| Illaenus crassicauda Temporal range: | |
|---|---|
| Fossil of Illaenus crassicauda from Sweden, on display at Galerie de paléontologie et d'anatomie comparée in Paris | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Clade: | †Artiopoda |
| Class: | †Trilobita |
| Order: | †Corynexochida |
| Family: | †Illaenidae |
| Genus: | †Illaenus |
| Species: | †I. crassicauda |
| Binomial name | |
| †Illaenus crassicauda Wahlenberg 1826 | |
Illaenus crassicauda is a species of trilobites belonging to the family Illaenidae. These trilobites lived in the middle Ordovician and in the Silurian age (443 - 418 million years ago). Fossils of this species have been found in the sediments of Sweden and Russia.
The Latin species name crassicauda means "fat-tailed", with reference to the shape of the pygidium.
Illaenus crassicauda can reach a length of about 14 centimetres (5.5 in). These trilobites are without glabella and without articulation of the tail. The cephalon has a high profile. The large bulbous head are distant from the axis of the head, close to the margin.