Discover 13 Living Fossils in North America

Key Points

• A living fossil is a living species that looks cosmetically the same or virtually identical to fossil records of the same or similar species.
• The Virginia opossum is the only marsupial living fossil living in North America.
• The science community has an ongoing debate about whether alligators and crocodiles are living fossils.

Nature is an amazing process of adapting animals to fit a specific environmental niche. By providing animals with certain abilities, they adapt and evolve into creatures suitable to fulfill their niche and survive in the wild. Some animals will continue evolving and changing for hundreds of years, while some animals reach perfection and remain the same.

These animals have lived the same way for thousands of years because nature considered them perfect with no further need for change. These “living fossils,” are a scientific dream to study because their habits provide humanity a glimpse of life back in ancient times.

Come along as this article discusses what are living fossils and what are living fossils living in North America today.

What Are Living Fossils?

First, a living fossil is a living species that looks cosmetically the same or nearly identical to fossil records of the same or similar species. Basically, the animal looks almost the same as their ancestors.

For something to be considered a living fossil, it has to fit three criteria.

1. Members of a taxon (classified group) must resemble the fossil records over a long period of time.
2. There must be little physical divergence from early members to the present species.
3. There is little divergence or evolution from the ancient taxonomic group.

Living Fossils in North America

The idea of any animal not having evolved for millions of years may seem unlikely, but there are a surprising number of living fossils around in and across North America. These animals are protected by environmental laws to prevent over-poaching to keep their lineage and populations stable.

Virginia Opossum

Didelphis virginiana, the Virginia opossum is the oldest and only living marsupial in North America. They have notoriously short lifespans for a small to medium-sized mammal, living two to three years in the wild, or six to eight years in captivity.

Virginia opossums are found across North American woodlands near sources of freshwater. This makes it easy to feed on insects, worms, amphibians, birds, bird eggs, fruits, reptiles, and carrion (dead animal carcasses).

The earliest known fossil record of opossums dates back 23-14 million years ago in the early Miocene Era. Other records indicate opossums evolved from a similar mammal 145-66 million years ago in the late Cretaceous Period.

Mountain Beaver

Aplodontia rufa, the North American Mountain Beaver is technically not a beaver. They are more closely related to squirrels, but their chubby bodies and tenacity to chew wood classified them as beavers.

Mountain beavers live about 6 years in the wild. As their name suggests, they live in mountainous regions in California, Washington state, and Oregon. Sightings of mountain beavers also have them residing near the coastlines. They eat assorted herbs, shoots, plants, ferns, and tree saplings, but balance their diet with fecal pellets from other animals.

Early fossil records indicate they are related to an extinct woodchuck that lived in the early Miocene era.

Pelicans

Believe it or not, pelicans count as living fossils since they have no known relatives alive today. Which makes sense considering how well they stand out among other bird species.

Pelecanus, pelicans have a lifespan of 15-25 years. They live near coastal beaches in the Atlantic Ocean, Pacific Ocean, and Gulf coasts, as well as some lagoons across the country. They primarily eat fish but will eat amphibians, turtles, crustaceans, and insects. When food is scarce, scientists report seeing pelicans eating other birds.

According to fossil records, pelicans have been living on Earth for nearly 30 million years.

Sandhill Cranes

Antigone canadensis, sandhill cranes are majestic birds that are well known for performing beautiful dances to attract mates and communicate. They stretch their wings, bow their heads, and leap in the air with their long legs in a beautiful display of balance and grace.

Sandhill cranes are around 3-4 feet tall, with a wingspan of nearly 6 feet across. To sustain their large size, they have a healthy appetite for insects, roots of water plants, rodents, snails, amphibians, reptiles, berries, and seeds. They love living in marshes, bogs, and prairies where access to prey is easy.

The earliest fossil records of sandhill cranes date back 2.5 million years ago. Preserved fossil remains were found in the Macasphalt Shell Pit in Florida.

Common Snapping Turtles

Many turtles have survived extinction-level events and lived to metaphorically tell the tale of how life has changed. The snapping turtle is one of those animals that still has its prehistoric edge while thriving in the modern day.

Chelydra serpentina, the common snapping turtle is a long-lived species, capable of surviving nearly 40 years or longer. They inhabit freshwater lakes, marshes, and nearly all sources of freshwater across North America. Some are capable of living in brackish (mixture of fresh and saltwater) environments. They use their powerful jaws to catch fish, insects, spiders, amphibians, smaller turtles, birds, and small mammal carrion.

Fossil records indicate common snapping turtles have not evolved since the late Cretaceous era.

American Alligators and Crocodiles

Let’s be clear, alligators and crocodiles are not the same thing. They have very distinct features and habits which make them separate species which is discussed in other articles.

In a quick difference comparison:

While both have similar habits of ambushing prey by camouflaging in water, they love to prey on small mammals, birds, frogs, turtles, and fish.

Fossilized skulls of these animals date back 2.5 million years ago, making them younger than the alligator snapping turtle. However, scientists debate if alligators and crocodiles count as living fossils because there might have been some divergence later.

For the sake of intrigue, they will be counted as living fossils because they fit the two other categories of little physical divergence from early members, and little taxonomic diversity between the groups.

Leatherback Sea Turtles

Dermochelys coriacea, the leatherback sea turtle is the largest in the world. Not to be confused with a tortoise, which has feet instead of flippers, the leatherback sea turtle roams across the Atlantic Ocean, Pacific Ocean, and all the tropical waters in the world. They gently glide through the ocean, feeding on jellyfish, squid, fish, algae, seaweed, and assorted crustaceans.

Fossil records indicate leatherback sea turtles dating from the early Cretaceous Period to the Pliocene Era (5.4-2.4 million years ago).

Hellbender Salamanders

Cryptobranchus alleganiensis, hellbender salamanders are the largest salamander species in North America. They can reach 12-29 inches and weigh nearly five pounds. These amphibians absorb 95% of their oxygen through their skin folds and wrinkles.

Hellbender salamanders live for approximately 30 years on a diet of crayfish, insects, earthworms, snails, fish eggs, tadpoles, and other salamander eggs.

To keep their skin moist, they live near fast-moving streams in the Ozarks and the Appalachian Mountains.

Fossil records indicate hellbender salamanders have not evolved in 160 million years.

Lake Sturgeon

Acipenser fulvescens, the lake sturgeon is the oldest and largest fish living in the North American Great Lakes. These massive fish can reach six feet long and weigh nearly 200 pounds. A record lake sturgeon weighed nearly 300 pounds.

These prehistoric fish swim along the bottom of freshwater lakes and rivers, feeding on mussels, snails, small fish, crustaceans, and assorted macroinvertebrates like silverfish, mosquitos, and hornets. A healthy lake sturgeon can live 55-150 years.

Fossil records show lake sturgeon have not evolved for 245-208 million years, making them residents of the Triassic Period. Unfortunately, they are currently endangered and vulnerable due to overfishing, slow reproduction cycles, and habitat destruction.

Frilled Sharks

Chlamydoselachus anguineus, the frilled shark or eel shark, is a unique shark species that looks more similar to an eel than an actual shark. Their serpentine bodies and long gills can make many fishers and sailors uneasy. It is entirely possible these fish could be mistaken for sea serpents like Tiamat or Jormungandr by someone unaware of their existence.

Reaching seven feet long, the frilled shark can live for 25 years in the deep oceans. They rarely contact humans, preferring to stay at depths of 1640-3280 feet down, with some living 4900 feet down. At these depths, they feed on squid, fish, and smaller sharks.

Fossil records indicate frilled sharks first appeared in the Late Cretaceous period and Late Jurassic period (150 million years ago).

Horseshoe Crab

That’s right, those hard-shelled helmet crabs people find on the beach are older than humans’ earliest ancestors.

Limulus polyphemu, the Atlantic horseshoe crab are not technically crabs, but related to spiders. They live along the coastlines of the Atlantic Ocean and feed on clams, crustaceans, worms, and algae.

Horseshoe crab fossil records indicate their earliest ancestors lived 445-200 million years ago.

American Cockroaches

Periplaneta americana, the American cockroach may seem unpleasant and problematic for all homeowners, but they are classified as living fossils. These critters only live for about a year, but they have been living the same way for nearly 99 million years.

Cockroaches will infest everything if given the chance to breed. They love wet, shady areas like hollow trees, wood piles, and mulch. With the limited time they have, cockroaches forage for food like plant shoots, milk, fermenting fruit, fungi, algae, and crumbs littered on kitchen floors.

The largest cockroach fossil ever found dates back 55 million years ago.

Dragonflies

Finally, we come to our last living fossil in North America, dragonflies. Dragonflies are expert fliers, having evolved to chase other insects’ midair to feast on their protein.

Typically, dragonflies live between 7-56 days. They live near slow-moving freshwater sources with no fish like streams and ponds, hunting assorted insects as their primary diet.

Fossil records indicate dragonflies mostly shrank in 275 million years since the Permian Era.

The thrill of having living fossils in our backyard is more exotic sounding than it seems. Many of these animals are small and unimpressive with the more exotic animals living in places away from humans. Still, next time one of these animals crosses your path, take a moment to remember they reached their evolutionary peak and humans are still evolving.