Genus
Helmersenia Pander, 1860
Aiheeseen liittyvät julkaisut
Nemliher, J., Kurvits, T., Kallaste, T., Puura, I. 2004. Apatite varieties in the shell of the Cambrian lingulate brachiopod Obolus apollinis Eichwald. Proceedings of the Estonian Academy of Sciences. Geology 53, 4, 246-256. DOI:10.3176/geol.2004.4.02
Kaljo, D., Borovko, N., Heinsalu, H., Khazanovich, K., Mens, K., Popov, L., Sergejeva, S., Sobolevskaya, R., Viira, V. 1986. The Cambrian-Ordovician boundary in the Baltic-Ladoga clint area (North Estonia and Leningrad Region, USSR). Eesti NSV Teaduste Akadeemia Toimetised. Geoloogia / Известия Академии наук Эстонской ССР. Геология 35, 3, 97-108. DOI:10.3176/geol.1986.3.01
Gorjansky, V. J. 1969. Bezzamkovye brahiopody kembrijskih i ordovikskih otloženij severo-zapada Russkoj platformy. pp. 1-176. Nedra.
List of species
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Luokittelu
| Organism group | Biota |
| Kingdom | Animalia |
| Phylum | Brachiopoda |
| Subphylum | Linguliformea |
| Class | Lingulata |
| Order | Siphonotretida |
| Superfamily | Siphonotretoidea |
| Family | Siphonotretidae |
| Genus | Acanthambonia |
| Alichovia | |
| Eosiphonotreta | |
| Gorchakovia | |
| Helmersenia | |
| Species | ladogensis |
| Genus | Mesotreta |
| Nushbiella | |
| Schizambon | |
| Siphonobolus | |
| Siphonotreta | |
| Siphonotretella |
See also