Devonian Period

• Ferns developed during the Devonian Period.fern image by ana malin from Fotolia.com
  
  The Devonian Period is also referred to as the Age of Fishes. It dates from 417 million years ago to 354 million years ago. The Devonian Period saw the development of tiny plants and vegetation which eventually formed ferns and seed-bearing plants. The seed plants developed into trees and forests.
  Another fossil group of the Devonian Period was tetrapods which are any creature with four feet; arthropods which have exoskeletons and segmented bodies, and early vertebrates which eventually developed into all land animals with vertebrae. During the Devonian Period, the vertebrate group included insects, corals, ammonites and many new fish types.
  
  

Hexagonaria

• Coral was preserved as hexagonaria fossils.coral reef image by Amjad Shihab from Fotolia.com
  
  The hexagonaria is a fossil of coral. In the Grand River, the hexagonaria was named the Petoskey Stone. The fossilized coral is not only found in Ohio's Grand River but also in Lake Michigan and Lake Huron. It is a form of ancient coral, originating in the shallow seas of Michigan over 350 million years ago. During the Devonian Period, the sea covered Ohio and was a natural habitat for coral as well as other marine creatures. The hexagonaria fossils from Grand River were named Petoskey Stone after an Ottowan Indian princess married a Frenchman. Her husband was given the name Petosegay by her tribe. Petosegay translates, "rays of dawn" or "rising sun."
  The Petoskey Stone of the Grand River features circular designs that are similar in shape to the sun and the rays of the sun.
  
  

Crinoids

• Crinoids are other fossils of the Devonian Period found in the Grand River. The crinoid's fossils come from shallow water and are also known as feather stars and sea lilies. Crinoid skeletons make up much of the limestone found in the Grand River and other waterways of the Paleozoic Era.
  The Devonian crinoids attached themselves to the shallow riverbeds, filtering food that passed them in the currents. They were similar in shape to a starfish but their mouths faced upward in order to catch passing food particles.
  
  

Brachiopods

• Clam-shaped brachiopodspirifer, coquillage fossile image by jcm from Fotolia.com
  
  Brachiopods of the Devonian Era were marine creatures similar in appearance to clams. The brachiopods were the first marine creatures to evolve into an immobile animal and grow an external shell. They used tentacles to reach out and grab food from the river. Brachiopods are often referred to as lamp shells. The Grand River is abundant with brachiopod fossils which formed in riverbanks. Brachiopods were part of the Triassic mass extinction approximately 250 million years ago.
  
  

Trilobites

• Trilobite fossilTrilobite of Morocco - Period Devonian image by santosilva from Fotolia.com
  
  Trilobite fossils are the most diverse and plentiful artifacts from the Paleozoic Era. There are over 20,000 species of trilobites recognized today. Trilobite fossils dating from the Devonian Period are plentiful in the Grand River. During this ancient period, trilobites were beginning their path toward extinction which occurred in the Permian Period, 250 million years ago.
  Trilobites had exoskeletons and walked along the riverbeds feeding on plankton and microscopic sea creatures. Some of the trilobite fossils found in the Grand River retained the legs, gills and digestive tracts of the trilobite but most fossils are incomplete. The trilobite shed its exoskeleton, so many of the fossils found are only the body shell. These little water bugs have been studied by paleontologists to determine different evolutionary periods.