8 Dinosaurs that Lived in Maryland (And Where to See Fossils Today)

Long before Maryland was a state renowned for its seafood and ocean views, this part of the United States was a bit of a hotbed for dinosaurs. At least, more evidence of dinosaurs that roamed Maryland exists than in other states, like those in the Midwest. Today, we’re going to look at some of the dinosaurs that lived in Maryland.

We’ll show you an array of the different creatures that once roamed this state. Keep in mind, though, that some of the entries on our list are well-known, but others are a bit of a mystery. This list will introduce them as specifically as possible via species, genera, and even just clades. 

What Is Maryland’s State Dinosaur?

Maryland’s state dinosaur is Astrodon johnstoni. This creature was named the state dinosaur in 1998. Several species of Astrodon lived in Maryland throughout its history. This is possibly the largest of the dinosaurs that lived in Maryland, and it was alive during the Early Cretaceous period, roughly 130 to 95 million years ago.

This herbivorous sauropod weighed about 40,000 pounds and featured small heads, long tails, and long necks. They could measure up to 60 feet long with half of their body length being their tails!

The dinosaur’s name may sound a little confusing, but there’s a good reason for that. Astrodon translates to “star tooth.” The name comes from the shape of the cross-section of the tooth taken by Christopher Johnston which he thought resembled a star.  

What Are the Dinosaurs that Lived in Maryland?

Maryland was home to many different types of dinosaurs throughout its long history. Unlike other states that spent the majority of their time underwater and never developed a good fossil record, Maryland scientists recovered dozens of high-quality fossils in the state.

We’re going to look at some of the dinosaurs that were found in this part of the U.S. Some of them are only known by their genus or less specifically by their clade. However, others are known by their species. Let’s see the various dinosaurs that lived in Maryland.

1. Astrodon johnstoni

We’ve already described “star tooth”, the first dinosaur discovered in Maryland. This large herbivore could have been 60 feet long and 30 feet tall at its utmost while weighing 40,000 pounds! The type species is Astrodon johnstoni.

The original fossils of this creature, two teeth, were found in 1858 in the Arundel Formation in Maryland. Since this was the first dinosaur found in Maryland, it received the honor of being the state dinosaur.

2. Propanoplosaurus marylandicus

Propanolosaurus was a large herbivore that lived in Maryland. Interestingly, paleontologists have not found any sort of bone fossils from this creature in the area. Instead, the discovery in Maryland was the cast and natural mold of a hatchling Propanoplosaurus.

Essentially, this is a rock with an imprint of the dinosaur lying on its back. The rock shows the creature’s back, head, ribs, forelimb, foot, and some backbones.

As an adult, Propanoplosaurus marylandicus would have been a heavy, armored dinosaur like the Ankylosaurus. This natural mold was one of the most interesting types of evidence of dinosaurs that lived in Maryland.

3. Deinonychus antirrhopus

Deinonychus was a medium-sized theropod that lived during the Early Cretaceous period, between 115 and 108 million years ago. A research paper from 1998 describes the possible first occurrence of this species in Maryland. However, the evidence of this dinosaur was scant— just a few teeth.

As an adult, Deinonychus would have measured up to 11 feet long, stood three feet tall at the hips, and weighed from 132 to 161 pounds or more.

The dinosaur was known for having strong jaws, curved teeth, and enlarged foot claws. It would have been a deadly predator for many other dinosaurs, possibly including the next dinosaur on our list.  

4. Tenontosaurus

The Tenontosaurus was a medium-sized herbivorous dinosaur known for the broadness of its tail near the specie’s body. Paleontologists have recovered several high-quality fossils of the creature. The Arundel Formation in Maryland has been the site of many Tenontosaurus fossil recoveries.

This dinosaur could grow about 20 to 23 feet long and weigh from 1,000 to 2,200 pounds. The creature could stand 10 feet tall while bipedal, but it was shorter while walking on all four legs. This was one of the biggest dinosaurs that lived in Maryland, or at least one of the largest with fossil evidence.

Deinonychus lived in the same area as this dinosaur and the fossil record suggests a predatory-prey relationship existed. The Deinonychus would prey on juvenile Tenontosaurus, but it may not have been large enough to bring down the adults.

5. Neoceratopsia

Very little information exists about Maryland’s members of the Neoceratopsia clade. The only fossils recovered from these creatures were teeth. That evidence was not enough to place this dinosaur in a particular genus or species. Like many others, the teeth were recovered from the Arundel Formation at the Muirkirk clay pit of Prince George’s County.

6. Priconodon crassus

Priconodon crassus is another dinosaur that is only known by teeth and a single tibia recovered in Maryland at the Muirkirk Arundel Formation. Not much is known about this dinosaur except that its fossils were recovered without armor plates, something unusual for a nodosaurid. Either way, this creature would have been a large, slow, well-protected herbivore.  

7. Acrocanthosaurus

Paleontologists recovered Acrocanthosaurus teeth in Maryland, but the dinosaur is far more widespread in states like Texas and Oklahoma. The dinosaurs in this genus are known for being bipedal carnivore predators, and this creature was no different.

This large theropod could grow as much as 38 feet in length while weighing between 10,000 and 14,500 pounds.

8. Ornithomimosauria

Lastly, we have unidentified members of the Ornithomimosauria clade, a group of theropods. These dinosaurs are believed to have looked like the present-day ostrich to an extent. Paleontologists recovered fossil material related to this dinosaur group, but not enough to identify it.  

Where Can You See Fossils of Dinosaurs That Lived in Maryland?

The Natural History Society of Maryland is a great place to start if you want to see fossils of dinosaurs that lived in Maryland. However, the fossils collections are not open to the public. Researchers can request access to the collections. The paleontology collection is curated by Dr. Adrien Malick and George Spicka. Make an appointment if you want to seriously study these collections.

Dinosaur Park is another great place to go if you want to learn more about the dinosaurs that lived in Maryland. The experts at this park in Laurel, Maryland host hands-on events that teach people, especially children, about dinosaurs found in the state. At some times, the public can join other volunteers to continue looking for fossils of dinosaurs that lived in Maryland. Call ahead and see about the events available and their associated costs.

Summary of 8 Dinosaurs That Lived in Maryland

The photo featured at the top of this post is © Dmitry Bogdanov / CC BY 3.0 – License / Original