Isotelus
| Isotelus | |
|---|---|
 |
|
| Isotelus brachycephalus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Trilobita |
| Order: | Asaphida |
| Superfamily: | Asaphoidea |
| Family: | Asaphidae |
| Genus: | Isotelus |
Isotelus is a genus of asaphid trilobite from the middle and upper Ordovician period, fairly common in the Northeastern United States, northwest Manitoba, southwestern Quebec and southeastern Ontario. One species, Isotelus rex, is currently the world's largest complete trilobite.
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[edit] Isotelus rex
A specimen of Isotelus rex, from Churchill, Manitoba, is the largest complete trilobite ever found. Discovered by Dave Rudkin (Royal Ontario Museum), Robert Elias (University of Manitoba), Graham Young (Manitoba Museum) and Edward Dobrzanske (Manitoba Museum) in 1999, it measures 720 millimetres (28 in) in length, 400 millimetres (16 in) in maximum width (across the cephalon) and 70 millimetres (3 in) in maximum height (at the posterior mid-point of the cephalon).[1][2][3]
Large specimens have also been found in Ohio, where Isotelus maximus is the state fossil.
[edit] Physical description
- very similar to Homotelus
- “double” posterior
- head and tail shields are semi-circular and very similar in shape (isopygus)
- thorax has 8 segments and slightly raised middle lobe (between the outer pleurae)
- Time range middle and upper Ordovician (500–480 mya)
[edit] References
- ^ Rudkin, D.A.; Young, G.A.; Elias, R.J.; Dobrzanske, E.P. (2003). "The World's biggest Trilobite: Isotelus rex new species from the Upper Ordovician of northern Manitoba, Canada". Palaeontology 70 (1): 99–112. doi:10.1666/0022-3360(2003)077<0099:TWBTIR>2.0.CO;2. ISSN 0022-3360. http://www.bioone.org/perlserv/?request=get-document&doi=10.1666%2F0022-3360(2003)077%3C0099%3ATWBTIR%3E2.0.CO%3B2&ct=1&SESSID=fabbe2cc5cbdcd233f972db91e24ae28
- ^ S. M. Gon III (2005-08-17). "The World's Largest Trilobites". http://www.trilobites.info/lgtrilos.htm.
- ^ P. Z. Myers (2005-04-25). "Isotelus rex, biggest trilobite ever". http://pharyngula.org/index/weblog/comments/isotelus_rex_biggest_trilobite_ever/.
