Triassic Period

The Triassic Period 248 MYA- 205 MYA Climate -Arid and dry climate -Coastal areas received seasonal monsoons -No polar ice caps and polar regions were so warm that they had lush forests -Also had few moist river and lake habitats with gymnosperm forests -Vast deserts and warm seas

Triassic Period ends as quickly as it began Began around 251 million years ago, after the Permian period (the biggest mass extinction ever). Life on Earth began to recover... slowly. Due to the warm environment and lack of life, this led to some evolutionary opportunities for the very first mammals and dinosaurs to evolve. Pangaea began to break apart.

Leading to the Triassic-Jurassic period During the final 18 million years of this period, there were 2 or 3 phases of mass extinction that led to the Triassic-Jurassic mass extinction event. Climate change, flood basalt eruptions, and an asteroid impact. Many animals died out, including: marine reptiles, large amphibians, reef-building creatures, and cephalopod molluscs. Strangely, plants were not so badly affected.

Major Events in Plant Evolution Most of these plants were recovering from Permian extinction… no major evolutionary changes On land, gymnosperms dominated: CONIFERS CYCADEOIDS FERNS and MOSSES Dicrodium (fern genus)

Forests dominated by conifers (mostly pines) Open areas dominated by cycads (similar to palm trees) sphenopsids (horsetails) ginkgos bennettitaleans Savannas or prairies - nutrient poor soil, dry, arid climate. Adaptations: exposed seeds, wind dispersal, scaly leaves, thick cuticles. Encouraged cynodont herbivores.

Phytoplankton assemblages including Dinoflagellates survived Permian extinction Supported marine food web

Animals of the Triassic Period - Terrestrial ●Reptiles ○Dinosaurs - coelophysis, therapods bird-hipped dinosaurs ○Postosuchus ○Pterosaurs - flying reptiles ○Snakes ●Insects ○Spiders, scorpions, millipedes, centipedes ○Beetles ○Grasshoppers, dragonflies ●Synapsids (proto-mammals) ○Cynodonts, placerias, therapsids

Animals, cont. - Semi-aquatic ●Reptiles ○Turtles ○Crocodiles ●Amphibians ○Salamanders ○Frogs

Animals, cont. - Aquatic Life ●Reptiles ○Ichthyosaur s : Marine, dolphin-like reptiles ○Plesiosauria: Large, carnivorous marine reptiles ●Fish, molluscs, some echinoderms ●Cephalopods ○Squid, nautilus, ammonite ●Cnidarians ○Jellyfish ○Early corals ●Porifera ○Sponges

Changes in Clade Sizes and Features Early Triassic lifeforms tend to be more Paleozoic, but as they begin to diversify they became more Mesozoic Conifer and cycad vegetation increased Dinosaurs appeared/diversified Therapsids nearly became extinct Mammals appeared and began to diversify, but were still not major players Ammonites, molluscs, and sea urchins began to diversify Reptiles diversified and increased in number Reptiles took flight for the first time (Pterosaurs), but flying reptiles became extinct at the end of the period

Major changes in fauna Ichthyosaurs, marine reptiles, grew to enormous sizes. ●Synapsids got smaller and became nocturnal to avoid the increasing numbers of Archosaurs. ●Significant changes in the ankle structure of Archosaurs gave rise to the groups Ornithodira and Crurotarsi. ○Crocodiles have the Crurotarsal ankle ○Birds and other dinosaurs have the Mesotarsal

Changes in Archosaurs Archosaurs split into two groups that gave rise to 1. Dinosaurs and Pterosaurs and 2. Crocodyliforms. Another important development was that of the semi-erect posture of crocodyliforms. Erect posture in birds and dinosaurs developed later

Sources ●An Illustration of a Typical Jurassic Ichthyosaur N.p. ○Photo of Ichthyosaur on Animals Slide ●BBC Nature. Oct Triassic-Jurassic mass extinction. [Accessed 31 Jan] ○Used this website for the other picture on the “Climate” slide. I chose it to represent the dry and arid climate of the period. ○Used this information to learn about the mass extinctions that took place during this time. ●BBC Nature. Oct Triassic Period. BBC. [Accessed 31 Jan] ○Used this article to find the length of the period. Also used a few facts to learn about the climate and I used a picture from this site for the “Climate” slide. ●Bagley, Mary. "Triassic Period Facts: Climate, Animals & Plants."LiveScience. TechMedia Network, 11 Feb [Accessed 1 Feb] ○Used for information on marine species, specifically ichthyosaurs. Earth Science. Feb The Triassic Period. [Accessed 30 Jan] Used this website to obtain the photo of the formation of Pangea during this time. Fuller, Nicolle Earth. The Science behind the Headlines. [Accessed 30 Jan] Used the image of the dinosaur with the asteroid extinction occurring in the background. ●Howard Hughs Medical Institute. Deep History of Life on Earth. HHMI Biointeractive. [Accessed 31 Jan] ○Used the “Age of Dinosaurs” section of the website to learn about changes in clade sizes and features. Used information on dinosaur diversity and dinosaur flight. ●"Huge Cretaceous Orthopteran Habrohagla." Lower Cretaceous Orthopteran Fossil Insect from Liaoning Province China. N.p., n.d. [Accessed 1 Feb] ○Used for photo of fossilized grasshopper ●Huw, Boulton. Department of geology. Dinosaur Evolution. [Accessed 30 Jan] ○Used for archosaur evolution information.

Sources continued Kentucky geological Survey Great Triassic Assemblages [Accessed 31 Jan] Used for information on posture and picture of posture types, ankle structures, and cladogram. Logan, Alan Triassic Period: Geochronology. Encyclopedia Britannica. [Accessed 31 Jan] Used the “Triassic Life” section to acquire information about the diversification of life. Used information on the first mammals and invertebrates. This site had a lot of useful information about ammonites and other marine invertebrates. ●Smith, David Introduction to Pterosauria. UCMP. [Accessed 31 Jan] ○Used this website for information on Pterosaurs and learned about early reptile flight. I learned about how and why flight evolved, as well as the characteristics of these early reptiles. ●"Thinnfeldia – a Triassic Fern." 600 Million Years. Melbourne Museum, n.d. Web. 01 Feb ○Used for photo of fossilized fern ●Triassic. (2008, December 1). New World Encyclopedia, [Accessed 30 Jan] ○Used for the information on Ichthyosaurs and mammalian origin and adaptations. ●Triassic Period. National Geographic. [Accessed 31 Jan] UCMP. Jun The Triassic Period. University of California Museum of Paleontology. [Accessed 31 Jan] Mostly used this article for facts about climate during the Triassic period. This is where I found the majority of my information regarding the climate. White, Toby. "The Late Triassic." Palaeos Mesozoic: Triassic: Late Triassic. Creative Commons Attribution Non-Commercial License, 9 Apr [Accessed 1 Feb]. Used for photo of Plateosaurus and ferns Used for details about marine fish and shark evolution Used for information on Plants that survived and evolved and in which climates they thrived in. Wiggins, Virgil D.. “Upper Triassic Dinoflagellates from Arctic Alaska”. Micropaleontology 19.1 (1973): 1–17. [Accessed 1 Feb] Used for dinoflagellate photo