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.


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