotes only much larger. Having no teeth, a sharp beak covered its mouth. Its arms are 3.5 feet long and tipped with wicked claws. Fast and agile, this predator probably ate small animals such as lizards and mammals as it roamed the Late Cretaceous deltas 66 million years ago. This dinosaur was about 8 feet tall when standing erect. It was discovered by Fred Nuss in 1998 in Harding County, South Dakota.

Shown above right is a replica of the largest known Pteranodon longiceps, which had a wingspan of 24 feet. These Cretaceous flying reptiles were highly developed and did not have teeth or tails like earlier Pterosaurs. Pteranodon is known from thousands of specimens, mostly disarticulated and crushed bits and pieces. At least one nearly complete skeleton is known. Discovered in 1871 and originally named "Pterodactylus", the first specimens of this giant Pterosaur created quite a sensation. Pteranodon is believed to have been warm blooded, may have had a thin covering of hair on its body and is thought to have fed primarily on fish and squid. Their niche was probably similar to modern sea birds such as the albatross and pelican, spending most of their lives soaring over the ocean looking for food. Presumably Pteranodon was able to climb trees despite its size, and was able to walk bipedally, although its wings would have provided convenient crutches to rest upon.

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