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Peace River Fossil Identification - Miocene and Pleistocene - Sharks and Ice Age Animals




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Ice Age Animals

One of the more popular type of fossils found are Ice Age animals that roamed Florida's ancient savannahs. Particularly, the large extinct megafauna are sought after by fossil hunters. Well known animals include the extinct elephants like the wooly mammoth and mastodon. Oversized herbivores such as the giant ground sloth, glyptodont, and the wooly rhino are also found on occasion. Large predators such as the American lion, saber toothed cat, and the dire wolf are rarely found. All of these large mammals died out at the end of the last ice age around 11,000 years ago.

These ice age fossils come from deposits of sand and gravel from the Pleistocene that lay above the Hawthorne formation. The layers erode out of river banks and bottoms throughout Florida. The Peace River is an ideal spot to find remains of these extinct Pleistocene animals. Fossil examples and descriptions of Ice Age animals found in the Peace River are shown below.





Deer - Cervidae Family

Ice Age Deer Antler sections are a common find in the Peaace River. They are usually found as fragments a few inches in length. They are very easy to identify, as they look like pieces of modern deer antlers. Somtimes water worn buttons and spikes resemble crocodile teeth. However, they do not have the caracteristic enamel of crocodile teeth.


Fragments of Pleistocene deer antler fossils.

This image shows a few deer antler fossils. Notice the spike on the left, they superficially resemble crocodile and alligator teeth.






Horse - Equus sp.

Horses are the most common non-marine mammal fossil found in the peace river.

They were very common in North America during the Ice ages. They also became extinct in the Americas at end of the Pleistocene with all the other ice age mammals. Luckily, before their demise, they were able to cross the Bering land bridge (along with camels) and spread into Asia, thus avoiding complete extinction.

Peace River Horse Fossils
Although some early horses from the Miocene can be found, by far the most common horse fossils are the modern Equus sp. from the Pleistocene deposits. Easily recognizable horse fossils are their teeth.






Glyptodont - Giant Armadillo Like Animal
Glyptotherium sp.

Glyptodonts are one of my favorite Ice Age fossils because there is nothing like them today! They are large round animals which could reach heights up to 5 feet tall and weigh 2 tons!

Glyptodonts came from South America around 3 million years ago when North and South America merged. These odd animals are related to armadillos, but sort of looked like a cross between an armadillo and a giant tortoise. They had a large round shell composed of up to 2000 thick rosette-patterned scutes, or osteoderms. The scutes were probably covered by scales with bristles sticking out, like an armadillo. Their short tail was also armored with scutes. They also have very short limbs and a very blunt skull. These odd mammals were herbivores and would graze on low-lying vegetation. Glyptodonts became extinct at the end of the Pleistocene with the other Ice Age Megafauna.

In the Peace River thier unique looking scutes are often found.


Closeup of Glyptodont scutes showing the rosette pattern

Close-up of the glyptotherium sp. shell, showing the numerous rosette shaped scutes. This one is from the Muséum national d'Histoire naturelle in Paris.


Glyptotherium Scutes from the Peace River of Florida

These are isolated Glyptotherium scutes from the Peace River. They are easy to identify, as they have a unique rosette pattern and are also very thick (about an inch in thickness).





Giant Ground Sloth - Megalonyx sp.

Ground Ground Sloths were group of giant sloths related to today's two and three toed sloths. They were much larger, with some reaching the size of elephants. Ground sloths evolved in South America and spread throughout North America during the Ice Ages. They were herbivores that had very large claws that could dig up roots and dig burrows. They had very blunt teeth for chewing vegetation. All ground sloths became extinct at the end of the Ice Age around 10,000 years ago.
Three Giant Ground Sloths are found in Florida:

1 .Wandering Giant Ground Sloth (Eremotherium eomigrans):
Reaching a size of around 20 feet, this is the largest Ground Sloth. This large species appears to have been restricted to Florida.

2. Jefferson's Ground Sloth (Megalonyx jeffersonii):
Jefferson's Ground Sloth is another large Ground Sloth. It reached a size of around 9 feet.

3. Harlan's Ground Sloth (Paramylodon harlani):
Herlan's Ground Sloth is a smaller Ground Sloth. It reached a size of around 6 feet. Harlan's Ground Sloth was probably a grazer and fed mainly on grasses.


Glyptotherium Scutes from the Peace River of Florida

These are two pieces of Giant Ground Sloth teeth. They are easy to identify as they are larger than most teeth, and the enamel has parallel groves running down them. These two teeth are actually from the Wando formation in South Carolina.

A life sized model of a Giant Ground Sloth - From Big Bone Lick, Kentucky

A life sized model of a Giant Ground Sloth - From Big Bone Lick, Kentucky.





Mastodons - Primitive Elephants
and
Mammoths - Elephants

Mastodons and Mammoths are discussed together here to distinguish the diferences between the two.

Mastodons are primitive elephants that are often confused with Mammoths which also can be found in Florida. Here, the main charateristics of both are distinguished:

Mastodons
Mastodons are primitive elephants that split from the elephant family tree around 25 million years ago!

Mastodons have teeth with rows of large crowns that are ideal for crunching up leaves and small branches from trees. Stomach contents from a well preserved specimen in Ohio show it ate sedges, swamp grass, and other wetland vegetation.

Mastodons were smaller than mammoths and had flatter heads than mammoths or elephants today. They grew to about 9 feet tall and weighed around 6 tons.

Mastodons probably lived in more forested environments feeding on vegetation, similar to moose today.




Mammoths
Mammoths are closely related to Asian Elephants, as they only split off the family tree around 6 million years ago. They are just a little larger with a little more fur.

The griding surfaces of thier teeth are flat with small ridges on them. These are ideal for grinding up grasses

Mammoths were larger than Mastodons and had dome shaped heads, like todays elephants.

The largest types of Mammoths, the Steppe Mammoths, grew to about 14 feet tall and weighed around 14 tons.

Mammoths probbably lived in grasslands and steppes grazing on tall grasses.



Mastodon tooth fragment from the Peace River of Florida

Although whole mastodon teeth can be found, it is much more common to find pieces of teeth. This is a fragment from a mastodon tooth.
It is very easy to identify, as the enamel is very rough.





Tapir - Large Pig Like Animal
A modern Tapir

A modern tapir from South America in the Viena Zoo, Austria. Author: Gerwin Sturm (cc-by-sa-2.0)


Many types of tapir lived in the Pleistocene of florida. They all looked very similar to todays tapirs that still live in South and Central America. They are hoofed animals that have a pig-like body with a short trunk-like snout. Tapirs are herbivores and came to North America with the rest of the large mammals when North and South America joined approximately 3 million years ago.

Often Tapir teeth can be found. Their molars are relatively easy to identify as they have distinct ridges with low crowns. This can be seen in the fossil specimens below.

Fossil Tapir jaw showing what the teeth look like

Fossil Tapir jaw showing what the teeth look like. This Tapir specimen is on display at the Mace Brown Museum in Charleston.

Tapir Tooth Fossil  from the Peace River of Florida

Fossil tapir teeth are one of the easier mammal teeth to identify, they are also one of the more common mammal teeth to be found.
Usualy only the crowns are found, as the roots are fragile and often break apart. Tapir molars have low crowns, usually around an inch in length, with two distinct ridges running across them.






Giant Armadillo
Holmesina sp.
Giant Armadillo

This is a Giant Armadillo (Holmesina septentrionalis) on display at the Mace Brown Museum in Charleston.


After arriving from South America, Giant Armadillos made their home in the southern United States, including Florida.

Two species of giant armadillo are found in the Pleistocene of Florida; the larger H. septentrionalis and the smaller H. floridanus.

There are two general shapes of scutes on armadillos. There are long rectangular "flex scutes" that overlap each other in the center of the shell, which give the shell flexibility and there are pentagon shaped scutes toward the front and rear of the shell. These can be seen in the fossil specimen of H. septentrionalis in the image above.

Interesting Fact:Giant Armadillos have a dentition sutible for eating vegetation, indicating they were herbavores, unlike modern armadillos.


Giant Armadillo Scutes from the Peace River of Florida

These are two of the general scute shapes of the Giant Armadillo. Giant Armadillo scutes are much thinner than Glyptodont scutes.




Marine Mammals

Remains of marine mammals such as cetacea (whales and dolphins), and dugongs are fairly common in the Peace River.




Dugong



Dugong Rib Sections

Dugong rib bones are very common in some places of the Peace River. They are easy to identify as they are incredibly dense. Their ribs are extra heavy to aid in buoyancy (it offsets some of the fat).




Reptiles

Reptile fossils are also pretty common in the Peace River. They mostly come from Crocodiles, Alligators, and Turtles, such as sea turtles and even gian land tortoises.




Sea Turtles and Tortoises

Turtle fossils are very common in the peace river of Florida. The most common fossils are pieces of their shells, either the Carpace (top shell), or the Plasteron (bottom shell). Carpaces usually have more ornamentation on them than the plasterons. There were many kinds of turtles, including many sea turtles and land turtles. The image to the right shows a skeleton of a sea turtle.




Turtle Shell Fragments

These are pieces of turtle shell. They come in many different shapes. They are all very thin and flat. Carpace fragments have ornamentation on them (little dimples and grooves), while plasteron fragments are more plain looking. The lower row are neural carpace pieces. These run down the center of the shell and have the vertebra attached.




Giant Land Tortoise

Florida during the Ice Age was home to Giant Land Tortoises, similar to the ones now only found in the Galapagos. The fossil below is a leg spur from a Giant Land Tortoise. There were a few different species of large tortoise in the florida Ice Age. This spur is very water worn, but still has the caracteristic shape. They are also very dense.





Crocodiles and Alligators

Alligators and Crocodiles have been inhabiting Florida for millions of years, and were very diverse in the past. In the Miocene a giant Saltwater Crocodile called Gavialosuchus even inhabited Florida! Today there are only two native species of alligator and crocodile, the American Alligator (Alligator mississippiensis) , and the American Crocodile (Crocodylus acutus) which only inhabits the southern tip of Florida. There is also an invasive species in Florida, the spectacled caiman (Caiman crocodilus).
Teeth and scutes from crocodiles and alligators are common fossils in the Peace River. The image to the right shows an American Alligator skull. Image by Didier Descouens (Own work). CC BY 3.0, via Wikimedia Commons.




Crocodile / Alligator teeth

These are two smaller teeth from either crocodiles or alligators. Notice the conical shape of the teeth.




Sharks and other Fish

Fossil shark teeth are some of the more popular fossils to look for in the Peace River. They range from Miocene to Pliocene. One of the more sought after shark is the Megalodon shark, a giant 60 foot shark!




Carcharocles megalodon - Megatooth Shark

The warm, shallow, and food rich waters of Florida in the Miocene made a perfect nursing ground for megalodon sharks. Adults would come here to give birth. The young megalodons would be sheltered from the open ocean and have ample food in the form of small whales, dolphins, and dugongs. Because this area was a nursing ground, the megaloton teeth found here are smaller than adult teeth. These juvenile teeth range in sizes from 1 - 3 inches.

Identification: Larger than other shark teeth - Serrations - Bourelette
Similar Fossils: C. subaruiculatus - This species has cusps

Here is your Complete guide to megalodon sharks.

Sample Megalodon Shark teeth from the Peace River of Florida

These are sample megalodon shark teeth from the Peace River of Florida. These are the typical sized teeth that are found.




Carcharinus sp. - Whaler Sharks

The Carcharinus Genera - or the Whaler Sharks are a genus of requiem sharks with over 30 extant species. They are very common and found virtually all over the globe. They feed on a variety of prey, from bony fish, other sharks and rays, and squid.

Many people know examples of Whaler Sharks: The Bull Shark, Gray Shark, Blacktip Reef Shark, Sandbar Shark, Copper Shark, Oceanic Whitetip, Silky Shark, Galapagos Shark, Spinner Shark, and the Dusky Shark are all species of Whaler Sharks.

Teeth from the Whaler Shark genus are among the most common teeth found. Unfortunately, there are many species of Carcharinus sharks, many are nearly impossible to tell apart based on isolated teeth.

Identification: Small triangular teeth with serrations, lower teeth are more peg like than upper teeth.
Similar Fossils: Lower teeth look very similar to Lemon shark teeth.

Fossil Whaler Shark teeth from the Peace River of Florida

These are sample Whaler shark fossil teeth from the Peace River of Florida.




Carcharias sp. - Sand Tiger Shark

Growing up to 10 feet in length, Sand Tigers are found in temperate waters worldwide along the coast, including the Eastern United States. They look ferocious in the water as they usually swim with their mouths partially open, showing rows of long and pointy teeth. These teeth are ideal for grasping onto bony fish, their prey.

Sand Tigers do not look like and are not related to the similarly named Tiger Shark.

Individual Sand Tiger teeth are highly variable. As a result, the research is a little muddy on fossil sand tigers. There is debate as to how many species of sand tiger are found in the Miocene formations along the East Coast.

Identification: Sand Tiger teeth have a distinctive shape, they have a long crown, small recurved cusplets (sometimes worn off), and long pointy root lobes with a deep nutrient groove.
Similar Fossils: From isolated teeth, it's very difficult, if not impossible to distinguish one Sand Tiger species from the next.

Fossil Sand Tiger Shark teeth from the Peace River of Florida

These are sample Sand Tiger Shark shark fossil teeth from the Peace River of Florida.




Galeocerdo sp. - Tiger Shark

Tiger sharks are found in tropical and temperate waters across the globe, including the Pacific. They are large sharks with an unmistakable appearance as they have very short and blunt snouts. They also have a unique color pattern. At birth, Tiger sharks have dark spots along their dorsal surface, which fuse into vertical bars or stripes at maturity. These unique stripes begin to fade as the shark ages.

Tiger sharks first appear in the fossil record in the Eocene as Galeocerdo latidens. Today there is one living species of tiger shark, Galeocerdo cuvier. In the Miocene, the living Tiger shark does not yet exist. There are two types of Tiger like sharks: Galeocerdo aduncus and Physogaleus contortus. By the late Miocene a third type of Tiger shark had appeared; G. mayumbensis. G. mayumbensis is is similar in size and shape to a modern tiger (C. cuvier), however the crown appears to be taller. Teeth from these species are seldom found in the Peace River formation.

By the Pliocene, the prehistoric Tigers were extinct leaving the living Tiger shark, G. cuvier. Go to the Tiger Shark Gallery to learn more about Tiger Sharks, including examples of the other Tiger shark species.

Identification: Sand Tiger teeth have a distinctive shape, they have a long crown, small recurved cusplets (sometimes worn off), and long pointy root lobes with a deep nutrient groove.
Similar Fossils: The species G. aduncus, G. mayumbensis, and G. cuvier all look similar. Check out the Tiger Shark page to see the differences.

Fossil Tiger Shark tooth from the Peace River of Florida.  This one is the rare species, G. mayumbensis.

Fossil Tiger Shark tooth from the Peace River of Florida. This one is the rare form, G. mayumbensis.




Hemipristis serra (Agassiz, 1843)
Snaggletooth Shark

This species lived from the late Oligocene into the early Pleistocene. They are commonly called Snaggeltooth Sharks due to the large serrations on their teeth. Species of Hemipristis are extant today, however, they are only found in tropical waters, and are much smaller than the fossil species. The fossil species are also found worldwide.

Go to the Snaggletooth Shark Gallery to view a composite dentition of a Snaggletooth shark and to learn more about these sharks.

Identification: Upper teeth are unmistakable, as they have very jagged serrations and the root makes a "Z" type shape Lower anterior teeth look similar to sand-tiger teeth, however, they have jagged cusps and a very thick bulge on the root. Lower lateral teeth are similar to upper teeth, but are more compressed length wise.
Similar Fossils: Worn lower anterior teeth may resemble sand-tiger teeth.

Fossil Sand Snaggletooth Shark teeth from the Peace River of Florida

These are sample Snaggletooth shark fossil teeth from the Peace River of Florida. The left is an upper tooth, the right is a lower tooth.




Negaprion sp. - Lemon Shark

Lemon Shark teeth can be easily confused with Carcharhinus sp. lowers, however they have smooth to very week serrated enameloid shoulders, where Carcharhinus sp. have serrated enameloid shoulders.

Identification: Crown has a smooth edge, shoulder is weakly serrated, root and blade are at a nearly 90 degree angle
Similar Fossils: Gray shark lower teeth.

Fossil Lemon Shark teeth from the Peace River of Florida

These are sample lemon shark fossil teeth from the Peace River of Florida.




Sphyrna zygaena
Hammerhead Shark

Hammer Head Sharks can get up to 11 feet in length. They feed on a variety of prey, including other sharks, bony fish, and crustaceans. The Common Hammerhead (Sphyrna zygaena) lives in Floridas waters today. For more information on Hammerhead Sharks, including better fossil examples, go to the Hammerhead Shark Gallery.

Identification: Small, No Serrations, Deep nutrient groove / notch on root, Notched margin on enamel Similar Fossils: Similar in shape and size to Thresher and worn Gray shark teeth.
Similar Fossils: Similar in shape and size to Thresher and worn Gray shark teeth.

Fossil Hammerhead Shark tooth from the Peace River of Florida

This is a very worn hammerhead tooth that has also been leached by water, turning it a light, white color.




Ray Fossils

Rays have modified teeth that form flat crushing plates. These crushing plates are adapted for eating mollusks and crustaceans on the sea floor. They suck their prey up like a vacuum and simply crush them between their upper and lower crushing plates.

Common fossils from rays are pieces of their crushing plates, barb pieces, and scutes.

Ray fossils from the Peace River of Florida

These are some common ray fossils from the Peace River. The left two are tail spine (barb) pieces. The right three are mouth pavement pieces.




Chilomycterus sp. - Burrfish

The crushing mouthplates of Burrfish are found throught Miocene and Pliocene exposures along the East Coast. Upper and lower mouthplates are easily distinguishable. Uppers are round, while lowers are triangular in shape. A common type of Burrfish is the Pufferfish.

Burrfish mouthplate from the Peace River of Florida

This is a Burrfish upper mouthplate from the Peace River, Florida.




Fish Teeth

Many types of fish teeth are found in the Peace River. They are usually jet black and cone or triangle shaped. Below is an example of a larger barracuda tooth.

Large barracuda tooth from the Peace River of Florida

This is a large barracuda tooth from the Peace River of Florida. These type of fish teeth are easy to identify. They are large (greater than 1/2"), very thin and triangular.