“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Near Laurel in Prince George's County, Maryland — The American Northeast (Mid-Atlantic)

Meet Astrodon johnstoni

The Maryland State Dinosaur

Meet <i>Astrodon johnstoni</i> Marker image. Click for full size.
Photographed By Devry Becker Jones, December 11, 2021
1. Meet Astrodon johnstoni Marker
Astrodon was a member of the group of long necked, plant-eating dinosaurs called sauropods. When fully grown, it may have exceeded 60 feet in length and weighed 20 tons.

Astrodon was discovered in 1858, right here in Prince George's County. It was the first dinosaur found in Maryland and one of the first dinosaurs to be scientifically described.

In 1998, The Maryland General Assembly named Astrodon the Maryland State Dinosaur. Astrodon joins other iconic state symbols like the Blue Crab, Black-Eyed Susan and Baltimore Oriole.

Putting the Bones Together
Astrodon is the most completely known Maryland dinosaur. Most Astrodon fossils come from horse-sized juveniles, but a few bones including a 6-foot femur (thigh-bone), confirm that the adults were truly gigantic.

All Astrodon bones discovered so far are shown here.

Johnston's Star Tooth
In 1858, geologist Phillip Tyson brougth some fossil teeth recovered in a Prince George's county iron mine to the Maryland Academy of Sciences. Academy member (and dentist) Christopher
Meet <i>Astrodon johnstoni</i> Marker image. Click for full size.
Photographed By Devry Becker Jones, December 11, 2021
2. Meet Astrodon johnstoni Marker
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Johnston recognized the teeth as similar to those of the dinosaurs that had recently been discovered in Europe. Johnston named the animal Astrodon, meaning star tooth, because the teeth have a starburst shape in cross section.

Leading 19th century naturalist Joseph Leidy published this drawing of the original Astrodon teeth in 1865.

Growing Up Dinosaur
Elephants and other big modern mammals invest lots of time and energy into one baby at a time. Auropods were different. They laid dozens of eggs and then abandoned them to their fate. Each baby was unlikely to survive to adulthood, but there were so many that some of them made it. Because they were not burdoned by the need to give live birth, sauropods could grow bigger and faster than elephants.

How do We Know?
Like most dinosaurs, Astrodon is known only from isolated, often fragmentary bones. Fortunately, Maryland fossils do not exist in a vacuum. We can compare Astrodon fossils to more completely known relatives. Scientists' reconstructions of Astrodon are based in part on the remnants of Brachiosaurus from Colorado and Giraffatitan from Tanzania.
Erected by Maryland-National Capital Parks and Planning Commission.
Topics. This historical marker is listed in these topic lists: Animals
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PaleontologyScience & Medicine. A significant historical year for this entry is 1858.
Location. 39° 4.246′ N, 76° 52.129′ W. Marker is near Laurel, Maryland, in Prince George's County. Marker is on Mid Atlantic Boulevard, 0.4 miles south of Contee Road when traveling west. Touch for map. Marker is at or near this postal address: 13100 Mid Atlantic Blvd, Laurel MD 20708, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within walking distance of this marker. Welcome to Dinosaur Park (here, next to this marker); The Dinosaurs of Dinosaur Park (here, next to this marker); a different marker also named Welcome to Dinosaur Park (a few steps from this marker); The Industrial Heritage of Dinosaur Park (a few steps from this marker); George Washington Carver (approx. 0.4 miles away); Veterans Memorial (approx. 0.4 miles away); Three Sisters: Close Knit Communities of the Laurel Area (approx. 0.8 miles away); Abraham Hall: An African American Benevolent Lodge (approx. 0.8 miles away). Touch for a list and map of all markers in Laurel.
Related marker. Click here for another marker that is related to this marker. This marker has replaced the linked marker.
Additional keywords. Meet Astrodon johnstoni
Credits. This page was last revised on December 16, 2021. It was originally submitted on December 11, 2021, by Devry Becker Jones of Washington, District of Columbia. This page has been viewed 157 times since then and 105 times this year. Photos:   1, 2. submitted on December 11, 2021, by Devry Becker Jones of Washington, District of Columbia.

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Dec. 2, 2022