- Education and Science»
- Life Sciences
I Found a Fossil on the Beach and Wondered
A favorite past time for many of us is combing the beaches for interesting items the surf washes in. Whether you're walking along the shoreline of one of the world's oceans or the USA's Great Lakes, your imagination is on high alert to pick up something you just can't let go! Suddenly, something catches your eye! But, it's not driftwood or beach glass or even a pretty rock. You may not know exactly why, but you suspect you have found something that was once a living creature.
Crinoid Fossils Found on Beach
Has that ever happened to you? A deep sense of curiosity and childlike imagination drives us to find out what we may have picked up along our freshwater and saltwater shorelines. Having collected quite a few samples from Lake Michigan's shoreline, I finally decided to fulfill my nagging curiosity and followed through with a rewarding investigation. The more I learned about my stony sand-smoothed findings, the more I wanted to know. I wondered what the creatures may have looked like when alive and how they lived. I also wanted to know how they showed up so prevalent along our fresh water beaches. Some time later, after many answered questions, I can honestly say I now enjoy a cool hobby. Taking things a step further, I have drawn illustrations of their living beings and started a more in-depth fossil blog of all my discoveries. You can find the link at the end of this article. For now, enjoy interesting information from seven of my favorite, beach fossil-finds in the pages below enhanced with photos and colorful living renditions.
Crinoid Fossils Found on Beach
Some of the most prevalent fossils found along the Great Lake's beaches are crinoids (shown above). They have been coined with a several names due to the animal's features and by the character of their fossils discovered throughout history. One common name for them is "Indian Beads". Native Americans were known to make necklaces with their broken pieces which resemble the shape of cheerios perfect for stringing. They've also been referred to as "Lucky Stones"! Spotting one takes a keen eye as most of the pieces are quite small.
As living creatures, each circular section was stacked one over the other constructing the animal's entire framework. They possessed branching arms that sat atop of long single stems. They were sessile creatures, in other words, they remained attached to the sea floor. Some varieties are known to have towered several meters in length. Their loose structure resulted in the living organism's beautifully colored and flower like appearance which granted them the nickname of "Sea Lilies". They captured tiny food particles passing by on ocean currents with their feathery network of arms that functioned like traps. Crinoids fit into the phylum of Echinoderm, meaning spiny skin, and are cousins of starfish, sea urchins and feather stars.
Sea lily crinoid's lengthy history began during the Ordovician Period around 500 million years ago, although most fossils are from the Mississipian Period around 345 mya and are preserved in limestone. Today there are far fewer species and most lack the long meandering stem common in Paleozoic varieties.
In the course of my investigation, I had often wondered why so many crinoid fossils ended up along the beaches of the freshwater Great Lakes; particularly by the fact that they had thrived in saltwater environments. The answer about saltwater creatures is easy enough to explain. During the "sea lily" crinoids lifetime, much of the world's continents were covered under warm, shallow, saltwater oceans where their living species died and settled on the ocean bottom buried in sediment. Millions of years later they fossilized. I've since learned their prehistoric fossilized remains have been discovered widespread throughout North America.Yet, I still wondered why their fossils are so prevalent lying on the beaches of the big lakes? Here's why; ten thousand years ago when the giant glaciers sculpted the deep basins forming the Great Lakes, they also dug into the deep layers of sediment where their remains rested. In the process, their remains were released and consequently the constant wave action of the lakes deposit them on the beach where we love finding them! It's a satisfying feeling when something you've been curious about for a long time is finally realized!
Bryozoan Fossils Found on Beach
Another common beach find are Paleozoic Era "bryozoan" fossils, often called lace corals because of their delicately threaded appearance, but they were not true corals. Instead, they were moss-like animals belonging to the family of Fenestellida for their fan-shaped, mesh appearance. They lived in tight colonies sculpted by hard, limy, branching structures. The colony consisted of thousands of individual animals called “zooids”. Each individual zooid lived inside its own limy tube called a zooecium. The zooecium were the size of sewing needles. A single zooid began the colony. A modern day bryozoan colony has been observed growing from a single zooid to 38,000 in just five months. Each additional zooid is a clone of the very first one.
Interesting how they feed, Each zooid has an opening through which the animal can extend its ring of tentacles called lophophores. Their lophophores capture microscopic plankton from the water passing by. If one zooid receives food, it nourishes the neighboring zooids because they are joined by strands of protoplasm. If only we humans could be more like them ensuring everyone on the planet is fed!
Their fossil record dates back 500 mya with 15,000 known species. Today there are about 3,500 living species.
Clam Fossils Found on Beach
I found these clam fossils on the shore of Oval Beach in Southwestern Michigan. The shell of the darker sample has been completely replaced by minerals and is petrified to stone. It's likely the mold of the shell where sediment and minerals permeated. Its smooth surface is a telltale demonstration of the lake's sand and water action. The lighter colored sample clearly reveals the hardened muddy sediment that has completely encrusted its shell.
"Clam" can be a term that covers all bivalves. Some clams bury themselves in sand and breathe by extending a tube to the water’s surface. Bivalve oysters and mussels attach themselves to hard objects and scallops can free swim by flapping their valves together. All types lack a head and usually have no eyes, although scallops are a notable exception. With the use of two adductor muscles they can open and close their shells tightly. Very fittingly, the word “clam” gives rise to the metaphor “to clam up”, meaning to stop speaking or listening.
Bivalves have occupied Earth as early as the Cambrian Period 510 million years ago, but they were particularly abundant during the Devonian Period around 400 million years ago. Their fossils are discovered in all marine ecosystems and most commonly in near shore environments. In 2007, off the coast of Iceland, a clam was discovered to be at least 405 years old. It was declared the world’s oldest living creature by North Wales, Bangor University researchers.
Brachiopod Fossil Found on Beach
No other organisms typify the Age of Invertebrates more than brachiopods. They are the most abundant Paleozic fossils, except for maybe trilobites. Because of this, paleontologists use them to date rocks and other fossils. Countless billions accumulated on the ocean floor with over 30,000 forms. Today there are far fewer species, only about 300 which live mostly in cold water, deep ocean environments.
Brachiopods look like clams but are very different inside. To tell them apart, clams have uneven shaped shells, but both top and bottom halves are identical. Brachiopods are symmetrical at a glance, but the bottom shell is smaller. Brachiopods are commonly called "lampshells" due to their similarity in shape to a Roman oil lamp.
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.
"Petoskey Stone" Coral Fossils Found on Beach
Petoskey Stone Corals
During the Devonian time slot over 350 million years ago, Michigan was covered by a shallow saltwater sea. That's where mass colonies of corals called Hexagonaria, percarinata, commonly known as Petoskey Stones, thrived and flourished. The saltwater seascape must have been lit up with a quilt-work of colors by the mass colonies. Unfortunately, they became extinct at the end of the Permian Period's mass extinction.
The name “Petoskey” originated from an Ottawa fur-trader chief named Petosegay. A northern Michigan city was named after him, except the name was modified to Petoskey. Because the coral fossils are so abundant along Michigan shorelines, especially in the northern regions near the city of Petoskey, Governor George Romney signed a bill in 1965 making the Petoskey Stone the official state stone.
When observing one of the fossils, each coral hexagon structure, visible to the eye, held a single animal which opened a mouth to expose tentacles. The tentacles took in food and were also used to sting any organism or other corallite that came too close. Calcite, silica and other minerals replaced the original corallite exoskeleton. The last photo example above demonstrates Lake Michigan's natural polishing process from the wind, wave and sand movement.
Favosite Coral Fossils Found on Beach
An extinct order of coral called tabulate corals also formed reefs and lived in warm shallow waters during the same period as the Petoskey Stone corals. They were the favosite corals. The tabulae (horizontal internal layers) were built outward as the organism grew. These layers can clearly be seen in the photo above. The favosites can also be identified by the honeycomb pattern on the exterior of their fossilized remains.
Stromatolite Fossil Found on Beach
You're combing the beach in search of something interesting to examine. You pick up a common smooth stone admiring its sleek texture. Little did you know, it's actually a fossil. When wet, the stone reveals its layers of striations. It's a stromatolite fossil, the oldest of all fossils dating as far back as 3.5 billion years ago. Their hay day was long before the Cambrian creatures evolved actually paving the way for their existence. Stromatolites were simple cyanobacteria capable of photosynthesis. Their structures grew solid, layered and varied, some of which looked like giant mushrooms reaching eight feet tall. Through photosynthesis, they changed Earth's atmosphere from carbon dioxde rich to oxygen rich. Scientists had believed they were extinct before 1956 when living stromatolites were discovered in Shark Bay of Australia. Since then there have been many more discoveries around the globe.
More Related Fossillady Articles
© 2010 Kathi