The Dinosaurs of Connecticut

Excerpted from Great Day Trips in the Connecticut Valley of the Dinosaurs, by Brendan Hanrahan.

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The dinosaurs of the Connecticut Valley are known from a sort of composite sketch.  What is known has been learned mostly from footprints, relatively few skeletons and even fewer natural casts.  The rest has been filled in by comparisons to dinosaurs that lived at about the same time elsewhere, and by more than a little bit of imagination.

Connecticut Valley fossils date from the earliest Jurassic, some 200 million years ago, and very early in the Age of Dinosaurs. “We know there were [carnivorous] theropod dinosaurs, similar to Podokesaurus and Dilophosaurus," says Columbia University paleontologist Paul Olsen.   Podokesaurus may have made [the footprint] Grallator and Dilophosaurus may have made [the footprint] Eubrontes.

"Then you have herbivorous [plant-eating] dinosaurs, of which there are two flavors.  There were small ornithischian dinosaurs that looked like Lesothosaurus that would have made [the footprint] Anomoepus.  They were considerably smaller than the carnivores.  The largest had a hip height of about three feet.  Most were turkey sized.  And then you had the prosauropods, Anchisaurus and Ammosaurus, and they made [the footprint] Otozoum.”

Classification

Dinosaurs were classified by the English paleontologist, Harry Seely, into two major groups, or orders, based on features of their hips.  Early forms known from the Connecticut Valley included dinosaurs belonging to each of these orders, the saurischians and ornithischians.

The prosauropods and theropods were both early forms of saurischian dinosaurs.  They are known from both fossil bone and footprint evidence.  The footprint known as Anomoepus provides the only local evidence of ornithischian dinosaurs.

Saurischian dinosaurs

Theropods

Connecticut Valley theropods were generalists—meat-eaters that would sink their teeth into anything—perhaps similars to the way bears behave today.  Footprints show theropods dominated the valley in the Early Jurassic and came in at least two sizes, small and medium, compared to more familiar theropod forms, such as Tyrannosaurus rex.

The theropods walked and ran on two feet.  The larger version may have been able to run at seven to ten miles per hour.  They had curved necks like modern-day herons and cranes, birds now thought to be their descendants and long tails. All had snouts filled with long, daggerlike teeth well suited for penetrating hides and tearing flesh.

Prosauropods

Prosauropod dinosaurs were early forms of plant-eaters.  They were among the first to feature long necks, long tails and capacious bellies.  Two dinosarus known from the valley from bones, Anchisaurus and Ammosaurus, have been identified as prosauropods. A third of the animal was neck, so they could reach higher than ornithischians.

Ornithischian dinosaurs

Ornithischian dinosaurs grew to be the most numerous and fantastic of the orders.  Early ornithischians, likely represented by the footprint Anomoepus, were forerunners of many bizarre-looking dinosaurs such as Stegosaurus, Triceratops and the duckbill, Hadrosaurus, which thrived much later, in Late Jurassic and Cretaceous times. 

The Moody Footprint Quarry as depicted in this lithograph published as part of an early study made of Connecticut Valley dinosaur footprints in the 1840s. While today the valley may seem tame, it is a place where incredible discoveries of dinosaur bones and footprints and about dinosaurs have been made for centuries.

The smaller of the valley's theropods, perhaps similar to Podokesaurus, were three to six feet long with snakelike heads and long, thin, hind legs. Computer model by Will Sillin.

Great Day Trips in the Connecticut Valley of the Dinosaurs, is a guide to the sites and tales of local discoveries.

The larger theropod dinosaurs, likely similar to Dilophosaurus, were up to 20 feet long, with thick, stout, hind legs and big heads bearing substantial jawbones. Computer model by Will Sillin. 

The valley's prosauropod dinosaurs, such as Anchisaurus, walked on two legs, occasionally dropping down on all fours.  They ranged from roughly five to eight feet in length to roughly 12 to 15 feet long. Computer model by Will Sillin.

The primitive ornithischian known from footprints found in the Connecticut Valley was turkey sized, with a long neck, relatively long legs and round belly. Computer model by Will Sillin.