Coprolite

When people say you can't polish a turd, don't believe them.

Coprolites are fossil dung. The one above is from a turtle. Probably quite a big turtle. I get asked how you can tell which animal 'laid' it. It's not always possible, but at times a direct comparison can be with recent examples. Preferably not that recent. In other instances, clues can often be found in the stratigraphy. It's usually possible to piece together a reasonable understanding of the palaeoenvironment; where and how the animal was living. Also, sections can be made, allowing a look inside the jobby. Exciting work.

A site in Moab, Utah provides a great deal of this stuff, and very often you can see little cross sections of undigested plant material in the polished surface. Found amongst the coprolites are the occasional gastrolith, or gizzard stone. Like some animals today, many dinosaurs ingested pebbles to help them break down tough plants in their gut. I wouldn't suggest you eat a handful of gravel before your tea, but it was very helpful for some of the sauropods of the Jurassic.

Much of the plant material in these coprolites is preserved as a vibrant red jasper, and the most colourful stuff is graded out and used to make jewellery. A few years ago there was a bit of a Hollywood craze for wearing coprolite jewellery. Didn't really catch on here, unfortunately.