Melanostrophus fokini Ă–pik, 1930
a Cephalodiscus - like hemichordate
The fossil genus Melanostrophus was proposed by Öpik
(1930) in order to embrace two Ordovician species:
Melanostrophus fokini Öpik, 1930 (type species) and M.
signum
 Öpik, 1930, both from the Ordovician of Estonia.
 Various authors were of conflicting opinions about the
taxonomic position of these forms. Öpik placed
Melanostrophus among sedentary polychaete annelids.
Gothan (1934) and Möldner (1934) interpreted it as
remnants of plant origin. Eisenack (1937) considered it
to be a graptolite. Bulman (1955, 1970) treated this
genus as a member of the  
Graptovermida or the
Stolonoidea. Moreover, the nature of Melanostrophus
was discussed by Kozłowski (1949), Howell (1962),
Mierzejewski (1988) and Zessin & Freiherr von
Puttkamer (1994). Recently, Mierzejewski & Urbanek
(2004) interpreted this form as a Cephalodiscus-like
hemichordate.

 SEM and TEM investigations show that the periderm of
M. fokini is similar to that in graptolites (Mierzejewski
&
Urbanek, 2004).
Specimen from an Ordovician erratic boulder, Schleswig-
Holstein, Germany. Diameter ca. 70 mm.

Photo from:
Zessin, W. & Freiherr von Puttkamer, K. 1994.
Melanostrophus fokini Öpik (Graptolithina, Stolonoidea) -
Fund einer vollständingen Kolonie in einem ordovizischen
Geschiebe von Rendsburg, Schleswig-Holstein. - Archiv für
Geschiebekunde
1, 10, 563-572.
Portal of Graptolites and Pterobranchs sponsored by M.M. PLUS M - Sztandary.
GRAPTOLITHOIDEA: Cephalodiscoidea?
           For fossil cephalodiscids see:
Cephalodiscus lutetianus Abrard et al., 1950 >>
Eocephalodiscus polonicus Kozłowskl, 1949 >>
Pterobranchites antiquus Kozłowski, 1967  >>
Fine structure of Pterobranchites   >>