Fossil Dig

Modern Day

Plesiosaurus was a large reptile built for swimming. Despite its size, it was not a good hunter. Its long neck and short tail made it difficult to maneuver quickly. It likely ate smaller fish and easy to catch shelled creatures.

Crinoids, commonly called feather stars, still exist today. They are commonly found in ocean environments such as coral reefs.

Corals are another example of one of the older animals on Earth. They are simple ocean filter feeders. Fossilized coral is so common in Michigan that it is actually the state stone. Because coral are still widespread, they are easily recognizable in the fossil record.

Clams are simple shelled organisms that are filter feeders. Fossilized clams do not preserve the remains of the inside, fleshy parts of a clam. However, their outer shell is clearly preserved. While the exact size and shape of prehistoric clams varies, they closely resemble modern clams.

Petrified wood is created when remains of trees are slowly filled in by minerals as they are buried beneath sediment. There are large sections of petrified trees found in this area during this time period.

Palaeolagus is an extinct species that closely resembles modern rabbits. They would make burrows for shelter, and graze on grasses and other small vegetation.

Mosasaurs were massive predators. Their limbs were adapted to swimming in water, and they contained sharp teeth for killing. Their diet would have consisted of larger fish, reptiles, and shelled creatures. While they have no close living relatives, they are distantly related to modern snakes and lizards as members of the reptile family.

The baenid turtles would have closely resembled modern cooter and slider turtles, with some differences. Like modern turtles, their shells were more flat and their limbs were better suited for swimming in water. However, baenids would have had a much longer tail from their ancestors, which likely helped them navigate in the water. They would have spent most of their time submerged in swamps or ponds, foraging for small animals and vegetation.

Protoceras is an extinct relative of some modern deer. They were able to run easily with hooved feet, and grazed on grasses and shrubs.

Sea sponges are one of the oldest living animals on the planet. They are simple ocean filter feeders. Because sea sponges are still widespread, they are easily recognizable in the fossil record.

Pollen

The presence of pollen suggests flowering plants, as these are the only organisms that produce pollen. Pollen fossils can be difficult to find and assess due to their microscopic size.

Fossilized pollen often comes from plants that are now extinct, but the general shape and size of pollen is consistent between prehistoric and modern times. There are many samples of pollen at this site that resemble grasses.

Fern fossils are very recognizable, as ferns are still widespread today. Ferns grow well in darker, wet environments like swamps and wetlands. Fern fossils are very common in this area.

Archelon is the largest known sea turtle to have existed. Given the lack of hard outer shell, they likely resembled a modern leatherback sea turtle, which has a thick outer skin rather than a shell. Interestingly, archelon is NOT related to any modern sea turtle (including leatherbacks); they went extinct about 65 million years ago and their lineage ended. Archelon were likely predators to smaller fish and shelled animals, and were likely preyed upon by large dinosaurs such as mosasaurs. It is unlikely that sharks could eat them, as they were far too big.

Trilobites are common fossils of extinct, segmented creatures. They had many legs use for walking, and lived in the ocean based on other fossils that they have been found near. While they no longer exist, their closest living relative is the horseshoe crab. Horeshoe crabs have some ability to swim, so trilobites likely did as well.

Oreodonts are an extinct species related to modern bison and some sheep, both of which can be found in this area in the present day. Given the Oreodont's body strucutre, they would have looked like a mix of camel, sheep, and pig. Their hooves and strong legs would have allowed them to run some distance, and they grazed heavily on grasses.

Corals are another example of one of the older animals on Earth. They are simple ocean filter feeders. Fossilized coral is so common in Michigan that it is actually the state stone. Because coral are still widespread, they are easily recognizable in the fossil record.

Ammonites are common fossils during this time. There were many different species of ammonite, but all contained shells. While their size could vary, some species grew quite large. Inside the shell would be a squid-like body, similar to a modern chambered nautilus (although the connection between ammonites and nautliuses is not yet clear).

The hackberry is a plant that is still found in modern times. Leaves of a hackberry plant have been found fossilized. The identification of fossilized organisms is much easier when we have living, modern samples to look at!

Sea sponges are one of the oldest living animals on the planet. They are simple ocean filter feeders. Because sea sponges are still widespread, they are easily recognizable in the fossil record.

Fossilized shark teeth are common from this time period. Shark teeth from this time are practically indistinguishable from modern sharks, indicating that prehistoric sharks would have very similar features to modern sharks. They would have been carnivores in the ocean, although they would have faced much more competition and predation from larger marine dinosaurs.

The extinct nimravid family is sometimes called the "false saber tooths". They strongly resemble members of the big cat family, although they are not actually cats. The most notable different is that their feet resemble bears more than cats. Otherwise, they were similar predators to true sabertooths, mostly hunting oreodonts and other smaller herbirvores.

Stylemys was a type of primitive tortoise. We know this because it had the characteristic dome-shaped shell of a tortoise, as well as feet fit for walking and digging. Turtle shells are much flatter, and their feet are better adapted to swimming. Based on this, we know that Stylemys likely spent most of his time on land, foraging for small plants and animals.

Hyracodon is an extinct group of organisms related to modern rhinos. While their body structure supports their relationship to rhinos, they likely lived more similarly to horses. Their long legs would help them run in open areas, and their teeth assisted them in grinding various plants.