Browsing the "Ordovician" Category

The Ordovician period is a division of earth’s history spanning from around 485 to 443 million years ago, and during which life continued to diversify following the Cambrian ‘explosion’. During the Ordovician, planktonic organisms increased in diversity, corals became common and the first vertebrates flourished. The continents were largely confined to the southern hemisphere, however they were rapidly drifting apart and northwards owing to an increase in production of new ocean crust. The Ordovician was a period of mountain building and volcanism owing to the gradual closing of the Iapetus Ocean, which separated the ancient super-continents of Laurentia and Gondwana. Sea levels reached 200 meters above present during the Ordovician, meaning much of the continental landmasses were flooded by shallow seas. The end of the Ordovician is characterised by severe glaciations contemporaneous with a major drop in sea level and the second largest extinction event in earth’s history.


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Episode 51: Eurypterids

Published on September 1st, 2015 | by Dave Marshall

Eurypterids, or ‘sea-scorpions’ are an extinct group of chelicerates: the group containing the terrestrial arachnids (such as spiders and scorpions) and the aquatic ‘merostomes’ (represented today solely by the horseshoe crabs). They bear a gross-morphological resemblance [&hellip... Read More



Episode 40: Brachiopods

Published on February 1st, 2015 | by Dave Marshall

Brachiopods are some of the most common fossils to be found in rocks worldwide. Their thick, hard and (often) calcareous shells make them preferentially preserved in the fossil record. We probably all have found one, but [&hellip... Read More



Episode 29: Medusae

Published on June 1st, 2014 | by Dave Marshall

One of the longest-ranging and outwardly primitive-looking groups of animals on the planet are the Medusozoa. In consisting of around 95% water, it may be surprising to know that there is a fossil record of jellyfish, [&hellip... Read More



Episode 18: Trilobites

Published on July 1st, 2013 | by Dave Marshall

Trilobites are one of the most instantly recognisable groups of fossils. They were present from the very start of the Paleozoic and went on the fill a great number of ecological roles before going extinct at the Permo-Triassic [&hellip... Read More


Alitta virens

Episode 12: Paleozoic Problematica

Published on February 15th, 2013 | by Dave Marshall

Fossils, at the best of times, are difficult to interpret. Palaeontologists attempt to reconstruct organisms from what little remains are left. This can be relatively simple for groups that we are familiar with today; you can [&hellip... Read More


Isotelus rex was discovered on the shore of the Hudson Bay, close to the town of Churchill, Manitoba, Canada.

Episode 2: Isotelus rex

Published on September 1st, 2012 | by Dave Marshall

In June we got the opportunity to speak to Dave Rudkin, curator of arthropods at the Royal Ontario Museum, Canada. In our interview we covered his discovery of Isotelus rex, the world’s largest trilobite, and discussed arthropod [&hellip... Read More

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