Discover 6 Dinosaurs That Start with D

Written by Arlene Mckanic
Updated: July 26, 2023
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It’s both a blessing and a curse that dinosaurs are extinct. We couldn’t live in a world with these beasts stopping around, and if we could, we probably wouldn’t want to. However, there’s a reason Jurassic Park and its sequels were such hits: these animals fascinate us! Besides, what other group of animals have such cool, tongue-twisty names? Here are some long lost dinos whose names start with D.

1. Deinocheirus, One of the Weirder Dinosaurs

This odd creature lived in the Late Cretaceous.


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This creature whose name means “terrible hand” lived in the Late Cretaceous period, which was between 70 and 66 million years ago. A few of its bones were found in Mongolia in 1965, but it wasn’t until 2014 that archaeologists found a complete skeleton. The first bones found were its shoulders, long arms, and hands with three fingers that bore large, scary claws.

After the rest of Deinocheirus was found, it was determined that it indeed had long arms, short legs, and a hump. It had a bill much like a hadrosaur, a long neck, and probably feathers. The biggest specimen was 36 feet long and probably weighed about seven tons. Because of its duck-like bill, archaeologists believe that the dinosaur probably ate aquatic plants and easy-to-catch aquatic animals. It used its claws to pull vegetation out of the water and used a large tongue to strain the water out of it as it ate.

2. Deinosuchus, Mother of All Crocodiles

Largest Crocodiles Ever Deinosuchus

The reconstructed skeleton of


, who was a 30-foot-long horror



©Daderot / CC0 1.0 – License

Gustave is a crocodile that lives in Burundi. He’s 20 feet long, weighs about a ton, and is about 67 or 68 years old. Amazingly, he’s probably still growing, as crocodiles continue to grow until death. Rumor has it that he’s killed as many as 200 people. However, if Gustave ever met something like Deinosuchus, the larger creature would easily bite him in two, similarly to what Gustave allegedly did to all those hapless humans.

Deinosuchus’ very name means “horror crocodile.” The largest that’s been discovered so far is about 35 feet long. Though this animal was insanely long, it’s the bite that was truly impressive. The bite force of this ancient crocodile was close to 103,000 Newtons. (Gustave’s bite force is about 15,000 Newtons).

Deinosuchus probably had no problem taking down large dinosaurs and anything else it fancied, such as fish and sea turtles. This dino was probably an ambush predator like modern crocodiles. Indeed, the basic body form of the crocodile hasn’t changed much since the time of Deinosuchus.

The prehistoric crocodile lived during the late Cretaceous, which was about 82 to 73 million years ago. The first fossils of this beast were found in North Carolina just before the Civil War, and over the years more fossils of Deinosuchus have surfaced.

3. Dimetrodon, Dinosaur with the Cool Sail


is famous for its spectacular sail.

©Daniel Eskridge/

Everyone who knows about this prehistoric creature loves it for its reptile-like stance and vertebrae that form a huge sail on its back. This dinosaur was an early one, living 295 to 272 million years ago in the Early Permian period. Though impressive, Dimetrodon wasn’t large as far as dinosaurs go. There were about 20 species of this animal, and most were between 5.6 and 15 feet long and weighed between 62 and 551 pounds. The smallest, D. teutonis from Germany, was only 2 feet long and weighed about 31 pounds. This Dimetrodon was the only member of the species found outside of what’s now the United States.

Dimetrodon wasn’t a proper dinosaur. It went extinct tens of millions of years before “real” dinosaurs ruled. But if you buy one of those toy dinosaur sets, Dimetrodon, whose name means “double measure of teeth” is there along with T. rex, Triceratops, and Stegosaurus, even though they didn’t live at the same time.

Scientists aren’t sure what the spectacular sail was for. Some believe it hid the animal among the reeds that grew around bodies of water. Others say it was used as an actual sail when Dimetrodon entered the water, or that it was used for warmth when it basked in the sun and to cool down when it was hot. Males possibly had larger sails than females and possibly used them to attract mates.

Dimetrodon was a carnivore, and the apex predator where it lived. Its diet was largely made up of fish, amphibians, reptiles, and other ancient four-legged animals such as Seymouria and Diplocaulus, a 3-foot-long salamander with a shield for a head.

4. Diplodocus, One of the Largest Dinosaurs

A Diplodocus walking peacefully in the water by sunset

was one of the largest dinosaurs that ever lived.


This huge, long-necked, long-tailed sauropod dinosaur lived during the last days of the Jurassic period, which was between 154 and 152 million years ago. Its fossilized remains were unearthed in Colorado in 1877. Scientists gave it its name, which means “double beam,” for its tail bones, which are chevron-shaped on the underside of the tail and have double beams. Diplodocus is one of the most studied and displayed of the dinosaurs because so many fossilized remains have been found.

What It Looked Like

This dinosaur walked on all fours, and its hind legs were a little longer than its front legs. The longest complete Diplodocus skeleton collected so far belonged to an animal that was between 79 and 85 feet long and probably weighed between 13 and 16 tons. Some archaeologists believe that there were individuals that were even longer and heavier than this, judging by the bones that have been collected.

The tail of Diplodocus was a wonder in itself. It was made up of 80 vertebrae with double beams. The end of the tail may have been able to be cracked like a whip. The skull was tiny compared to the rest of the body, and the teeth were like pegs and found only at the front of the jaws. The long neck had 15 vertebrae, and scientists believe the dinosaur was forced to hold it horizontally thanks to a ligament at the back of the neck. This meant Diplodocus could not raise its head very high. The animal’s skin was scaly, and some individuals appeared to have spines, especially on the tips of their tails.

Diet and Reproduction

Diplodocus dinosaurs were herbivores, and they were able to balance on their hind legs to browse the very tops of trees. The long tail would stabilize the animal. They probably also dipped their heads in the water to access aquatic plants. As for reproduction, these dinosaurs were egg layers and probably laid their eggs in communal nests. The hatchlings grew quickly and were ready to breed when they were about 10 years old. Like crocodiles, Diplodocus grew throughout its life, which could last for 70 to 80 years.

5. Diadectes, Half Reptile, Half Amphibian


dinosaurs seemed to be crosses between a reptile and an amphibian.

©Dmitry Bogdanov / CC BY-SA 3.0 – License

The name Diadectes is taken from the Greek and means “crosswise biter.” This bulky creature was sort of a cross between a reptile and an amphibian. It lived between 290 and 370 mya during the early years of the Permian. This creature was about 10 feet long, with heavy, thick bones, especially in regard to its skull and vertebra. Its legs were short and powerful. Despite its massive size, Diadectes was an herbivore, as can be shown by its teeth, which were peg-like in the front to snip up vegetation and broad in the cheeks for grinding. Interestingly, the animal could breathe and chew at the same time. There are at least two species of this primitive dinosaur: D. tenuitectes and D. sideropelicus. Diadectes fossils have been found all around North America, most notably in Texas.

6. Dicynodon, A Group of Dinosaurs With Tusks


Lystrosaurus was a type of dicynodont with two tusks and a turtle-like beak.


This dinosaur lived later than Diadectes in the upper Permian, about 253 to 251 million years ago. Its name means “two dog tooth.” That’s because it had no teeth save two tusks that possibly stuck out of its mouth. It used these tusks to dig up tubers and had a horny, turtle-like beak to snip vegetation. There are an astonishing number of species of Dicynodon, and the genus is considered what scientists call a “wastebasket taxon.” This is a taxon where scientists put organisms they can’t seem to put anywhere else. Thus, lots of animals that look like Dicynodon are simply added to the genus. The type species is D. lacerticeps.

Dicynodon was about 4 feet long, depending on the species, and its fossilized bones have been found in Tanzania and South Africa. It had splayed-out limbs, a blunt head, and a stumpy tail, and was considered a type of reptile.

The photo featured at the top of this post is © Catmando/

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About the Author

Arlene Mckanic is a writer for A-Z Animals whose focus is on plants and animals of all kinds, from ants to elephants. She has a Bachelor's Degree from City College of New York. A resident of South Carolina, she loves gardening and though she doesn't have pets, a black racer snake does live in her kitchen.

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