Hudsonelpidia brevirostris is a small Late Triassic ichthyosaur from British Columbia. Its nearly complete type skeleton combines a short snout with unusual limb-bone proportions, and the original description found no signs that the animal was immature.
Quick facts
| Species | Hudsonelpidia brevirostris |
|---|---|
| Type specimen | ROM 44629 |
| Age | Early Norian, Late Triassic |
| Place | Peace Reach, Williston Lake, British Columbia |
| Size | Probably under 1 m in the 1995 description |
| Rock unit | Pardonet Formation |
Evidence guide
The articulated skeleton preserves an informative skull and limbs. The original description found no signs that the individual was immature.
An elongated tibia and notched hindfin phalanges occur alongside a large femur. These bones do not measure speed or a particular swimming style.
McGowan noted foramina in the snout but allowed that they could be pathological. They should not be treated as a normal feature of every individual.
A small skeleton from Williston Lake
Christopher McGowan described Hudsonelpidia brevirostris in 1995 from Upper Triassic rocks at Williston Lake in northeastern British Columbia. The holotype is Royal Ontario Museum specimen ROM 44629, a small, nearly complete skeleton. McGowan estimated that the animal probably did not exceed one metre in total length and found no signs of immaturity in the preserved bones.
The name brevirostris refers to the short snout. The genus name honours Hudson's Hope, a community whose residents supported McGowan and his field crew. The fossil is a named species based on a particular skeleton, not a juvenile stage inferred from its size.
For related comparisons, see Mixosaurus Shastasaurus Callawayia.
A mosaic of limb proportions
McGowan described an elongated tibia with notches along its margins and notched phalanges in the hindfin. The humerus, pubis and ischium are also relatively long. The femur is unusually large for the hindlimb and approaches the humerus in length.
The orbit appears large relative to the shortened snout. Foramina were reported in the rostrum, but the original description raised the possibility that they were abnormal. Their presence in ROM 44629 does not establish a normal anatomical condition for the whole genus.
Some limb characters resemble those described in Mixosaurus, while other proportions recall later ichthyosaurs. These are comparisons among anatomical features, not evidence that Hudsonelpidia was a direct ancestor of Jurassic forms.
An early Norian sea
The type came from the Pardonet Formation on the northern shore of the Peace Reach arm of Williston Lake. McGowan assigned the beds to the early Norian using associated conodonts. The fossils establish a marine reptile in a dated rock sequence; they do not provide a precise calendar age for the skeleton.
The small skeleton preserves enough anatomy to recognise a distinctive combination of features, but it does not record colour, exact diet, behaviour or swimming performance. The cover image is an artistic reconstruction, not a photograph of ROM 44629 or of the original field locality.
Frequently asked questions
Where was Hudsonelpidia found?
ROM 44629 came from the northern shore of Peace Reach, an arm of Williston Lake in British Columbia, Canada.
How large was Hudsonelpidia?
McGowan's 1995 description estimated that the animal probably did not exceed one metre. The author found no signs that the specimen was immature.
What makes its limbs unusual?
The description notes a long, notched tibia, notched hindfin phalanges and a large femur that approached the humerus in length.
Were the openings in its snout normal?
That is uncertain. McGowan considered the rostral foramina unusual and suggested they might be pathological rather than a normal feature of the species.