Conodonts - Our Favourite Fossils!

Conodont elements

Conodont elements are some of the most beautiful yet enigmatic fossils known (the image above shows conodont elements atop a pinhead). They came from a group of extinct worm-like animals, at least some of which are known to have been about 4 cm long. These were relatively common in the seas of Palaeozoic times, and are thought to have been primitive craniates (‘agnathans’). In general these animals are only represented in the fossil record by these small (0.2 mm to 13 mm), disarticulated, tooth-like skeletal elements made of calcium phosphate – probably forming part of their ingestive apparatus.

Conodont elements were first described by Christian Heinrich Pander in 1856, although he thought he was looking at fish teeth, but it was not until 1983 that the nature of the conodont-bearing animal was first revealed – following a study of Carboniferous sediments from Granton, Edinburgh. The animals described are 40 mm long and 1.9 mm wide, and the conodont elements form an apparatus in the head region – just behind 2 lateral lobes. The body is divided into a series of v-shaped muscle blocks, and an asymmetrical series of fin rays are commonly preserved about the tail. This suggests that the animal was an active swimmer.

Conodont animals?

Conodont animals of the Upper Palaeozoic generally had a range of differently shaped elements in their apparatuses (e.g. ‘bars’, ‘blades’ and ‘platforms’), and the way in which these fitted together to function in 3D has been much debated. Stover Geology teacher, Dr Stone (with PhD student Davida Geraghty) did some work on this as a Research Fellow in Trinity College Dublin, and had great fun making scale models of the elements and trying to fit them together in a meaningful way (Stone, J. J. and Geraghty, D. A. 1994 ‘A Predictive Template for the Apparatus Architecture of the Carboniferous Conodont Idioprioniodus’, Lethaia, 27, No. 2, pp. 139-142.).

Year 10 Geologists Learn About Ammonites

Year 10 Geologists display some of the fossils in the Stover collection

In a new departure for Stover, 6 Year 10 pupils have taken up the study of Geology this academic year. They are following the WJEC syllabus, and have recently been learning about various fossil groups, including ammonites.





Annie points out an ammonite

Ammonites are an extinct group of marine cephalopod molluscs, which lived in Jurassic and Cretaceous times. Cephalopods (ammonites, nautiloids, octopuses, squids etc.) are the most highly evolved of the molluscs, and in many ways are the most highly evolved of the invertebrates in general (complex eye, large brain etc.). The mouth is surrounded by tentacles, which usually have suckers. Some modern forms have lost their shells (octopus), some have a straight internal shell (cuttlefish, squid) and some still have a coiled external shell (nautilus).

Most ammonites were probably active carnivores and accomplished swimmers. They were able to control their buoyancy by filling the inner chambers of their coiled shells with water or gas through their siphuncle (see diagram). The outside of the shell was often ribbed or keeled in a distinctive way (which is how most fossil species are told apart). Other fossil forms with external shells include: Nautiloids (Cambrian to Recent) and Goniatites (Devonian to Permian).

Ammonite

 

Humour in the Classroom 2

The quest for humour in the classroom continues...

2. Chemistry

Q. What's this: h, i, j, k, l, m, n, o?
A. Water

My old Chemistry teacher was a bit boron, but Mr Baillie thinks he's sodium funny that he tells jokes all the time - sadly he never seems to get a reaction. Maybe he should take all his jokes and barium.