Introduction to Trilobites

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	What are Trilobites? These animated trilobite images courtesy K. Harada's TRILOBYTE

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last revised 22 June 2012

Trilobites are remarkable, hard-shelled, segmented creatures that existed over 520 million years ago in the Earth's ancient seas. They went extinct before dinosaurs even came into existence, and are one of the key signature creatures of the Paleozoic Era, the first era to exhibit a proliferation of the complex life-forms that established the foundation of life as it is today. Although dinosaurs are the most well-known fossil animals, trilobites are also a favorite among those familiar with Paleontology (the study of the development of life on Earth), and are found in the rocks of all continents.

fossil (left) and reconstruction (right) of Flexicalymene meeki ANCIENT ARTHROPODS
Trilobites were among the early arthropods, a phylum of hard-shelled creatures with multiple body segments and jointed legs (although the legs, antennae and other finer structures of trilobites only rarely are preserved). They constitute an extinct class of arthropods, the Trilobita, made up of ten orders, over 150 families, about 5,000 genera, and over 20,000 described species. New species of trilobites are unearthed and described every year. This makes trilobites the single most diverse class of extinct organisms, and within the generalized body plan of trilobites there was a great deal of diversity of size and form. The smallest known trilobite species is under a millimeter long, while the largest include species from 30 to over 70 cm in length (roughly a foot to over two feet long!). With such a diversity of species and sizes, speculations on the ecology of trilobites includes planktonic, swimming, and crawling forms, and we can presume they filled a varied set of trophic (feeding) niches, although perhaps mostly as detritivores, predators, or scavengers. Most trilobites are about an inch long, and part of their appeal is that you can hold and examine an entire fossil animal and turn it about in your hand. Try that with your average dinosaur!

cephalon, thorax, and pygidium
all line drawings ©1999 - 2009 by S. M. Gon III

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THE TRILOBITE BODY PLAN

Whatever their size, all trilobite fossils have a similar body plan, being made up of three main body parts: a cephalon (head), a segmented thorax, and a pygidium (tail piece) as shown at left. However, the name "trilobite," which means "three lobed," is not in reference to those three body parts mentioned above, but to the fact that all trilobites bear a long central axial lobe, flanked on each side by right and left pleural lobes (pleura = side, rib). These three lobes that run from the cephalon to the pygidium are what give trilobites their name, and are common to all trilobites despite their great diversity of size and form. You can examine the trilobite body plan in more detail using the links on the navigation bar below, or link directly to a page describing trilobite major features.

three lobes: left, right, and middle (axial)

PLEASE EXPLORE FURTHER
Now that you know generally what trilobites are, please feel free to explore this illustrated web guide to the orders of trilobites. You'll learn about trilobite body parts, how scientists classify trilobites, when, where, and how they lived, and how to tell the major groups apart. You'll also learn where to turn for more trilobite information on the web and in the literature. I hope in the end you come to better appreciate their amazing variety. Although they are all extinct now, they represent among the first explosions of biological diversity that this amazing planet of ours has generated over the eons. Return at any time to the home page for access to all pages of this site. This Cheirurus trilobite is a representative of the Order Phacopida

all line drawings ©1999 - 2009 by S. M. Gon III	. THE TRILOBITE BODY PLAN Whatever their size, all trilobite fossils have a similar body plan, being made up of three main body parts: a cephalon (head), a segmented thorax, and a pygidium (tail piece) as shown at left. However, the name "trilobite," which means "three lobed," is not in reference to those three body parts mentioned above, but to the fact that all trilobites bear a long central axial lobe, flanked on each side by right and left pleural lobes (pleura = side, rib). These three lobes that run from the cephalon to the pygidium are what give trilobites their name, and are common to all trilobites despite their great diversity of size and form. You can examine the trilobite body plan in more detail using the links on the navigation bar below, or link directly to a page describing trilobite major features.

PLEASE EXPLORE FURTHER Now that you know generally what trilobites are, please feel free to explore this illustrated web guide to the orders of trilobites. You'll learn about trilobite body parts, how scientists classify trilobites, when, where, and how they lived, and how to tell the major groups apart. You'll also learn where to turn for more trilobite information on the web and in the literature. I hope in the end you come to better appreciate their amazing variety. Although they are all extinct now, they represent among the first explosions of biological diversity that this amazing planet of ours has generated over the eons. Return at any time to the home page for access to all pages of this site.

Most popular pages of this website: Trilobite Ecology | Trilobite Body Parts | Trilobite Feeding Habits | Trilobite Eyes | Trilobite Classification

stroll with me among the topics below...

Summary Fact Sheets
Review diagnostic characters and detailed line drawings for each Order

Trilobite Order Galleries
Click on any of the images below to be sent to a gallery featuring photos of trilobites in that Order



Agnostida	Redlichiida	Corynexochida	Odontopleurida	Lichida	Phacopida	Asaphida	Proetida	Harpetida	Ptychopariida

Some of My Favorite Trilobite Links


The links shown below are primarily informational and educational. In keeping with the educational purpose of this website, I am limiting my links to those without a commercial element. If you have any additions, please do contact me via the email at the bottom of this list. Many thanks! Here is a 88x31 blog banner for this site:
YAHOO TRILOBITE CLUB All trilobitophiles welcome! Trilo-experts dwell here!
LES NOCTURNE DES TRILOBITES Mimetaster's offering of trilobite images and info (en français & in english)
TRILOBITES OF EASTERN NORTH AMERICA Thomas Whiteley's collaborative summary of this amazing regional fauna
BACK TO THE PAST Carlo Kier presents the world's only trilobite exclusive museum
THE SOMNIUM Alfer van Rossum's new site on Devonian Trilobites from Belgium
MICROMACRO Sinclair Stammers' fossil section includes great trilobite images
TRILO 08 Fourth International Trilobite Conference, Toledo, Spain
WIR TRILOBITEN Arne Felden's guide to trilobites (auf deutsch and in english)
MARSHALL'S TRILOBITES Mark Marshall's gallery of nicely prepared trilobites from Cambrian to Post-Devonian
ORDOVIC BARRANDIENU Martin David's gallery Ordovician Barrandian fossils (including trilobites!)
TRILOBITE CENTRAL Chris Jenkins' celebration of a rich site bearing undescribed trilobites
TRILOBLOG Andrew Scott's eclectic and artistic blog series on trilobites
MIDWEST PALEO Al and Caleb Scheer's focus on trilobites of the Upper Mississippi Valley
THE ONTOGENY OF TRILOBITES Rudy Lerosey-Aubril's comprehensive ontogeny pages
TRILOBITE RESEARCH DIRECTORY A growing global database of trilobite workers by Rudy Lerosey-Aubril
WEEKS TRILOBITES Robert Schacht's exceptional Weeks Formation trilobites
TRILOBYTE Keichi Harada's trilobite site w/a great gallery (in Japanese)
PER HANSSON'S TRILOBITE GALLERY Per Hansson's ground-breaking trilobite page
AMONG MY TRILOBITES Frank Galef's superb chronological showcase
MY TRILOBITE GALLERY Mgr. Petr Budill's elegant gallery of Czech trilobites
MR. B. BUG'S TRILOBITE WORLD Charlie Ryan's take on Paleontology's favorite mascot
PALÉONTOLOGIE DE LA MONTAGNE NOIRE Nicolas Tormo's regional guide to fine trilobites (en français)
PALACE OF TRILOBITES Yoshihiro "Agnostus" Fujita's trilobite display (in Japanese)
LES TRILOBITES ORDOVICIENS DE BRETAGNE Christophe Guillou's regional trilobite showcase (en français)
DENMAN INSTITUTE FOR RESEARCH ON TRILOBITES Rolf Ludvigsen's trilobite institute (and The Trilobite Papers!)
LOWER CAMBRIAN TRILOBITES OF SOUTH AUSTRALIA Dave Simpson's collection of Emuella & other Australian endemics
WORLD'S BIGGEST TRILOBITE The record-holder courtesy of the Manitoba Museum, Canada
TRENTONIAN TRILOBITES FROM WISCONSIN Jeremy Shaw's display of the local Ordovician fauna
UNIVERSITY OF UTAH FOSSIL PAGE Superb images of trilobites et al, from Wheeler, Marjum, Weeks, etc
THE FOSSIL MUSEUM Attractive pages highlighting fossils and evolution
THE PERIPATUS TRILOBITE PAGE Chris Clowes' well-ordered site of trilobite information
FOSILES DE JOAN CORBACHO Exceptional collection of Moroccan & other trilobites (en español)
TRILOBITES: INHABITANTS OF THE PALEOZOIC A. Ivantsov's very attractive Russian trilobite website " "
TRILOBITES FROM MOROCCO A web article by the staff of the Natural History Museum, London
THE AUSTRALIAN MUSEUM'S TRILOBITE PAGE Greg Edgecombe's trilobite research pages
BOLIVIA'S FOSSILS & TRILOBITES LeGrand Smith's superb set of Trilopics & Links
THE TRILOBITE OBSERVER Allart van Viersen's expression of trilobite passion
BEDROCK BUGS Dave Mielke's select gallery of fine trilobites
COLLECTION DE TRILOBITES DU MONDE Jean-Brice Gayet's photographic trilobite diagnoses (en français)
TRILOBITEN.DE Jens Koppka & Heiko Sonntag's superb trilobite website (auf deutsch)
AUSTRALIAN MUSEUM TRILOBITE COLLECTION PAGE A revolving gallery of trilobites in the Australian Museum
WESTERN TRILOBITE ASSOCIATION An online reference for trilobites of Western NA by trilobitologists
TRILOBITES OF THE TRENTON GROUP Superb site by the Harvard Museum of Camparative Zoology
CANADA TRILOBITES Mark Bourrie's site of exceptional Canadian trilobites
WWW.TRILOBITA.DE Mike Kipping's "most fascinating creatures of the Paleozoic" (auf deutsch)
THE TRILOBITE DATABASE Benedikt Magrean's collaborative trilobite image database
OLD AS THE HILLS... Joe Botting's Ordovician Mid Wales fossil pages include trilobites
PUBLIKATIONEN VON LUTZ KOCH Lutz Koch's superb trilobite gallery & publications (auf deutsch)
BEDROCK BUGS GALLERY Justin Maurer's great collection of trilobite images
TRILOBITI Enrico Bonino's page dedicated to trilobites (in italiano)
CINCINNATIAN TRILOBITES Dan Cooper's highlights of Upper Ordovician Trilobites
MINGAN ISLANDS TRILOBITES Roger Barriault's regional trilobite page
DEVONIAN TRILOBITES Harald Prescher's impressive website on trilobites of the Eifel region

Please email me your favorite trilobite links if you do not see yours above
Also, please let me know if any of the links have problems or need updating


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If you are interested in getting the 90 page printout
Chock full of trilobite information!

Best books on Trilobites and Paleozoic Animals!

RECOMMENDED TRILOBITE BOOKS