Triassic–Jurassic extinction event

Extinction intensity.svgCambrianOrdovicianSilurianDevonianCarboniferousPermianTriassicJurassicCretaceousPaleogeneNeogene
Marine extinction intensity during the Phanerozoic
Millions of years ago
Extinction intensity.svgCambrianOrdovicianSilurianDevonianCarboniferousPermianTriassicJurassicCretaceousPaleogeneNeogene
The blue graph shows the apparent percentage (not the absolute number) of marine animal genera becoming extinct during any given time interval. It does not represent all marine species, just those that are readily fossilized. The labels of the traditional "Big Five" extinction events and the more recently recognised End-Capitanian extinction event are clickable hyperlinks; see Extinction event for more details. (source and image info)

The Triassic–Jurassic extinction event marks the boundary between the Triassic and 201.3 million years ago,[1] and is one of the major extinction events of the Phanerozoic eon, profoundly affecting life on land and in the oceans. In the seas, a whole class (conodonts)[2] and 23-34% of marine genera disappeared.[3][4] On land, all archosaurs other than crocodylomorphs (Sphenosuchia and Crocodyliformes) and Avemetatarsalia (pterosaurs and dinosaurs), some remaining therapsids, and many of the large amphibians became extinct.


Ranges of families tetrapods through the Triassic and Early Jurassic

About 42% of all terrestrial tetrapods[5] went extinct. This event vacated terrestrial ecological niches, allowing the dinosaurs to assume the dominant roles in the Jurassic period. This event happened in less than 10,000 years and occurred just before Pangaea started to break apart. In the area of Tübingen (Germany), a Triassic-Jurassic bonebed can be found, which is characteristic for this boundary.[6]

The extinction event marks a floral turnover as well. About 60% of the diverse monosaccate and bisaccate pollen assemblages disappear at the T-J boundary, indicating a major extinction of plant genera. Early Jurassic pollen assemblages are dominated by Corollina, a new genus that took advantage of the empty niches left by the extinction.[7]

Statistical analysis of marine losses at this time suggests that the decrease in diversity was caused more by a decrease in speciation than by an increase in extinctions.[8]

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