The Astrodon johnstoni was a Sauropod that lived during the Early Cretaceous period 130 million years ago. It is considered the state dinosaur of Maryland, as suggested by Peter Kranz. Its remains have been found in the Arundel formation of North America dating back several million years ago. It was first discovered in 1858 in an iron mine and named in 1859 by Christopher Johnston. The Sauropod was a herbivore with a long neck and heavy body. It weighed over 30 tons (30,000 kg). Its remains consisted of teeth, vertebrae, and limb bones. Another genus later discovered by O. C. Marsh is now considered its synonym.
Astrodon is pronounced as 'as-stro-don'. Its species name johnstoni is pronounced 'jon-sto-nee'. The dinosaur was named after Christopher Johnston, its discoverer. It was named in 1859.
The Astrodon was a herbivorous Sauropod (lizard-hipped) belonging to the clade Titanosauriformes. It was a relative of the Brachiosaurus.
The Astrodon johnstoni lived on Earth during the Early Cretaceous period (lower Cretaceous) approximately 130 million years ago during the Mesozoic era.
The dinosaur Astrodon became extinct during the Cretaceous-Paleogene mass extinction event. A comet or meteor hit the Earth and wiped out more than 75% of dinosaur species around 66 million years ago.
The dinosaur Astrodon johnstoni lived on the North American continent. The first discovery of its fossils was in the Arundel formation, Maryland state, Muirkirk, Texas, Oklahoma, and Portugal.
The formations where remains of the Astrodon were found, the Antlers formation and the Arundel formation, consisted of broad, flat plain regions near the coast, through which many streams and rivers may have flowed. Since these dinosaurs were herbivores, water and plenty of vegetation was part of the Astrodon prehistoric wildlife and habitat.
Young and old formed herds and middle-aged adults could sometimes live or forage for food alone. They lived alongside other small dinosaurs in the area as well as carnivorous predators.
The exact lifespan or age of Astrodon johnstoni dinosaurs is not known. Of Astrodon johnstoni fossil remains found, some belonged to adults and some to juveniles. Two species, the Pleurocoelus nanus and the Pleurocoelus altus, were considered to be Astrodons at different growth stages. The Astrodon and the Pleurocoelus are now considered synonyms.
Astrodon dinosaurs had a fixed breeding season and were oviparous like other dinosaurs. The Maryland Astrodon dinosaur laid eggs after internal fertilization. Juveniles hatched from eggs after an incubation period which differed depending on the species.
The Astrodon johnstoni was a large dinosaur, one of the largest in its area during the Early Cretaceous period. It had a long, stiff neck; large, muscled torso and legs; and a stiff, comparatively short tail. This state dinosaur of Maryland was popular for its teeth. When two teeth were first found by John. D. Latchford, it was discovered by Dr Johnston, a dentist and professor, that the Astrodon had a star-shaped dental cross-section. Its torso was high off the ground. It shared many similarities with the Brachiosaurus. Front limbs ended in flat, hoof-like formations and hind limbs ended with three toes. It didn't have a long snout and had a rounded skull.
The total number of bones in an Astrodon johnstoni is not known. Complete Astrodon skeletal remains have not been found. Most teeth have been identified as Astrodon's and Astrodon post cranial remains consist of vertebrae and hind limb bones belonging to the Pleurocoelus (named by O. C. Marsh). Its teeth had a unique, star-shaped cross-section.
Like other dinosaur groups, it can be assumed that Astrodon johnstoni dinosaurs communicated using their body and vocalization. Dinosaurs could create loud, open-mouthed sounds and closed-mouthed sounds. The close-mouthed sounds of a lower frequency could travel long distances, which helped them communicate with the rest of the herd or warn rivals of their territory. Vocalizations also held importance during mating displays.
The Astrodon johnstoni was a large, plant-eating dinosaur that measured around 50-60 ft (15-18 m) long and 30 ft (9 m) tall. Astrodon fossils showed that its size was around seven times that of a lion and three times the size of an elephant.
Due to its large size and heavy weight, the Astrodon johnstoni could not walk or run very fast. Very few predators would try to attack it so it would not need to rely on its speed as defense. If required it could run at a slow speed. The exact speed is not known. The speed of the dinosaur can be calculated using fossilized Astrodon tracks.
The state dinosaur of Maryland, the Astrodon johnstoni, named by Dr Johnston and Leidy, was a heavy dinosaur weighing around 30 tons (30,000 kg). Its weight was largely due to its muscular torso and limbs, more muscular than most dinosaurs. It was around 9-10 times heavier than an Indian Rhinoceros.
Males and females do not have specific names. Astrodon johnstoni fossils have not indicated any sexual dimorphism either. Sexual dimorphism in a species helps distinguish between males and females. It is common for the female to be smaller than the male, but the claim is not backed by evidence for an Astrodon.
The baby of an Astrodon does not have a specific name. Dinosaur young are usually called juveniles or babies. Scientific names of two dinosaurs that are considered to be Astrodons in different growth stages are the Pleurocoelus nanus and the Pleurocoelus altus.
These large Sauropods were herbivores. The state dinosaur of Maryland fed on leaves, plants, ferns and conifers. Its cross-sectional star tooth was flat and broad like the tooth found in herbivores, which hinted at their dietary preferences.
Like most large, herbivorous dinosaurs, the Astrodon state dinosaur was a calm and peaceful dinosaur. It travelled in herds with its conspecifics and did not hunt or prey on smaller dinosaurs despite its advantageous size. Detailed information on the behavior of these Sauropods is not available.
The discovery and naming of this dinosaur genus were done by four different men. Its tooth was first discovered by Latchford in November 1858 in Maryland, North America. The genus was named by Dr. Johnston in 1859 (a professor at the Baltimore Dental College and mentioned in the American Journal for Dental Sciences). The species was named by Leidy in 1965. Juvenile fossils, the P. nanus and the P. Altus, were found by O. C. Marsh in 1888.
The Astrodon is known as the first Sauropod to be found in North America and the second to be named. Since the star tooth dinosaur was found in Maryland it is considered the state dinosaur of Maryland. It was the first dinosaur to be found in Maryland. Peter Kranz was the one who posed the idea to name it the state dinosaur.
'Aster' means star and 'odon' means tooth. It was thus named the Astrodon meaning star tooth.
The Nigersaurus is a herbivorous dinosaur with 500 teeth.
Two teeth were found by John. D. Latchford in November 1858 in an iron mine in the Maryland state. The genus was named by Christopher Johnston in 1859. Further bones, a star tooth, and fossils were found in Muirkirk, Texas, and Oklahoma.
The total number of Astrodon teeth is not known since a complete jaw or skull have not been found yet. The first specimen of Astrodon which led to its discovery and naming consisted of two teeth. Its star tooth is the reason for its popularity.
Here at Kidadl, we have carefully created lots of interesting family-friendly dinosaur facts for everyone to discover! Learn more about some other creatures from our Austroraptor facts and Atrociraptor facts for kids.
You can even occupy yourself at home by coloring in one of our free printable Astrodon coloring pages.
Second image by Dmitry Bogdanov.