Ptychagnostus atavus

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Ptychagnostus atavus
Temporal range: Drumian
Ptychagnostus Atavus.jpg
Scientific classification e
Kingdom: Animalia
Phylum: Arthropoda
Class: Trilobita
Order: Agnostida
Family: Ptychagnostidae
Genus: Ptychagnostus
Species: † P. atavus
Binomial name
Ptychagnostus atavus
(Tullberg (sv), 1880)
  • Acidusus atavus (Tullberg, 1880)
  • Agnostus atavus Tullberg 1880

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 (sv) as Agnostus atavus in 1880.[1] 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).[2][3]


  1. ^ "Ptychagnostus atavus". Paleobiology Database. Retrieved 16 November 2012. 
  2. ^ Babcock, L. E.; Robison, R. A.; Rees, M. N.; Peng, S.; Saltzman, M. R. (2007). "The Global boundary Stratotype Section and Point (GSSP) of the Drumian Stage (Cambrian) in the Drum Mountains, Utah, USA" (PDF). Episodes. 30 (2): 85–95. 
  3. ^ Ogg, G. "GSSP for Drumian Stage". Geologic TimeScale Foundation. Retrieved 16 November 2012.