| Olenoides | |
|---|---|
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| Olenoides superbus from the Upper Marjum Formation | |
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| 3D reconstruction ofOlenoides serratus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | †Trilobita |
| Order: | †Corynexochida |
| Family: | †Dorypygidae |
| Genus: | †Olenoides Meek, 1877 |
| Species | |
Olenoides was atrilobite from theCambrian period. Its fossils are found well-preserved in theBurgess Shale in Canada. It grew up to 10 cm (3.9 in) long.
Olenoides – fromOlenus, in Greek mythology a man who, along with his wife Lethaea, was turned to stone.Olenus was used for a trilobite genus name in 1827; the suffix -oides(“resembling”) was added later.
Olenoides followed the basic structure of all trilobites — acephalon (head shield), athorax with seven jointed parts, and finally a semicircularpygidium. Its antennae were long, and curved back along its sides. Its thin legs show that it was no swimmer, instead crawling along the sea floor in search of prey. This is also evidenced by fossil tracks that have been found. Conspicuous W-shaped wounds, often partially healed, onOlenoides specimens may be due to predation byAnomalocaris.[2]
Its major characteristics are a large parallel-sidedglabella, deep interpleural furrows on thepygidium, and slender pygidial spines, as well as the fact that it is the most common limb-bearing trilobite species in theBurgess Shale.
Specimens have been found in theMarjumian of the United States (Utah andNew York). GeneralCambrian fossils have been found in Canada (British Columbia andNewfoundland),Greenland,Kazakhstan, Russia, and the USA (Idaho,Nevada for whichO. nevadensis is named,New York,Pennsylvania for which O. pennsylvanicus is named,Virginia,Utah, andWyoming).[3]
213 specimens ofOlenoides are known from the GreaterPhyllopod bed, where they comprise 0.4% of the community.[4] The Burgess Shale's preservative qualities have helpedOlenoides become one of the best known of trilobites.
Olenoides was formerly known asNeolenus. Species ofKootenia are no longer considered different enough from those inOlenoides to warrant placement in a separate genus.[5]
Olenoides is an average size trilobite (up to 9 cm long), broadly oval in outline. Itscephalon is semi-circular. The glabella is parallel-sided, rounded at its front and almost reaches the anterior border. Narrow occular ridges curve backwards from the front of the glabella to the small, outwardly-bowed eyes. The librigenae narrow backward into straight, slender genal spines that reach as far as the third thorax segment. Thorax consists of seven segments that end in needle-like spines.pygidium) has six axial rings that decrease in size backwards and four or five pairs of rearward pointing marginal spines. Cephalon, thorax and pygidium are of approximately equal length.[1]
Olenoides serratus is one of about twenty species of which the non-calcified parts are known, due to so-calledsoft tissue preservation. Theantennae are the most anterior pair of appendages in trilobites. InO. serratus, these are attached about halfway the immediately adjacent to thehypostome, and appear from thedorsal side under the cephalon in front of the side of the glabella. They were flexible, having a tubular shape that became narrower towards anterior and composed of between 40 and 50 segments that are each shorter than wide.Olenellus serratus is the only known trilobite withcerci,uniramousappendages onventral side of lastpygidialsegment, and these are shaped like the antennas.[6]
