Name:
Bothriolepis
(trench scale).
Phonetic: Bo-free-oh-lep-is.
Named By: Karl Eichwald - 1840.
Synonyms: Bothriolepis coloradensis,
Bothriolepis minor.
Classification: Chordata, Placodermi,
Antiarchi, Bothriolepidae.
Species: B. darbiensis, B. nitida, B.
rex,
B. viginiensis - Over 100 species are named.
Diet: Detritivore.
Size: Usually about 30 centimetres long, depending
upon the species. The species B. rex possibly up to about 170
centimetres long.
Known locations: Worldwide.
Time period: Givetian to Fammenian of the Devonian.
Fossil representation: Hundreds of specimens.
As
a detritivore Bothriolepis lay at the bottom of
aquatic environments
and sifted through the mud and silt for organic matter. Evidence for
this comes from fact that not only is its gut filled with sediment,
but it is spiral shaped. A spiral shaped gut would have given
organic material a longer course to travel giving Bothriolepis
more
time to digest the nutrients. Superficially however Bothriolepis
had
an armoured box like construction to its body with a softer and more
usual fish tail towards the rear. The large expanses of fossil
remains of Bothriolepis mean that it was possibly
one of the most
successful placoderms
ever to exist.
The
broad pectoral fins of Bothriolepis were formed
like blades which were
jointed both at their base and about half way along their length.
These appear to have had the practical functions of lifting
Bothriolepis off the bottom as well as maybe
stirring up sediment,
either burying it from view, or throwing up a cloud that predators
could not see through. This would have been a useful tactic as
Bothriolepis would have likely been prey for
arthrodire placoderms like
Dunkleosteus
and Eastmanosteus.
Another
area of interest is the fact that not only did Bothriolepis
have
gills, but it also had pouches that connected to the oesophagus.
Some palaeontologists think that these areas may have been rudimentary
lungs that may have allowed Bothriolepis to live
for short periods out
of the water. Further credence for this notion is leant by the
powerfully built pectoral fins that could have been used to push itself
along when out of the water.
Locations
of Bothriolepis remains seem to primarily come from
freshwater
deposits, although some of the remains coupled with its broad
geographic distribution indicate that Bothriolepis
may have lived in
salt water as well. This might reflect a different area depending
upon its life stage. Some have also made the suggestion that
Bothriolepis may have migrated between saltwater and
freshwater for
spawning like salmon do today. Again the idea that Bothriolepis
could
live for short periods out of the water comes into play as such an
ability would allow Bothriolepis to navigate over
and around
obstacles, by using its fins.
Further reading
- A new species Bothriolepis (Placodermi: Bothriolepidae) from the
Upper Devonian of Virginia (U.S.A.) - R. E. Weems, K. A. Beem &
T. A. Miller. 1981.