Thoracetron

From Wikipedia, the free encyclopedia

Thoracetron is an entire plate formed by the fusion of opisthosomal tergites behind opercular tergite (free abdominal segments) in Xiphosura of the order Xiphosurida, being considered a synapomorphy for this order (Anderson & Selden, 1997). The order Xiphosurida includes all recent species of Xiphosura — the horseshoe-crabs.

Fusion of opisthosomal tergites to form a thoracetron has previously been considered a characteristic of the xiphosuran superfamilies Euproopoidea Eller, 1938 and Limuloidea Zittel, 1885. Evidence was presented by Anderson & Selden (1997) that fusion also occurs in Bellinuroidea Zittel & Eastman, 1913. Giribet et al. (2005) used it in their character matrix resulting in a synapomorphy for Limulus + Carcinoscorpius.

[edit] References

Anderson, L. I. & Selden, P. A. 1997. Opisthosomal fusion and phylogeny of Palaeozoic Xiphosura. Lethaia, 30 , 19-31

Giribet, G., S. Richter, G.D. Edgecombe & W.C. Wheeler. 2005. The position of crustaceans within the Arthropoda -- evidence from nine molecular loci and morphology. Crustacean Issues 16: 307-352.