| Isotelus Temporal range:
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|---|---|
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| Isotelus gigas fossil at the Smithsonian National Museum of Natural History | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | †Trilobita |
| Order: | †Asaphida |
| Family: | †Asaphidae |
| Genus: | †Isotelus Dekay, 1824 |
| Species | |
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See text | |
Isotelus is a genus of asaphid trilobites from the Middle and Late Ordovician Period, fairly common in the northeastern United States, northwest Manitoba, southwestern Quebec and southeastern Ontario.
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Isotelus
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Isotelus, the Titan Trilobite
Transcription
Gigantism
The mostly complete holotype specimen of Isotelus rex, from Churchill River Group, 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 midpoint of the cephalon).[2][3][4] It was probably exceeded in size only by Hungioides bohemicus, in which the specimens probably exceeding I. rex in size are only known from partial remains.[5]
Being found in Manitoba, which was equatorial during the Ordovician, I. rex is a dramatic example of low-latitude gigantism, contrasting with many modern marine benthic arthropods which adhere to Bergmann's rule of polar gigantism.[1]
Species
A number of species have been described:
- I. aktchokensis Weber, 1948
- I. bradleyi Amati, 2014
- I. copenhagenensis Ross, Jr. & Shaw 1972
- I. frognoensis Owen, 1981
- I. gigas Dekay, 1824
- I. harrisi Raymond, 1905 (synonym I. platymarginatus Raymond, 1910)
- I. iowensis Owen, 1852
- I. kimmswickensis Bradley, 1930
- I. maximus Locke, 1838
- I. megistos Locke, 1842
- I. parvirugosus Chatterton & Ludvigsen, 1976
- I. skapaneidos Amati, 2014
- I. susae Whitfield, 1882
- I. violaensis Amati, 2014
- I. walcotti Walcott, 1918 (synonym I. planus De Mott, 1963)
Many specimens have been found in Ohio, where Isotelus is the State Invertebrate Fossil.[6][7]
References
- ^ a b Rudkin, David M.; Young, Graham A.; Elias, Robert J.; Dobrzanski, Edward P. (January 2003). "The World's Biggest Trilobite—Isotelus rex New Species From the Upper Ordovician of Northern Manitoba, Canada". Journal of Paleontology. 77 (1): 99–112. doi:10.1666/0022-3360(2003)077<0099:TWBTIR>2.0.CO;2. ISSN 0022-3360.
- ^ 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". Journal of Paleontology. 70 (1): 99–112. doi:10.1666/0022-3360(2003)077<0099:TWBTIR>2.0.CO;2. ISSN 0022-3360.
- ^ S. M. Gon III (2005-08-17). "The World's Largest Trilobites".
- ^ P. Z. Myers (2005-04-25). "Isotelus rex, biggest trilobite ever". Archived from the original on 2007-11-12.
- ^ Gutiérrez-Marco, Juan C.; Sá, Artur A.; García-Bellido, Diego C.; Rábano, Isabel; Valério, Manuel (2009). "Giant trilobites and trilobite clusters from the Ordovician of Portugal". Geology. 37 (5): 443–446. Bibcode:2009Geo....37..443G. doi:10.1130/g25513a.1. ISSN 1943-2682.
- ^ "Ohio's State Fossil - Isotelus".
- ^ Babcock, L. E. (1996). "Chapter 8. Phylum Arthropoda, Class Trilobita". Fossils of Ohio. Columbus, Ohio: Ohio Division of Geological Survey, Bulletin 70. pp. 90–113. ISBN 0-931079-05-5.
This page was last edited on 18 May 2024, at 13:07