Size of a Trilobite Based on Hypostome Size

[minnbuckeye]

Yesterday, I split open a piece of Ordovician matrix in attempts to extract a Hormatoma. To my surprise, a HUGE Isotelus hypostome was hidden inside the rock. Is there a formula to calculate to the size of the trilobite based on the size of the hypostome? I will post pictures of it later on in a separate post (fossil hunting trips).

[Fossildude19]

@piranha

[Isotelus2883]

If you estimate cephalon size with your hypostome, there is some good data you can use to find body length.

Biometric and Taxonomic Analysis of the Genus Isotelus (Trilobita) from Cincinnatian (Upper Ordovician) Rocks of Ohio, Kentucky, and Indiana

The type species of the Ordovician trilobite genus Isotelus: I. gigas Dekay, 1824

[minnbuckeye]

@Isotelus2883, Thanks for the articles. All I have is the hypostome. Scanning the above articles does not seem to provide the correlation of trilobite size to the hypostome.

[Isotelus2883]

I couldn’t find anything about that. I think the best you can do is find some images of ventrally preserved Isotelus with their hypostomes in place.

[minnbuckeye]

@Isotelus2883, I did some ratios of hypostome length to trilobite length from a drawing in one of the articles suggested. The length of the trilobite belonging to this hypostome would be in the neighborhood of 15 inches!