Kingdom Animalia Family †Ptychagnostidae Genus Ptychagnostus Order Agnostida | Class †Trilobita Phylum Arthropoda Rank Species | |
Similar Ptychagnostus, Lejopyge laevigata, Agnostida, Peronopsis, Agnostus | ||
Ptychagnostus atavus is a species of agnostid trilobite. It belongs to the genus Ptychagnostus in the family Ptychagnostidae. It was originally described by Swedish paleontologist Sven Axel Tullberg as Agnostus atavus in 1880. It is used in biostratigraphy as an index fossil. Its first appearance at the GSSP section in the Wheeler Shale of Utah is defined as the beginning of the Drumian Age (around 504.5 million years ago) of the Cambrian Series 3 (Middle Cambrian).
References
Ptychagnostus atavus Wikipedia(Text) CC BY-SA