Fossils - Historic Markers of Earth

Fossils - Historic Markers of Earth

Fossils - Historic Markers of Earth

Fossils - Historic Markers of Earth

Fossils - Historic Markers of Earth

Trilobites are remarkable, hard-shelled, segmented creatures that existed over 520 million years ago in the Earth's ancient seas. They went extinct before dinosaurs even came into existence, and are one of the key signature creatures of the Paleozoic Era, the first era to exhibit a proliferation of the complex life-forms that established the foundation of life as it is today. Although dinosaurs are the most well-known fossil animals, trilobites are also a favorite among those familiar with Paleontology (the study of the development of life on Earth), and are found in the rocks of all continents


Whatever their size, all trilobite fossils have a similar body plan, being made up of three main body parts: a cephalon (head), a segmented thorax, and a pygidium (tail piece) as shown above. However, the name "trilobite," which means "three lobed," is not in reference to those three body parts mentioned above, but to the fact that all trilobites bear a long central axial lobe, flanked on each side by right and left pleural lobes (pleura = side, rib). These three lobes that run from the cephalon to the pygidium are what give trilobites their name, and are common to all trilobites despite their great diversity of size and form.






All Photos on this page are Fossils in my private collection.

I found this Trilobite in Delta Utah. It is very tiny and I had to discover it on the Matrix under a Microscope. It is the smallest one I have ever seen.

Rollover the image for a closer look at this tiny Trilobite.




Megalodon has a cosmopolitan (global) distribution and its giant teeth are found in deposits throughout the world. Some are collecting on land in phosphate deposits while many are collected from rivers and coastlines after eroding out of the rocks. This contributes to the water worn, polished appearance to many teeth.


The standard measure for Megalodon teeth is slant height, or the longest edge of the tooth. Adult Megalodon teeth were typically in the 4-5 inch range, with teeth over 6 inches being rare and representing super-sized individuals. There have only been a handful of teeth ever found over seven inches.


No one knows for sure why the Megalodon went extinct 2.6 Million years ago, but the cooling of the climate and gradual disappearance of many of the large whales it relied on for food are suspects.









The Tooth is 4 7/8" I Long and 4" Across the top. It is said that to tell the size of the "SHARK" would make this one around 40 feet long. That is the size of a City Bus!


The (Carcharodon) Megalodon is thought to have looked something like a Great White Shark, only a bit more stocky and overall bigger… much bigger, with an average adult Megalodon estimated to have weighed around 70-100 tons (about 30 times that of a Great White Shark which full grown tend to be about 2.5-3 tons)

The Megalodon was not only the biggest and bad prehistoric shark that ever lived; it was the largest marine predator in the history of the planet. Today’s great white sharks would be a mere bite size snack for this monster. It terrorized the diverse ocean waters around the world from 15.9 to 2.6 million years ago (late Oligocene to early Pleistocene). This massive, extinct species of shark estimated to grow to nearly 60 feet in length and often been declared the greatest vertebrate predator which ever lived.


These mega-tooth sharks were a giant and more robust version of the great white. They had 276 teeth in five rows and like today’s sharks shed their teeth throughout their lifetime. The largest Megalodon teeth on record reached a stagger 7.25 in (184mm). Compare this to the largest great whites whose teeth top out around 3 inches long. Wow.


Their teeth were bone crunching and flesh cutting tools, which evolved for grasping powerful prey such as Baleen whales. Fossil evidence supports that Megalodon focused its attack on the hard boney parts of its prey, such as rib cages, flippers, shoulders, and spines- effectively disabling large whales and harming major organs such as the heart and lungs. This strategy explains the thick, robust teeth of the Megalodon.


Roll Over Me

What is a Mosasaur?


Mosasaurs are not Dinosaurs. Although they are often referred to as the T-Rex of the seas, they were reptiles that returned to the sea during the Cretaceous Period. Even though they are aquatic, these greats beasts were still reptiles, and therefore breathed air, kind of like whales today.


Mosasaurs are considered one of the Great Marine Reptiles that ruled the seas during the Cretaceous period. Other great marine reptiles at that time include: the dolphin like ichthyosaurs, the long-necked plesiosaurs, and the short-necked pliosaurs. Luckily, for us, all Great Marine Reptiles became extinct at the end of the Cretaceous period 65 million years ago. Representatives of these Great marine Reptiles are shown to the left.


Once mosasaurs returned to the seas in the Cretaceous, around 100 million years ago, they rapidly diversified. Numerous subfamilies, genera, and species appear near-globally throughout the Cretaceous. They even expanded into fresh water environments. In 2012 Laszlo Makadi published a paper on the discovery of a fresh water mosasaur from Hungary that lived in the rivers, similar to the freshwater river dolphins today.



Although each genera has slightly different morphological features, they all share similar traits. Mosasaurs are all long and sleek. They have arms and legs that evolved into flippers. Their jaws contain numerous conical teeth. These teeth are not designed for cutting, but instead for grasping. Their jaws are also double hinged, meaning they can greatly expand in order to swallow prey whole, like a snake. Fossil skin impressions have been found on occasion, indicating mosasaurs had a scaly skin, similar to a snake.


Mosasaurs, like snakes had two rows of teeth in their upper jaw, the main set, and a smaller set toward the rear and center of their mouths. These teeth, like snakes, were thought to help hold on to and swallow lager prey whole. Also, like snakes, their jaws could expand, again to help them swallow whole prey.


Knightia is an extinct genus of clupeid clupeiform bony fish that lived in the fresh water lakes and rivers of North America and Asia during the Eocene epoch.

Diplomystus is an extinct genus of freshwater clupeomorph fish distantly related to modern-day extant herrings, alewives, and sardines.

The fish on the left of this Mortality Plate is a Diplomystus. It is a young fish and appears to be chasing the two Knightia on the right of the plate.

The problem with this is that the Knightia  are a favorite meal for the Diplomystus but the  Knightia are too big for the Diplomystus to swallow. No one said that fish are smart and this kind of an occurrence has been recorded on many matrix of this happening with the Knightia stuck in the mouth of the Diplomystus causing death to both fish

The Plate is 24" x 16" and the Diplomystus is six inches long. The largest Knightia is 6" long.

This plates was discovered in the Green River Formation. The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of inter mountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah.


Anna Haas