The Devonian

SarahMargaret McGuirt

Trevor Mehard

Christopher Olivieri

Red Hill, Pennsylvania

  • Where: Red Hill Geological Site - central Pennsylvania
  • Time Slice: Late Devonian times (roughly 410-360 million years ago)
  • What: Many plant and animal fossils have been found at Red Hill. However, the most renowned discovery at Red Hill is the tetrapod. The tetrapods found at Red Hill are the earliest known tetrapods to be discovered in North America.

Depositional Environment

  • During the Devonian period, Red Hill was a wide, meandering river in a tropical/sub-tropical environment.

  • This river system flowed in a northwest direction into the Catskill Sea.

  • Red Hill is composed mostly of red mudstone (from which it gets its name) and sandstone - sedimentary rock that was deposited by the river.

  • Mudstones suggest the river was subject to seasonal flooding but was not powerful enough to be considered destructive.

  • The fossil soils indicate that the area went through arid stages but was more consistently moist.

  • There is also believed to be numerous low-lying ponds on the floodplains located around the river during the time.


Remember: Many plant and animal fossils have been discovered at Red Hill. However, the most renowned discovery is the tetrapod.

What exactly is a tetrapod?

  • "Tetrapoda" means " legs" in Greek.


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  • Amphibians, reptiles, and mammals are the main groups of tetrapods.

  • Early tetrapods were the first vertebrates to walk on land. Before tetrapods existed vertebrates were bound to living in the water.

  • Around 360 million years ago is when tetrapods began to emerge.

Which one of these creatures (found at Red Hill) played an important role in life moving from water to land?


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Hynerpeton bassetti (early tetrapod)

Jaw fossil

What: Hynerpeton bassetti - late Devonian tetrapod

Where: Red Hill Geological site - Hyner, Pennsylvania

  • First late Devonian tetrapod discovered in North America outside of Greenland

  • One of the earliest known tetrapods found anywhere

  • It's name means creeping animal from Hyner (Pennsylvania)

  • It's remains were found in a shallow channel-margin at Red Hill

Hynerpeton lindae

Reconstruction of late Devonian fish

What: Hyneria lindae - late Devonian -fin fish


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Where: Red Hill Geological site - Pennsylvania

  • The distinctive scales of Hyneria lindae are common at the Red Hill site

  • Most of its remains have been recovered from shallow channel margins but some have been found in floodplain ponds.

  • Based on Hyneria lindae's jaw size, it is estimated to have been about 3-4 meters in length.

  • Hyneria belongs to the Tristicoptereridae, the family of lobe-fin fishes most closely related to tetrapods.

Turrisaspis Elektor (groenlandaspid placoderm)

What: Turrisaspis Elektor fish


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Where: Red Hill Geological site - Pennsylvania

  • One of the most common vertebrate fossil found at Red Hill

  • Common in both shallow channel margin and floodplain pond facies

  • One of two members of the Groenlandaspidae found in Catskill formation

  • 5 meters long

From Water to Land

Early Devonian

  • Located below the equator

  • Completely submerged under water


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Modern World

  • Red Hill is located in Clinton County, an area in central Pennsylvania

  • Located above the equator in the Western Hemisphere

  • The Red Hill is no longer submerged under water. It is located in a mountainous region.

Method used to date the rocks at Red Hill

Palynological dating was used to determine the age of Red Hill. Palynological dating uses fossilized plant spores to determine the rocks age. The rocks used to date the site place it in the Upper Famenian of the Late Devonian.


  • Cressler, Walter L., III, Cyrille Prestianni, and Ben LePage. "INTERNATIONAL JOURNAL OF COAL GEOLOGY." Late Devonian Spermatophyte Diversity and Paleoecology at Red Hill, North-central Pennsylvania, USA (2010): 91-102. Web of Science. Web. 17 Sept. 2012.

  • Cressler, Walter L., III. "Plant Paleoecology of the Late Devonian Red Hill Locality, North-central Pennsylvania, an Archaeopteris-dominated Wetland Plant Community and Early Tetrapod Site." Special Papers (2005)

  • Daeschler, Edward B., Jennifer A. Clack, and Neil H. Shubin. "ACTA ZOOLOGICA." Late Devonian Tetrapod Remains from Red Hill, Pennsylvania, USA: How Much Diversity? 90 (2009): 306-17. Web of Science. Web. 17 Sept. 2012.

  • Slingerland, Rudy, Mark Patzkowski, and Dan Peterson. "Facies and Sedimentary Environments of the Catskill Systems Tract in Central Pennsylvania." PAPG FIELD TRIP. Department of Geosciences, May 2009. Web. .

  • Walter L., Cressler II, and Hermann W Pfefferkorn. "A Late Devonian isoetalean lycopsid, Otzinachsonia Beerboweri, gen. et sp. nov., from north-central Pennsylvania, USA." 92.7 (2005): 1131-1140. Web. 17 Sep 2012.