Common Name: Sun Ray
H.radians is the only recognized member of the genus
heliobatis within the family
H.radians has a roughly
circular disc that is slightly longer than wide. Snout
terminates in an obtuse point. Tail (when intact) is roughly the same
length as the body. Tail has up to three barbs (modified denticles).
Teeth triangular and tightly spaced for crushing crustaceans.
Most collected fossils are between 30-40cm. The smallest fossil recorded
was 8cm in length from nose to tail.
A freshwater, demersal (bottom
dwelling) ray confined to river and lake beds.
Extinct. Heliobatis radians
flourished during the Wasatchian stage in the early Eocene 50-55 million years
It was discovered in the Green River Formation in southwest Wyoming. Fossils are
particularly common at a spot called Fossil Lake.
Diet: The abundance of H.radians fossils at
Fossil Lake (the only place where the crayfish Procambarus primaevus and
the prawn Bechleja rostrata are found) suggest that small crustaceans
were an important part of this ray's diet.
Unborn fetuses have been identified within the fossils of adult animals.
Similar species: So far
H.radians appears to be the only dasyatid ray present in the Green River
Formation but further analysis of minor variations in disc shape of collected fossils may
lead to the discovery of multiple species living sympatrically.
Reaction to divers: Not