The Dinosaurs and Prehistoric Animals of Massachusetts

Anchisaurus 3D Render — Elenarts/Getty Images

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Updated on February 12, 2019

For much of its prehistory, Massachusetts was pretty much a geological blank: shallow seas covered this state during the early Paleozoic Era, and terrestrial fossils only managed to accumulate during brief periods, during the Cretaceous period and Pleistocene epoch. Even still, the Bay State wasn't entirely devoid of prehistoric life, yielding the remains of a couple of important dinosaurs and a plethora of dinosaur footprints, as detailed in the followings slides.

01

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Podokesaurus

For all practical purposes, the early dinosaur Podokesaurus can be considered an eastern variant of Coelophysis, a small, two-legged theropod that assembled by the thousands in the western U.S., notably the Ghost Ranch region of New Mexico. Unfortunately, the original fossil of Podokesaurus, discovered in 1910 near Mount Holyoke College in South Hadley, Massachusetts, was destroyed years ago in a museum fire. (A second specimen, found in Connecticut, was later assigned to this genus.)

02

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Anchisaurus

Thanks to the Connecticut River Valley that spans both states, the fossils discovered in Massachusetts are very similar to those of Connecticut. The first, fragmented remains of Anchisaurus were unearthed to Connecticut, but it was subsequent discoveries in Massachusetts that cemented this prosauropod's credentials: a slender, bipedal plant-eater remotely ancestral to the giant sauropods and titanosaurs of the later Mesozoic Era.

03

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Stegomosuchus

Not technically a dinosaur, but an ancient crocodile-like reptile known as a "protosuchid," Stegomosuchus was a tiny creature of the early Jurassic period (the only known fossil specimen was discovered in Massachusetts sediments dating to about 200 million years ago). As you can infer from its family name, Stegomosuchus was a close relative of Protosuchus. It was a family of archosaurs, closely related to these early crocodiles, that evolved into the first dinosaurs during the late Triassic period.

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Dinosaur Footprints

The Connecticut River Valley is famous for its dinosaur footprints—and there's no difference between the dinosaurs that traversed the Massachusetts and Connecticut sides of this late Cretaceous formation. Unfortunately, paleontologists are unable to identify the specific genera that made these prints; suffice it to say that they included various sauropods and theropods (meat-eating dinosaurs), which almost certainly had complex predator-prey relationships.

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The American Mastodon

In 1884, a team of workers digging a trench on a farm in Northborough, Massachusetts discovered a bunch of fossilized teeth, tusks and bone fragments. These were later identified as belonging to an American Mastodon, which roamed North America in vast herds during the Pleistocene epoch, from about two million to 50,000 years ago. The discovery of the "Northborough Mammoth" generated newspaper headlines around the U.S., at a time when the fossils of these ancient proboscids weren't quite as common as they are today.

06

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Paradoxides

The 500-million-year-old Paradoxides is one of the world's most common fossil trilobites, a vast family of sea-dwelling crustaceans that dominated the Paleozoic Era and went extinct by the start of the Mesozoic Era. Massachusetts can't lay any particular claim to this ancient organism--numerous intact individuals have been discovered all over the globe--but if you're lucky, you can still identify a specimen on a trip to one of this state's fossil formations.

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Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Massachusetts." ThoughtCo, Jun. 25, 2024, thoughtco.com/dinosaurs-and-prehistoric-animals-of-massachusetts-1092079. Strauss, Bob. (2024, June 25). The Dinosaurs and Prehistoric Animals of Massachusetts. Retrieved from https://www.thoughtco.com/dinosaurs-and-prehistoric-animals-of-massachusetts-1092079 Strauss, Bob. "The Dinosaurs and Prehistoric Animals of Massachusetts." ThoughtCo. https://www.thoughtco.com/dinosaurs-and-prehistoric-animals-of-massachusetts-1092079 (accessed April 4, 2025).