Earth Science Club of Northern Illinois - ESCONI

Trilobite Tuesday #47: Six new species of Western Australian trilobites discovered #fossil #paleontology #trilobite #TrilobiteTuesday #australia

One described species of trilobite (Kayseraspis cf. brackebuschi, partially complete (articulated) specimen, 2160.78 m). Credit: Peter Haines, Geological Survey of Western Australia

Phys.org has a story about the discovery of six new species of Australian trilobites.  The new animals hail from deep underground in Canning Basin of Western Australia.  Their discovery was via a stratigraphic drilling program by the Geological Survey of Western Australia and Geoscience Australia.  It sheds light on both ancient life and the geologic history of the region.  The description of these trilobites has been published in the journal Alcheringa: An Australasian Journal of Palaeontology.

The discovery of trilobites at such a time and place is not too surprising. However, what was unexpected was the diversity and abundance within this core.

Normally, cored rocks only have a small area for fossils to be captured so usually there's little chance of hitting a fossil, let alone something useful for identification. Yet, in this sequence trilobites were so abundant that almost every single layer of rock contained a fragment. In fact, the rock is entirely made of trilobites in places, stacked one on top of each other, like a pack of playing cards!

Among the six new species of trilobite identified were a few highly unusual forms. For example, one species had a subtriangular tail with an extraordinarily long backwards pointing spine ornamented with blade-like serrations on either side. This feature appears to be characteristic of the genus Sanbernardaspis and is not found in other closely related trilobites.

Trilobite Tuesday #46: Trilobite's last meal #fossil #paleontology #trilobite #ordovician #taphonomy #TrilobiteTuesday #lastmeal

Artist's impression of Bohemolichas, a species of extinct trilobite as it feeds on the sea floor (Jiri Svoboda)

CBC Radio's Quirks and Quarks show has a segment about a trilobite's last meal.  The trilobite specimen, Bohemolichas incola, was found in a 465 million year old (Ordovician Period) shale deposit.

A 465 million year old trilobite fossil with remarkably preserved gut contents reveals for the first time what these extinct arthropods ate. Per Ahlberg, a paleontologist at Uppsala University in Sweden found hundreds of shell fragments from a variety of animals crushed up in the digestive tract. The research suggests this three centimetre long trilobite ate indiscriminately as it moved along the sea floor. His study was published in Nature. 

More information here on Science Alert.

The complete Bohemolichas incola trilobite was preserved in fine 3D details within encasing siliceous pebbles called Rokycany Balls. Inside this specimen's staggering 465 million-year-old digestive system paleontologist Petr Kraft from Charles University in the Czech Republic and colleagues found tightly packed fragments of shell.

The shells did not show signs of being dissolved with their sharp edges still intact, suggesting the trilobite's digestive system isn't acidic but rather neutral or basic along its entire length, the researchers explain. This is how modern crustaceans and spiders do their digesting too – animals belonging to the two different modern groups in contention for the closest trilobite relatives.

Almost the entire digestive tract was packed full, with some fragments still large enough to be identified. Those bits and bobs of trilobite prey all belong to benthic invertebrates that dwelled at the bottom of the sea during the Ordovician.

This story was suggested by a few ESCONI members, thanks for sending it in!

Trilobite Tuesday #45: Taphonomy of non-biomineralized trilobite tissues preserved as calcite casts from the Ordovician Walcott-Rust Quarry, USA #fossil #paleontology #trilobite #ordovician #taphonomy

a MCZ:IP:111710 prone Flexicalymene senaria. b MCZ:IP:111708 prone Ceraurus pleurexanthemus. c Photomicrograph of transverse thin section through cephalon of MCZ:IP:104973 with preserved exopodite and lamellae. d Photomicrograph of sagittal thin section along axial lobe of MCZ:IP:158215 with preserved protopodites. e Photomicrograph of sagittal thin section of MCZ:IP:104956 with preserved protopodites. f Magnification of exopodite of MCZ:IP:104973 showing calcite crystals within lamellae. g Magnification of protopodites in MCZ:IP:104956 showing pyrite, fibrous and sparry calcite. Abbreviations: ax, axial lobe; cep, cephalon; ey, eye; ex, exoskeleton; exo, exopodite; fib, fibrous calcite; gl, glabella; L1, lobe 1; pt, protopodite; pyg, pygidium; pyr, pyrite; sp, sparry calcite; th, thorax.

Nature's journal communication Earth & environment has a paper about the preservation of trilobites in the Wolcott-Rust quarry.  The Walcott-Rust quarry was discovered by Charles Wolcott in the 1870's.  It dates to the Ordovician Period and yielded the first known trilobite appendages.  This paper details research into the mechanism of the delicate, three dimensional preservation.

Abstract

Trilobites with appendages from the Rust Formation of New York State were discovered in the 1870s and represent one of the earliest known cases of exceptional preservation of non-biomineralized tissues. The Rust Formation trilobites feature three-dimensionally preserved walking legs and delicate respiratory lamellae, but the mechanism behind their fossilization remains unknown. Here we show that after burial, carcass decay produced framboidal pyrite, while fibrous calcite precipitated on the visceral side of the body, followed by the widespread formation of sparry calcite crystal replicating non-biomineralized morphological features. Trilobites and co-occurring calcite veins show no chemical or petrographic differences, rejecting the hypothesis that exceptional preservation was caused by a local microenvironment within enrolled trilobites. These results suggest that fine-grained sediment provided support for the appendages and facilitated their fossilization through calcite replacement. Our findings carry broader implications for understanding the exceptional three-dimensional preservation of animal Paleozoic body fossils through calcite casts.

Trilobite Tuesday #44: Trilobite of the Month, August 2023 #fossil #paleontology #trilobite #facebook

Sam Ohu Gon III posted some awesome photos for Trilobite of the Month, August 2023 over on Facebook.  If you don't know of Sam's work, have a look at trilobites.info for everything you ever wanted to know about trilobites!

Coronocephalus gaoluoensis Wu 1979

Telychian Xiushan Fm., L. Silurian (Llandovery)

near Wanmin Town, Yongshun Cty., W. Hunan, China

Order Phacopida, Suborder Cheirurina, Family Encrinuridae

image courtesy York Yuxi Wang

Trilobite Tuesday #43: Ancient sea creature sported a big fork on its head to toss away the competition, study suggests #fossil #paleontology #trilobite #quirksandquarks #CBC @CBCQuirks

A 3D model of a Walliserops trifurcatus trilobite, which sports a unique trident at the front of its head. (Alan D. Gishlick)

CBC Radio's Quirks and Quarks had a recent segment about trilobites.  New research published in the journal Proceedings of the National Academy of Sciences suggests a use for the large forks that some trilobites grew on their heads.

A species of ancient trilobites grew big forks on their heads to fight their opponents and impress potential mates, in what scientists say could be the earliest known example of ritualized combat. 

A new study published in the Proceedings of the National Academy of Sciences suggests that one trilobite species used a strange appendage on its head for sexual selection — and most likely for fighting other male trilobites. 

Though they've been extinct for 250 million years, trilobites were one of the most successful and diverse animal groups ever — dominating the ancient oceans for hundreds of millions of years. All trilobites shared certain traits — like a three-lobed body — and visually resembled modern woodlice or pillbugs, ranging in size from a few millimetres to the size of a sea turtle.

But a striking feature of one trilobite species, Walliserops trifurcatus, stands out from the rest: at the front of its head was a trident-like structure as long as the trilobite's body. This trident has made Walliserops a popular find among fossil collectors and an evolutionary puzzle for biologists. 

"The trilobite's fork most resembled the structures of animal weapons involved in a type of fighting behavior that's been characterized as shoveling," Alan Gishlick, assistant professor at Bloomsburg University and one of the study authors, told Quirks & Quarks. 

Trilobite Tuesday #42: Trilobites' growth may have resembled that of modern marine crustaceans #fossil #paleontology #trilobite #TrilobiteTuesday #trilobites #fossils

Phys.org has a story about trilobite growth.  Research published in the journal Paleobiology shows that trilobites grew in a fashion similar to modern extant crustaceans.  Data for the study came from exceptionally preserved trilobites from "Beechers Trilobite Bed" in upstate New York.  For more information about "Beecher's Trilobite Bed", have a look at Trilobite Tuesday #5.

In a paper published in the journal Paleobiology, researchers from the University of British Columbia and Uppsala University show that the Ordovician trilobite Triarthrus eatoni, some 450 million years ago, reached a length of just above 4 cm in about 10 years, with a growth curve very similar to that of small, slow-growing crustaceans.

"T. eatoni lived in low-oxygen environments and, similarly to extant crustaceans exposed to hypoxic conditions, exhibited low growth rates compared with growth under more oxygenated conditions," said Daniel Pauly, principal investigator of UBC's Sea Around Us initiative and lead author of the study. "Low-oxygen environments make is more difficult for water-breathers to grow, and add to the difficulties of breathing through gills, which, as 2D surfaces, cannot keep up with the growth of their 3D bodies. Thus, under hypoxic conditions, they must remain small if they are to maintain the rest of their body functions."

In the case of trilobites, their exopods—external branches on the upper part of their limbs—functioned as gills. Thus, these ancient animals had similar growth constraints to those of their modern counterparts.

To reach these conclusions, Pauly and his colleague from Uppsala University, paleontologist James Holmes, resorted to the analysis of length-frequency data, a method developed within fisheries science and marine biology for studying the growth of fish and invertebrates lacking the physical markings that indicate their age.

Trilobite Tuesday #41: Travels with Trilobites #fossil #paleontology #trilobite #TrilobiteTuesday #fossils

There's a new trilobite book coming out on June 21st, 2022.  It's called "Travels with Trilobites".   The author is Andy Secher a prolific collector of trilobites.  He lives in New York City just a few blocks from the American Museum of Natural History.  He's co-editor of the AMNH's very informative trilobite website.

Trilobites were some of the most successful and versatile organisms ever to exist. Among the earliest forms of complex animal life, these hard-shelled marine invertebrates inhabited the primal seas of the Paleozoic Era. Their march through evolutionary time began in the Lower Cambrian, some 521 million years ago, and lasted until their demise at the end of the Permian, more than 250 million years later. During this vast stretch of planetary history, these adaptable animals filled virtually every available undersea niche, evolving into more than 25,000 scientifically recognized species.

In Travels with Trilobites, Andy Secher invites readers to come along in search of the fossilized remains of these ancient arthropods. He explores breathtaking paleontological hot spots around the world—including Alnif, Morocco, on the edge of the Sahara Desert; the Sakha Republic, deep in the Siberian wilderness; and Kangaroo Island, off the coast of South Australia—and offers a behind-the-scenes look at museums, fossil shows, and life on the collectors’ circuit. The book features hundreds of photographs of unique specimens drawn from Secher’s private collection, showcasing stunning fossil finds that highlight the diversity, complexity, and beauty of trilobites. Entertaining and informative, Travels with Trilobites combines key scientific information about these captivating creatures with wry, colorful observations and inside stories from one of the world’s most prolific collectors.

The Smithsonian Magazine website has a nice review of the book.

Hooked is an understatement. Fast forward to adulthood and Secher has amassed a personal collection of some 5,000 fossils, which he houses inside his 1,650-square-foot Manhattan apartment. His passion for fossils, and specifically trilobites—extinct hard-shelled marine invertebrates that existed during the Paleozoic Era, a time period that stretched around 289 million years—led him to a career as a field associate in paleontology at the American Museum of Natural History (AMNH). There, for the past 15 years, he has been co-editor of the museum’s popular Trilobite website.

“I often joke that I have the largest trilobite collection on the Upper West Side,” Secher says. (The fact that the world-renowned museum, with its thousands of specimens, is less than a half-mile walk from his apartment makes the quip all the more humorous.)

So, what is it about trilobites that make them different from other fossils? For Secher, the answer is simple. In his book he writes, “Even at a very early stage in the history of life on our planet, the trilobite design had already proven to possess a certain degree of evolutionary perfection.” Add to that the fact that there’s such a variety of specimens out there, resembling everything from what he describes as a “hydrodynamic spaceship” to “nothing more than a primordial meatloaf,” and it’s easy to see why collectors like Secher are thirsty for trilobites.

More recently, Secher added another bullet point to his résumé with the release of his book Travels with Trilobites: Adventures in the Paleozoic, which takes readers on a journey to some of the best places around the world to see these ancient arthropods, from museum collections to quarry fossil beds.

Trilobite Tuesday #40: Find the Trilobite! #fossil #paleontology #trilobite #trilobites #fossils #ordovician

ESCONI recently held a field trip to the St. Paul Quarry in St. Paul, Indiana.  As part of that trip, a few of us paid a visit to the famous St. Leon roadcut on Indiana Route 1 just off Interstate 74 at exit 164 for St. Leon.  The road cut is huge and loaded in fossils.  Head on over to The Fossil Forum for many trip reports.

As part of that visit, we went looking for trilobites.  Here you can see ESCONI President Keith Robitschek with Phil Anderson looking for interesting fossils.  The ground is littered with brachiopods, bryozoans, and other bits.

To have the best chance of finding a trilobite, you'll need to crawl on your hands and knees along the first bench in the "butter shale".  It was fairly wet when we were there, but with a little effort we all found a few complete trilobites - of the genus Flexicalymene.  You'll also see many pieces of a large trilobite called Isotelus.  Whole Isotelus have been found, but are rare.

Here is a few photos of trilobites in situ for a game we like to call "Find the Trilobite".  The first is a little easier and was found by Phil Anderson.

This one is more challenging.  It was found by Keith Robitschek.

Trilobite Tuesday #39: Before There Were Birds or Bees, This Is How Trilobites Made Babies #fossil #paleontology #cambrian #trilobite #reproduction

An adult male Olenoides serratus trilobite with its claspers, left, and its counterpart.Credit...Sarah Losso

The New York Times Trilobites column has a story about trilobite reproduction.  Trilobites first show up in the fossil record back in the Cambrian Period, some 500 million years ago.  Their closest living relative is most likely the horseshoe crab.  Now, a team of paleontologists from Harvard have published a paper in the journal Geology that looks into the sex lives of trilobites.  They found that they used methods similar to their modern relatives.

A recently re-examined fossil from the Burgess Shale is pulling back the shroud of mystery over the ancient arthropods’ sex lives, and revealing that some trilobites most likely sported a loving grip. In a study published Friday in Geology, paleontologists at Harvard University identified a pair of modified appendages that probably helped males of one trilobite species grasp females during copulation in a similar manner to that of modern horseshoe crabs.

The team examined several spiny Olenoides serratus trilobites collected from the Cambrian site. Most were just under four inches long. While the Burgess Shale is known for its detailed preservation of even delicate tissue, one of the Olenoides specimens the team examined at the Royal Ontario Museum in Toronto looked more like a badly broken lobster tail than an intact trilobite.

“It’s a sad looking specimen — it’s missing most of the head and half of the body,” said Sarah Losso, a Ph.D. candidate at Harvard and an author of the study.

The fragmented nature of the specimen was a lucky break because it revealed the anatomy often hidden under a trilobite’s shell. Importantly, nine of the arthropod’s rarely fossilized appendages were preserved in detail. “There are millions of broken trilobites and you don’t see limbs in many of them,” said Javier Ortega-Hernández, a co-author on the new study and Ms. Losso’s Ph.D. adviser. “Having this specimen that is broken in just the right way that you can see these limbs is a one in a million sort of situation.”

Trilobite Tuesday #38: Inspired by prehistoric creatures, researchers make record-setting lenses #fossil #paleontology #lens #trilobite

Inspired by the compound eyes of a species of trilobite, researchers at NIST developed a metalens that can simultaneously image objects both near and far. This illustration shows the structure of the lens of an extinct trilobite. Credit: NIST

Phys.org has a story about technology derived from fossils.  Some researchers at NIST have took inspiration in the eyes of the trilobite Dalmanitina socialis to make special bifocal lenses for a miniature camera.  Their work can be found in a recent paper published in the journal Nature Communications.

Five hundred million years ago, the oceans teemed with trillions of trilobites—creatures that were distant cousins of horseshoe crabs. All trilobites had a wide range of vision, thanks to compound eyes—single eyes composed of tens to thousands of tiny independent units, each with their own cornea, lens and light-sensitive cells. But one group, Dalmanitina socialis, was exceptionally farsighted. Their bifocal eyes, each mounted on stalks and composed of two lenses that bent light at different angles, enabled these sea creatures to simultaneously view prey floating nearby as well as distant enemies approaching from more than a kilometer away.

Inspired by the eyes of D. socialis, researchers at the National Institute of Standards and Technology (NIST) have developed a miniature camera featuring a bifocal lens with a record-setting depth of field—the distance over which the camera can produce sharp images in a single photo. The camera can simultaneously image objects as close as 3 centimeters and as far away as 1.7 kilometers. They devised a computer algorithm to correct for aberrations, sharpen objects at intermediate distances between these near and far focal lengths and generate a final all-in-focus image covering this enormous depth of field.

Such lightweight, large-depth-of-field cameras, which integrate photonic technology at the nanometer scale with software-driven photography, promise to revolutionize future high-resolution imaging systems. In particular, the cameras would greatly boost the capacity to produce highly detailed images of cityscapes, groups of organisms that occupy a large field of view and other photographic applications in which both near and far objects must be brought into sharp focus.

Trilobite Tuesday #37: Trilobite Fossils Suggest Cannibalism Is More Ancient Than Once Thought #fossil #paleontology #trilobite

Three trilobites found at the Emu Bay Shale in Australia showing injuries suggesting possible cannibalism.Credit...Russell Bicknell

The New York Times Trilobites column has a story about cannibalism among trilobites.  A new study published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology found evidence of cannibalism in 512 million year old fossils from Emu Bay on Kangaroo Island off the south Australia coast.  

Cannibalism is common among the millions of modern arthropod species. A praying mantis consumes her mate after copulation, termites suck blood out of wounded peers, and mosquitoes snack on larvae. But how far back does this gruesome mode of dining go in the history of life feeding on life?

Previous studies place the earliest cannibalism about 450 million years ago in the Late Ordovician period. But a study published last month in the journal Palaeogeography, Palaeoclimatology, Palaeoecology says even older evidence of cannibalism can be found in a 514-million-year-old treasure trove of trilobites on an island off the South Australian coast, at a site called Emu Bay. There, old wounds on trilobite shells abound, and fossil excrements, likely produced by trilobites, contain yet more trilobite shells. These hint that cannibalism could be dated to the early Cambrian era — over 50 million years earlier than previously thought.

Paleontologists consider a preserved meal inside fossilized guts the best evidence that one animal consumed another. But such fossils are rare.

The site at Emu Bay, however, had optimal conditions to preserve a different kind of evidence for who ate whom: fossilized injuries and fossilized feces.

 

Trilobite Tuesday #36: 7th International Conference on Trilobites & Their Relatives - Cincinnati July 14th to 18th, 2022 #trilobite #cincinnati #paleontology

The Cincinnati Museum Center is sponsoring the 7th International Conference on Trilobites & Their Relatives from July 14th to 18th, 2022.  There are field trips both before and after the conference. 

• Registration
• Session Topics and Schedule
• Pre-Conference Field Trip
  Madison, Wisconsin
• Intra-Conference Field Trip
  Potential sites to visit: Sycamore Creek, Indian Hill; Mt. Orab, OH; Maysville, KY
• Post-Conference Field Trip
  Ordovician-Devonian of the Mohawk and Niagara-Lake Erie regions of western New York State

A Warm Welcome!

Welcome to the 7th International Conference on Trilobites & Their Relatives to be held at Cincinnati Museum Center in Cincinnati, Ohio, U.S.A, July 14 to 18, 2022. We look forward to hosting participants from all corners of the globe in our iconic 1933 Art Deco Train Station, Union Terminal. To learn more about the history and architecture of this national historic landmark, pleased click here.

This international conference occurs every 4 years and attracts professional scientists, graduate and undergraduate students, serious amateur paleontologists, and interested members of the public. The goals of the conference are to present and discuss recent progress in studies on all aspects of trilobites and their relatives (e.g., morphology, evolution, phylogeny, ecology, development, and geography).

On-site registration and conference check in will be the evening of July 14 at the icebreaker event at Rhinegeist Brewery and the morning of July 15 in the rotunda of Union Terminal (Cincinnati Museum Center). More details to follow.

The Icebreaker Event will be the evening of July 14 at Rhinegeist Brewery. Light hors d’oeuvres will be provided. For more information on this venue, please see rhinegeist.com.

Morning and afternoon coffee, tea, snacks, and lunch will be provided during the three days of sessions at Union Terminal. Dinner is not provided except for the banquet on July 18.

The intra-conference field trip to the type-Cincinnatian Series will be Sunday July 17. Water, snacks, lunch, and transportation will be provided for the day.

Please be advised that CMC is a smoke- and tobacco-free building.

 

Trilobite Tuesday #35: Ceraurinus icarus #fossil #trilobite #ordovician #paleontology #indiana

How about a Trilobite Tuesday post?  Here is a rare species of trilobite from Indiana, Ceraurinus icarus.  This specimen is from the Whitewater Formation in Union Co., Indiana.  The pictures were contributed by Dan Damrow.  Thanks, Dan!  Awesome trilobite!

 

Trilobite Tuesday #34: 450-million-year-old sea creatures had a leg up on breathing #fossil #trilobite #TrilobiteTuesday #gills #trilobites

(A to I) YPM 204 (part). (A) Dorsal view. (B) Posterior view of the truncated filaments in stacked (A). (C) Same area of (B) with nonstack function. (D and E) The sixth and seventh filaments showing dumbbell-shaped outline, tilted about 40° to the dorsal view. (D) High-contrast backscattered electron (BSE) image. (E) High-contrast, gaseous secondary electron (GSE) image. (F and G) The eighth filament showing dumbbell-shaped outline, tilted about 40° to the dorsal view. (F) BSE image. (G) GSE image. (H and I) Top view of the eighth and ninth filaments showing dumbbell-shaped outlines. (H) BSE image. (I) GSE image. Yellow dotted lines mark the cross section of the filaments (E and G). Arabic numbers are references for locating the cross section of filaments in (A). Asterisks locate the top and bottom inflated marginal bulbs of dumbbell-shaped filaments. Small white arrows indicate the narrow central region of dumbbell-shaped filament. The BSE image distinguishes bright filament from dark surrounding matrix. The GSE image distinguishes dark filament from bright surrounding matrix. ar, article of shaft; lob, lower branch of the limb; upb, upper branch of the limb. Scale bars, 500 μm (A), 100 μm (B and C), and 50 μm (D to I).

Science Daily has a story about trilobite gills.  A paper in Science Advances looked at the limbs of trilobites and found that the biramous legs of the trilobites Triarthrus eatoni and Olenoides serratus functioned as gills in a manner similar to the gills of horseshoe crabs.

A new study has found the first evidence of sophisticated breathing organs in 450-million-year-old sea creatures. Contrary to previous thought, trilobites were leg breathers, with structures resembling gills hanging off their thighs.

Trilobites were a group of marine animals with half-moon-like heads that resembled horseshoe crabs, and they were wildly successful in terms of evolution. Though they are now extinct, they survived for more than 250 million years -- longer than the dinosaurs.

Thanks to new technologies and an extremely rare set of fossils, scientists from UC Riverside can now show that trilobites breathed oxygen and explain how they did so. Published in the journal Science Advances, these findings help piece together the puzzle of early animal evolution.

"Up until now, scientists have compared the upper branch of the trilobite leg to the non-respiratory upper branch in crustaceans, but our paper shows, for the first time, that the upper branch functioned as a gill," said Jin-Bo Hou, a UCR paleontology doctoral student who led the research.

Trilobite Tuesday #33: Some trilobites crushed their prey to death with their legs #fossil #trilobite #trilobites #TrilobiteTuesday

A well-preserved set of appendages of Olenoides serratus from the Burgess Shale, one of the two trilobite species analysed in the recent study. You can see the delicate spines on the trilobite's pair of opposing limbs. Image by Sarah Losso

The Science News column from the Natural History Museum in London has a story about trilobites.  A new paper by Dr. Greg Edgecombe, a researcher at the museum who focuses on the evolutionary history of arthropods, about how some trilobites fed was published in the Royal Society B.  Instead of teeth, it appears that these trilobites used their legs to crush and shred their prey before passing the food to their mouths.

By studying modern horseshoe crabs, researchers have been able to build up a picture of how some extinct arthropods such as trilobites may have fed on hard-shelled prey.

Some trilobites probably used their legs to crush their prey before passing the food to their mouths.

Trilobites are arthropods that lived on Earth between 521 to 252 million years ago. To date there are more than 20,000 species recorded, making them one of the most successful groups of early arthropods to have evolved. Despite leaving a vast fossil record, very little is known about how they may have eaten.

It turns out that just like we use chopsticks to move food towards our mouth, some trilobites may have stabbed and crushed their prey with their legs as they ate.

'We used the horseshoe crab, a living arthropod that eats hard prey, to bring life to models of how two species of trilobite used their legs when feeding,' says Greg. 

The researchers found that one trilobite species, Redlichia rex, shows a similar leg structure and pattern of strain at its leg base as the horseshoe crab, indicating it used its legs to crush shelled creatures before eating them, a behaviour called durophagy. 

This feeding behaviour may have accelerated the 'arms race' between trilobite predators and their shelled prey. 

Trilobite Tuesday #32: They Put the Bite in Trilobite #fossils #trilobite #trilobites #TrilobiteTuesday

A fossil of Olenoides serratus, one of two types of trilobite whose appendages were studied.Credit...Dave Rudkin

The New York Times Trilobites column has an article about predatory trilobites.  While we have learned much about trilobites over the many years of study, there are some aspects of their life that we still don't know.  Those unknowns are mostly associated with soft parts like the guts and delicate parts like the legs and antennae.  A recent paper published in Proceedings of the Royal Society B, looks at some of those delicate legs that have been preserved and compares them to modern animals to provide understanding as to how these animals might have lived.

Horseshoe crabs have a messy but impressive feeding style: Before chowing down on clams and other mollusks, they use their appendages around their mouths to pulverize their shells. (Imagine picking up an unshucked oyster, crushing it between your hands, and stuffing it into your mouth.)

Trilobites “look like a horseshoe crab, and they probably walked like a horseshoe crab,” said Russell Bicknell, a postdoctoral researcher at the University of New England in Australia and the lead author of the paper. He began to wonder, he said, “Did they also eat like a horseshoe crab?”

Dr. Bicknell and his co-authors studied two very different trilobite species with distinct appendage types. The first, Redlichia rex, was one of the largest known trilobites of the Cambrian Period — Frisbee-size in a world of tea saucers. It was “a walking tank,” he said. “A big, bad beastie.” Its appendages were blunt, with wedged protrusions, like the arms of a metal nutcracker.

Trilobite Tuesday #31: Sexual Dimorphism / Trilobite Eggs #trilobites #eggs #fossils #TrilobiteTuesday #fossil

For many types of animals, there are differences between males and females, sometimes it's size, sometimes color, and sometimes structure - either or both soft and hard body structures.  Unfortunately, color and soft-body structures aren't usually preserved and even when it's preserved it doesn't leave enough information in the fossil record.  For size and hard body structures, without other clues, which sometimes from living animals, we still can't know which sex is which.  So, how can we tell the difference for trilobites?  What if you found eggs?  That would be a clue that could help in the determination. There is a good discussion on the Sexual Dimorphism / Trilobite Eggs page over an the AMNH's great Trilobite website.

Hen's teeth… unicorn droppings… trilobite eggs… all apparently stuff of myth, mirth and legend. However, before we place each of these hallowed “rare as” punch-lines into a singular derisive category, let it be stated loudly and proudly that at least one of our entries -- and unquestionably the one that would most intrigue those perusing this section of The Trilobite Files - is very much the real deal. Make no mistake about it; trilobite eggs did indeed exist! 

The fact is that evidence of trilobite eggs has long been sought yet never previously seen in the fossil record. Some scientists have even referred to any such irrefutable indicator of trilobite reproductive behavior as the Holy Grail of invertebrate paleontology. Famed French naturalist Joachim Barrande cited the subject of trilobite eggs as far back as 1872. The legendary Charles Walcott (perhaps best known for his discovery and exploration of British Columbia's storied Burgess Shale) wrote a subsequent paper in 1877, and spent much of his later career searching in vain for signs of trilobite eggs amid the myriad specimens he unearthed during his various excursions across the face of North America. 

Walcott was confident that fossilized evidence existed of these primal arthropod ova. Yet despite his extensive efforts to uncover these elusive signs of trilobite reproductive practices, during his lifetime he was unable to find definitive proof of their presence. But now, nearly 150 years after Barrande and Walcott made their initial forays into trilobite egg research, a recent scientific study (conducted and written by paleontologist Thomas Hegna and amateur enthusiast Markus Martin) has finally offered unassailable confirmation of the long-standing beliefs shared by these paleontological stalwarts. 

This pyritized Triarthrus eatoni trilobite from the famed Beecher Bed of upstate New York shows evidence of gills, claws and clusters of tiny eggs.

This is a close-up view of the underside of the Triarthrus eatoni cephalon showing the small, circular eggs, some in a multi-cellular zygote stage.

Here are a few more scattered eggs amid the claws and gills of the Triarthrus specimen.

A paper from 2017 in the journal Nature describes trilobite eggs. 

 

Trilobite Tuesday #30: How to hunt for fossils in Ohio #fossils #Ohio #trilobites #brachiopods #TrilobiteTuesday #cephalopods

Flexicalymene from Ohio

Here's a page that lists some places to find fossils in Ohio.  I'm not sure the trilobite on the page is correct... looks like an Elrathia kingii.  The one above is from Ohio and is a Flexicalymene.  But, the page has a nice list of places to go and what you can find.  Trilobites are a big part of what you can find... Check it out!

Southwestern Ohio

• Caesar Creek State Park (Warren and Clinton Counties) – requires permit, which is available free from the U.S. Army Corps of Engineers Visitor Center.
• Cowan Lake State Park (Clinton County)
• East Fork State Park (Clermont County)
• Hueston Woods State Park (Preble and Butler Counties)
• Oakes Quarry Park (Greene County)
• Stonelick State Park (Clermont County)
• Trammel Fossil Park (Hamilton County)

Northwestern Ohio

• Fossil Park (Lucas County)

Trilobite Tuesday #29: Why did trilobites go extinct? #fossils #trilobites #TrilobiteTuesday

(Image: © Shutterstock)

LiveScience has a piece about the extinction of the trilobites.  Trilobites existed on Earth for about 270 million years from the early Cambrian until the Permian Mass Extinction.  Many organisms went extinct during that time... perhaps upward of 90% of species.  But, it's still an open question that has not been completely answered.  During their heyday in the Cambrian and Ordovician, their genera consisted of 10 orders.  But, by the Permian, after making it through a couple mass extinctions, they had dwindled to just one family, the Proetidae.  Were they out competed by other animals?  Probably. But was that the whole story?  Other arthropods had flourished.  What was their fatal flaw?  

Trilobites are weird creatures — they look like giant swimming potato bugs wearing helmets, and lived on Earth for a whopping 270 million years. These armored invertebrates, whose species once numbered in the thousands, thrived in the oceans as they scavenged and dug for food, and even managed to survive two mass extinctions.

But about 252 million years ago, trilobites disappeared from the fossil record. What finally wiped out this class of resilient bottom dwellers? 

The trilobite's disappearance coincided with the end-Permian extinction (also known as the Permian-Triassic extinction), the third and the most devastating mass extinction event. Volcanic eruptions in Siberia spewed enormous amounts of lava for around 2 million years, according to Melanie Hopkins, an associate curator of paleontology at the American Museum of Natural History in New York City. These fiery eruptions sent trillions of tons of carbon dioxide into the atmosphere, triggering ocean acidification, which in turn made it very difficult for marine animals to survive, according to a 2010 paper published in the journal Proceedings of the National Academy of Sciences. Up to 95% of marine species succumbed to the end-Permian extinction, also known as the Great Dying, including the trilobites.

Trilobite Tuesday #28: A new middle Cambrian trilobite with a specialized cephalon from Shandong Province, North China #fossils #trilobites #China #Cambrian #TrilobiteTuesday

Acta Palaeontologica Polonica has a that describes newly discovered trilobites from the Middle Cambrian of Northern China.  These trilobites had a strangely lobed cephalon that suggests "rabbit ears".  Actually, the species name Phantaspis auritus comes from the Latin aurītus, having ears; in reference to the cranidium having a pair of long “ears”.

Trilobites achieved their maximum generic diversity in the Cambrian, but the peak of morphological disparity of their cranidia occurred in the Middle to Late Ordovician. Early to middle Cambrian trilobites with a specialized cephalon are rare, especially among the ptychoparioids, a group of libristomates featuring the so-called “generalized” bauplan. Here we describe an unusual ptychopariid trilobite Phantaspis auritus gen. et sp. nov. from the middle Cambrian (Miaolingian, Wuliuan) Mantou Formation in the Shandong Province, North China. This new taxon is characterized by a cephalon with an extended anterior area of double-lobate shape resembling a pair of rabbit ears in later ontogenetic stages; a unique type of cephalic specialization that has not been reported from other trilobites. Such a peculiar cephalon as in Phantaspis provides new insights into the variations of cephalic morphology in middle Cambrian trilobites, and may represent a heuristic example of ecological specialization to predation or an improved discoidal enrollment.

Key words: Trilobita, Ptychopariida, ontogeny, specialization, Miaolingian, Paleozoic, Longgang, Asia.

Zhixin Sun [[email protected]], Han Zeng [[email protected]], and Fangchen Zhao [[email protected]] (corresponding author), State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (for details please see creativecommons.org), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.