List of the prehistoric life of South Dakota facts for kids

This article is about the amazing ancient creatures and plants whose fossils have been found in South Dakota. These fossils tell us a lot about what life was like millions of years ago in this area. From tiny sea creatures to giant dinosaurs and woolly mammoths, South Dakota has a rich history of prehistoric life!

Paleozoic Era: Ancient Sea Life

The Paleozoic Era was a very long time ago, from about 541 to 252 million years ago. During much of this time, parts of South Dakota were covered by shallow seas. This means many of the fossils found from this era are of sea creatures.

Tiny Trilobites and Other Sea Dwellers

Many of the fossils from the Paleozoic Era in South Dakota are from creatures called trilobites. These were ancient sea animals with hard, segmented bodies, a bit like modern-day crabs or insects. They are now extinct, meaning they no longer exist.

• †Agnostus was a small trilobite.

Assemblage of fossils of the Cambrian trilobite Agnostus

• †Crepicephalus was another type of trilobite found here.
• †Dikelocephalus was a larger trilobite.
• †Tricrepicephalus was also a trilobite.

Fossil of the Cambrian trilobite Tricrepicephalus

Besides trilobites, other ancient sea animals lived in South Dakota:

• †Hyolitha were cone-shaped creatures that lived in shells. They might be related to brachiopods.

Fossilized shells of the Cambrian-Permian brachiopod relative Hyolitha

• †Cladodus was an early type of shark.
• †Caseodus was a relative of modern-day chimaeras, which are deep-sea fish.

Life restoration of the Carboniferous Chimaera relative Caseodus

• †Edestus was a very unusual shark with a spiral-shaped jaw.

Life restoration of the Late Devonian-Carboniferous Chimaera relative Edestus

• †Janassa was a ray-like cartilaginous fish.

Restoration of the Carboniferous-Permian ray-like cartilaginous fish Janassa (top and left)

• †Listracanthus was another cartilaginous fish.

Restoration of the Carboniferous-Early Triassic cartilaginous fish Listracanthus

Mesozoic Era: The Age of Dinosaurs

The Mesozoic Era, from about 252 to 66 million years ago, is often called the "Age of Dinosaurs." South Dakota has many famous dinosaur fossils, as well as other amazing creatures from this time.

Dinosaurs of South Dakota

Many different kinds of dinosaurs roamed South Dakota during the Mesozoic Era.

• †Allosaurus was a large, meat-eating dinosaur.

Restoration of the Late Jurassic theropod dinosaur Allosaurus

• †Apatosaurus was a huge, long-necked plant-eating dinosaur.
• †Barosaurus was another giant plant-eating dinosaur. South Dakota is where this dinosaur was first discovered!

Restoration of the Late Jurassic sauropod dinosaur Barosaurus rearing to defend itself against a pair of the theropod Allosaurus

• †Camarasaurus was a large, plant-eating sauropod dinosaur.

Life restoration of a herd of the Late Jurassic sauropod dinosaur Camarasaurus

• †Dakotaraptor was a speedy, feathered predator. Its fossils were first found in South Dakota.
• †Diplodocus was one of the longest dinosaurs, known for its very long neck and tail.
• †Edmontonia was a heavily armored dinosaur.
• †Edmontosaurus was a common duck-billed dinosaur.

Life restoration of the Late Cretaceous duck-billed dinosaur Edmontosaurus annectens

• †Gorgosaurus was a large, meat-eating tyrannosaur.
• †Hoplitosaurus was an armored dinosaur.
• †Hypsilophodon was a smaller, fast-running plant-eater.
• †Ornithomimus was a bird-like dinosaur that looked a bit like an ostrich.
• †Osmakasaurus was a duck-billed dinosaur first found in South Dakota.
• †Pachycephalosaurus was a dinosaur with a thick, dome-shaped skull. This type of dinosaur was first found in South Dakota.

Fossilized skeleton of the Late Cretaceous dome-headed dinosaur Pachycephalosaurus

• †Tatankaceratops was a horned dinosaur, also first found here.
• †Thescelosaurus was a small, plant-eating dinosaur.
• †Torosaurus was a large, horned dinosaur, similar to Triceratops.
• †Triceratops was a famous horned dinosaur.
• †Tyrannosaurus was one of the largest and most famous meat-eating dinosaurs.

Fossilized skeleton of the Late Cretaceous tyrannosaur Tyrannosaurus

Flying and Swimming Reptiles

The Mesozoic Era also had amazing reptiles that flew in the sky or swam in the seas.

• †Pteranodon was a large flying reptile, or pterosaur, with a long crest on its head.

Life restoration of the Late Cretaceous pterosaur Pteranodon

• †Archelon was a giant sea turtle. Its fossils were first found in South Dakota.

Mounted fossilized skeleton of the Late Cretaceous sea turtle Archelon

• †Clidastes was a type of mosasaur, a large marine reptile.
• †Dolichorhynchops was a short-necked plesiosaur, a marine reptile with four flippers.
• †Elasmosaurus was a very long-necked plesiosaur.
• †Mosasaurus was a huge marine reptile, a top predator in the ancient seas. This type of mosasaur was first found in South Dakota.

Life restoration of two of the Late Cretaceous Mosasaurus

• †Platecarpus was another type of mosasaur.

Life restoration of the Late Cretaceous mosasaur Platecarpus

• †Styxosaurus was a long-necked plesiosaur, first found in South Dakota.

Animated life restoration of the Late Cretaceous plesiosaur Styxosaurus

• †Tylosaurus was a very large and powerful mosasaur.

Other Mesozoic Life

• †Baculites were straight-shelled ammonites, a type of ancient mollusk.
• †Collignoniceras were coiled ammonites.

Fossilized shell of the Late Cretaceous ammonoid Collignoniceras

• †Inoceramus were very large marine clams.

Fossilized shell of the Early Jurassic-Late Cretaceous marine bivalve Inoceramus with a human indicating its size

• †Cycadeoidea were ancient plants that looked a bit like modern cycads or palms. Many types were first found in South Dakota.

Fossil of the Jurassic-Cretaceous cycad relative Cycadeoidea

• †Hesperornis was a toothed diving bird.

Life restoration of the Late Cretaceous toothed bird Hesperornis

• †Leidyosuchus was an ancient alligator relative.

Fossilized skull of the Late Cretaceous alligator relative Leidyosuchus

Cenozoic Era: The Age of Mammals

The Cenozoic Era began about 66 million years ago and continues to the present day. After the dinosaurs died out, mammals became the dominant large animals. South Dakota has many fossils from this era, showing a variety of ancient mammals.

Giant Mammals and Other Animals

• †Amebelodon was an ancient elephant relative with shovel-like tusks.

Life restoration of the Miocene elephant relative Amebelodon. Margret Flinsch (1932).

• †Mammuthus columbi, or the Columbian mammoth, was a huge elephant relative with long, curved tusks.

Life restoration of a herd of Mammuthus columbi, or Columbian mammoths. The extent of the fur depicted is hypothetical. Charles R. Knight (1909).

• †Stegomastodon was another elephant relative.

Mounted fossilized skeleton of the Pliocene-Pleistocene elephant relative Stegomastodon

• †Eubelodon was also an ancient elephant relative.

Life restoration of the Miocene elephant relative Eubelodon

• †Megacerops was a rhino-like mammal with a large horn on its snout.
• †Teleoceras was a short-legged rhinoceros.

Restoration of the Miocene-Pliocene rhinoceros Teleoceras

• †Dinohyus was a giant pig-like animal.
• †Megalonyx was a giant ground sloth.
• †Bison latifrons was a very large, long-horned bison.

Mounted fossilized skeleton of the Pleistocene Bison latifrons, or long-horned bison

• †Canis dirus, the dire wolf, was a large wolf that lived alongside mammoths and saber-toothed cats.

Modern mounted skeleton of Canis lupus, the grey wolf, to scale with a fossilized skeleton of the Pleistocene wolf Canis dirus, or dire wolf

• †Hemiauchenia was an ancient llama relative.

Fossilized lower jaw of the Miocene-Pleistocene llama relative Hemiauchenia

• †Cosoryx was an early pronghorn relative.

Fossilized skull of the Miocene pronghorn Cosoryx

• †Poebrotherium was an early camel.

Life restoration of the Eocene-Oligocene camel Poebrotherium

• †Merychyus was a type of oreodont, an extinct group of hoofed mammals.

Restoration of a herd of the Eocene-Miocene oreodont mammal Merychyus

Ancient Predators

• †Barbourofelis was a saber-toothed cat.
• †Dinictis was an early false saber-toothed cat.

Life restoration of the Eocene-Miocene false saber-toothed cat Dinictis. Robert Bruce Horsfall (1913).

• †Hyaenodon was a large, wolf-like predator.

Life restoration of the Eocene-Miocene creodont mammal Hyaenodon

• †Pseudaelurus was an early cat.

Restoration of the Miocene cat Pseudaelurus

• †Leptocyon was an early dog.

Illustration of a fossilized skull of the Oligocene-Miocene dog Leptocyon

Other Cenozoic Animals

• †Palaeocastor was an ancient beaver that dug spiral-shaped burrows.

Spiral-shaped fossilized burrow and associated skeleton of the Oligocene-Miocene beaver Palaeocastor

• †Peltosaurus was an ancient lizard.
• †Stylemys was an ancient tortoise.