Petrified Animals Trilobites Died Quickly Live Science - February 26, 2008
Petrified Animals Trilobites Died Quickly Live Science - February 26, 2008
BBC - April 2004
Direct evidence has now been found to show that trilobites - among the most diverse of fossil animal groups - were eaten by other ancient sea creatures. Scientists discovered cracked trilobite body parts in the gut of a 510-million-year-old fossil marine animal. It was long suspected that the ubiquitous trilobites, which survived for about 300 million years, were a major food source for larger creatures.
Trilobites are an extinct group of arthropods, animals with an outer skeleton, a segmented body and jointed limbs. They are probably the most common fossils of the Paleozoic Era (about 545-250 million years ago) and scientists use them to help date different layers of rock.
US, French and Chinese researchers identified fragments of the hard outer shell of trilobites in the fossilised gut contents of an unknown animal from the Kaili Formation, a sequence of rocks from southern China dating to Middle Cambrian times.
The broken up pieces of trilobite exoskeleton are each about 1mm in length and are stacked on top of each other. But by using a scanning electron microscope, the researchers were able to identify features on the chewed-up shell fragments known as scrobicules, pitting on the surface of the shell, that are typical of so-called eodiscoid trilobites.
Predatory pursuit
The only eodiscoid trilobites known from the Kaili Formation are from the family Pagetia and the researchers suggest these could be the ones that ended up as the Chinese meal.
"It's very interesting. It's about as direct evidence as you can get, even better than having coprolites - fossilised faeces," Professor Simon Conway Morris, a palaeobiologist at the University of Cambridge, UK, told BBC News Online. "Eodiscoid trilobites are normally thought to be swimmers that live up in the water column, which either means that they weren't - that they lived on the seabed - or that [this predator] is going up into the water column and chasing them."
Professor Conway Morris suggested that the find could be indicative of a complex ecology at Kaili in Middle Cambrian times. The researchers say the animal which ate the trilobites is unlikely to have scavenged them because all the gut contents appear to belong to one animal. "We're fairly confident this specimen provides actual evidence of predation," co-author Heyo Van Iten, associate professor of geology at Hanover College in Indiana, US, told BBC News Online. "There are a variety of other explanations for the presence of the trilobite parts in the gut of this fossil. But they are all less probable than the simplest one, which was that they were actually eating these things."
Taking chunks
They have also found dark-coloured nodules in the digestive canal of the creature, which appear to contain spherical bacteria. The team suggests these nodules are well-developed digestive glands, which are present in other Cambrian arthropods with presumed predatory habits. The gut contents belong to an arthropod which has some similarities to the creature Fuxianhuia, known from early Cambrian rocks in Chengjiang, China. But not enough of the creature remains for it to be named. Other, indirect evidence of predation on trilobites has been known for some time. Bite marks in the animals are common, with many more appearing on the right-hand side than the left-hand side - an observation that has not yet been fully resolved. Many scientists also believe that the hard exoskeleton of trilobites evolved as a defence against predators.
About twice the size of the previous record holder
October 9, 2000 - BBC
The largest trilobite yet discovered has been identified by Canadian palaeontologists. The creature, which dates from 445 million years ago, measures 72 centimetres in length. This is about twice the size of the previous record holder.
Trilobites are an extinct group of sea-dwelling arthropods (animals with an outer skeleton and jointed body and limbs) that are distantly related to crabs, scorpions and beetles. They are probably the most common fossils of the Paleozoic Era (about 545-250 million years ago) and scientists use them to help date different layers of rock.
"A trilobite of this size really is an amazing discovery," said Dr Graham Young, a member of the team that discovered it. The specimen is an example of a previously unknown species, and was found by researchers studying ancient tropical coasts, of the Late Ordovician and Early Silurian geological periods (458-408 million years ago), near Manitoba, Canada.
The creature, which dates from 445 million years ago, measures 72 centimetres in length. This is about twice the size of the previous record holder. Trilobites are an extinct group of sea-dwelling arthropods (animals with an outer skeleton and jointed body and limbs) that are distantly related to crabs, scorpions and beetles. They are probably the most common fossils of the Paleozoic Era (about 545-250 million years ago) and scientists use them to help date different layers of rock. The specimen is an example of a previously unknown species, and was found by researchers studying ancient tropical coasts, of the Late Ordovician and Early Silurian geological periods (458-408 million years ago), near Manitoba, Canada.
The team found the specimen just outside their intended search area
When the fossil was unearthed, most of its segmented exoskeleton was missing and only the rear most portion of the tail shield was present. Scientists realised just what a monster they had when they started to clean up the specimen. The fossil is now on display in the Manitoba Museum of Man and Nature in Winnipeg. Most trilobites are between 3 and 10 cm (1 - 4 inches) in length. The creatures evolved quickly and were widely distributed, making them useful tools to compare the ages of rock strata in different parts of the world. "There is nothing familiar about this particular specimen! It is an important and amazing find," says Manitoba Museum's Dr Bob Elias.
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