| Xenognath type of polychaete jaw apparatuses Piotr Mierzejewski & Grażyna Mierzejewska Acta Palaeontologica Polonica 1975, 20, 3, 437-444 |
| [abstract, p. 437] A new type of ?eunicid jaw apparatuses designated xenognath is described; it differs from previously known jaw apparatuses in having the denticulated ridges in compound jaws perpendicular to apparatus axis. It includes the Ordovician genus Archaeoprion nov., assigned to a new family Archaeoprionidae. |
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| Archaeoprion quadricristatus Mierzejewski & Mierzejewska, 1975 |
| Nearly complete jaw apparatus devoid of ridges IV; venral view of the right jaw and lateral view of the left one. |
| Specimen derived from the erratic boulder (Baltic coast, Caradoc). |
| Diagnosis (p. 441) of Archaeoprion: Almost triangular, plate-like compound jaws. Each jaw with four denticulated ridges. Denticulated ridge I lowermost, sometimes smooth. Denticulated ridge IV with chisel teeth. Pseudocarrier delicate, longer than jaws. |
| Dimensions of the holotype: lenght 0.355 mm, width 0.178 mm. |
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| Archaeoprion quadricristatus |
| left compound jaw |
| right compund jaw |
| pseudocarrier |
| Dorsal view of the xenognath jaws apparatus |