Thalattotheria

## Taxonomy

Polypodia

Sarcopodia

Neopoda

Osteopoda

Synischia

Deinognatha

Odontognatha

Dolichognatha

Pelagotheria

**Thalattotheria**

## Immediate subtaxa

Isopterygia

Anisopterygia

**Thalattotheria** (lit. "ocean beasts") are a clade of Pelagotheria, and the first clade of Osteopoda to evolve a fully aquatic lifestyle.

## Description

First emerging around 4224ma, the Thalattotheres are the first clade of fully marine animals to descend from terrestrial species.

Thalattotheres are the first clade of animals to evolve a form of life birth, which in their case takes the form of ovoviviparity: the ootheca is stored inside the mother until the young reach a suitable development, at which point they are birthed directly into the water. It was this development that allowed Thalattotheres to make the transition to fully aquatic lifestyles.

Thalattotheres are the largest animals yet observed, with species in the Isopterygia clade measuring as long as 13 meters. Their system of active respiration grants them greater potential sizes than Acanthopods but restricts them to shallower waters.

## Navigation

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												* File:StenopsidaeEvo.pngArchestenopsidae
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									* **Thalattotheria**†
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											- *Pontodrakon nicholsi*†

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 † = Extinct