Trilobites (Introduction)
by David Turell 
, Tuesday, March 04, 2014, 14:38 (3708 days ago)
Everywhere. They are everywhere, so evolved, so complex. Just for dhw, because he has one:-http://www.nytimes.com/2014/03/04/science/when-trilobites-ruled-the-world.html?nl=todaysheadlines&emc=edit_th_20140304
Trilobites: molting fossil
by David Turell , Tuesday, September 29, 2015, 01:04 (3135 days ago) @ David Turell
Just like arthropods do now:-http://www.uncommondescent.com/evolution/trilobite-caught-in-act-of-molting/
Trilobites: molting fossil
by David Turell , Thursday, March 02, 2017, 02:02 (2615 days ago) @ David Turell
It is now found that Trilobites were egg layers just like their relatives, the horseshoe crabs, do now:
http://www.evolutionnews.org/2017/02/roe-roe-roe-never-before-seen-check-out-fossilized...
Comment: There are no known relatives preceding Trilobites. They simply appear in the fossil record, like all of the Cambrian Explosion animals. Great evidence for God.
Trilobites: gills on legs
by David Turell , Wednesday, March 31, 2021, 20:35 (1124 days ago) @ David Turell
A new finding:
https://phys.org/news/2021-03-million-year-old-sea-creatures-leg.html
"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.
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"A CT scanner was able to read the differences in density between the pyrite and the surrounding rock and helped create three-dimensional models of these rarely seen gill structures.
"'It allowed us to see the fossil without having to do a lot of drilling and grinding away at the rock covering the specimen," said paleontologist Melanie Hopkins, a research team member at the American Museum of Natural History.
"'This way we could get a view that would even be hard to see under a microscope—really small trilobite anatomical structures on the order of 10 to 30 microns wide," she said. For comparison, a human hair is roughly 100 microns thick.
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"The researchers could see how blood would have filtered through chambers in these delicate structures, picking up oxygen along its way as it moved. They appear much the same as gills in modern marine arthropods like crabs and lobsters.
"Comparing the specimens in pyrite to another trilobite species gave the team additional detail about how the filaments were arranged relative to one another, and to the legs.
"Most trilobites scavenged the ocean floor, using spikes on their lower legs to catch and grind prey. Above those parts, on the upper branch of the limbs, were these additional structures that some believed were meant to help with swimming or digging."
Comment: Amazing finding. They required oxy gen and had to breathe somehow.
Trilobites: spears to fight
by David Turell , Monday, January 16, 2023, 20:42 (468 days ago) @ David Turell
Present but purpose unclear to me:
https://www.newscientist.com/article/2354846-trilobites-used-trident-like-horns-to-figh...
'Trident-like horns on the heads of some trilobites were probably used in fights over mates. This hypothesised behaviour is the oldest example of sexual combat that has been identified in the fossil record.
“'Extraordinary structures in organisms cry out for functional explanations,” says Alan Gishlick at Bloomsburg University in Pennsylvania.
"Previously, palaeontologists had suggested that the tines on Walliserops, a trilobite that lived around 400 million years ago, could have been used as a defence against ancient nautilus that were hungry for these marine invertebrates. The prongs could grow to more than 25 millimetres long, nearly the size of the rest of the animal.
"But Gishlick and his colleague Richard Fortey at the Natural History Museum in London have come to a different conclusion, after studying an unusual specimen of Walliserops with four tines instead of three.
"The four-pronged trilobite stuck out to Gishlick because it was comparable in size to other adult Walliserops, indicating that it had the expected lifespan for its species. This appeared to be evidence against the trident being a defensive weapon, as such an abnormality in a defensive structure might have made the trilobite more vulnerable.
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"While the sex of the fossil trilobites is difficult to discern, the similarities between Walliserops and the rhinoceros beetles led Gishlick and Fortey to suspect the trident-bearing Walliserops were males.
“'It is amazing to see that such complex behaviours appeared very early in the course of evolution and have endured to the present day,” says Jean Vannier at the University of Lyon, France, who wasn’t involved in the study.
“'Anything that enables us to better understand past life and test our hypotheses as rigorously as possible is crucial to understand evolution of form and function,” says Gishlick."
Comment: Trilobites are always astounding. The horns could be defensive tools as well as sexual helpers to fight off other suiters.