Discover 6 Extinct Animals That Lived in Arizona

Written by Jeremiah Wright
Updated: July 20, 2022
© Liliya Butenko/
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Arizona, better known as the Grand Canyon State, is located in the Western United States. It is the 6th largest state in the US. In terms of fauna, the state hosts many species, ranging from mammals such as the coyote and javelina to reptiles such as the Gila monster and birds such as the great blue heron.

However, when discussing a country or state’s fauna, one must consider extinct animals. After all, they were and still are, one way or another, part of the area’s history and sometimes even evolutionary process.

Therefore, without any further ado, let’s discover 6 extinct animals that lived in Arizona!

1. Rutiodon

The rutiodon is also known as the Wrinkle Tooth.

©Nobu Tamura ( / CC BY-SA 3.0 – License

Extinct sinceLate Triassic period
208.5 million years ago

The rutiodon, based on a restoration of R. carolinensis, resembles a crocodile with small differences. This dinosaur, also known as the Wrinkle Tooth, is part of the phytosaur genus and went extinct during the Late Triassic period.

Most of the rutiodon fossils in the US were found in New Jersey, New York, North Carolina, and Pennsylvania. However, Late Triassic fossil deposits found in Arizona show that this species also used to live here.

Unlike the modern crocodile, the rutiodon was much larger. It could reach up to 26 ft (8 m) in length, making this species one of the largest carnivorous animals to live in its period and environment. It was named the “wrinkle tooth” due to its long, narrow mouth riddled with tens of teeth.

2. Chindesaurus

Chindesaurus went extinct in the Late Triassic period.

©Maurissauro / CC BY-SA 4.0 – License

SpeciesChindesaurus bryansmali
Extinct sinceLate Triassic period
210 million years ago

The Chindesaurus is known today thanks to its single species discovered, Chindesaurus bryansmalii. The fossils that helped identify it were found in the Petrified Forest National Park in Arizona. The original specimen, which is a partial skeleton, was named Gertie

The species went extinct in the Late Triassic period, around 210 million years ago. It was a small, nimble dinosaur, smaller than a human. There is, however, some debate around the species’ family, an aspect that influences its size as well. In 2012, Holtz estimated that the dinosaur was around 6.6 ft (2 m) long and weighed about 50-100 pounds (23-45 kg).

Debates regarding the dinosaur’s size and classification stem from the fact that its skeletal anatomy isn’t entirely known. The holotype specimen of Chindesaurus may not be fully grown. As such, estimates of weight and size at maturity might be quite inaccurate.

3. Sarahsaurus

The Sarahsaurus had shorter forelimbs featuring powerful grasping hands.

©Art by Brian Engh, used with permission ( Published by Adam D. Marsh, Timothy B. Rowe. / CC BY 2.5 – License

SpeciesSarahsaurus aurifontanalis
Extinct sinceEarly Jurassic period
182.7 million years ago

The Sarahsaurus lived in the Early Jurassic period and went extinct around 182.7 million years ago. This species was not only discovered in Arizona. All of the fossil specimens attributed to the Sarahsaurus were collected near Gold Spring, Arizona, from the Lower Jurassic Kayenta Formation.

The main characteristics of this dinosaur are its long neck and the fact that it was two-legged, despite closely resembling sauropods. Namely, the Sarahsaurus had shorter forelimbs featuring powerful grasping hands. In terms of size, the average length of the vertebral column of a Sarahsaurus was over 10 ft (3.1 m). It was estimated that the total length of this dinosaur was 13 ft (4 m), while its weight was around 440 lb (200 kg). 

Despite its long neck, the Sarahsaurus didn’t have the size of sauropods – as in a much longer neck. This is where their powerful grasping hands come into play. To feed, the Sarahsaurus would grab onto tree trunks and partially climb them to reach leaves, fruits, and so on. The dinosaur is mainly known as a herbivore. Still, the aforementioned powerful hands suggest that it might have been an omnivore.

4. Sonorasaurus

Sonorasaurus thompsoni
The Sonorasaurus was a herbivorous sauropod.

©Creator:Dmitry Bogdanov / CC BY 3.0 – License

SpeciesSonorasaurus thompsoni
Extinct sinceLate Cretaceous period
93 million years ago

The Sonorasaurus was a herbivorous sauropod (a relative of the Sarahsaurus) that lived during the Early and Late Cretaceous Periods. Its fossils were first found in southern Arizona, in the Sonoran Desert. It went extinct around 93 million years ago. In 2018, it was declared Arizona’s state dinosaur.

This dinosaur was large, to say the least. According to estimates, the Sonorasaurs might have been about 26 ft (8 m) tall and 49 ft (15 m) long. The genus is not fully known or discovered as the holotype specimen is incomplete. 

5. Mastodons

Illustration of a Mastodon on a white background
The mastodon genus averaged 7 ft 7 in (2.3 m) in height.

©Liliya Butenko/

Extinct sinceEnd of the Pleistocene period
10-11,000 years ago

The Mastodon genus, also known as Mammut, includes five extinct species. These species are found in North and Central America. They went extinct around 10-11,000 years ago, at the end of the Pleistocene period. Mastodon fossils were found in Graham County, Arizona, accompanied by rodent, camel, and giant sloth fossils.

It is worth noting that a mammut is not the same thing as a mammoth or elephant. This genus is closely related to the Elephantidae family but diverged from it long ago. What helped differentiate between the two were the many discovered Mammut teeth. Unlike the mammoth teeth, they feature rows of conical cusps; something researchers hadn’t seen before in any mammoth fossils. 

When it comes to size, the mastodon genus averaged 7 ft 7 in (2.3 m) in height. Larger specimens were discovered to be around 10 ft (3 m) high and 7.8 to 11 tonnes in weight.

6. Giant Ground Sloths

Giant ground sloths are also known as Megatherium.

©Esteban De Armas/

Giant Ground Sloths
Type speciesMegatherium americanum
Extinct sinceLate Pleistocene period
12,000 years ago

Giant ground sloths, also known as Megatherium, were common throughout the southwestern part of the US. They lived from the Early Pliocene to the Late Pleistocene and went extinct around 12,000 years ago. They are called “giants” mainly because they could be as heavy as 8,800 lb (4 tonnes). The Megatherium is one of the largest discovered land mammals to have existed, making it an impressive discovery, to say the least. They could grow up to 20 ft (6 m) in height.

The giant ground sloth was supposedly mostly hairless and resembled today’s sloths. It experienced difficulty walking due to its large claws. The Megatherium had strong forelegs equipped with claws that were used to pull down branches filled with food, namely leaves.

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Illustration of a Mastodon on a white background
Mastodons were approximately the size of modern elephants.
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About the Author

I hold seven years of professional experience in the content world, focusing on nature, and wildlife. Asides from writing, I enjoy surfing the internet and listening to music.

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