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Evolution in the Mid-Atlantic

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Notable Fossil Finds:

  • In 1835, a fossil snail discovered near Johnstown, Pa., was one of the first animal fossils to be described and illustrated by a paleontologist.

  • A 25-foot long, 10-foot tall duck-billed hadrosaur dug up in 1858 in Haddonfield, N.J., is thought to be the first near-complete dinosaur skeleton in the world. Hadrosaurs lived about 70-100 million years ago. (See it at Philadelphia's Academy of Natural Science.)

  • The world's oldest known fossilized seed was discovered in West Virginia. It dates to the Devonian period, and is at least 350 million years old.

  • In 1994, North America's oldest known reptile fossil, a 320-million-year-old trackway, was found in McCreary County, Ky.

  • A well-preserved "fossil garden" was discovered outside Turbotville, Pa. It dates to 395 million years ago and contains marine invertebrates, including sea lilies (crinoids), corals, and lamp shells.

  • In 1997, a fossil fish at least 360 million years old was found near Williamsport, Pa. The fish, which had eight fingerlike bones encased in its fins, offered evidence that fingers evolved in the water before being used on land.

  • In 1995, geologists discovered a 5-foot-long, 330-million-year-old amphibian fossil in a western Kentucky coal field.

  • The Calvert Cliffs in Maryland are one of the Atlantic coast's most important sites for Miocene epoch fossils. Examples of the state's official fossil, a predatory marine snail, can be found there.

Endangered Species:

Photo of Delmarva fox squirrel The following animal and plant species are among those listed in the federal government's register of endangered species in this region.

 Delmarva fox squirrel

Delmarva fox squirrel (land mammal)
  • Appearance: Slate gray, with a white belly and fluffy tail (two feet long)
  • Habitat: Primarily in hardwood trees and loblolly pines; sometimes in tree groves along streams or salt marshes
  • Threat: Land development, tree cutting
  • Fast fact: This large squirrel was once found throughout the Delaware, Maryland, and Virginia ("Delmarva") peninsula, but is now found naturally only in three counties in Maryland.

Virginia big-eared bat (land mammal)

  • Appearance: Moderate-sized with brown fur and large (one-inch) ears
  • Habitat: Roosts in caves in the winter and summer, and feeds on insects in forests and old fields
  • Threat: Human disturbance in caves, especially during hibernation
  • Fast fact: Most remaining individuals in the world hibernate in one of three caves; one in West Virginia has more than 6,000 bats.

Clubshell (invertebrate)
  • Appearance: Yellow-brown, wedge-shaped shell with green rays that resembles a golf club head (three inches)
  • Habitat: River- and stream-bottom sand, gravel, and other sediment
  • Threat: Erosion, dams, water pollution, non-native zebra mussels
  • Fast fact: While zebra mussels effectively clear cloudy waters, their high populations are literally squeezing out native species from their habitats.

Maryland darter (fish)

  • Appearance: A small member of the perch family
  • Habitat: Confines itself to where fast-moving water from the hills flows onto the flat coastal plain
  • Threat: Land development, water pollution
  • Fast fact: Endemic species live in one place -- and no other -- in the world. Today, the Maryland darter can only found in a clear, cool creek in Harford County, Md.

Dwarf wedgemussel (invertebrate)

  • Appearance: Brown/yellowish-brown, oval-shaped bivalve (1.5 inches)
  • Habitat: Atlantic coast freshwater river and stream bottoms
  • Threat: Water pollution
  • Fast fact: Larvae attach to the tissue of fish, where they develop. At the end of this parasitic stage, the mussels detach themselves from the hosts without having done any harm.


The Mid-Atlantic region, known today for its unique mix of rugged hills, fertile valleys, and coastal plains, has a remarkable geological past.

More than 300 million years ago, the backbone of the region, the Appalachian mountain range, formed when ancient North America and Africa collided near the equator. The coal deposits for which Pennsylvania and West Virginia are famous are fossil remains of plants and animals that lived about this time. Back then, the climate was hot and steamy. Forests were lush, giant insects crawled or buzzed, and amphibians and primitive reptiles crept across swampy land. Recurrent flooding prevented organic matter from fully decomposing. Over the next several million years, heat and pressure turned the remains of life into coal.

Dinosaur fossils are uncommon in the Mid-Atlantic, but the remnants of other intriguing animals from later time periods are abundant. Fossils mixed in with snail shells and shark teeth on the Maryland and Virginia coastline tell us that tapirs, rhinoceroses, elephants, and mastodons all walked the sandy beaches between 5 million and 20 million years ago. In the region's interior, caves in West Virginia and Kentucky contain bones of Ice Age mammals. While some may have sought shelter from the cold, others probably fell through sinkholes that still form today in the region's soft limestone.

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