Straight Shelled Nautiloids Have a Long History

September 25, 2010 by Fossillady

Straight-shelled nautiloids date back from the Cambrian Period roughly 500 million years ago and survived into the Late Triassic Period around 230 mya. That’s approximately 270 million years of living on earth . . . overwhelming and astounding! Their fossilized shells have been discovered all around the world in large assemblages commonly occurring in marine limestone rock.

During the 18th and 19th centuries, all the straight-shelled nautiloids were named orthoceras, creating a wastebasket taxon and confusion. To clarify, orthoceras is a specific genus of extinct nautiloids restricted to Middle Ordovician aged marine limestones of the Baltic States and Sweden. And more recently to add to the confusion, orthocone refers to just the straight shell.

**Orthocone (Orthoceras) Straight-Shelled Nautiloid Fossil**

The straight-shelled nautiloids were an abundant group of marine mollusk cephalopods that flourished during the Paleozoic timeslot and diminished by the end of the Triassic period into extinction. They are related to modern day cephalopods including octopus, squids, cuttlefish and the nautilus. They were also related to the extinct ammonites possessing coiled shells, which evolved after them. The straight-shelled nautiloids likely were not as agile as their cousin coiled-shelled ammonites. Both species possessed a siphuncle tube that ran through the entire lenght the animal’s inner chambers inside their shells. Each inner chamber was separated by a wall called, a septa wall. As the animal grew, it added another septa wall and a new septa chamber of a larger size.

To move throught the ocean water, the straight-shelled nautiloids and ammonites filled their inner chambers with water by using the siphuncle tube. They then forced the water out which propelled them backward with a kind of jet propulsion. The tube also served as a buoyancy device by releasing the water and leaving air space. This allowed the animal to raise and lower itself through various ocean depths.

The straight-shelled nautiloids possessed 8 to 10 powerful tentacles which protruded from the wide opened end of its shell and out its head. The tentacles detected and captured prey. The animal possessed well developed eyes, a beak and a well developed brain and head with a hood.

**(Orthoceras) Straight-Sheled Nautiloid Fossil**

Their fossils have been quarried by Europeans for many years and adorn floors, stairs, jewelry, gravestones and more with their durable and desirable beauty.

The straight-shelled nautiloids displayed extreme diversity in size from a few inches to 14 feet in length. One of the largest straight-shell giants from the earliest years, Cameroceras, reached approximately 30 feet ( 9 meters) in length.

CLASSIFICATION

Kingdom: Animalia

Phylum: Mollusk (large diverse group of invertebrates with soft bodies encased in a shell i.e. clams, snails, oysters )

Class: Cephalopoda (means prominent head and tentacles i.e. squid, octopus, nautilus, cuttlefish)

Subclass: Nautiloidea (series of chambers of increasing size connected by a central tube)

Order: Orthocerida (extinct group of cephalopods possessing long straight shells)

Family: Orthoceridae (early Ordovician to the Triassic period (approx. 490–200 million years ago) straight horn nautiloids)

Genus: Orthoceras (means straight horn)

Scan_Pic0006 — Cephalopod Straight Shelled **Nautiloid** **Orthoceras Drawing Rendition**

Check out my fiction book, one of two in a series, featuring factual prehistory insights blended with imaginative storytelling that educates as it entertains. Also availabale, a coloing/activity book featuring scenes from both books along with many of the plants and animals that lived during the amazing Devonian Time Period; fossil photos and descriptions included. Perfect for young explorers interested in fossils or young readers who simply like a good story. Ages 11-15+ available on a Amazon.com

Earth’s Original Land Tree Plant

September 17, 2010 by Fossillady

Was the “Calamite” the first tree-like plant to grow on land? Many scientists believe so. It possibly grew up to 100 feet (30 meters) tall, towering above the sparse landscape during its lengthy lifespan. Its earliest ancestral calamites were herbaceous and small appearing approximately 400 million years ago during the Devonian Time Period. The Calamite tree-like species trived during the tropical coal swamps of the Carboniferous roughly 360 million years ago before dying out at the end of the Permian mass extinction roughly 250 million years ago.

**Devonian to Carboniferous Age Calamite Tree Leaf Imprint **“Annularia”** Trace Fossil**

The trunk of the Calamite tree-like plant was a woody hollow tube, lacking true bark. The calamite resembled modern day bamboo with segments and ribbing. The leaves called “annularia” were primitive and needle like, arranged in whorls around a stem.

**Trace Fossil Imprint of Devonian to Carboniferous Age Calamite Tree Stem**

The Calamite-tree reached its zenith durng the hot swamp tropics of the past, particularly during the Pennsylvanian Period around 300 mya. Many of their fossils have been found worldwide including, USA, China, Canada, South America and Europe.

**Internal and External Imprint Fossil of Calamite Tree Stem**

The three amazing fossils above were found in Sebastian County, Arkansas in an old coal strip mine in 1993 by Michael A. Whitkanack, who donated them to my classroom. They are actually the imprints of the Calamite’s leaves and stems which scientists refer to as trace fossils.

Scan_Pic0012a — **Devonian to Carboniferous Era Calamite Tree (Earth’s First Tree-Like Land Plant) Rendition Drawing**

CLASSIFICATION

Scientific Name: Calamite Common Name: Horsetail / Wiskfern

Kingdom: Plantae

Division: Pteridophyta (ferns, reproduce by spores)

Class: Sphenopsida or Equisetopsida (means ribbed, vertical jointed stem; bamboo like in appearance)

Order: Equisetales (ancient, arborescent (tree-like) relative of modern-day horsetails (Equisetum)

Family: Calamitaceae (extinct family of tree-sized, spore-bearing plants closely related to modern horsetails)

Genus: (STEM) Calamite (LEAF) Annularia

Special Note: The Calamite may look familiar to some. Their modern descendants are the “horsetails” of today. They grow in open fields and edges of woodlands, but only reach a few feet tall.

The “horsetail” or Equisetum is an amazing living fossil related to the Calamites, the only surviving genus from the entire class of Equisetopsida. For millions of years, the Equisetopsidas were much more diverse and flouished during the late Paleozoic, Permian and Carboniferous forests. Through the millenniums, they decomposed layer by layer, sinking deep and eventually contributing to the coal deposits of today.

The Extinct Medullosa Tree and its Leaves called “Neuropteris”

September 14, 2010 by Fossillady

Extinct Neuopteris leaves are associated with the extinct tree called Medullosa, an ancestor of the flowering plant group. They flourished at the same time as the tree called Psaronius associated with the leaf called Pecopteris during the hot swamps of the Carboniferous through the Permian time slots around 360 to 250 million years ago. Earth’s cooling temperatures likely contributed to both of these trees disappearances.

Comparison Neuropteris Vs. Pecopteris Leaf Fossil Identification: One way to tell the difference between these two leaf fossil imprints is by examining the mid-vein of their leaflets. In Neuropteris, the vein stops midway up the leaflet and splits into several fine veins, whereas the mid-vein in Pecopteris extends up to the tip. Neuropteris leaflets are more blunt tipped and attach by a single stem as opposed by the entire base, as with Pecopteris. Also, Neuropteris has a more overall heart shape. A link to my article about the Psaronius tree, associated with the Pecopteris leaf, for photo comparison is provided at the end of this article.

Note: The reason these extinct trees have different names from their leaves is because scientists discovered them at different times and assigned them separate names before they put them together. If you think this creates confusion, I would have to agree.

NEUROPTERIS LEAF CLASSIFICATION

Kingdom: Plantae

Division: Tracheophyta (vascular plants with system of transporting nutrients and liquids)

Class: Gymnosperm (means bare seeds – today’s examples i.e. conifers, cyads, ginkgo)

Order: Pteridospermales (extinct group of seed-ferns which bore seeds on leaves)

Family: Medullosales (plants with complex pollen organs and large fronds)

Genera: Neuropteris (given name of foliage)

Scan_Pic0011c — **Carboniferous to Permian Era Medullosa Seed Fern Tree Rendition Drawing**

Medullosa seed-bearing tree is associated with the leaves called “Neuropteris”. Medullosa was a medium sized tree, often called seed-fern tree, reaching about 33 feet (10 meters) tall. It was not a true fern because it produced seeds, instead of spores. It only resembled fern trees and grew during the same era as the true fern trees, for example the “Psaronius” tree associated with the “Pecopteris” leaves. The leaves of Medullosa had many leaflets attached to a leaf stem which could grow quite large, as much as 10 feet (3 meters) long.

MEDULLOSA TREE CLASSIFICATION

Kingdom: Plantae

Clade: Traceophytes (Large group of vascular plants with transport system for nutrients and fluids)

Division: Pteridosperm(aphyta) (Extinct group of seed bearing plants)

Order: Medullosales (Plants with complex pollen organs and large fronds)

Family: Neurodontopteridaceae (Neuropteris Leaf)

Genus: Medullosa (Seed-bearing, fern-like plants)

For photos and descriptions of the Psaronius tree and its Pecopteris leaves that lived during the same time period of Medullosa go HERE , otherwise keep scrolling if you are viewing from the “Categories” list under “Tree Fossils”

Brachiopods and Their Fossils Are Significant

September 7, 2010 by Fossillady

No other organisms typify the Age of Invertebrates more than brachiopods. They are the most abundant Paleozoic fossils ever found, except for maybe trilobites. Paleontologists use them to date rocks and other fossils along the same rock strata. Countless billions accumulated on the ocean floor with over 30,000 forms. Today, there are far fewer species, only about 300 species which live mostly in cold, deep ocean environments.

**Brachiopod Fossilized Mold Cast found along Lake Michigan Shoreline**

The brachiopod fossil specimens shown above and below are casts of the animal’s former shells which has filled in with sediment after the creature died and later the sediment turned to stone leaving an impression of the shell. The original shells very possibly broke up into pieces and washed away settling onto the seafloor along with multitudes of other brachiopod and clam shells which ultimately develop into limestone.

fossils 005 — **Fossilized Brachiopod Mold Cast**

How They Lived – Thick shelled forms of brachiopods are ribbed and live in shallow water. Thin shelled forms are smooth and live in deep water. Some brachiopods grow to 9 inches across, but most are about an inch in diameter. They live in communities attached to objects by a muscular foot called a pedicle. They strain water in and out of their shells filtering microorganisms with their lophophores, a crown of tentacles.

**Sample of stone found on Lake Michigan beach embedded with broken shell pieces**

Brachiopods were the first of their kind to lose mobility and develop a hard covering. They look like clams but are very different inside. To tell them apart, clams (pelecypods) have uneven shaped left and right shell valves, but the tops and bottoms are identical. Brachiopods have evenly shaped (symmetrical) left to right valves, but the bottom valve is smaller.

CLASSIFICATION

Common Name: Brachiopod or Lamp Shell (named for resemblance to ancient Roman oil lamps)

Kingdom: Animalia

Phylum: Brachiopoda (means arm and foot)

Class: Articulated (shells clamp together by a hinge)

Inarticulated (shells clamp together by a muscle)

Genus: Brown Sample possibly Pseudoatrypa sp Grey Sample possibly Atrypa, reticularis

Check out my two fiction books blended with prehistory insights and imaginative storytelling that entertain as they educate. Geare toward young exlporers interested in early life and fossils, or young readers who simply like a good story; ages 11-15+. Also available, a coloring/activity book featuring scenes from the books along with many of the plants and animals that lived during the amazing Devonian Time Period; fossil photos and descriptions included. Available on Amazon.com

Sea Lily Crinoid Fossils

September 3, 2010 by Fossillady

DSC01197-studio — **Crinoid “Sea Lily” Fossil Pieces**

Beachcombers with a keen eye become obsssessed trying to find these tiny crinoid fossil pieces shaped like cheerios mixed among the beach stone rubble and sand along the shores of Lake Michigan. If they are lucky, they will find a piece or two everytime, hence the common name “Lucky Stones“. The largest crinoid fossil in the photo above is just under the size of a dime so you can imagine the luck and patience required to find them.

These extinct fossil species are also referred to as “Sea Lilies“ explained by their colorful flower-like appearance as living creatures. They were a type of ocean invertebrate animal that possessed long branching arms and a midsection that sat atop of a single slender stem, sometimes reaching two meters above the seafloor. Feathery tentacles at the tips of their branching arms trapped tiny food particles floating by in the ocean currents.

Crinoids were sessile creatures, meaning they attached themselves directly to the seafloor or to underwater rocks or sunken wood. A spawning of their offspring from these bottom bound creatures may have resembled the spring releasing of thousands of dandelion seeds blowing by in a gust of wind.

Crinoid skeleton fossils are usually found broken up into individual “cheerio” shaped sections or partial stems. Each circular section was stacked one on top of another forming the entire animal framework. The Native Americans used the fragmented fossilized sections for stringing necklaces. Consequently, yet another fitting common name for them is “Indian Beads“.

**Embedded** **Crinoid Pieces found on Oval Beach, Lake Michigan**

Crinoid’s amazing history dates back as early as the Ordovician Period around 500 million-years-ago, but their heyday happened during the Mississippian Period around 345 mya. Their fossil remains are found widespread in North America explained by the fact that much of the continent was covered under warm shallow seas. The sea lily crinoids were a dominant feature in the Paleozoic Era seas, but most varieties succumbed to the great Permian extinction around 252 mya. Today, a few species survive in cold deep-water environments, but dwarf in length compared to the prehistoric varieties.

Crinoid Classification

Kingdom: Animalia
Phylum: Echinoderm (means spiny skin, i.e. starfish, sea urchins, feather stars, crinoids)
Class: Crinoid (means flower form)

Scan_Pic0007bbcca — **Sea Lily Crinoids Drawing in the Ancient Seas**

What We Can Learn From Oysters

September 3, 2010 by Fossillady

*Exogyra ponderosa* Oyster Fossil (Cretaceous Period 65 to 100 million-years-ago)

A lesson we can learn from oysters is that even though they have no heart to feel and no brain to reason, many of their species build massive reef communities which provide protection for one another; and not only for their own kind, but for many other ocean organisms. Very fittingly, they’ve been referred to as the “unshellfish”.

Exogyra is a large extinct oyster species that lived in the soft sediment of ancient shallow marine waters. It possessed a thick shell with a distinct pattern of ribbing and pitting representing growth lines. Many of its kind thrived during the Upper Cretaceous Period around 65 to 100 million years ago. Their shells opened using a strong abductor muscle to expose a foot which pushed it along and a siphon to filter food and take in oxygen from the ocean water. The abductor muscle scars on the valves are observable in the photo below.

Oyster Exogyra Insides — *Exogrya ponderosa* Oyster Fossil Upper and Lower Valves

Oysters and Love

In Greek mythology, the Greek Goddess of Love “Aphrodite” was said to have sprang up out of the ocean on an oyster shell. The term “Aphrodisiac”, meaning to heighten love, has been related to oysters ever since. Also, the charismatic Casanova was known to have eaten twelve oysters a day, believing it would enrich his love life.

Oyster Exogyra Under — *Exogyra ponderosa* Oyster Fossil Underside with Upper and Lower Valves **in Closed Position**

The Exogyra in my collection is a beautiful specimen that is quite heavy from being fossilized into solid stone. In the two photos above of its underside, you can clearly see how the valves fit together and how the lower valve is much smaller and flatter than the convex upper valve.