Thelodontiformes is an extinct order of jawless fish of the Silurian.^[1]

Quick Facts Scientific classification, Families ...

Thelodontiformes
Comparison of Thelodus and Loganellia
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Infraphylum:	Agnatha
Class:	†Thelodonti
Order:	†Thelodontiformes Kiaer, 1932
Families
†Coelolepidae †Eestilepididae †Helenolepididae †Longodidae †Palaeodontidae †Phlebolepididae †Shieliidae †Talivaliidae †Turiniidae Genera without placement in any family: †Katoporodus – †Kawalepsis
Synonyms
†Coelolepidiformes Berg, 1937

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Because the paucity of intact fossils, especially since some families are known entirely from scale fossils, taxonomy of thelodonts is based primarily on scale morphology. 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 (because of scale morphology) and establishes Archipelepidiformes as the basal-most order.^[2]