Henodus

Length: 3 ft. Period: Late Triassic

Far beneath the sun-warmed waves lay the cold sands of the ocean floor.  It was a dim, hazy world of slow currents and exotic shellfish.  Through this peaceful darkness cruised the Henodus, slowly churning through the water like an armored submarine as he plucked the tasty clams from their quiet beds.       

Bottom Swimmers 
The Placodonts 
The Mesozoic Seas 
How Do We Know That? 
Mesozoic Timeline 

From 227 million years ago to 206 million years ago, the Mesozoic oceans were home to a slow-moving marine reptile called Henodus. 

Bottom Swimmers   
A slow, heavy swimmer at the bottom of the sea, Henodus was a type of prehistoric marine reptile.  At about 3.25 feet long (1 meter), Henodus had a flat body, a boxy head, four short legs, and a small, pointed tail.  This reptile spent its time paddling slowly along the ocean floor, searching for clams and shellfish.  Although Henodus had no actual teeth, it had an extremely strong, horny beak which it used to crush shells.  Henodus was protected from predators by bony shell plates on its back and stomach.
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The Placodonts   
Henodus was not a dinosaur, but a member of a family of prehistoric marine reptiles called placodonts.  These reptiles lived in shallow seas where they could move slowly about the ocean floor, hunting for clams and slow-moving shellfish.  Some placondonts had special teeth for eating shellfish.  Their front teeth were long and outwardly curved, perfect for plucking clams out of the seabed.  Other teeth on the roof and sides of the placodonts’ mouths were broad and flat.  These flat teeth, combined with superior jaw strength, allowed the placodonts, to easily crush the heavy shells of their food.  

Placodonts were also characterized by their heavy armor.  These reptiles had bony, protective plates, which sometimes encased their whole bodies like turtle shells.
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The Mesozoic Seas   
The Mesozoic Age has long been known as the Age of Reptiles.  It was a time when huge aquatic reptiles, the largest predators the oceans have ever known, filled the seas.  The Mesozoic Age spanned millions of years and is divided into three main periods, the Triassic, the Jurassic and the Cretaceous.   Each of these periods saw a great diversity in the animals that lived in the Mesozoic seas.  The placodonts, however, were a relatively short-lived group of reptiles.  They existed for only a few million years, during the Triassic period.
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How Do We Know That?   
Deep, sheltered bays in the prehistoric Tethy’s Sea were once popular feeding grounds for aquatic reptiles.  Fossilized remains of life in the Tethy’s Sea are now found in modern Germany.  Most Henodus fossils have been found with the remains of the Tethy’s Sea.
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Mesozoic Timeline

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