o The Frog Blog: Conodonts - Our Favourite Fossils!

Sunday, 7 November 2010

Conodonts - Our Favourite Fossils!

Conodont elements are some of the most beautiful yet enigmatic fossils known (the image above shows conodonts 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. One of us 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.).

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