How quickly did marine life recover after the Triassic-Jurassic extinction?

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Jurassic paleogeography — Jurassic Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Jurassic Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

Following the mass extinction at the Triassic-Jurassic boundary, marine life experienced a rapid increase in diversity for approximately the first four million years, spanning the Hettangian Age and the early part of the Sinemurian Age.1

This initial recovery phase slowed over the subsequent five million years and was further interrupted by another extinction event among bottom-dwelling invertebrates at the Pliensbachian–Toarcian boundary, roughly 183 million years ago. Due to these setbacks, a full recovery of marine ecosystems was not achieved until the Middle Jurassic. Despite these interruptions, the Jurassic Period overall was characterized by the modernization and evolutionary radiation of many important marine groups.1