Named By: Friedrich von Huene - 1936.
Classification: Chordata, Reptilia, Sauropterygia, Placodontia, Henondontidae.
Species: H. chelyops (type).
Size: 1 meter long.
Known locations: Europe, Germany.
Time period: Carnian of the Triassic.
Fossil representation: Well preserved specimen.
many of the placodonts
had shells only a few like Henodus
had single shells that covered the entire body, while
others like Cyamodus
had two shells. Henodus has one of the most well
developed single shells of all placodonts made up by a fusion of a
large number of scutes with a covering of horn, and is almost as
wide as it is long. Aside from being very tough this made the shell
was so large that most marine predators of the Triassic couldn’t get
the shell of a full grown adult between their jaws. This shell
however would have been a great hindrance when Henodus
was on land and
it may be that as a result Henodus spent most of
its life in the water
except for laying eggs (assuming that placodonts laid eggs).
This is especially the case when you consider that Henodus
plastron (lower shell) like a turtle, while the carapace (upper
shell) was actually fused to the spine.
Henodus differed from most other placodonts in that the mouth was broad and squared off instead of pointed. Henodus probably used this mouth to shovel through sediment to find shellfish that were buried just below the surface, while other placodonts with pointed mouths were better able to get shell fish wedged between rocks. Such feeding behaviour would also make Henodus a niche specialist that allowed it to share ecosystems with other placodonts without competition with them.
- Henodus chelyops, ein neuer placodontier. - Sonder-Abduck aus Palaeontographica Beiträge zur Naturgeschichte der Vorzeit, Abteilung A 84:99-148. - F. von Huene - 1936.
- Der Dritte Henodus ergänzungen zur Kenntnis des Placodontiers Henodus chelyops Huene. - Sonder-Abdruck aus Palaeontographica Beiträge zur Naturgeschichte der Vorzeit, Abteilung A 89:105-114. - F. von Huene - 1938.