scale was attached to the fish. The "teardrop" often contains lines, ridges, furrows and spikes running down its length in an array of sometimes complex patterns. Scales found around the gill region were generally smaller than the larger, bulkier scales found on the dorsal/ventral sides of the fish; some genera display rows of longer spikes. The scaly covering contrasts them with most other jawless fishes, which were armor-plated with large, flat scales. Aside from scattered scales, some specimens do appear to display imprints, giving an indication of the structure of the whole animal – which appeared to reach 15–30 cm in length. Tentative studies appear to suggest that the fish possessed a more developed braincase than the lampreys, with an almost shark-like outline. Internal scales have also been recovered, some fused into plates resembling gnathostome tooth-whorls to such a degree that some researchers favour a close link between the families. Despite the rarity of complete fossils, these very rare intact specimens do allow us to gain an insight into the internal organ arrangement of the Thelodonts. Some specimens described in 1993 were the first to be found with a significant degree of three-dimensionality, ending speculations that the Thelodonts were flattened fish. Further, these fossils allowed the gut morphology to be interpreted, which generated much excitement: their guts were unlike those of any other agnathans, and a stomach was clearly visible: this was unexpected, as it was previously thought that stomachs evolved after jaws. Distinctive fork-shaped tails – usually characteristic of the jawed fish (gnathostomes) – were also found, linking the two groups to an unexpected degree. The fins of the thelodonts are useful in reconstructing their mode of life. Their paired pectoral fins were combined with a single, usually well-developed, dorsal and anal fins; these and the hypercercal and much larger hypocercal lobes forming a heterocercal tail resemble features of modern fish that are associated with their deftness at predation and evasion. Taxonomy Due to the small number of intact fossils, the taxonomy of thelodonts is based primarily on scale morphology. In fact, some thelodont families are only recognised based on their scale fossils. A recent assessment of thelodont taxonomy by Wilson and Märss in 2009 merges the orders Loganelliiformes, Katoporiida and Shieliiformes into Thelodontiformes, places families Lanarkiidae and Nikoliviidae into Furcacaudiformes on the basis of scale morphology, and establishes Archipelepidiformes as the basal-most order. A newer taxonomy based on