Big Teeth
Rhizodus is a tooth from certain types of lobe-finned fishes
(coelacanths) known as rhizodontiforms. According to Long (p.190),
these fish attained lengths of 6-7 metres and individual teeth
attained lengths of 22 centimetres. In other words, the specimen
illustrated here is a small one :-)
Rhizodus -- about 9cm long From Zittel, 1887, p.182
(fig.189): "Rhizodus Owen (Megalichthys Ag. p.p.).
Very large, incompletely known fishes with rough, rugose cycloidal
scales. Clavicle with a long upwardly directed process. Teeth
smooth, compressed to a sharp edge in front and behind.
R. hiberti Ag., and R. ornatus Traq., from Lower
Carboniferous [Mississippian], Scotland and Northumberland.
Allied species in Coal Measures [coal-bearing
Carboniferous-age strata] of North America." Translation from
Eastman, 1932. The figure at the bottom is a cross section, showing
the lenticular shape and sharp edges. In my experience, many
Rhizodus teeth are rounder than this.
The internal structure of fossil teeth is what distinguishes them
from coincidentally-shaped rocks. Note the highly folded structure of
the bone in the tooth of this cross section of Dendrodus,
also produced from a type of lobe-finned fish similar to Rhizodus.
Dendrodus Zittel, 1887, p.178 (fig.183).
Back to the evaluation of Carboniferous bone
Andrew MacRae
macrae@geo.ucalgary.ca
Rhizodus -- about 9cm long From Zittel, 1887, p.182
(fig.189): "Rhizodus Owen (Megalichthys Ag. p.p.).
Very large, incompletely known fishes with rough, rugose cycloidal
scales. Clavicle with a long upwardly directed process. Teeth
smooth, compressed to a sharp edge in front and behind.
R. hiberti Ag., and R. ornatus Traq., from Lower
Carboniferous [Mississippian], Scotland and Northumberland.
Allied species in Coal Measures [coal-bearing
Carboniferous-age strata] of North America." Translation from
Eastman, 1932. The figure at the bottom is a cross section, showing
the lenticular shape and sharp edges. In my experience, many
Rhizodus teeth are rounder than this.
Dendrodus