The Earth Story

Dragon rock Hivitserkur is a 15 metre high volcanic plug, the eroded remains of magma frozen on its way up a volcanic conduit towards the vent at the surface. Located in Iceland's Gulf of Hunafloui, it resembles a grazing dragon or dinosaur. The local legend says that it is a frozen troll, caught by the rising sun on its way to raid a nearby abbey. The name means white shirt, and comes from the guano stains from fishing birds running down it. The foundations were whored up with concrete to save the monument from the Atlantic ocean. Loz Image credit: Stephan Rebernik http://ourworldinpictures.net/world/223-icelandic-dinosaur-hvtserkur.html http://www.mymodernmet.com/profiles/blogs/hvitserkur-dinosaur-rock

Pretty as a flower

Crinoids, or sea lilies, resemble flowers, however, they are not plants. Crinoids are marine animals that are related to starfish, brittle stars and other echinoderms. These critters can be found both in shallow waters and at great depths of around 9,000 meters.

These critters are plankton eaters and they have muscles, a gut, a nervous and reproductive systems and some other features of advanced animals that you would not expect to see in an animal that looks more like a plant.

Crinoids have pentaradial symmetry, which is typical from echinoderms. These animals present three main sections: stem (or column), calyx (where the body cavity and digestion takes place) and the arms (which are responsible to filter food). Most of the species live attached to the seabed, but there are some free-swimming species. Early crinoids from the Paleozoic were completely immobile. Mobility is a feature that only appeared later, since crinoids were vulnerable to predators and they had to adapt.

These creatures have been present on Earth since the Ordovician period (roughly 490 million years ago) and they still exist to this day, which shows how successful they are. Crinoids not only survived the Permian and the Cretaceous-Tertiary mass extinction events, but they also were able to diversify and proliferate into hundreds of species, many of them still alive today (around 625 species).

Due to its beauty, crinoid fossils are quite desired by collectors. A good thing is that these animals are common fossils, however, notice that wholly preserved crinoids (with stem, calyx and arms) are a rare finding. This happens because the plates of the animal’s skeleton fall apart when ligaments and muscles decompose after death. Crinoids that underwent a quick burial are the ones with the best chances of producing a complete fossil and they are quite esteemed by paleontologists for the scientific value and by collectors due to its aesthetic.

The calyces of crinoids are a common find if you look for them in Paleozoic sedimentary rocks that present noticeable crinoid columnals, however, if you do not see these, then it is not likely for you to find any calyces. In my case, I would definitely need the help of a professional, and if that is your situation as well, you should reach a paleontologist from a university or from a natural history museum. At the end of the day, that would surely be a great field trip.

Sources: http://bit.ly/2w0BiY0 http://bit.ly/2vZl7ek

Photo credits: http://bit.ly/2wEbqiq - photo by Vassil http://bit.ly/2vPgzXf - photo by Alexander Vasenin http://bit.ly/2uAto4d - photo by Kevinzim/Kevin Walsh http://bit.ly/1Zh8SyM - photo by Berengi