Rhabdotubus

Rhabdotubus; Temporal range: Cambrian Stage 3–Middle Cambrian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Hemichordata
Class:	Pterobranchia
Genus:	Rhabdotubus
Species
	R. robustus; R. johanssoni (type);

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]

^ 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
^ 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
^ 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
^ Urbanek, A. (1994), "When is a pterobranch a graptolite?", Lethaia, 27 (4): 324, doi:10.1111/j.1502-3931.1994.tb01582.x

[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

[Urbanek1994-4] Urbanek, A. (1994), "When is a pterobranch a graptolite?", Lethaia, 27 (4): 324, doi:10.1111/j.1502-3931.1994.tb01582.x

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