The Lower-Middle Cambrian animal Rhabdotubus is the earliest known pterobranch.[1] It bears strong similarity to the graptolites - indeed for some time it was misclassified as a dendroid graptolite.[2][3][4]

Rhabdotubus
Temporal range: Cambrian Stage 3–Middle Cambrian
Scientific classification
Kingdom:
Phylum:
Class:
Pterobranchia
Genus:
Rhabdotubus
Species
  • R. robustus
  • R. johanssoni (type)

References

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  1. ^ Bengtson, S.; Urbanek, A. (1986), "Rhabdotubus, a Middle Cambrian rhabdopleurid hemichordate", Lethaia, 19 (4): 293–308, doi:10.1111/j.1502-3931.1986.tb00743.x, archived from the original on 2012-12-16, retrieved 2009-06-06
  2. ^ Maletz, J.; Steiner, M.; Fatka, O. (2005), "Middle Cambrian pterobranchs and the Question: What is a graptolite?" (PDF), Lethaia, 38 (1): 73–85, doi:10.1080/00241160510013204, retrieved 2009-06-06
  3. ^ Durman, P.N.; Sennikov, N.V. (1993), "A new rhabdopleurid hemichordate from the Middle Cambrian of Siberia" (PDF), Palaeontology, 36: 283, retrieved 2009-06-06
  4. ^ Urbanek, A. (1994), "When is a pterobranch a graptolite?", Lethaia, 27 (4): 324, doi:10.1111/j.1502-3931.1994.tb01582.x