California, as we know it today, didn’t exist back in the Mesozoic and Paleozoic eras.
Most of the state was underwater, with a coastline up to 100 miles further east than its current position.
The period was also characterized by significant geologic changes such as active volcanism and mountain building.
While these changes led to the formation of geologic structures like the Sierra Nevada, they also destroyed many of the fossils that would have been preserved in the region.
Consequently, California’s terrestrial fossil record is quite sparse.
So, while many dinosaurs and other prehistoric animals may have inhabited the state, we have limited records of them.
Despite this, there have been a few significant discoveries of prehistoric animals in California and neighboring states over the years.
In this article, we’ll explore 15 dinosaurs and other prehistoric animals that once lived in present-day California.
15. Saurolophinae
| Name | Saurolophinae |
| Name Meaning | “Lizard crest” |
| Pronunciation | sow-roh-loh-fus-ee-nay |
| Era | Mesozoic Era |
| Classification | Dinosauria, Ornithischia, & Ornithopoda |
| Diet | Carnivorous |
| Length | Unknown |
| Weight | Unknown |
The name Saurolophinae refers to a group of non-crested hadrosaurid dinosaurs (duck-billed dinosaurs) that were alive during the Cretaceous Period.
Most of the Saurolophinae fossils found so far in California are isolated bones that are yet to be fully identified.
The bones discovered in California may have belonged to Saroplophinae dinosaurs such as the Edmontosaurus and Saurolophus.
Scientists can tell that they’re hadrosaurids, but the specific genus and species of this dinosaur group have not been identified.
14. Nodosaur
| Name | Nodosaur |
| Name Meaning | “Knobbed lizard” |
| Pronunciation | No-do-sa-ur |
| Era | Mesozoic – Late Cretaceous |
| Classification | Dinosauria, Ornithischia & Thyreophora |
| Diet | Herbivorous |
| Height | 3 meters (10 feet) |
| Length | 4–6 meters (13–20 feet) |
| Weight | 2–4 tons (4,000–8,000 pounds) |
The nodosaurids are heavily built armored dinosaurs that lived in North America and other parts of the world during the Late Jurassic Period.
Like the closest relatives, the ankylosaurids, nodosaurs had rows of spines and bony plates arranged on their backs.
They were medium-sized dinosaurs that fed on plant materials abundant within their habitats during the Jurassic Period.
In 1987, scientists uncovered parts of a nodosaur during an excavation near Carlsbad, California.
This find was the first instance of a nodosaurid dinosaur found anywhere west of the Rocky Mountains.
The discovery of a nodosaurid fossil in California suggests that the West Coast and the Interior area of the United States were once connected.
Although scientists could not conclusively identify the specific type of nodosaur due to the fragmentary fossils, the discovered species was found to be similar to species native to Wyoming and Kansas.
13. Tyrannosaurus rex (T-Rex)
| Name | Tyrannosaurus |
| Name Meaning | “Tyrant lizard” |
| Pronunciation | tie-RAN-oh-SAWR-us |
| Era | Mesozoic – Late Cretaceous |
| Classification | Dinosauria, Saurischia & Theropoda |
| Diet | Carnivorous |
| Height | 3–4 meters (12–13 feet) |
| Length | 12–15 meters (40–50 feet) |
| Weight | 5–8 metric tons (11,000–17,600 pounds) |
The T-rex was one of North America’s biggest and most iconic dinosaurs.
It is also considered the largest meat-eating dinosaur to have ever lived on the continent.
It was also one of the most abundant dinosaurs of the Late Cretaceous Period, with a widespread distribution that extended to the west Coast of North America.
The T-rex lived in the Rocky Mountains of California between 68 and 66 million years ago.
Expectedly, it was the apex predator of the region.
The bipedal carnivore is renowned for its massive skull and powerful bone-crushing jaws.
Tyrannosaurus hunted herbivorous dinosaurs, like the armored ceratopsians, ankylosaurs, and hadrosaurs actively.
Experts also think it scavenged on carcasses occasionally.
12. Anchisauripus
| Name | Anchisauripus |
| Name Meaning | “Anchisaurus-foot” |
| Pronunciation | An-chi-sau-ri-pus |
| Era | Mesozoic – Triassic to Jurassic |
| Classification | Dinosauria, Saurischia & Theropoda |
| Diet | Likely Carnivorous |
| Height | Unknown |
| Length | Unknown |
| Weight | Unknown |
Anchisauripus is not really a dinosaur.
Instead, the name applies to the footprints of a non-avian dinosaur that have been found across various locations in the United States, including California.
Although scientists are not certain of the true identity of the dinosaurs that left the footprint behind, experts think it belongs to a small theropod dinosaur that lived in parts of the present-day Mojave Desert in Southeastern California.
It was a small and nimble theropod and was likely a carnivore.
Anchisauripus footprints are typically about three to five inches long.
The dinosaur had three toes, with the middle toe being the longest.
Since the dinosaur left no notable body fossils beyond the preserved footprints, very little is known about what it really looked like or how it lived.
Anchisauripus lived between the Late Triassic and Early Jurassic Period, around 230 to 200 million years ago.
11. Californosaurus
| Name | Californosaurus |
| Name Meaning | “California lizard” |
| Pronunciation | Cal-e-for-noe-sore-us. |
| Era | Mesozoic — Late Triassic |
| Classification | Reptilia, Diapsida, & Ichthyopterygia |
| Diet | Piscivore |
| Length | 3 meters (9.8 feet) |
| Weight | 226 kilograms (500 pounds) |
From the name, it’s obvious that Californosaurus is named after California.
This fish-like reptile belongs to a group of marine lizards known as ichthyosaurs.
Californosaurus lived in California during the Triassic Period.
Fossils of this marine reptile have also been found in other parts of the world, such as in Germany.
This ichthyosaur genus measured about three meters (9.8 feet) long with a fish-like body.
It had a long-snouted head, which was small compared to the rest of its body.
Californosaurus also had a small downturned tail with a vertical tail fluke.
Like other Ichthyosaurs, the forelimbs and hindlimbs of this marine reptile were fully transformed into flippers, which helped with locomotion underwater.
Californosaurus was a fully aquatic reptile that fed on fish and other small marine animals.
10. Plotosaurus
| Name | Plotosaurus |
| Name Meaning | “Swimmer lizard” |
| Pronunciation | Plo-toe-sore-us. |
| Era | Mesozoic – Late Cretaceous |
| Classification | Reptilia, Squamata, & Mosasauridae |
| Diet | Carnivore/Piscivore |
| Length | 9–13 meters (29–42 feet) |
| Weight | 5 tons (10,000 pounds) |
Plotosaurus was a 40-foot-long marine reptile discovered in Late Cretaceous sediments in California.
It was originally named Kolposaurus, which means “bay lizard,” after its discovery in 1942.
However, the name had to be changed to Plotosaurus (swimmer lizard) in 1951 because the previous name had already been assigned to another animal.
Two Plotosaurus species have been identified so far.
Plotosaurus bennisoni was about nine meters long, while the second species, Plotosaurus tuckeri, was up to 13 meters long.
Plotosaurus was a mosasaur, a type of marine reptile related to modern snakes and lizards.
It had a long, streamlined body and is considered one of the largest mosasaur species ever discovered.
It had narrow flippers and large tail fins and seemed to be better adapted to an aquatic lifestyle compared to other related mosasaurs.
9. Cetotherium
| Name | Cetotherium |
| Name Meaning | “Whale beast” |
| Pronunciation | See-toe-fee-ree-um. |
| Era | Cenozoic — Tertiary |
| Classification | Mammalia, Cetacea, Mysticeti |
| Diet | Filter feeder |
| Length | 5–6.8 meters (16.4–22.3 feet) |
| Weight | Unknown |
Cetotherium was a genus of baleen whales that lived in the waters of California back in the Miocene Epoch.
It is considered one of the earliest baleen whales to have ever evolved, as earlier whales were toothed predators that preyed on fish and other marine animals.
Being a baleen whale, Cetotherium was a filter-feeder with a sieve-like structure in its mouth to strain small organisms out of the water.
Cetotherium furlongi is the Cetotherium species found in California.
Unfortunately, very little is known about this whale species because the holotype specimen had been lost.
Other Cetotherium fossils have been found in other places, such as Russia and Italy.
8. Smilodon
| Name | Smilodon |
| Name Meaning | “Knife tooth” |
| Pronunciation | SMY-lo-don. |
| Era | Cenozoic — Quaternary |
| Classification | Carnivora, Feliformia, & Felidae |
| Diet | Carnivorous |
| Height | 1 meter (3.3 feet) |
| Length | 1.5–2.5 meters (5–8 feet) |
| Weight | 160–280 kilograms (350–620 pounds) |
The Smilodon is commonly referred to as the saber-toothed cat due to its long saber-like upper teeth.
This felid is one of California’s most notable prehistoric animals due to the abundance of Smilodon fossils that have been found in the State.
The famous La Brea Tar Pits in Los Angeles, California, holds hundreds of Smilodon fossils (the largest collection in the world).
Smilodon lived in California during the Pleistocene Epoch, from 2.5 million years ago until about 10,000 years ago.
Smilodon was a large cat about the same size as a modern lion but with a more robust build.
The large size of this giant cat allowed it to hunt large herbivores like giant bison, camels, and other megaherbivores that lived in California around the same time.
7. Helicoprion
| Name | Helicoprion |
| Name Meaning | “Spiral saw” |
| Pronunciation | HEE-lih-koh-PREE-on |
| Era | Paleozoic — Permian to Triassic |
| Classification | Chondrichthyes, Elasmobranchii, & Euchondrocephali |
| Diet | Carnivorous |
| Length | 5–8 meters (16–26 feet) |
| Weight | 500–700 kilograms (1,100–1,500 pounds) |
Helicoprion was a genus of shark-like cartilaginous fish that lived during the Permian Period.
The most notable trait of this fish was the distinct arrangement of its teeth.
Helicoprion had its teeth arranged in spiral clusters (known as tooth whorls) in its lower jaws.
This gave them the appearance of a buzz saw.
This unusual dentition allowed the Helicoprion to feed on soft-bodied animals.
Experts think it may have used its tooth whorls for deshelling hard-bodied prey such as ammonoids and nautiloids that were abundant in the Permian waters.
California is one of several places where Helicoprion fossils have been found.
6. Dire Wolf
| Name | Aenocyon dirus |
| Name Meaning | “Dreadful wolf (Dire wolf)“ |
| Pronunciation | dai-ur wulf |
| Era | Cenozoic — Quaternary |
| Classification | Carnivora, Canidae, Caninae |
| Diet | Carnivorous |
| Height | 0.6–0.8 meters (2.25–2.7 feet) |
| Length | 1.5–2 meters (5–6.6 feet) |
| Weight | 68 kilograms (150 pounds) |
Like the Smilodon, the dire wolf is another Cenozoic Era animal preserved in the La Brea Tar Pits in Los Angeles, California.
Apart from California and other parts of North America, the dire wolf also lived in South America and Asia.
This large prehistoric canine is about the same size as some of the largest gray wolf species, such as the Yukon wolf and the northwestern wolf.
The dire wolf’s feet were smaller, but it had a bigger head compared to similarly-sized modern wolves.
The dire wolf lived during the Late Pleistocene and Early Holocene epochs, between 125,000 and 9,500 years ago.
It hunted America’s megaherbivores, such as wild horses, ground sloths, mastodons, and prehistoric bison.
It lived alongside the Smilodon, and both predators may have competed for similar prey animals.
5. Plesiotylosaurus
| Name | Plesiotylosaurus |
| Name Meaning | “Near Tylosaurus” |
| Pronunciation | Ples-e-o-ty-loe-sore-us. |
| Era | Mesozoic – Cretaceous |
| Classification | Reptilia, Squamata, Mosasauridae |
| Diet | Carnivorous |
| Length | 6 meters (20 feet) |
| Weight | Unknown |
Plesiotylosaurus was a large marine reptile of the mosasaur family.
Its name translates as “near Tylosaurus,” referencing the reptile’s similarity to the Tylosaurus, one of the largest and most popular mosasaur ever discovered.
Interestingly, the Plesiotylosaurus and Tylosaurus are not very closely related, and the physical similarities between them are only due to convergent evolution.
Plesiotylosaurus lived in California during the Cretaceous Period.
This marine reptile was up to six meters (20 feet) long, with a robust skull and streamlined body.
The mosasaur’s jaws were elongated, and it likely preyed on sea turtles, fish, and other large marine animals.
4. Enchodus
| Name | Enchodus |
| Name Meaning | “Spear tooth” |
| Pronunciation | En-coe-dus. |
| Era | Mesozoic – Cretaceous |
| Classification | Actinopterygii, Autopiformes, Enchodontidae |
| Diet | Herbivorous Carnivorous |
| Length | 78.7–172.2 centimeters (30.2–67.8 inches) |
| Weight | Unknown |
Enchodus was a genus of ray-finned fish closely related to modern lancetfish and lizardfish.
It lived during the Late Cretaceous but survived until the Late Eocene Epoch.
Enchodus was a small-to-medium-sized fish that preyed on small fish within its habitat.
It is also commonly referred to as a “saber-toothed herring” due to the prominent fangs in its upper and lower jaws.
The genus name, which means “spear tooth,” also references this unique dentition.
The large fangs can be up to six centimeters long in the largest species.
Although a predator itself, the small size of this fish also means it was a common prey to larger marine animals, including sharks and marine reptiles.
It is commonly found in the stomach content of larger bony fishes, mosasaurs, plesiosaurs, and seabirds of the Cretaceous Period.
3. Cymbospondylus
| Name | Cymbospondylus |
| Name Meaning | “Cupped vertebrae” |
| Pronunciation | Sim-boe-spon-dil-lus |
| Era | Mesozoic – Triassic |
| Classification | Reptilia, Ichthyosauria, & Cymbospondylidae |
| Diet | Carnivorous |
| Length | 5–17 meters (16–57.9 feet) |
| Weight | 44.7 tons (98,500 pounds) |
Cymbospondylus was a large marine reptile (ichthyosaur) that lived in Nevada and California during the Triassic Period.
Fossils of this fish-like reptile have also been found in parts of Europe.
Its genus name translates as “cupped vertebrae,” referring to the cup-like shape of its backbone.
Cymbospondylus was a primitive ichthyosaur.
It was discovered in 1868, which makes it one of the earliest ichthyosaurs ever named.
It was also one of the earliest marine reptiles to evolve in Earth’s oceans.
The jaws of the Cymbospondylus were lined with numerous small teeth.
This suggests that it fed on smaller and softer prey, such as fish and cephalopods, unlike the bigger and tougher prey consumed by the ichthyosaurs that evolved later.
2. Aletopelta
| Name | Aletopelta |
| Name Meaning | “Wandering small shield” |
| Pronunciation | Ah-let-o-pel-tah. |
| Era | Mesozoic – Late Cretaceous |
| Classification | Dinosauria, Ornithischia, & Ankylosauria |
| Diet | Herbivorous |
| Height | 2 meters (6.6 feet) |
| Length | 5 meters (16 feet) |
| Weight | 2 tons (4,409 pounds) |
Aletopelta was an ankylosaurid dinosaur that lived in Southern California during the Cretaceous Period.
This 75-million-year-old dinosaur was an armored herbivore that lived near the ancient California coast during the Cretaceous Period.
It was nicknamed “the Carlsbad Ankylosaur” because its fossils were found in a reef near Carlsbad on the coast of California.
The genus name Aletopelta translates as wanderer shield.
It references the osteoderms preserved on the dinosaur’s body, which would have formed an armored shield on its body when it was alive.
The remains of this dinosaur formed a miniature reef that housed many invertebrates and sharks.
Only one specimen of this dinosaur has ever been discovered.
1. Augustynolophus
| Name | Augustynolophus |
| Name Meaning | “Augustyn’s crest” |
| Pronunciation | Aw-gus-tin-o-lo-fus. |
| Era | Mesozoic – Late Cretaceous |
| Classification | Dinosauria, Ornithischia, & Hadrosauridae |
| Diet | Herbivorous |
| Height | 3.5 meters (11.4 feet) |
| Length | 8 meters (26 feet) |
| Weight | 3 tons (6,613 pounds) |
Augustynolophus was a hadrosaurid dinosaur that lived on the Island continent of Laramidia back in the Cretaceous Period.
This herbivorous dinosaur is named after the Augustyn family in honor of their support for the Los Angeles County Museum.
Augustynolophus was initially identified and described as a species of the Saurolophus genus due to the similarities between both dinosaurs.
This was reviewed about a year later, and the dinosaur was identified as a unique genus.
Augustynolophus is one of the most notable dinosaurs from California and is the state’s official state dinosaur.
The herbivorous dinosaur last walked the region’s landscape roughly 66 million years ago.
This makes it one of the last dinosaurs that survived until the end of the Cretaceous Period, when all the dinosaurs were wiped out.
Sources
- https://en.wikipedia.org/wiki/Aletopelta
- https://www.smithsonianmag.com/smart-news/meet-augustynolophus-morrisi-californias-new-state-dinosaur-180965038/
- https://en.wikipedia.org/wiki/Cetotherium
- https://www.britannica.com/animal/dire-wolf
- https://en.wikipedia.org/wiki/Cymbospondylus
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