ROCKS and FOSSILS GALLERY
All of the specimens shown on this website are taken from my personal
collection. Click on the thumbnails for more images.
(Note: mya = "million years ago")
> AMBER
Certain conifers and tropical trees secrete a sticky resin (containing
aromatic organic compounds such as terpenes, alcohols, and esters) as a
natural defense against wood-boring insects and other pests. Over time,
the terpenes can become linked and polymerized as the resin eventually
hardens to become fossilized amber. Along with general organic debris,
amber also often contains within it such "biological inclusions" as
entrapped insects and other invertebrates (gnats, ants, bees, wasps,
flies, beetles, moths, spiders, and termites are very common; true
mosquitoes are rare), botanical parts (flowers, leaves, bark, etc.),
occasional mammal hairs, small feathers, and extremely rarely,
small vertebrates such as frogs and lizards. Amber is worldwide in
distribution, with different locations corresponding to distinct
geological ages, but most commercially available amber is mined in the
Dominican Republic and the Baltic region. The former, which contains a
great abundance and diversity of inclusions, comes from the extinct
leguminous tree Hymenaea protera - a relative of the pea - and
has been dated from 15 to 40 mya, although the most recent research
places it at about 20 mya. (Despite "Jurassic Park," this is clearly
too recent to recover DNA from dinosaurs, who became extinct some 65
mya. The movie also incorrectly depicts the mines themselves; they are
in reality long, hot, dark shafts, so narrow and cramped that they can
accommodate only one worker at a time.) Amber also sustains an electrostatic
charge (its name in ancient Greek is elektron), and has been
used for centuries by many civilizations for its magical healing
properties, as well as for currency, a preservative, and for the carving
of exquisite figurines, amulets, and other magnificent works of art and
jewelry. It also occurs in a variety of colors with suggestive names:
"butterscotch," "cherry," and even "blue" amber; see below.
Mastotermes
electrodominicus, Dominican amber
An ancient order of insects, termites are extremely common in amber.
The relic genus Mastotermes (of which survives only a single
large species, M. darwiniensis, in northern Australia)
possesses many ancestral characteristics, including phylogenetic,
morphological and behavioral similarities with cockroaches. It has also
been recently established that the extinct M. electrodominicus
harbored the same kinds of hindgut microbes that aid in cellulose
digestion as do many extant termites: link
A juvenile praying mantis in Dominican
amber (RARE), and an unidentified Microlepidopteran (tiny moth) in
Baltic amber.
"Blue amber" (RARE)
This beautiful and distinctive form of Dominican amber is very
infrequently encountered. The exact physical and chemical processes
that cause its formation are not fully understood. Curiously however,
the vast majority of blue amber is completely devoid of insects or other
organic materials; when present, they are usually severely crushed or
washed out, offering possible testimony to the powerful geological
forces involved in its creation. True "green amber" is rarer still.
Copal ("young amber"), Colombian Andes
Before maturing into true amber, resin polymerizes into a subfossil
substance called copal, that has distinct physical and chemical
properties. Dated at a much younger age than amber - perhaps only a few hundred
years old (much to the violent disagreement of amber dealers) - it can
nevertheless contain spectacular sprays of insects, such as this huge
specimen, which formed on the inside of a tree.
> AMMONITES and AMMOLITE
Relatives of the octopus, squid, and cuttlefish, these cephalopod
mollusks thrived from the late Paleozoic Era (Devonian Period, ~ 400
mya) until the end of the Mesozoic Era (Cretaceous Period, ~ 65 mya),
when they became extinct along with the dinosaurs and pterosaurs. Very
similar in form to their other living cousins, the Chambered Nautilus (Nautilus
pompilius and others in that genus), these soft-bodied, tentacled
animals occupied the last chamber of a tight, spirally coiled shell.
(Although, some forms were loosely coiled or partially coiled; still
others were completely uncoiled and straight). As the animal grew, it
would secrete a thin wall (septum) behind it that sealed off a
new, slightly larger "living chamber" from the previous chambers; these
would become filled with a gas-liquid mixture that provided buoyancy in
the water column. The walls (septa) that separated these
chambers met the internal shell wall in characteristic shapes, generally
from simple curves (goniatitic)
in early forms, to elaborate "hill-and-valley" patterns (ceratitic), to
extremely complicated fractal-like curves (ammonitic) in late forms,
which have been informally described as "jigsaw" or "seaweed" patterns.
Often in fossil ammonites, these so-called suture lines clearly
show through in areas where the outer shell material (the iridescent
mother-of-pearl, or nacre, which is occasionally preserved) had
flaked off sometime after the creature died, revealing deeper layers.
Most ammonites were only a few inches to a foot or two in diameter, and
smooth-shelled. Others - such as Douvilleiceras, Mammites, and the extremely rare "robust" form of Prionocyclus - bore prominent ribs, knobs, horns, or other
adornments, as a defense against shell-crushing predators (chiefly
mosasaurs, huge marine reptiles described as the "Tyrannosaurus rex
of the Cretaceous seas"); still others reached truly gigantic
proportions, reminiscent of monstrous creatures straight from the tales
of Jules Verne. With enormous beasts like the Giant Squid (Architeuthis)
known to exist in the ocean depths, is it possible that giant ammonites
still lurk there too?
Sphenodiscus lenticularis, Fox Hills Formation,
South Dakota
Late Cretaceous (~ 70 mya)
Both sides of this handsome specimen display the extraordinarily
intricate suture patterns that are characteristic of this species. Also
evident is part of the beautifully iridescent nacreous layer. A
laterally flattened ammonite, this animal is thought to have been a
relatively fast swimmer.
Toxoceratoides taylori, Queensland, Australia, Mid Cretaceous (~ 115 mya)
Hyphantoceras reussianum, Halle, Germany, Late Cretaceous (~ 75 mya)
Aegocrioceras spathi, Resse Hannover, Germany, Late Cretaceous (~ 130 mya)
Some unusual species of ammonite were heteromorphic, with
bizarre coiling, sometimes in two, or even all three planes of rotation.
Possibly, this served the animal as a mobile burrow into which it could
retreat, making it difficult for a hungry predator to extract.
Heteromorphs are rare, and extremely prized by collectors. ($$$)
Baculites
compressus, Jeletzkytes nodosus, Jeletzkytes brevis
Pierre Shale Formation, Meade County, South Dakota
Late Cretaceous (~ 80 mya)
This impressive specimen was acquired in a trade with the Black Hills
Institute of Geological Research. The Baculites, an example of a
straight-shelled cephalopod, is over a foot long, and clearly displays
the characteristic suture pattern. The two coiled Jeletzkytes
ammonites came to rest lying next to each other. (J. brevis is
on top of J. nodosus.)
In the late
Cretaceous, much of North America was submerged under the warm shallow
Western Interior Seaway, which teemed with life. One region in
particular - the Bearpaw Formation of southern Alberta, Canada - has
revealed two species of Placenticeras ammonite, whose organic
shell mineral aragonite had not been converted to stable calcite
(both forms of calcium carbonate), due to unique geological conditions.
Rather, stacked layers of aragonite plates (lamellae) of varying
thicknesses, together with a middle layer of randomly interspersed
crystals of organic conchiolin, and several trace minerals, have
the capability of refracting light into brilliant, vibrant colors. The
resulting gem-like material, called ammolite, can range from
bright iridescent reds (corresponding to ordered, thick lamellae) and
greens (less ordered, thinner lamellae), to the very rare blues and
purples (unordered, very thin lamellae), as shown in these two large
specimens. Some pieces are even known as "color changers," depending on
their lamellar arrangement and the angle viewed. Often rivaling
precious opal in its fire and color play, ammolite was officially
recognized as a gemstone by the Gemological Institute of America in
1981.
See gem pics!
See more rough ammolite: #1
See more rough ammolite: #2
See my best rough ammolite!
> EURYPTERIDS ____("you-RIP-ter-ids")
"Sea Scorpions" (Eurypterus remipes)
Fiddlers Green Formation, Herkimer County, New York (**State Fossil**)
Late Silurian dolomite (~ 430 mya)
These extinct aquatic arthropods were relatives of horseshoe crabs (Limulus),
bearing a single pair of anterior feeding legs (chelicerae),
four pairs of walking legs, a pair of swimming paddles, twelve flexible
body segments, and a posterior tail spine (telson). This
particular species typically grew to a length of under one foot.
However, members of another genus, Pterygotus, could reach a
maximum size of 5 feet or even larger. Equipped with large compound
eyes, a broadly flattened rudder-like telson, and oversized chelicerae
that ended in large claw-like pincers, they must have been extremely
formidable predators. Usually, only disarticulated partial molts are
fossilized; complete preservation, as in these specimens, is rare.
Dorsal Ventral
> TRILOBITES ____(correctly pronounced "TRY-lo-bites")
> LAGERSTÄTTEN
> OPALIZED FOSSILS
Opalized cockle shell
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