Post Triassic Period

Just prior to the Triassic Period, during the Late Permian Period, most of the worlds land mass was composed of the supercontinent of Pangea.  North America was apart of what has been termed the Laurasia subcontinent.  Texas was located just north of the Central Pangean Mountains that separated Laurasia from the Gondwana subcontinent.  During the Permian much of the interior of Pangea was probably arid, with great seasonal fluctuations (wet and dry seasons), because of the lack of the moderating effect of nearby bodies of water.  This drying tendency continued through to the late Permian, along with alternating warming and cooling periods.

As Pangea was assembled by the converging subcontinents, most of North America was being uplifted during the Permian.  This uplift generated the famous fold belts of the Appalachian Mountains and exposed more land in present-day central North America.  Shallow seas covered much of modern western North America, including the western portion of Texas.  Large reef complexes such as the Capitian Reef Formation and associated development of extensive evaporite deposits formed in restricted lagoons at the shoreline.  Farther west, subduction began, generating volcanic activity in the region of the modern Sierra Nevada.

During the Permian, trilobites and other marine groups became extinct.  However, a group of small pre-dinosaur reptiles (lizard-like diapsids) thrived.  These were the ancestors to most modern reptiles and the dinosaurs as well as pterosaurs and crocodiles.  Thriving also, were the early ancestors to mammals (synapdia), which included reptiles such as dimetrodon, pelycosaurs and the therapsids. Bennettites, Some significant groups of plants evolved during the Permian in the climatic conditions which became progressively drier; these being the Bennettites, Cycads, Ginkgos and Glossopterids.

Texas Dinosaurs    Post Triassic Period    Triassic Period     Jurassic Period