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Fossil, and Forum, Friday

I’m sorry, but I forgot to post the Mystery Monday fossil on the blog. I posted the fossil on the Facebook page, but somehow failed to get it posted here, for which I apologize. Here is the fossil I posted, including the identifying portion cropped from the original picture. This image was taken from, a great website for all things trilobite.


Here is Bristolia for comparison. This image is also from

Here is Bristolia for comparison. This image is also from

It was correctly identified as a trilobite, although this one is the species Irvingella, not Bristolia as was guessed. Irvingella is very similar, but lacks the tail spine and the second set of spines is a little farther down the body. They are both listed as “fast-moving low-level epifaunal” feeders by the Paleobiology Database, which means they scurried quickly about over the ocean floor. But whereas Bristolia is thought to have been a deposit feeder, much like a crawfish, Irvingella was a carnivore, preying on worms, bugs, and such. They both lived in offshore marine environments, but whereas Bristolia has been found mostly in shallower waters, Irvingella has been found widespread from offshore throughout the continental shelf and even deeper water. This may have more to do with Bristolia having only been found in a few places in the southwestern United States while Irvingella has a much broader range throughout much of North America and Asia. They both lived in the Cambrian Period, although Bristolia seems to have lived a little earlier than Irvingella (there are some discrepancies in the published records making it difficult to compare exactly, this is partly due to revisions of the time scale and refinements in age estimates over the decades making detailed comparisons problematic).

Since our last Forum Friday recap, we have started a new year. We have reviewed the Walking with Dinosaurs movie. We identified an Exogyra ponderosa oyster,  Archimedes bryozoan, Aetobatus eagle ray, and this Irvingella trilobite.

Over on the Facebook page so far this year, we have seen some amazing animals, including sharks that glow in the dark, a fish that walks on land, and a caterpillar who’s tobacco breath repulses spiders. We even learned why sharks don’t make bone, but polygamous mice have big penis bones and an organism that changes its genetic structure seasonally.

A green biofluorescent chain catshark (Scyliorhinus retifer). Credit: ©J. Sparks, D. Gruber, and V. Pieribone

A green biofluorescent chain catshark (Scyliorhinus retifer). Credit: ©J. Sparks, D. Gruber, and V. Pieribone

We saw two articles on fighting dinosaurs. We learned how they took over the planet and discussed scaly dinosaurs for a change. We found out some ancient marine reptiles were black and Tiktaalik had legs.

A lot of articles hit the press on human evolution in 2013. We also found out (some) humans developed the ability to tolerate lactose to not starve and how we smell sickness in others. We also found a great book on Evolution & Medicine. We also saw evidence of how our actions affect the evolution of other animals and someone who thinks they can understand dog language.

We read that plants may have caused the Devonian extinction event, a genetic study saying placental mammals originated before the end-Cretaceous extinction event despite no fossils ever having been found, and that small mammals with flexible schedules handle climate change better than big mammals that keep a stricter schedule.

We found a great , concise explanation of evolution and three different short videos on the history of life on earth, two of them animated and set to music. We also heard Neal DeGrasse Tyson urge more scientists to do more science outreach (and how to cook a pizza in 3 seconds). Unfortunately, we also heard about the deplorable conditions during filming on Animal Planet and creationism in Texas public schools, as well as how the failure to take evolution into account can screw up conservation efforts.

So what did you like? Did you guess the fossil? Is there anything you want to see? Let us know.

Comments are welcomed, although please be considerate. This site is moderated and rudeness will be ruthlessly eliminated.

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