Fins 102; Knightia

Knightia Species Identification

The two species of genus Knightia reported from the Green River Formation are so similar that it is possible they actually represent a single species.
Some researchers have reported a "bimodal" distribution of body depth in examples from the three Eocene lakes so, at present, we continue to consider them to be separate species.
Differentiation of the species based on meristic data is not possible, fin ray counts and scale counts are not sufficiently different to allow species identification.

When body dimensions are calculated as a proportion of standard length, an avenue to species identification is revealed. The difference in the ratio of body depth to standard length can be exploited to differentiate the species. The table below illustrates the differences in body depth of the two knightia species.

	K. eocaena	K. alta
body depth ratio	.20-.29	.33-.41
head length	.25-.29	.25-.30
predorsal length	.45-.51	.45-.50