| Name | Hadrosaurus | Diet | Herbivorous |
| Name Meaning | Bulky Lizard | Height | 3 meters (10 ft.) |
| Pronunciation | Had-row-sore-us | Length | 7.6 meters (25 ft.) |
| Era | Mesozoic – Late Cretaceous | Weight | 2 to 4 tons (4000 – 8000 lbs) |
| Classification | Dinosauria, Ornithischia, & Ornithopoda | Location | North America |
Hadrosaurus Pictures
The Hadrosaurus
The Hadrosaurus is an ornithopod that lived in North America during the late Cretaceous period, dating back to around 80.5 to 66 million years ago.
Hadrosaurus was discovered in New Jersey, and not only is this genus considered the state dinosaur, but where it was discovered is also considered a historical land site.
This dinosaur was discovered in the Woodbury Formation, which dates to the Early Campanian and is a fluvial marine environment.
Hadrosaurus foulkii is the only species in their genus, and this dinosaur is one of the first in North America that is known from a complete specimen.
Hadrosaurid dinosaurs lived in North America and Asia during the Jurassic and Cretaceous periods, and these dinosaurs are famous for their duck-billed faces.
The near-complete fossils of Hadrosaurus and other related species are what helped paleontologists learn how this dinosaur fit into its habitat in prehistoric times.
In this article, you will learn about the many amazing features of the Hadrosaurus and what has been uncovered about their ancient lifestyle.
Hadrosaurus is not only one of the oldest dinosaurs discovered within the United States but also is one of the few specimens with a nearly complete skeleton.
Physical Characteristics
Hadrosaurus is a member of the Hadrosaurid family, which are called duck-billed dinosaurs due to their flat, wide mouths, similar to a duck.
The Hadrosaurus was a large species that walked primarily on its four legs but also had the ability to stand on its hind legs if necessary.
This large dinosaur had a length ranging between 7 to 8 meters (23 to 26 ft.) and estimates have them weighing as much as 2 to 4 tons (2.2 to 4.4 short tons).
Hadrosaurus, when standing on all fours, stood around 3 meters (10 ft.) tall, and their front legs were much less developed than their back, but still could support their weight.
The holotype of Hadrosaurus had a femur length of 1.05 meters (105 cm), and a tibia length of 93.3 cm (9.33 cm).
The Hadrosaurus, similar to other members of their family, had a large bony crest on their head, which some theories suggest they used to make low-frequency sounds.
When discovered, only parts of a skull were found, which is why their crest is still relatively unknown, and it was difficult to classify this species at first.
Habitat and Distribution
Hadrosaurus lived in North America during the Late Cretaceous period, around 80 million years ago.
Hadrosaurus was one of the first of the Hadrosauridae family discovered, and dinosaurs from this family lived across North America, and Asia.
New Jersey is where the Hadrosuaurs were discovered, and pulled out of the Woodbury Formation in 1858.
This dinosaur was found near the town of Haddonfield, and the area they lived in looked much different during the Cretaceous period.
North America during the Cretaceous period was made up of the two land masses of Laramidia and Appalachia.
These masses of North America were split by the Western Interior Seaway, and Appalachia had the Hudson Seaway to its North.
Hadrosaurus, while found in New Jersey, lived in Appalachia during the Cretaceous period.
Along with being surrounded by seaways, Appalachia had lots of wetlands, coastal plains, and forest habitats.
Modern Laramidia is where the majority of dinosaurs in North America have been discovered, while Appalachia has overall had fewer dinosaur discoveries.
The Hadrosaurus is important as it helps paleontologists better understand the life that lived in Cretaceous Appalachia, and also, their discovery yielded a nearly complete specimen.
Excavations sites in the eastern United States have yielded findings of plants like Metasequoia, Rhizophora, Liriodendron, Detrusandras, Hamamelidaceae, Pinaceae, and many more that give insight into the types of habitats Hadrosaurus lived in.
Behavior and Diet
Hadrosaurus was a herbivore, but ever since their discovery, it has been debated exactly what type of plant eater they were.
The mouth of Hadrosaurus had small teeth that would regrow when broken, and their beak helped them bite through vegetation.
Since their discovery, there have been several studies looking at how these dinosaurs could have chewed their food and what role they played in their prehistoric ecosystem.
Instead of the lower flexible jaws seen in today’s mammals, Hadrosaurus had a hinge in its upper jaw used to chew outwards and cheeks that held onto their food.
The unique chewing method of Hadrosaurus was discovered by looking at the scratches in their teeth left by what they ate and also revealed they probably relied on a diet of foods like leaves.
Hadrosaurus was likely a grazer instead of a browser and ate plants like horsetails.
Fossilized feces from their relatives also gave insight into their diet and suggested these diets could have eaten wood for the fungi and crabs.
Paleontologists finding leaf fragments in the gut region of other Hadrosaurids and other research suggest Hadrosaurus was a browser similar to herbivorous animals today like deer.
With more fossil evidence, exactly what these herbivorous dinosaurs ate may become more clear.
Life Cycle
Hadrosaurids have left remains of many types of fossils like juvenile specimens, egg shells, and baby footprints that have helped paleontologists learn a bit about these dinosaurs’ life cycles.
Hadrosaurus laid eggs in both upland and lowland habitats, and before laying them, they would dig out an area to place their nest.
When young Hadrosaurus spent the majority of their time on their hind legs, and as they got older, they became more quadrupedal but still occasionally walked on two legs.
The crest that Hadrosuarids had was likely used to make a sound, possibly to attract mates, and communicate with each other.
The lifespan of dinosaurs like Hadrosaurus is estimated at 25 years, but many young dinosaurs’ lives were cut short due to predators and other natural deaths.
Juvenile Hadrosaurids found fossilized have a similar appearance and body structure to their adult forms, and they grew very quickly to increase their chance of survival.
There is still lot of mystery about the lifecycle of Hadrosaurus, including things like how long their gestation period was and how often they reproduced that may be solved in the future with greater research.
Evolution and History
Hadrosaurus was discovered in 1838 by Estaugh Hopkins in a marl pit near the Cooper River in Haddonfield, New Jersey.
In North America, the first dinosaurs discovered were species like Troodon, which were only known from teeth.
Hadrosaurus was one of the most complete fossils discovered at its time and was the first genus described in the region from more than just a tooth.
While Hadrosaurus was named the type genus for the Hadorsauridae family, scientists believed this genus a nomen dubium, or dubious classification, since the skull was missing for proper identification.
In 2011 a re-evaluation of the genus was done, taking a look at its material and confirming its status.
Hadrosaurus is related to other duck-billed dinosaurs like Saurolophus, Lambeosaurus, Maiasaura, and Corythosaurus.
There is still much to be learned about the Hadrosaurus, like where they evolved from.
With more fossil discoveries Hadrosaurus’s appearance and what is accepted about them may change, as with all dinosaurs.
Interactions with Other Species
In the Appalachian region of North America during the Cretaceous period, Hadrosaurus lived with a variety of other prehistoric wildlife.
While there has not been as much fossil evidence found in Appalachia as Laramidia, we still know lots of species that coexisted with Hadrosaurus.
Some of the other animals that lived with Hadrosaurus include:
- Hierosaurus
- Niobrarasaurus
- Saurornitholestes
- Silvisaurus
- Lophorhothon
- Hyspibema
- Ornithotarsus
- Dryptosaurus
Predatory dinosaurs like Tyrannosaurids and even large prehistoric crocodiles are what preyed on Hadrosaurus.
These dinosaurs lived in large herds, and their numbers would help increase their chance of survival.
Compared to other herbivores like the Triceratops or Ankylosaurus, the Hadrosaurus did not evolve to have any prominent defenses to protect themselves from predators.
While large in size, horns or spikes are typically seen in herbivore dinosaurs since they live alongside Earth’s superpredators, which Hadrosaurus lacked.
Despite not being the smartest dinosaur, Hadrosaurus had one of the largest brains-to-body ratios when compared with other Ornithischians.
What helped Hadrosaurus survive along with its large herd was its speed and smarts.
Hadrosaurus and their young were prey for many prehistoric carnivores, but paleontologists believe they may have evolved with better senses to help them survive.
Cultural Significance
Hadrosaurus has been an important dinosaur in learning about Ornithopods dinosaurs.
When discovered over a decade ago, Hadrosaurus was one of the most complete dinosaurs of its time and allowed for more in-depth studies on dinosaurs that were previously not possible.
This genus was also the first publicly mounted dinosaur in the world when put on display in 1868.
Due to where they were discovered and their importance, the Hadrosaurus was named the state dinosaur of New Jersey in 1991.
Even the land site where Hadrosaurus was discovered has significance, and the area was designated a National Historic Landmark in 1994.
Hadrosaurus Foulkii Leidy Site honors the prehistoric giant that once roamed New Jersey and protected the area where Hadrosaurus was discovered.
Relatives of the Hadrosaurus have been the inspiration for many of the dinosaurs seen in movies like Jurassic Park.
Like the Velociraptor, Hadrosaurids are some of the most well-known dinosaurs and continuously bring people wonder.
Conclusion
Hadrosaurus is one of the many dinosaurs that lived in Appalachia during the Cretaceous period before going extinct.
These dinosaurs have mainly been found in the eastern United States, and they are the state dinosaur of New Jersey.
Hadrosaurus is not only one of the oldest fossils discovered and described in the United States but also has one of the most complete skeletons despite their lack of overall specimen findings.
The discovery of Hadrosaurus has been essential in learning about the ecosystem of North America during the Cretaceous period.
There has been lots of debate on the Hadrosaurus, mainly due to the lack of a complete head fossil.
The holotype, and most complete species, was preserved since its body was washed into a fluvial environment, where it fossilized without disturbance.
The Hadrosaurus is one of the many dinosaurs that roamed North America, and there are still lots of questions that many have about this dinosaur that only better preserved fossils can solve.
This genus has been a key piece in learning about Ornithopods and their overall evolution through the Mesozoic era.
FAQS
How fast was the Hadrosaurus?
Scientists are able to estimate the speed of extinct animals like Hadrosaurus using their skeleton structures, and the speed of Hadrosaurus is estimated at 45 kph (28 mph) at their quickest.
Compared to other dinosaurs of their time Hadrosaurus had very little defenses, and their speed was a tool used to escape dangerous predators that preyed on them.
Hadrosaurus had a speed of around 16 kph (10 mph), faster than dangerous dinosaurs like the Tyrannosaurus Rex, who relied mostly on strength to take out prey.
How many teeth did Hadrosaurus have?
Duck-billed dinosaurs are known for having lots of teeth, and dinosaurs like Hadrosaurus had up to 1,400 teeth.
Hadrosaurus had teeth closely packed together, and they continuously re-grew their entire life.
Why did Hadrosaurus go extinct?
Hadrosaurus lived in the Cretaceous period and went extinct at the end of the period during the Chicxulub asteroid impact.
When the asteroid impact hit, many of the dinosaurs died, like Hadrosaurus, but those that didn’t die instantly were killed by the period of little food and darkness that occurred soon after.
Sources:
- https://ucmp.berkeley.edu/diapsids/ornithischia/hadrosauria.html
- https://www.biotaxa.org/Zootaxa/article/view/zootaxa.2765.1.6
- https://micro.magnet.fsu.edu/primer/techniques/phasegallery/hadrosaurus.html
- https://www.pnas.org/doi/abs/10.1073/pnas.0812631106
- https://www.science.org/doi/abs/10.1126/science.1224495
- https://www.cambridge.org/core/journals/paleobiology/article/abs/hadrosaurid-migration-inferences-based-on-stable-isotope-comparisons-among-late-cretaceous-dinosaur-localities/1EC0A3E972F77DF6F8F22F260A808FE2
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