Glossary of terms
Glossary of terms
Key to the Orders
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Trimerus delphinocephalus Green 1832
Rochester Shale Fm., Clinton Grp., Burleigh Hill Mbr.
Middle Silurian, Wenlockian Series
Monroe County, New York, USA
image courtesy of Wayne Ciluffo, coll.
Trilobite of the Month for November 2018 is an exceptionally large (8.25") specimen of a classic member of the Rochester Shale trilobites. In the order Phacopida, suborder Calymenina, family Homalonotidae, it shows remarkably beautiful preservation. It demonstrates many of the classic characteristics of its family: it is quite effaced, and there is very little distinction between the median and thoracic pleurae at all. The facial sutures of calymenids are typically gonatoparian, and this specimen bears the usual 13 thoracic segments of the family, and a large cephalon lacking genal spines. This specimen, like many of those from this locality is dark, contrasting handsomely against a lighter matrix.
Images like this help explain why trilobites are one of the best-known and appreciated groups of prehistoric animals. Each month, a new example of trilobite diversity will be showcased here. With over 20,000 described species, we may never exhaust the possibilities! If you have a stunning image of a trilobite that you could share as a future "Trilobite of the Month," please let me know!
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This site has enjoyed feedback from a growing number of trilobite workers from all over the world who have
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In these pages, you may recognize species that are common, well-known, or sitting in a familiar museum collection!
This guide might help you arrange trilobite diversity systematically, aid in identification of specimens, and enhance your understanding of these fascinating elements of Paleozoic biodiversity. Happy browsing! -- Sam Gon III
detailed, descriptive characters and representative line drawings
The information in these pages was developed via examination and synthesis of the data present in a variety of works, including the two "Trilobite Treatises:" Moore 1959 (Treatise on Invertebrate Paleontology, Part O, Arthropoda 1, including Trilobitomorpha) and Whittington et al 1997 (Treatise on Invertebrate Paleontology, Part O, Arthropoda 1, Trilobita, Revised, Volume 1: Introduction). Both may be reviewed here. Other important sources are cited in specific pages of this site, and are also listed in a brief bibliography. Sources of photos and line drawings (where not original) are clearly cited. Other trilobite web sites and individuals were inspirational sources and are cited where relevant. The three trilobite thumbnail images in the left column, for example, are c/o Andrew Milner. If you find your information or images on these pages without proper attribution, this is unintentional. Please contact me to rectify the situation.
Information about extinct animals is always subject to interpretation and differences of opinion. In particular, the higher classification of arthropods and trilobites is neither simple nor agreed upon by all trilobite workers. The summaries here are complicated by the fact that the 1997 revision of the Treatise only covers two orders in detail: Agnostida and Redlichiida. The others are in preparation, so my attempts to synthesize data on the other orders is likely to be incomplete, although the arrangement of the families and some characteristic descriptions were provided by Fortey (in Whittington et al 1997), and adjusted via recent articles (e.g., papers dealing with higher classification of the Asaphida, Proetida, Harpetida, Agnostida, and Lichida). Additional revisions continue to be suggested by various workers. Any errors in the information here should be attributed to the compiler, Sam Gon III. Please inform him of any problems in accuracy or interpretation.
THE AUTHOR: |
This site's pages (and the majority of its figures) were designed and created by Dr. Sam Gon III, a biologist (PhD, Animal Behavior; MA, Zoology (Ecology, Behavior and Evolution) who is greatly intrigued by the expression of ancient biodiversity that trilobites represent. Sam's professional work is in the conservation of global biodiversity today. He serves as the Senior Scientist for The Nature Conservancy's Hawai‘i Field Office in Honolulu. Sam has long been interested in paleobiology, and in teaching himself about trilobites, using hyperlinks to cross-reference terminology and concepts, found himself developing a web resource of potential interest to a broader audience. The site was first unveiled in August 1999 and has attracted feedback from around the world, generating ongoing updates. For all the accolades this site has gathered, Sam is not a professional trilobitologist, but a devoted trilobitophile! In 2006 this culminated in his first paleontological publication, dealing with trilobite origins.
Dr. Sam Gon III c/o The Nature Conservancy of Hawai‘i, 923 Nuuanu Avenue, Honolulu, HI 96817, USA
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