Jurassic Period

What happened during this time?

Biological

Flora

• Diversification of ginkgophytes

  • Common in mid-latitude to high, northern latitudes

• Domination of conifers

  • Araucariaceae, Cephalotaxaceae, Pinaceae, Podocarpaceae, Taxaceae, and Cupressaceae

  • Cheirolepidaceae dominates in low latitude areas

• Cycads common throughout landscape

• Increase in the Bennettitales, which dominate in low latitude areas

• Caytoniales small-sized trees, possibly related to angiosperms

• Czekanowskiales were present, but not common

• Ferns

  • Cyatheaceae tree ferns become abundant in the tropical region

  • Osmundaceous, Matoniaceous, and Dipteridaceous ferns are dominant undergrowth in Jurassic forests

  • Marsileaceae is first recorded in the Middle to Late Jurassic, and diversify in the Aptian–Albian of the Early Cretaceous (De Benedetti et al. 2021)

• Coralline red algae appear

Fauna

• Domination of dinosaurs (saurischian)

• First squids and birds

• First frogs and salamanders

Geophysical

• Warm tropical greenhouse conditions world-wide 

  • Carbon dioxide level begin ~1,350 ppm, and increase to ~1,600 ppm before dropping to 1,330 ppm

  • Oxygen levels hover around 20-21%

• The break-up of Pangaea; super-continent begins to rotate, 

• North America drifting westward, opening the Gulf of Mexico, forming the central Atlantic. 

• Mountain-building events are triggered that created the Rocky Mountains and the Sierra Nevada 

• Sea level rose and flooded large portions of the continents; shallow continental seas spilled out of the Tethys and Proto-Atlantic and spread across Europe, 

• Warm shallow seas were home to a rich diversity of life. 

• Much of central North America was flooded by wide sea way that at its height extended into central Utah called the Sundance Sea