Name:
Heliobatis
(Sun ray).
Phonetic: Hel-ee-oh-ba-tiss.
Named By: Othniel Charles Marsh - 1877.
Synonyms: Dasyatis, Palaeodasybatis
discus, Xiphotrygon acutidens, Xyphotrygus species.
Classification: Chordata, Chondrichthyes,
Myliobatiformes, Dasyatidae.
Species: H. radians (type).
Diet: Carnivore.
Size: Up to 90 centimetres long.
Known locations: USA, Wyoming - Green River
Formation.
Time period: Wasatchian of the Eocene.
Fossil representation: Many specimens.
Heliobatis
is a prehistoric ray that was discovered in the Green River Formation,
a deposit well known for its numerous fossils of fish including
Knightia
and Diplomystus.
Specimens of Heliobatis range between eight
and ninety centimetres, although the average is between thirty and
forty centimetres. Half of the total body length of Heliobatis
is
taken up by the tail. The tail of Heliobatis has
up to three modified
denticles that form barbs, but no one can say for certain how toxic
these
barbs could have been.
Heliobatis
seems to have preferred crustaceans such as crayfish and shrimps as
indicated by the abundance of Heliobatis fossils in
association with
their prey items. The teeth in the mouth of Heliobatis
are small and
triangular, making the teeth better suited for crunching the
exoskeletons of prey.
Like
many American prehistoric animals, Heliobatis was
discovered during
the bone wars, a rivalry between the palaeontologists Othniel Charles
Marsh and Edward Drinker Cope. Marsh named the first albeit
incomplete specimen Heliobatis. Two years later
Cope came across
another specimen and named it Xiphotrygon, but
because Marsh named
his first, Xiphoctrygon became a synonym to Heliobatis.
Heliobatis
itself means 'sun ray', but it should be remembered that the ray
part is in reference to the type of fish that Heliobatis
is, and is
not in reference to a 'ray of sunshine'.
Further reading
- Paleontology of the Green River Formation, with a review of the fish
fauna. - Bulletin of the Wyoming State Geological Survey. - Lance
Grande - 1984.
- Freshwater stingrays of the Green River Formation of Wyoming (early
Eocene), with the description of a new genus and species and an
analysis of its phylogenetic relationships (Chondrichthyes,
Myliobatiformes). - Bulletin of the American Museum of Natural History
284: 1–136. - M. R. Carvalho, J. G. Maisey & L. Grande - 2004.